Provenance analysis on detrital zircons from the back-arc Arivechi basin: Implications for the Upper Cretaceous tectonic evolution of northern Sonora and southern Arizona

Accepted Manuscript Provenance analysis on detrital zircons from the back-arc Arivechi basin: Implications for the Upper Cretaceous tectonic evolution of northern Sonora and southern Arizona José Luis Rodríguez-Castañeda, Amabel Ortega-Rivera, Jaime Roldán-Quintana, Inocente Guadalupe Espinoza-Maldonado PII:

S0895-9811(17)30509-6

DOI:

10.1016/j.jsames.2018.04.007

Reference:

SAMES 1906

To appear in:

Journal of South American Earth Sciences

Received Date: 8 December 2017 Revised Date:

5 April 2018

Accepted Date: 5 April 2018

Please cite this article as: Rodríguez-Castañeda, José.Luis., Ortega-Rivera, A., Roldán-Quintana, J., Espinoza-Maldonado, I.G., Provenance analysis on detrital zircons from the back-arc Arivechi basin: Implications for the Upper Cretaceous tectonic evolution of northern Sonora and southern Arizona, Journal of South American Earth Sciences (2018), doi: 10.1016/j.jsames.2018.04.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT PROVENANCE ANALYSIS ON DETRITAL ZIRCONS FROM THE BACK-ARC ARIVECHI BASIN: IMPLICATIONS FOR THE UPPER CRETACEOUS TECTONIC EVOLUTION OF NORTHERN SONORA AND SOUTHERN ARIZONA.

José Luis Rodríguez-Castañeda1*, Amabel Ortega-Rivera2 Jaime Roldán-Quintana3, & Inocente Guadalupe

1, 2, 3

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Espinoza-Maldonado4 Estación Regional del Noroeste, Instituto de Geología, UNAM, Blvd. Luis Donaldo Colosio y Madrid,

Hermosillo, Sonora, CP 83000, México.

Unversidad de Sonora, Departamento de Geología, Rosales y Luis Encinas, Hermosillo, Sonora, México,

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Tel. 662 2175019

CP 83000, México. Tel. 662 2592110

[email protected], [email protected], [email protected],[email protected].

*Corresponding author

ABSTRACT

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In the Arivechi region of eastern Sonora, northwestern Mexico, mountainous exposures of Upper

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Cretaceous rocks that contain monoliths within coarse sedimentary debris are enigmatic, in a province of largely Late Cretaceous continental-margin arc rocks. The rocks sequence in the study area are grouped in two Upper Cretaceous units: the lower Cañada de Tarachi and the younger El Potrero Grande. Detrital zircons collected from three samples of the Cañada de Tarachi and El Potrero Grande units have been analyzed for U–Pb ages to constrain their provenance. These ages constrain the age of the exposed rocks and provide new insights into the geological evolution of eastern Sonora Cretaceous rocks. The detrital zircon age populations determined for the Cañada de Tarachi and El Potrero Grande units contain distinctive 1

ACCEPTED MANUSCRIPT Precambrian, Paleozoic, and Mesozoic zircon ages that provide probable source areas which are discussed in detail constraining the tectonic evolution of the region. Comparison of these knew ages with published data suggests that the source terranes, that supplied zircons to the Arivechi basin, correlate with Proterozoic, Paleozoic and Mesozoic domains in southern

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California and Baja California, northern Sonora, southern Arizona and eastern Chihuahua. The provenance variation is vital to constrain the source of the Cretaceous rocks in eastern Sonora and support a better

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understanding of the Permo-Triassic Cordilleran Magmatic Arc in the southwestern North America.

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Key words: U-Pb detrital zircon dates, 40Ar39Ar step-heating date, Upper Cretaceous, northwestern México.

1. INTRODUCTION

The Upper Cretaceous geologic evolution of eastern Sonora, Mexico, is dominated by three NW-

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trending tectonic elements: westward, (1) the subduction of the oceanic Farallon plate beneath the North America plate, (2) a magmatic arc, and (3) a back-arc basin towards the east. Before that period, a major change in the western Atlantic Ocean occurred, from Middle Jurassic to Lower Cretaceous, with the breakup

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extension of the Gulf of México and formation of sedimentary basins (Anderson and Nourse, 2005). Also, it has been found that uplift and exhumation associated with several tectonic events (Late Cretaceous to early

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Cenozoic extension, mid-Cenozoic Core Complex, and late Cenozoic Basin and Range) during post breakup deformation is suggested by an angular unconformity, separating tilted Upper Cretaceous rocks sequences from underlying faulted and folded Proterozoic, Paleozoic, and Mesozoic rocks (Rodríguez-Castañeda, 2002).

The Upper Cretaceous sedimentary and volcanic rocks in eastern Sonora can be traced for more than three hundred kilometers, from the Sonora-Arizona border, to the Arivechi region and even further south (González-León and Lawton, 1995; McDowell, et al., 2001; McKee and Anderson, 1998; McKee et al., 2

ACCEPTED MANUSCRIPT 2005; Rodríguez-Castañeda, 1994, 2002) (Fig. 1). The rock exposures allow to distinguish a north-south belt of dominantly non-marine clastic sedimentary rocks about 6,000 m thick as result of a widespread extension (Rodríguez-Castañeda, 2002).

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Upper Cretaceous volcanic and volcano-sedimentary rocks in the Arivechi region record proximal volcanic sources. These rocks, which constitute one of the best preserved Upper Cretaceous magmatic arc segments in the North American Cordillera, are of importance since they play a key role for the understanding of the geologic and tectonic setting of eastern Sonora. The volcanic, volcaniclastic, and

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intrusive rocks that comprise this magmatic arc have been described by several workers including McDowell

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et al. (2001), Roldán-Quintana (2002), Rodríguez-Castañeda (2002), González-León et al., 2011; RodríguezCastañeda et al. (2015).

The structural, stratigraphic and petrologic attributes of these rocks in Arivechi have been previously described by various authors (King, 1939; Fernández-Aguirre and Almazán-Vázquez, 1991; FernándezAguirre et al., 1995; Minjárez-Sosa et al., 1985; Palafox et al., 1984; Pubellier, 1987; Rivera-Cabrera, 2007),

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who attributed their formation to a contractional tectonic environment. However, new structural information obtained by Rodríguez-Castañeda et al. (2015) suggest a complex scenario involving filling of one or more

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basins during the development of the Late Cretaceous magmatic arc, indicating that these basin(s) are probably Jurassic and Upper Cretaceous as suggested earlier by McKee et al. (2005). During Upper

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Cretaceous time, the main tectonic environment across eastern Sonora was that of extension, where massgravity deposits and recognition of geological structures as the Arivechi back-arc basin (?); and a pair of positive structural land forms, the Cananea High (McKee and Anderson, 1998; Rodriguez-Castañeda et al., 2015) and the Aldama Platform (Ramirez and Acevedo, 1957) are tectonic features in the history of the region. Although some researchers have suggested the existence of Laramide foreland basins based upon sedimentologic and stratigraphic studies (e.g. Gonzalez-León and Lawton, 1995; García y Barragán, 2003), 3

ACCEPTED MANUSCRIPT Rodríguez-Castañeda et al. (2015) suggest that the back-arc basin received debris from structurally positive landforms in western Sonora. Although there have been several interpretations of the structural geology of the Arivechi region, the tectonic models of McKee (1991) and Rodríguez-Castañeda (2002) are more consistent with the new study by Rodríguez-Castañeda et al. (2015), where they propose a thicker that includes several megablocks (Blair and McPherson, 1999). The

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stratigraphic column (Fig. 2).

megablocks include Precambrian, Paleozoic, and Mesozoic rocks derived probably from the CananeaAldama high. Identified structures (Rodríguez-Castañeda et al., 2015) suggested that megablocks were

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initiated as slumps or slides because of an extensional regime, and emplaced on the lower part of the slope causing intense deformation and fragmentation. Such large-scale mass-gravity megablocks are a

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characteristic feature of the San Antonio-Arivechi basin(s), the Cabullona basin (McKee et al., 2005) and other basins like east Sierra Los Ajos and the El Tigre area (Montaño-Jimenez, 1988) where such processes have not been recognized. Previously, the megablocks were interpreted as thrust faults structures related to a contractional regime by other authors (Rangin, 1977; Pubellier, 1987). 40

Ar/39Ar geochronological studies were carried out to constrains the

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Hence, U-Pb and

paleogeography and tectonic evolution of northwest Mexico, the tectonic development of the basin and its fill, and the timing and manner of translation of crustal blocks. In this study U-Pb age spectra of detrital

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zircons, collected from the two units exposed in the area, were studied to identify provenance of sediments and to locate the source terranes that contributed sediments to the study area.

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The results of this study will provide new insights on the geological evolution of Arivechi’s stratigraphy and allow us to establish a correlation between units exposed in northern and northwestern Sonora and southern Arizona. The data and interpretations presented here, although largely limited to one locality, provide a foundation for further studies on the Upper Cretaceous volcano-sedimentary sequence.

2. GEOLOGY 4

ACCEPTED MANUSCRIPT 2.1 Study area The study area, Arivechi region, is located in eastern Sonora (28° 50′ 00″ to 28° 57′ 00″ north Latitude and 109°03´00´´ to 109°09´00´´ west Longitude (Fig. 3). Three sandstone samples were collected

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from the Arivechi area one in the Cañada de Tarachi unit and two from the El Potrero Grande unit along the Arivechi – Tarachi road.

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2.2. Geological Setting

The Upper Cretaceous was a period of major global tectonism, when the Laurasia and Gondwanan

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supercontinents had already broken up and tectonic activity in southwestern North America was characterized by strike-slip and normal faulting, magmatism, and denudation. (Iriondo and Premo, 2011; Iriondo et al., 2003; Rodríguez-Castañeda, 2002; Roldán-Quintana, 2002; Rodríguez-Castañeda et al., 2015). These plate tectonic patterns caused a change from primarily compressional tectonics to a tensional stress

and Nourse, 2005).

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field, transmitted as strike-slip fault movements across the Sonora on ancient Jurassic structures (Anderson

Through the Late Cretaceous time, uplift, erosion, downslope movements of sediment were

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concurrent with the widespread emplacement of plutons and batholiths and related volcanism (McDowell et al., 2001; Kimbrough et al., 2001).

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The Arivechi region is in the margin of a basin that may have originally developed as a back-arc basin of the California-Baja California-Sonoran magmatic arc during Mesozoic contraction associated with subduction of the Farallon plate along the western margin of North America (Rodriquez-Castañeda et al., 2015).

2.2.1. Upper Cretaceous stratigraphy

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ACCEPTED MANUSCRIPT The Arivechi basin includes two lithological units: (a) Cañada de Tarachi, and (b) El Potrero Grande accompanied by the Oligocene-Miocene Sierra Madre Occidental volcanic sequence (Fig. 2; Rodríguez-

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Castañeda et al., 2015).

2.2.1.1. Cañada de Tarachi Unit

This unit comprises conglomerate, sandstone, siltstone, shale, andesitic dikes, and a significant

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presence of megablocks of Precambrian, Paleozoic and Mesozoic origin (Rodriquez-Castañeda et al., 2015).

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Regarding the conglomerates, they are abundant throughout the unit, distributed at various levels, with 1-10 m in thickness although occasionally reaching ~100 m. The conglomerate beds are composed of several lithologies. The pebble-cobble conglomerate that occurs in the Cerro Zoropuchi to the north (Fig. 3), the clasts that are principally limestone (Fig. 4a, 4b), indicate Paleozoic and Early Cretaceous ages (R. Monreal, written communication, 2014), and therefore the age of the Cañada de Tarachi unit is situated in the Upper

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Cretaceous sequence.

In addition to those included in the slipped blocks, no fossils have been identified in the Cañada de Tarachi Unit. This observation has genetic significance for the sedimentary environment, as the fossil

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absence could be interpreted as an inland development for the Arivechi basin. Our geological mapping and strike and slip direction of bedding data suggest a minimum thickness of ~2000 m.

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Pebble-cobble conglomerate well exposed in the Cañada de Tarachi stream and along the ArivechiTarachi road, comprises two types of conglomerates: one constituted by angular sedimentary rock clasts (siltstone, quartzite, chert, and less limestone) supported by matrix of the same composition as the coarse portion with sizes varying from 0.5 centimeters to 30 centimeters and bigger; another type includes rounded volcanic (andesite and tuff) clasts that vary between 0.5 and 30 centimeters. Matrix composition is like the coarse portion (Fig. 4c to 4h).

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ACCEPTED MANUSCRIPT Monoliths exposed in the section consist of Proterozoic, Paleozoic, and Mesozoic rocks (Fig. 2) (Rodríguez-Castañeda et al., 2015). The megablocks show a gradational transition from coherent beds in their upper and middle parts to fragmented and sheared beds along their edges and bases. Rodríguez-

the development of structures associated to slump.

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Castañeda et al. (2015) report different type of structures within the megablocks that were used to reconstruct

The Precambrian monolith (long ~ 7 km) is exposed at Cerro El Palmar (Fig. 3). It is mainly composed of quartz sandstone and dolomite beds intercalations. The dolomite beds contain stromatolites,

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possibly of the Jacutophyton genus, like those found in the Caborca region of a Neoproterozoic age (Weber et al., 1979). A 10-m thick bed disruption (breccia) represents the contact between the Neoproterozoic rocks

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and the Cañada de Tarachi Unit.

Paleozoic monoliths (long ~2 km; Fig. 3) consist of Mississippian fossiliferous limestone and quartz sandstone (Fernández-Aguirre and Almazán-Vázquez, 1991). These megablocks can be observed at Cerro Peñasco Blanco and Cerro Las Conchas. At Cerro Las Conchas (Fig. 3), another monolith is exposed being

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composed of limestone, shale, and sandstone, containing fossils of Early Cretaceous age (Fernández-Aguirre and Almazán-Vázquez, 1991). Bartolini (1993) suggested that these rocks are correlated with exposed units in western Chihuahua. Smaller megaclasts of dozens of meters in size of different composition and ages are

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also found imbedded within the sequence.

The fact that these are glided fragments and because of their size, they were not previously identified

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as megaclasts, was the main reason for assuming that the structures were incorrectly interpreted by previous authors. Hence, the exposures of Cerro Las Conchas, Cerro Peñasco Blanco and Cerro El Palmar are considered as gliding megaclasts.

In a previous work (Rodríguez-Castañeda et al., 2015), several granitic megaclasts were found at the base of this unit. One was collected next to stream Cañada de Tarachi, being dated by U-Pb zircon geochronology at 76.0 ± 2.0 Ma (Campanian, Late Cretaceous; Figure 3) and another sample collected at the Arivechi-Tarachi road dated by 40Ar/39Ar step-heating of a K-feldspar at 69.57 ± 0.48 Ma (Fig. 3). 7

ACCEPTED MANUSCRIPT The basal section of the Cañada de Tarachi Unit is not exposed in the study area. However, by correlation with other localities to the north, this contact must be an angular unconformity between the Upper Cretaceous rocks and older rocks. The upper contact with the El Potrero Grande Unit is transitional to a younger volcanoclastic sequence. The Cañada de Tarachi unit records a strong deformation, probably

than the result of a compressive tectonic deformation.

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2.2.1.2. El Potrero Grande Unit

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synsedimentary and related to gravitational movement (vertical uplift and sliding) of the megaclasts, rather

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The El Potrero Grande unit is exposed in the eastern part of the study area and this unit comprises conglomerate, sandstone, siltstone, and shale with interbedded rhyolitic tuff and andesitic and dioritic dikes (Fig. 3). An andesitic tuff collected at the base of this unit yield an 40Ar/39Ar age of 261.9±1.8 Ma (Permian, Capitanian age). These rocks together form a partial column of ˃2400 m in thickness. However, the thickness

Occidental volcanic rocks.

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of this unit could not be determined, because this sequence is covered by the Cenozoic Sierra Madre

The age of this unit can be fixed by isotopic K/Ar ages in biotite concentrates yielded Upper

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Cretaceous (Santonian) dates of 83.4 ± 4.2, 84, and 86 Ma for two tuffs from the upper part of the sequence (Grajales-Nishimura et al., 1990); and, an andesite at Cerro San Miguel (southward of the study area) yield

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an 83.4±4.17 Ma age (Pubellier, 1987). Northward, along the Sahuaripa-Natora road, Rodríguez-Castañeda et al. (2015) reported a tuff, from a comparable section to the area, dated as 76.30 ± 1.98 Ma (Campanian) by U-Pb method in zircon.

Stratigraphically, the El Potrero Grande unit is transitional with the lower Cañada de Tarachi unit and is uncomformably covered by the Cenozoic Sierra Madre Occidental volcanic rocks.

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ACCEPTED MANUSCRIPT 3. METHODOLOGY

Three sandstone samples were selected for detrital zircons (290 grains) U-Pb analysis (one sample from Cañada de Tarachi unit and two sandstone samples from El Potrero Grande unit) and, an andesitic tuff 40

Ar/39Ar geochronology (Samples localities are

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sample from El Potrero Grande unit was also selected for

shown in Figure 3). Sample A78-11 (99 grains), coordinates UTM Zone 12 0682651E, 3198616N; Sample A82-11 (93 grains), UTM Zone 12 0685321E, 3199261N; and Sample A79-11 (98 grains), UTM Zone 12,

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0686647E, 3198030N (datum WGS84). Sample JR10, coordinates UTM Zone 12R 0685245E, 3198845N). Stratigraphically, sample A78-11 lies in the lower part of Cañada de Tarachi unit, whereas samples A82-11

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and A79-11 were collected from the lower and middle parts of the El Potrero Grande sequence, respectively. Sample JR10 is located near to base of the El Potrero Grande unit.

Minerals were concentrated by standard technics at the Estación Regional del Noroeste of the Instituto de Geología, UNAM. The number of grains analyzed from three samples were 289 from a total of

3.1. U-Pb dating

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297 zircon grains.

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U-Pb geochronological analyses were carried out at the Laboratorio de Estudios Isotópicos (LEI) of the Centro de Geociencias Isotopic lab, UNAM. U-Pb ages were obtained using laser-ablation inductively-

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coupled-plasma mass spectrometry (LA-ICPMS) employing a 193-nm excimer laser workstation (Resolution M-050) coupled with a Thermo X-ii quadrupole ICPMS. The protocol reported by Solari et al. (2010) was used, employing a 23-µm analytical spot and the Plešovice zircon (Slama et al., 2008) as the bracketing standard. Time-resolved analyses were then reduced off-line with in-house developed software written in R (Solari and Tanner, 2011), and the output was then imported into Excel, where the concordia as well as ageerror calculations were obtained with Isoplot v. 3.70 (Ludwig, 2008).

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ACCEPTED MANUSCRIPT During the analytical sessions, the observed uncertainties (1-sigma relative standard deviation) on the 206

Pb/238U,

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Pb/206Pb and

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Pb/232Th ratios measured on the Plešovice standard zircon were 0.75, 1.1 and

0.95% respectively. These errors were quadratically added to the quoted uncertainties observed on the measured isotopic ratios of the unknown zircons. This last factor considers the heterogeneities of the natural 204

Pb, used to correct for initial common Pb, was not measured (because its

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standard zircons. The isotope

signal is swamped by the 204Hg normally present in the He carrier gas); common Pb was thus evaluated using the

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Pb/206Pb ratio, and all the analyses graphed on Tera- Wasserburg (1972) diagrams. Corrections, if

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Pb/238U ages are used for zircons < 1.0 Ga, whereas

207

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needed, was then performed using the algebraic method of Andersen (2002). In figures, tables and results, Pb/206Pb ages are cited for older grains. The

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TuffZirc algorithm of Ludwig and Mundil (2002) was used to calculate the best mean of which is preferred for estimating the apparent age of those young zircons in which the

207

206

Pb/238U ages,

Pb signal is low.

The 207Pb/206Pb ages were furthermore considered as minimum ages because of the effect of possible Pb loss. The results have been plotted in pie diagrams, where the total number of analyzed grains appears. The

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same data have been plotted in relative probability diagrams showing the different ages and their uncertainty

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3.2. 40Ar/39Ar dating

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(only for deviations in the measurement) as a normal distribution for all ages of a sample in a single curve.

Age analyses were carried out in the Queen's University

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Ar/39Ar geochronology laboratory. For

each mineral separate, ~5-10 mg of material was wrapped in Al foil and stacked vertically into Al canisters, which were then irradiated in the McMaster University Nuclear Reactor in Hamilton, Canada, with the 40

Ar/39Ar flux monitor - LP-6 biotite (128.5 Ma, Roddick, 1983). Following irradiation, the samples and

monitors were placed in small pits, ~2 mm in diameter, drilled in a Cu sample holder. This was placed inside a small, bakeable, stainless steel chamber with a ZnSe viewport connected to an ultra-high vacuum purification system. Monitors were fused in a single step, using a focused New Wave MIR-10 30-watt CO2 10

ACCEPTED MANUSCRIPT laser. For the total-fusion experiments, the laser beam was focused to melt single grains of muscovite in a single step. The evolved gases were purified using a SAES C50 getter for ~5 minutes. Argon isotopes were measured using a MAP 216 mass spectrometer, with a Bäur Signer source and an electron multiplier. All data were corrected for blanks, atmospheric contamination, and neutron-induced interferences (Roddick, 1983;

using the decay constants recommended by Steiger and Jager (1977).

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4. RESULTS

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Onstott and Peacock, 1987). All errors are reported as ±2σ, unless otherwise noted, and dates were calculated

4.1. U-Pb Geochronology

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Sample A78-11 is a middle bedded sandstone that petrographically corresponds to a quartz-feldspatic sandstone with quartz and microcline grains in a matrix composed by fragments of quartz, sericite and opaque minerals. Ninety-nine zircon grains were selected for U-Pb analysis. Sample A78-11 is dominated by Precambrian grains in which 7% are Paleoproterozoic (1602 to 1688 Ma) and 82% are Mesoproterozoic

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(1341 to 1591 Ma). In addition, 6% are Permian grains (255 to 274 Ma); and 4% are Triassic detrital zircons (247 to 250 Ma) (Fig. 5a, Table 1).

Sample A82-11 is a middle bedded sandstone and petrographically classified as an arkose where

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quartz, and plagioclase are the main mineralogy. 92 zircons were analyzed, being, 79% of the grains of a Cretaceous age (86 to 146 Ma). Other small percentage of grains are Jurassic (147 to 160 Ma; 6%), Permian

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(250 to 256 Ma, 2%), and Mesoproterozoic (1417 to 1650 Ma, 5%) (Fig. 5b, Table 2). Sample A79-11 correspond to a thick bedded sandstone composed of quartz and feldspars. Of the 99 grains analyzed in this sample, 96% have ages from 71 to 97 Ma; only 1 grain is Triassic and 2 grains are Mesoproterozoic (Fig. 5c, Table 3).

4.2. 40Ar/39Ar Geochronology 11

ACCEPTED MANUSCRIPT An andesitic tuff in the lower part of the Cretaceous El Potrero Grande unit (sample JR10) was dated by whole-rock 40Ar/39Ar step-heating. As seen in Figure 6 and Table 4, the whole-rock age spectra is disturbed; the first steps yield a Cretaceous date (~80 Ma) that can be correlated to the age of the El Potrero Grande unit sequence at this level. An age segment (steps 7 to 13) yields an integrated 40Ar/39Ar age of 262±1 Ma (2s),

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with a similar correlation age of 262±2 Ma (2s), initial 40Ar/36Ar =281 ± 5 and a MSWD = 0.80, providing a maximum age for the rock. Ca/K values are consistent with degassing from hornblende. The initial argon ratio is close to the atmospheric ratio of 295.5, indicating that the rock does not contain excess argon and

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further supporting the reliability of the age. A 261 Ma age is also consistent with the U-Pb ages of detrital zircons from sample A78-11, A82-11, and A79-11 and strongly supports the presence of Permian and

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Triassic rocks in the region, occurring as megablocks in the Cañada de Tarachi unit. A 261 Ma age for this andesitic tuff suggests that it was a megablock, reheated and disturbed at around 80 Ma while being imbedded in the fine-grained sequence of the El Potrero Grande unit, which was still being deposited.

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5. DISCUSSION

5.1. Provenance implications from detrital zircon U-Pb geochronology

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The detrital zircon age populations (Fig. 5) determined in the Cañada de Tarachi and El Potrero Grande units contain distinctive Precambrian, Paleozoic, and Mesozoic zircon ages. The U-Pb dates provide

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probable source areas which are discussed in detail constraining the tectonic evolution of the region.

5.1.1 Precambrian zircons

The older zircon age peaks are greater than 1600 Ma, with the most dominant peak at 1400 Ma (Fig. 5). Older zircons (1600 Ma), correlate with a region in northeast Sonora, where a significant area of Proterozoic crystalline basement (1700 – 1600 Ma) can be correlated with the Pinal Schist or the Mazatzal province of southern Arizona and northern Sonora. Two localities with ancient zircons of 1600 Ma age 12

ACCEPTED MANUSCRIPT population can be identified in northeast Sonora, the Sierra Los Ajos and Cerros Mesteñas (Figs. 7 and 8), which are associated with the Pinal province of southern Arizona and northern Sonora. Within the Pinal Province, there are two blocks, the Pinal block to the northwest and Cochise block to the southeast. Sedimentation within the Pinal block occurred around 1.68 Ga, whereas volcanic activity in the younger

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Cochise block recorded between 1.647 and 1.630 Ga (Anderson and Silver, 2005). The Pinal Schist forms the basement rock of most of southern Arizona and may also extend some distance into northern Sonora, Mexico (Anderson and Silver, 1981). Anderson and Silver (1981) sampled a rhyolitic tuff exposed in a pass-through

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Sierra Los Ajos, west of rancho Mababi; zircons from the rhyolite yielded an upper-intercept age of ca. 1.69 Ga.

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The 1400 Ma age population may be derived from Proterozoic suite of anorogenic, consanguineous plutons of porphyritic granodiorite to granite (Loiselle and Wones, 1979; Anderson, 1983). These anorogenic plutons crop out throughout the southwestern United States and into northern Mexico that consistently yield zircon U-Pb ages of 1425 – 1475 Ma (Anderson and Silver, 1977; 2005) (Fig 8). Anorogenic intrusives are

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also common in northwest Sonora together with Permian and Triassic granitoids in the Sonoyta region (Stewart et al., 1986; Arvizu et al., 2009). The ages of the two geotectonic domains in northern Sonora, the Pinal terrane (located in the northeast) and the Caborca terrane (located in the northwest Sonora) are also

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similar (Fig. 7). Other localities are in northwest Sonora, Sierra Los Alacranes and Sierras Cabeza PrietaChoclo Duro have exposures of Proterozoic metaplutonic rocks interlayered with fine-grained gneisses. The

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granitic intrusions have ages of ca. 1645 Ma and were, in turn, intruded by non-foliated granites with an age of 1432±6 Ma (Nourse et al., 2005). Detrital zircons with an age of 1400-1300 Ma can be associated with anorogenic plutons that are widespread in Sonora and Arizona (Fig. 8). Magmatism migrated westward with time and reached northern Mexico about 1410 Ma ago (Anderson and Silver, 2005).

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ACCEPTED MANUSCRIPT Several ~1300 Ma zircons grains are present in the A78-11 sample. Rocks within these age range have not yet been identified in the Sonora region and may reflect 1400–1300 Ma granite sources throughout the North American Southwest (Windley, 1993; Anderson, 1989; Van Schmus et al., 1993).

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5.1.2. Permian-Triassic zircons

A population of much younger zircons have ages that range from 247 to 274 Ma, spanning from the Permian to the Lower Triassic periods (Fig. 5a). Triassic and Permian zircons may have come from arc

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terranes exposed in northwestern Sonora around Sonoyta town and/or southern Arizona (Stewart et al., 1986). From U-Pb isotopic geochronology and regional stratigraphic studies, widespread Mesozoic volcanic

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rocks in northern Sonora are similar in age to those in southern Arizona (Anderson and Silver, 1978, 1979). No plutonic rocks of Triassic age are known in southern Arizona, except for one small area in the Trigo Mountains of southwesternmost Arizona (Stewart et al., 1986). In the other hand, in Sierra Los Tanques, southwest from Sonoyta, Stewart et al. (1986) obtained a U-Pb zircon age of 225 Ma from a small pluton,

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whereas in the same locality Campbell and Anderson (2003) obtained a U-Pb Triassic age of 233 Ma from a monzodiorite. With these two exceptions, Phanerozoic granitoids in this region have been dated as MiddleLate Jurassic, or younger.

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Riggs et al. (2009) obtained U-Pb zircon ages from three samples of the nearby Sonoyta pluton, which yielded a composite age of ~270 Ma. In addition, Riggs et al. (2010) reported Permian U-Pb zircon

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ages of 280±3 Ma from Sierra Los Tanques pluton, and an age of 273±6 Ma from two clasts of the El Antimonio Formation in northwest Caborca, Riggs et al. (2014) reported also a group of Permian zircons in the El Antimonio Formation that yields a TuffZirc age of 273 Ma. Arvizu and Iriondo (2015) reported U-Pb Permo-Triassic granitoids at Sierra Los Tanques that range in age between 284 and 221 Ma, and which may be considered as a potential source rocks for the detrital zircons in the study area.

14

ACCEPTED MANUSCRIPT 5.1.3. Jurassic zircons Jurassic zircons (147-160 Ma) according to the literature (Tosdal et al., 1989, Anderson et al., 2005) may be related to the Jurassic magmatic arc widely distributed throughout northwest and central Sonora and southern Arizona. These Jurassic Sonoran rocks ages are assigned based upon interpreted ages derived from

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U-Pb isotopic results on zircon ages obtained from igneous rocks across Sonora (Anderson and Silver, 1978, 1979).

North of the Mojave-Sonora megashear arc-related volcanic, volcaniclastic, and clastic rocks are

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intruded by plutons ranging age between 175 and 160 Ma that are part of the Middle Jurassic igneous province. In south-central Arizona and northern Sonora, the Upper Jurassic volcanic and sedimentary rocks

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exposed in the region can be associated to the Artesa sequence, which in turn, is closely associated with the Late Jurassic plutonism of the Ko Vaya super unit (Tosdal et al., 1989). U-Pb ages of the Ko Vaya suite are 146±3 Ma, while the Ko Vaya granite is Ca. 150 Ma (Haxel et al., 2008). Other ages are Baboquivari peak (146±3 Ma; Haxel et al., 2008), San Moises granite (149 Ma; Anderson et al., 2005), volcanics from the

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Cucurpe Formation in central Sonora (150±1 Ma, 152±2 Ma; Mauel et al., 2011), El Sahuaro granodiorite (153 Ma, Anderson et al., 2005). Therefore, the tectonic environment for emplacement for the Upper Jurassic

(2014).

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5.1.4. Cretaceous zircons

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rocks is associated to extension, rifting, magmatism and transtension according with Lawton and Molina

Cretaceous zircons (86-146 Ma, Table 2, Fig. 5b) likely reflect an admixture of California-BajaSonora magmatic arc. Erosion has stripped off most of the volcanic rocks, leaving a series of batholiths as remnants of the magmatic arc. The Peninsular Ranges Batholith of California and Baja California as well as the Sonoran batholiths have a key role in the paleogeography of western North America. Before the opening of the Gulf of California, the rocks of the Peninsular Ranges batholith were contiguous with the plutonic rocks of Sonora (Fig. 8). 15

ACCEPTED MANUSCRIPT The plutons of the Peninsular Ranges in California and Baja California were emplaced from west to east between 140 and 80 Ma (U-Pb zircon dates) (Ortega-Rivera, 2003). The western Peninsular Ranges consist of Jurassic and Cretaceous (140-105 Ma) age plutons, where some of them intrude their own volcanic rocks with ages of 125-118 Ma. Meanwhile, the eastern Peninsular Ranges plutons are younger ranging from

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105 to 80 Ma. These plutons together comprise the La Posta-type granite province of the eastern Peninsular Ranges batholith, which is large, widely exposed, and consists of composite bodies of more than hundreds of square kilometers in surface exposure. Plutons 90 to 65 Ma in age were emplaced throughout Sonora as the

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manifestation of the magmatic arc (Ortega-Rivera, 2003).

Detrital zircons of 71-97 Ma on sample A79-11 (Table 3, Fig. 5c) yield different Cretaceous ages

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compared to sample A82-11. Zircons with these ages are recorded in the Coastal Sonoran batholith, where granitoids in the Kino and Punta Tepopa region range in age between 69-90 Ma (Anderson and Silver, 1969; Gastil and Krummenacher, 1977; Ramos-Velazquez et al., 2008) (Fig. 8). The main peak age population for this sample range between 71 and 79 Ma. The Coastal Sonoran batholith and other batholiths further east in

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Sonora and Sinaloa are interpreted to be a continuation of the Eastern Peninsular Ranges Batholith, which is presently separated from Sonora and Sinaloa by the Gulf of California and is related to the subduction of the

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Farallon plate beneath North America during the Late Cretaceous and early Cenozoic (Ortega-Rivera, 2003).

5.2. Permo-Triassic rocks in the Arivechi region

40

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Permo-Triassic rocks in the Arivechi region are recorded by an andesitic tuff megablock dated by a Ar/39Ar whole-rock age at 262±1 Ma (2s) and U-Pb detrital zircons ages (274 - 247 Ma) obtained from

sandstone samples. The provenance of the early Permian to Middle Triassic zircons are problematic because Permo-Triassic igneous rocks are not widely distributed in Sonora, i.e., they are very locally distributed (Anderson and Campbell, 1992; Arvizu et al., 2009; González-León et al., 2009; Riggs et al., 2015; Stewart et al., 1986). Nevertheless, the Arivechi´s Permian rocks can be correlated with Permian igneous rocks in the Mojave Desert region include volcanic rocks dated at ~283 Ma (Walker, 1988), 281±8, and 262±2 (Martin 16

ACCEPTED MANUSCRIPT and Walker 1995) and granitoids dated at ~249 Ma (Cart et al., 1984) and 240-260 Ma (Miller et al., 1995). Recently, Riggs et al (2015) reported new U-Pb ages from Permian metasedimentary units in the Inyo Mountains of eastern California and plutons in the central Mojave Desert – a foliated granite of ~270 Ma, an orthogneiss at ~261 Ma, and the plutons at ~257 Ma. Riggs et al (2015) suggest these ages document the

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initiation of arc magmatism by Middle Permian time, consistent with pluton ages from Sonora, Mexico. In eastern California, deep- to shallow-water carbonate to siliciclastic rocks yield zircon ages that suggest a maximum depositional age of ~260 Ma. It is possible that such rocks are continuous through Sonora but have

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not been widely recognized or are overlain by Mesozoic or Cenozoic cover. Meanwhile, the Permian plutonic rocks near Los Filtros, Chihuahua, are part of a discontinuous igneous belt (230-280 Ma) that extends from

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Chihuahua to southern Mexico (Torres et al., 1999; Torres et al., 1986).

Sarmiento-Villagrana, et al. (2016) reports Early Triassic U-Pb ages of 249.6±2.1 Ma and 241.3±2.4 Ma (for granodiorite and a quartz-monzonite, respectively) for the Western Sonobari Complex located at the border between Sonora and Sinaloa. These ages are similar to the detrital zircons ages reported for the

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studied area and maybe a possible source for the sandstones in the Arivechi region. Another possible source area for the Permian-Triassic zircons (296-222 Ma) besides Sonora and Chihuahua localities are the rocks of the Guacamaya Formation in the Huizachal region in northeastern

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Mexico (Rubio-Cisneros and Lawton, 2011). Other localities for Permian-Triassic zircon ages have been reported mostly in southern Mexico (Torres et al., 1999; Keppie et al., 2003; Pack et al., 2016). Armstrong‐

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Altrin, et al. (2018) and Tapia-Fernandez et al. (2017) reported detrital zircon ages between 216 and 286 Ma, obtained from sandstone beaches, that are related to erosion of Permian granitoids and metasedimentary rocks of the Chiapas Massif Complex. Although more detailed paleogeography work needs to be carry out, the source of zircons from the northeastern and southeastern Mexico cannot be rejected as plausible sediment contributors to the Arivechi area.

17

ACCEPTED MANUSCRIPT Meanwhile, the presence of Lower Triassic rocks in Sonora is limited and the outcrops seem to be remnants of an ancient magmatic arc (Stewart et al., 1986). Triassic sections are exposed in northwestern and central Sonora, southern Arizona, and equivalent strata have been recognized in sections in eastern California and western Arizona. U-Pb zircon ages from the Arivechi region provide the possible estimate of the age of

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Triassic magmatic arc activity in that area. These zircon ages also provide a basis for understanding the paleogeography and stratigraphy of Triassic rocks in the Arivechi region, where the source of the volcanic debris was presumably a major magmatic arc related volcanic system. Notably, the U-Pb ages obtained in

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this study are older than those proposed for the Chinle Formation in northern Arizona (Riggs, 2013). Locally, our preliminary field work, in the areas of Cerro El Mogallón, Cerro La Sata, and Cerro El

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Santisimo, west of Arivechi, suggests that the distribution of Triassic rocks in the region is likely to be more widespread that has been recognized previously.

The paleogeography, tectonic evolution, location and configuration of the Permo-Triassic Cordilleran margin in Sonora is not well stablished. The 40Ar/39Ar age and U-P detrital zircons ages data obtained from a

rocks.

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5.3. Regional Tectonic Setting

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volcanic megablock and sedimentary rocks respectively, in the study area, suggest the occurrence of such

The two Upper Cretaceous units (Cañada de Tarachi unit and the El Potrero Grande unit) are similar

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in terms of the age and source composition, although their provenance can be distinguished by the population distributions of zircon ages. The different populations of detrital zircons obtained from Cretaceous sediments from eastern Sonora reflect sources from: (a) igneous suites that are widespread in the southwestern North American craton and (b) from less predominant sources that reflect the evolution of the Arivechi region in Cretaceous time.

5.3.1. Cretaceous sedimentation 18

ACCEPTED MANUSCRIPT Although the focus of this paper is the provenance of detrital zircons, we believe is important to try to explain the evolution of the Arivechi basin and its relationship to other Cretaceous basins, such as the Bisbee basin. Cretaceous Bisbee Group sedimentary rocks in southeastern Arizona and northeastern Sonora were

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deposited along the northwestern edge of the Chihuahua trough, a west-northwest-trending rift type basin (Bilodeau, 1978, 1982), filled with carbonate and siliciclastic sediments. Erosion of Paleozoic carbonate rocks and Precambrian crystalline basement supplied lithic and arkosic sediment to the basin (Glance

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Conglomerate). By middle Aptian the rift shoulder was substantially reduced in relief, and carbonate deposition was widespread (Mural Limestone). In southeastern Arizona and northeastern Sonora, Mexico,

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similar thickness variations and local provenance of the Glance Conglomerate are associated with syndepositional movement of high-angle normal faults (Bilodeau, 1982; Bilodeau and Lindberg, 1983). Hayes (1970) proposed that Lower Cretaceous detrital sedimentary rocks in southeastern Arizona and northeastern Sonora were derived primarily from a source to the west or southwest of the basin.

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In late Albian-Cenomanian, however, northeastern and eastern Sonora experienced a dramatic increase in tectonic subsidence and siliciclastic sedimentation rate (> 6000 m), as well as changes in sediment dispersal and provenance. These changes could mark the beginning of a Arivechi back-arc basin

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that persisted into the Late Cretaceous.

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Some lines of evidence suggest that the increase in subsidence and sedimentation rate was the reactivation (uplift) of positive land(s) like the Cananea High – Aldama Platform or some other orogens. (1) Quartz-arenites of the lower Cañada de Tarachi unit were derived from crystalline basement and Paleozoic rocks, (2) the megaclasts of Precambrian, Paleozoic, and Mesozoic rocks derived from the positive land were overlapped by shallow-continental sediments, (3) the volcaniclastic material in the El Potrero Grande unit and the diminishes of the lower siliciclastic sediments suggest the proximity within a few tens of kilometers

19

ACCEPTED MANUSCRIPT of an eroded magmatic arc and reactivated positive land, and (4) sediment provenance is from northwest to southeast, north-south, northeast, and east. The great thickness of sedimentation identified in the Upper Cretaceous rocks conform best a back-

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arc basin were erosion of orogens (Precambrian basement, Paleozoic rocks, the Cretaceous magmatic arc itself) increase the tectonic loading and produce a great volume of siliciclastic and volcaniclastic material that spread eastward and northeastward Sonora across the former rift basin (Bisbee basin) and overlapped the

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former positive land, e.g. Cananea high and the Aldama Platform.

Critical to the argument of an Upper Cretaceous back-arc basin in north-northeastern Sonora is the

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evidence of late Albian-early Cenomanian extensional deformation suggested by the presence of a regional angular unconformity along eastern Sonora. The identification of syntectonic sedimentary rocks (megablocks) indicates that extension belt was active in north, northeast and east Sonora in mid-Cretaceous time (McKee, 1991; McKee and Anderson, 1998, Rodriguez-Castañeda, 2002; McKee et al., 2005). In

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southeastern Arizona scattered evidence also indicates mid-Cretaceous extensional deformation. In addition to providing information about sediment source regions, detrital zircons ages can help to constrain a depositional age. The Proterozoic zircons suggest that source rocks were eroded and transported

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from N to S and/or NW to SE – the most important source regions for these sediments being the Mazatzal and the Yavapai terranes and/or the anorogenic plutons exposed in northern Sonora and southern Arizona.

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The detrital zircons with ages ranging between 274 and 255 Ma likely come from the PermianTriassic Cordilleran magmatic arc which occur as isolated outcrops in northern Sonora (Arvizu et al., 2009; Riggs et al., 2009, 2010, 2013, Fig. 9). The lack of detrital zircons with ages younger than 247 Ma implies a valuable time constraint, i.e. that 247 Ma is the maximum time of sedimentation for these rocks. These data therefore imply that these rocks, that are exposed in the Cañada de Tarachi unit are part of a Triassic megablock. Consequently, the Triassic

20

ACCEPTED MANUSCRIPT megablock can be correlated (in time) with the Barranca Group, although correlation with other units exposed in Chihuahua and southern Arizona may also be possible. El Potrero Grande lower sample (A82) contains detrital zircon populations of predominantly Lower Cretaceous (146-100 Ma) and Upper Cretaceous (99-86 Ma) ages, whereas an upper sample (A79) contains

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detrital zircon populations of Upper Cretaceous (97 to 71) ages. These detrital zircons were derived from the rocks inherited in the Cretaceous magmatic arc which is widely exposed in Sonora. The Lower Cretaceous zircons are derived from the denudation of the gabbro, diorite and tonalites of the western Peninsular Ranges

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Batholith-Santiago Peak Volcanics in California-Baja California and/or the Vizcayno Volcanics in Baja California. The Upper Cretaceous population in both samples can be correlated with the denudation of the

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eastern Peninsular Ranges Batholith or the La Posta-type plutons composed of tonalite, granodiorite and granites (i.e. Long Potrero, La Posta, El Pinal, El Topo, Laguna Juárez and San Pedro Mártir). Rocks of this age around the Bacanora region were also described by Perez-Segura (2006). The detrital zircons come from source rocks that were generated during the development of magmatic

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arc during subduction processes in Cretaceous times. Because the Baja Peninsula was attached to the mainland during the Mesozoic (Ortega-Rivera, 2003) (Fig.10), we propose that the main source of the Mesozoic detrital zircons were sediments derived by denudation of the Peninsular Ranges Batholith and their

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host rocks during this time. Palinspastic restoration of both Californias to their pre-drift position with respect to the rest of Mexico during Mesozoic is consistent with the eastward younging of ages (chrontours) that

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systematically cross from California and Baja California into mainland Mexico, from Sonora to Jalisco, i.e. the decrease in ages across the region and within individual plutons is attributed to the regional eastward migration of granitic intrusions (Ortega-Rivera et al., 1997; Ortega-Rivera, 2003). This supports the interpretation that the Peninsular Ranges Batholith and the Coastal Sonora batholith are the source of the Upper Cretaceous detrital zircons. Although these rocks are rather distal from the proposed San Antonio back-arc basin, they are considered the main sedimentary source for the Upper Cretaceous zircons in this study. These ages reflect the so-called Laramide magmatic arc that is widespread in Sonora, although it is of 21

ACCEPTED MANUSCRIPT interest to note that zircons from younger batholiths are not present in the Cretaceous sedimentary rocks of the Arivechi region. This study of the Cretaceous strata on the western foothills of Sierra Madre Occidental, in eastern Sonora, Mexico, shows that analysis of detrital zircons can reflect an extensional regime history that is not as

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simple as previously thought.

6. CONCLUSIONS

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U-Pb detrital zircons from the Cañada de Tarachi and the El Potrero Grande units in the Arivechi region yield ages that constrain the age of the exposed rocks and provide new insights into the geological

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evolution of eastern Sonora Cretaceous rocks. Histograms showing relative age probability distribution and comparison of detrital zircon age population of this study show similarities and very distinct differences between representative samples of the units indicated that the potential source areas are distal and proximal. U-Pb detrital zircons ages obtained from sedimentary rocks of the Arivechi area indicate that these

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rocks were supplied by rocks of different age groups, these groups are dominated by the Proterozoic, Paleozoic, and Mesozoic. The Proterozoic is represented by Paleoproterozoic-(1688 -1602 Ma) and the Mesoproterozoic (1591-1341 Ma) ages, meanwhile, the Paleozoic-Mesozoic by the Permian-Triassic (274-

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247 Ma) ages. The Mesozoic is represented by Jurassic (160 to 147 Ma), Lower Cretaceous (146 to 100 Ma), and Upper Cretaceous (99 to 71 Ma) ages. In addition, a 40Ar/39Ar whole-rock Permo-Triassic age (262 ± 2

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Ma (2s) (Permian, Capitanian age)) was obtained for an andesitic megablock in the El Potrero Grande unit. These U-Pb and 40Ar/39Ar ages, constrain the provenance and composition of the sediments that conforms the Upper Cretaceous stratigraphy of the study area. Potential source areas for the Proterozoic detrital zircons discussed in this study are crystalline rocks exposed in the Caborca block, in the Pinal Province, and anorogenic plutons widely distributed in northern Sonora and southern Arizona. Meanwhile, the Paleozoic detrital zircons the potential source areas are southern California and northwestern Sonora and perhaps southern Arizona. 22

ACCEPTED MANUSCRIPT Also, the new Permo-Triassic detrital zircon U-Pb and whole rock 40Ar/39Ar age data in sediments of the Arivechi area strongly support a new provenance clast source, since the presence of Permo-Triassic age clasts in sedimentary rocks for eastern Sonora have not been previously reported. However, the provenance of the Early Permian to Middle Triassic zircons (274 – 247 Ma) are problematic because Permo-Triassic

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igneous rocks are not widely distributed in Sonora, they are very locally distributed. Plausible rock sources for these Permo-Triassic andesitic tuff megablock and andesitic clasts conglomerate, could be linked to the volcanic rocks of the Permo-Triassic Cordilleran magmatic arc, exposed mainly in the Mojave Desert region

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of southern California and northwestern Sonora or the granitoids of Permo-Triassic age, exposed in the Los Filtros and Carrizalillo ranches area of central Chihuahua located to the east of Arivechi region.

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Meanwhile, the Jurassic and Cretaceous ages populations can be related to rocks of the same age (plutons and volcanics) from southern California and Baja California, northern Sonora, southern Arizona and eastern Chihuahua(?), these rocks may be the potential Jurassic-Cretaceous contributors of sediments to the Arivechi sequence.

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Building on the megablocks gliding model for the geologic evolution of the region, the identification of Proterozoic to Mesozoic megablocks in both units confirm that Arivechi Upper Cretaceous was deposited in a deep sedimentary basin that received sediments from an existing magmatic arcs and from both the now

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exposed northwestern and northeastern basements.

In this work, the characterization of important tectonic processes throughout time was paramount to

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better understand the evolution of the successive periods of crustal formation. Knowledge of such events allowed the identification of possible source areas for the zircons. The results of this study combined with previous structural and stratigraphic data provide a better understanding of the tectonic evolution for southwestern North America and northwest Mexico.

Acknowledgements 23

ACCEPTED MANUSCRIPT Funding for this study was provided by the PAPIIT-UNAM through grant 22-IN103710. Grinding of samples and preparation of thin sections were performed by Pablo Peñaflor and Aime Orci, respectively, from the Estación Regional del Noroeste, Instituto de Geología, UNAM. U-Pb dating was completed at the Centro de Geociencias, UNAM, where Carlos Ortega and Ofelia Pérez carried out the laboratory analysis.

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We are grateful to the reviewers Rogelio Monreal Saavedra, John S. Armstrong‐Altrin, and a third

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anonymous reviewer for numerous helpful comments, which significantly improved the manuscript.

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30

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México, Instituto de Geología, Revista, 1, 44-47. Riggs, N.R., Barth, A.P., González-León, C., Walker, J.D., and Wooden, J.L., 2009, Provenance of Upper Triassic strata in southwestern North America as suggested by isotopic analysis and chemistry of zircon crystals: Geological Society of America Abstracts with Programs, 41-7, 540. Riggs, N.R., Barth, A.P., Wooden, J., Walker, J.D., 2010, Use of zircon geochemistry to the volcanic detritus to source plutonic rocks: an example from Permian northwestern Sonora, Mexico: Geological Society of America, Abstracts with Programs, 42, 267. 31

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47, 262.

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ACCEPTED MANUSCRIPT Lawton, T.F. (eds.), Mesozoic Sedimentary and Tectonic History of North-Central Mexico: Geological Society of America, Special Paper 340, 191-196. Tosdal, R.M., Haxel, G.B., and Wright, J.E., 1989, Jurassic geology of the Sonoran Desert region, southern Arizona, southeastern California, and northernmost Sonora: Construction of a continental-margin

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FIGURES CAPTION

34

ACCEPTED MANUSCRIPT Figure 1. Location of the study area to the east of Arivechi, Sonora, Mexico and outcrops of Upper Cretaceous rocks. Figure 2. Schematic stratigraphic column, without scale, that shows the relationship between the La Cañada

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de Tarachi and El Potrero Grande units in the Arivechi area and the interpreted monoliths in the Cañada de Tarachi and the El Potrero Grande units. a). The megablocks are separated by a shear zone from the underlying unit. Intense shearing between Paleozoic rocks and underlying Lower Cretaceous rocks around Cerro Las Conchas. b) Block constituted by conglomerate of unknown age in the Cañada de Tarachi stream.

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The block is surrounded by conglomerate of possible Triassic age. c) Megablock constituted by Paleozoic

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rocks exposed along the Arivechi-Tarachi road. d and e) Blocks of Precambrian rocks along the Cañada de Tarachi stream. The block of figure e contains stromatolites that indicate the Precambrian age. Figure 3. Geologic map showing the main synsedimentary megablocks of the Arivechi area. The map is modified from Rodríguez-Castañeda et al. (2015). The new interpretation (this study) includes the Permo-

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Triassic rocks in the study area.

Figure 4. The Cañada de Tarachi conglomerate in the Cerro Zoropuchi (a and b locality). Clasts are limestone of Paleozoic and Cretaceous ages. Conglomerates exposed along the Arivechi-Tarachi road (c, d,

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e, and f) show sedimentary clasts with angular shapes, whereas, in the Cañada de Tarachi stream conglomerates (g and h) show well-rounded volcanic clasts. Sedimentary clasts are composed of quartzite,

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sandstone, chert, and mudstone, whereas the volcanic clasts are mainly andesite and some tuffs. Figure 5. U-Pb detrital zircon age-probability plots and the Concordia diagrams for (a) sample A78-11, (b) sample A82-11, and (c) sample A79-11. The second set of diagrams displays the younger populations in more detail. Figure 6.

40

Ar/39Ar step-heating age spectrum and isotope correlation diagram of whole-rock sample JR10

from the block found in the El Potrero Grande unit. 35

ACCEPTED MANUSCRIPT Figure 7. Tectonostratigraphic terranes in northern Sonora and southern Arizona. The Pinal Province extends through Sonora and Arizona (modified from Anderson and Silver, 2005). Figure 8. Map showing the 1) Eastern and Western Peninsular Ranges Batholith of Baja California

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(modified from Kimbrough et al., 2001; Ortega-Rivera, 2003); geology from the Carta Geológico-Minera Estado de Baja California, Servicio Geológico Mexicano, (2008). 2) outcrops of 1400 Ma anorogenic granites in Sonora (circles) and Arizona and their relationship with major geologic structures in Sonora

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(modified from Carta Geológica-Minera del Estado de Sonora, scale 1:500,000, Servicio Geológico Mexicano, 2008; and Meijer, 2012); and 3) exposed batholiths in Sonora (geology from the Carta Geológico-

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Minera Estado de Sonora, Servicio Geológico Mexicano, 2008); U-Pb data compiled from the literature (Anderson and Silver, 1969); Ortega-Rivera, 2003; Ramos-Velázquez et al., 2008; McDowell et al., 2001; Perez-Segura, 2006; González-León et al., 2011). Inset square shows pre-Cenozoic reconstruction of Baja California and Sonora.

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Figure 9. Map of southwestern North America and northern Sonora showing location of the Permo-Triassic Cordilleran Magmatic Arc that can be extended to the Arivechi region. Modified from Riggs et al. 2013. Figure 10. (a) Palinspastic reconstruction for western Mexico before opening the Gulf of California in the

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Mesozoic and U-Pb chrontours for plutons of the Mesozoic western arc and for the Peninsular Ranges. (b) Zircon U-Pb chrontours; (c) Hornblende 40Ar/39Ar plateau and K/Ar chrontours; (d) Biotite 40Ar/39Ar plateau

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and K/Ar dates chrontours for the Peninsular Ranges batholith. Modified from Ortega-Rivera (2003). Arrows indicate the likely direction of provenance of some detrital zircons in the study area.

TABLES 36

ACCEPTED MANUSCRIPT Table 1. Summary of LA-ICPMS U-Pb data of zircons from sample A78-11 (Cañada de Tarachi Unit). Table 2. Summary of LA-ICPMS U-Pb data of zircons from sample A82-11 (El Potrero Grande Unit). Table 3. Summary of LA-ICPMS U-Pb data of zircons from sample A79-11 (El Potrero Grande Unit). 40

Ar/39Ar analytical data from the andesitic sample JR10 (El Potrero Grande Unit), in the

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Table 4. WR

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Arivechi region, eastern Sonora.

37

ACCEPTED MANUSCRIPT

Table 1. Summary of LA-ICPMS U-Pb data of zircons from sample A78-11 (Cañada de Tarachi Unit).

Zircon_1_78-11_008

220

92

0.37

0.08967

0.001

3.0534

0.048

0.2463

0.002

1419

9

1421

1419

27

1419

27

349

152

0.38

0.08823

0.001

2.9589

0.039

0.24306

0.001

1403

7

1397

10

1387

22

1387

22

Zircon_100_126

126

53

0.37

0.09043

0.001

3.107

0.048

0.24891

0.002

1433

8

1434

12

1435

25

1435

25

Zircon_11_020

379

170

0.40

0.0872

0.001

2.8534

0.041

0.23745

0.002

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12

Zircon_10_018

1373

8

1370

11

1365

23

1365

23

Zircon_12_021

860

244

0.25

0.08894

0.001

3.0754

0.041

0.25099

0.001

1444

8

1427

10

1403

22

1403

22

Zircon_13_022

698

273

0.35

0.10074

0.001

4.0385

0.055

0.29041

0.002

1644

9

1642

11

1638

21

1638

21

Zircon_14_023

1290

973

0.67

0.09014

0.001

3.1351

0.046

0.25217

0.002

1450

8

1441

11

1428

23

1428

23

Zircon_15_024

111

65

0.52

0.08771

0.001

3.1374

0.055

0.25934

0.002

1486

12

1442

14

1376

27

1376

27

Zircon_16_026

419

188

0.40

0.08745

0.001

2.9483

0.042

0.24443

0.001

1410

8

1394

11

1370

24

1370

24

Zircon_17_027

256

110

0.38

0.08912

0.001

3.1098

0.045

0.25311

0.002

1454

9

1435

11

1407

23

1407

23

Zircon_18_028

104

47

0.40

0.09298

0.001

3.1991

0.056

0.24961

0.002

1436

9

1457

14

1487

29

1487

29

Zircon_19_029

114

43

0.33

0.08935

0.001

3.077

0.049

0.24941

0.002

1435

10

1427

12

1412

25

1412

25

Zircon_2_009

589

248

0.37

0.09024

0.001

3.0777

0.044

0.24729

0.001

1424

8

1427

11

1431

23

1431

23

Zircon_20_030

236

112

0.42

0.08953

0.001

3.115

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CORRECTED AGES (Ma)

0.046

0.25226

0.002

1450

9

1436

11

1416

23

1416

23

Zircon_21_032

284

110

0.34

0.08908

0.001

2.8047

0.045

0.22821

0.002

1325

10

1357

12

1406

25

1406

25

Zircon_22_033

216

109

0.44

0.09053

0.001

3.0691

0.045

0.24554

0.002

1415

8

1425

11

1437

23

1437

23

Zircon_23_034

201

122

0.54

0.09049

0.001

3.2271

0.054

0.25852

0.002

1482

10

1464

13

1436

27

1436

27

Zircon_24_035

230

98

0.38

0.08784

0.001

2.7652

0.045

0.22819

0.001

1325

7

1346

12

1379

27

1379

27

Zircon_25_036

156

59

0.34

0.0919

0.002

2.8615

0.063

0.22582

0.002

1313

9

1372

17

1465

35

1465

35

Zircon_26_038

697

453

0.57

0.09033

0.001

3.05

0.042

0.24471

0.002

1411

9

1420

11

1433

21

1433

21

Zircon_27_039

242

124

0.45

0.10146

0.001

4.0967

0.061

0.29284

0.002

1656

10

1654

12

1651

23

1651

23

Zircon_28_040

405

159

0.35

0.08909

0.001

2.9514

0.042

0.23989

0.001

1386

7

1395

11

1406

23

1406

23

AC C

CORRECTED RATIOS ±1s

207

Pb/235U

Zircon_29_041

211

86

Zircon_3_010

487

344

Zircon_30_042

175

82

Zircon_31_044

1319

491

Zircon_32_045

521

186

Zircon_33_046

119

65

0.49

Zircon_34_047

493

154

0.28

Zircon_35_048

566

284

0.44

0.09034

±1s

206

Pb/238U

±1s

206

Pb/238U ±1s

SC

Pb/206Pb

TE D

207

EP

U(ppm) Th (ppm) Th/U

207

Pb/235U ±1s

207

Pb/206Pb ±1s Best age (Ma) ±1s

0.36

0.08939

0.001

3.0913

0.048

0.25032

0.002

1440

8

1431

12

1413

25

1413

25

0.63

0.08945

0.001

3.0351

0.041

0.24585

0.001

1417

8

1416

10

1414

22

1414

22

0.42

0.08827

0.001

2.9929

0.044

0.24522

0.002

1414

8

1406

11

1388

24

1388

24

0.33

0.05298

0.001

0.31763

0.005

0.04348

0.000

274

2

280

4

328

32

274

2

0.32

0.08929

0.001

3.0428

0.039

0.24684

0.002

1422

8

1418

10

1410

20

1410

20

0.08863

0.001

2.8758

0.044

0.23507

0.002

1361

8

1376

12

1396

24

1396

24

0.08922

0.001

2.7405

0.047

0.2227

0.003

1296

14

1340

13

1409

21

1409

21

0.001

2.7748

0.037

0.22266

0.001

1296

7

1349

10

1433

21

1433

21

ACCEPTED MANUSCRIPT

218

118

0.48

0.08923

0.001

3.0097

0.046

0.24437

0.002

1409

8

1410

12

1409

24

1409

24

Zircon_37_051

468

245

0.46

0.09

0.001

3.2016

0.046

0.25773

0.002

1478

8

1458

11

1426

22

1426

22

9

1625

188

72

0.34

0.0988

0.001

3.9551

0.057

0.28998

0.002

1641

12

1602

22

1602

22

836

299

0.32

0.08842

0.001

2.7726

0.038

0.22694

0.002

1318

8

1348

10

1392

21

1392

21

Zircon_4_011

278

189

0.60

0.08968

0.001

3.063

0.044

0.24785

0.001

1427

8

1423

11

1419

23

1419

23

Zircon_40_054

128

51

0.35

0.08957

0.001

3.0059

0.052

0.24345

0.002

1405

8

1409

13

1416

28

1416

28

Zircon_41_056

718

589

0.73

0.09901

0.001

3.3672

0.060

0.24679

0.003

1422

15

1497

14

1606

22

1606

22

Zircon_42_057

556

328

0.52

0.08948

0.001

3.1173

0.043

0.25245

0.002

1451

9

1437

11

1414

21

1414

21

Zircon_43_058

850

277

0.29

0.08904

0.001

3.0281

0.041

0.24639

0.002

1420

8

1415

10

1405

21

1405

21

Zircon_44_059

172

81

0.42

0.08924

0.001

3.0026

0.044

0.24356

0.002

1405

8

1408

11

1409

23

1409

23

Zircon_45_060

166

130

0.69

0.08981

0.001

3.1508

0.054

0.25444

0.003

1461

13

1445

13

1421

24

1421

24

Zircon_46_062

357

204

0.51

0.0877

0.001

2.9219

0.043

0.24155

0.002

1395

9

1388

11

1376

23

1376

23

Zircon_47_063

112

44

0.35

0.08812

0.001

2.9826

Zircon_48_064

705

250

0.31

0.08926

0.001

3.1093

Zircon_49_065

477

289

0.54

0.08827

0.001

3.4381

Zircon_5_012

135

89

0.58

0.05445

0.002

0.29255

Zircon_50_066

229

111

0.43

0.09126

0.001

3.1958

Zircon_51_068

406

163

0.36

0.08849

0.001

2.9153

M AN U

SC

Zircon_38_052 Zircon_39_053

RI PT

Zircon_36_050

0.040

0.23883

0.002

1381

8

1386

10

1393

21

1393

21

Zircon_52_069

1020

208

0.18

0.08997

0.001

2.52141

0.059

0.20326

0.003

1193

15

1278

17

1425

27

1425

27

Zircon_53_070

432

210

0.43

0.10094

0.001

4.221

0.067

0.30266

0.003

1704

14

1678

13

1641

22

1641

22

Zircon_54_071

151

75

0.44

0.08933

0.001

3.0038

0.049

0.24349

0.002

1405

8

1409

12

1411

26

1411

26

Zircon_55_072

698

320

0.41

0.08916

0.001

3.0806

0.042

0.25034

0.002

1440

8

1428

10

1408

21

1408

21

Zircon_56_074

646

280

0.38

0.0896

0.001

3.0751

0.041

0.24879

0.001

1432

8

1427

10

1417

21

1417

21

Zircon_57_075

163

77

0.42

0.08778

0.001

3.0225

0.051

0.24953

0.002

1436

10

1413

13

1378

26

1378

26

Zircon_58_076

392

220

0.50

0.08978

0.001

3.1291

0.045

0.25244

0.002

1451

8

1440

11

1421

23

1421

23

Zircon_59_077

644

332

0.46

0.04948

0.001

0.28109

0.005

0.04115

0.000

260

2

252

4

171

39

260

2

Zircon_6_014

179

66

0.33

0.08613

0.001

0.048

0.21756

0.002

1269

8

1296

14

1341

28

1341

28

Zircon_60_078

186

82

25

Zircon_61_080

217

121

Zircon_62_081

1503

746

0.2453

0.002

1414

8

1403

12

1385

24

1385

24

0.25238

0.002

1451

8

1435

10

1410

21

1410

21

0.055

0.28245

0.002

1604

11

1513

13

1388

24

1388

24

0.011

0.03916

0.000

248

2

261

8

390

73

248

2

0.049

0.25369

0.002

1457

8

1456

12

1452

24

1452

24

AC C

EP

TE D

0.046

0.042

2.58369

0.52

0.09688

0.001

3.6587

0.058

0.2735

0.002

1559

10

1562

13

1565

24

1565

24

0.45

0.08928

0.001

3.0542

0.053

0.24766

0.002

1426

9

1421

13

1410

28

1410

28

0.001

3.039

0.049

0.24799

0.002

1428

8

1417

12

1401

26

1401

26

0.001

4.0354

0.059

0.2908

0.002

1646

10

1641

12

1634

22

1634

22

0.39

0.08952

0.001

2.8401

0.044

0.2298

0.002

1333

8

1366

12

1415

25

1415

0.49

0.09823

0.001

4.0899

0.070

0.30096

0.003

1696

15

1652

14

1591

24

1591

24

0.44

0.08933

0.001

3.0334

0.040

0.24589

0.001

1417

7

1416

10

1411

21

1411

21

Zircon_63_082

311

181

Zircon_64_083

130

66

Zircon_65_084

143

61

0.38

0.08885

Zircon_66_086

286

103

0.32

0.10053

1416

346

0.22

0.05006

0.001

0.2732

0.005

0.0395

0.000

250

2

245

4

198

36

250

2

Zircon_68_088

765

565

0.65

0.0904

0.001

3.1277

0.043

0.25035

0.002

1440

9

1440

11

1434

21

1434

21

Zircon_69_089

1531

802

0.46

0.05264

0.001

0.28318

0.005

0.03904

0.000

247

2

4

313

29

247

2

Zircon_7_015

98

37

0.33

0.08782

0.001

2.7469

0.045

0.22702

0.002

1319

8

1379

27

1379

27

Zircon_70_090

47

35

0.66

0.08967

0.002

3.131

0.059

0.25287

0.002

1453

10

1440

14

1419

30

1419

30

Zircon_71_092

177

76

0.38

0.08979

0.001

3.0448

0.045

0.24572

0.002

1416

9

1419

11

1421

23

1421

23

Zircon_72_093

93

47

0.44

0.08962

0.001

3.0781

0.052

0.24905

0.002

1434

10

1427

13

1417

26

1417

26

Zircon_73_094

380

161

0.38

0.08931

0.001

3.1726

0.059

0.25655

0.003

RI PT

12

1472

16

1451

14

1411

25

1411

25

Zircon_74_095

200

96

0.42

0.0892

0.001

2.8676

0.043

0.23299

0.002

1350

9

1373

11

1408

23

1408

23

Zircon_75_096

471

189

0.35

0.08927

0.001

3.1526

0.046

0.25603

0.002

1469

11

1446

11

1410

21

1410

21

Zircon_76_098

270

172

0.56

0.05155

0.001

0.28551

0.007

0.04029

0.000

255

2

255

5

266

46

255

2

Zircon_77_099

1044

345

0.29

0.08863

0.001

2.7853

0.049

0.22754

0.003

1322

14

1352

13

1396

23

1396

23

Zircon_78_100

436

204

0.41

0.08881

0.001

2.9442

23

Zircon_79_101

279

140

0.44

0.05182

0.001

0.29392

Zircon_8_016

293

143

0.43

0.08991

0.001

3.1208

Zircon_80_102

340

151

0.39

0.09045

0.001

3.1379

Zircon_81_104

540

231

0.38

0.0908

0.001

3.1478

Zircon_82_105

338

152

0.40

0.0883

0.001

3.0552

Zircon_83_106

765

599

0.69

0.05125

0.001

0.29255

Zircon_84_107

570

371

0.58

0.08961

0.001

Zircon_85_108

149

70

0.41

0.08895

Zircon_86_110

342

186

0.48

0.08998

Zircon_87_111

188

89

0.42

0.08875

0.001

Zircon_88_112

201

92

0.40

0.1035

Zircon_89_113

263

84

0.28

0.05441

Zircon_9_017

759

307

0.36

0.08949

Zircon_90_114

146

79

0.48

Zircon_91_116

857

287

Zircon_92_117

445

145

Zircon_93_118

457

333

Zircon_94_119

352

239

Zircon_95_120

358

205

Zircon_96_122

936

624

0.59

Zircon_97_123

134

60

0.39

0.09098

253 1341

0.24033

0.002

1388

8

1393

11

1400

23

1400

0.04139

0.000

261

2

262

6

277

51

261

2

0.045

0.25134

0.002

1445

10

1438

11

1424

21

1424

21

0.046

0.25126

0.002

1445

9

1442

11

1435

23

1435

23

0.047

0.25111

0.002

1444

10

1444

12

1442

23

1442

23

0.043

0.25065

0.001

1442

7

1422

11

1389

23

1389

23

0.006

0.04137

0.000

261

2

261

4

252

38

261

2

2.7839

0.043

0.22496

0.002

1308

10

1351

12

1417

23

1417

23

0.001

2.9044

0.043

0.23648

0.002

1368

9

1383

11

1403

23

1403

23

0.002

2.95984

0.076

0.23857

0.002

1379

13

1397

19

1425

36

1425

36

2.9771

0.043

0.24314

0.002

1403

8

1402

11

1399

24

1399

24

0.001

4.1619

0.064

0.29179

0.002

1650

10

1667

13

1688

25

1688

25

0.001

0.32417

0.008

0.04315

0.000

272

2

285

6

388

49

272

2

0.001

3.0885

0.042

0.25021

0.002

1440

9

1430

11

1415

22

1415

22

0.09274

0.001

3.2733

0.051

0.25491

0.002

1464

9

1475

12

1483

25

1483

25

0.30

0.08909

0.001

3.1452

0.051

0.25569

0.003

1468

13

1444

13

1406

24

1406

24

0.29

0.08881

0.001

3.0494

0.044

0.24866

0.002

1432

8

1420

11

1400

24

1400

24

0.65

0.05014

0.001

0.2699

0.007

0.03899

0.000

247

2

243

6

201

55

247

2

0.60

0.09019

0.001

3.0361

0.041

0.24371

0.002

1406

8

1417

10

1430

22

1430

22

0.51

0.0897

0.001

3.0973

0.058

0.25024

0.003

1440

13

1432

14

1419

29

1419

29

0.09149

0.001

3.1797

0.049

0.25095

0.002

1443

9

1452

12

1457

25

1457

25

0.001

3.0242

0.050

0.24034

0.002

1388

9

1414

13

1446

27

1446

27

EP

TE D

0.043

0.007

AC C

SC

Zircon_67_087

M AN U

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT

0.09086

0.001

2.8664

0.040

0.22855

0.002

1327

8

1373

M AN U

SC

RI PT

0.41

TE D

180

EP

391

AC C

Zircon_98_124

10

1444

22

1444

22

ACCEPTED MANUSCRIPT

Table 2. Summary of LA-ICPMS U-Pb data of zircons from sample A82-11 (El Potrero Grande Unit).

Zircon_10_018

Th (ppm)

Th/U

106

62

0.52

207

206

Pb/ Pb

0.10138

±1s

207

235

Pb/ U

0.002

4.1258

±1s

206

238

Pb/ U

0.073

0.2943

±1s

CORRECTED AGES (Ma) 206

RI PT

CORRECTED RATIOS U (ppm)

238

Pb/ U ±1s

0.002

1663

11

207

235

Pb/ U

±1s

1659

14

207

Pb/206Pb 1650

±1s

Best age (Ma)

±1s

28

1650

28

Zircon_100_126

418

199

0.43

0.05442

0.003

0.11172

0.006

0.01492

0.000

95

1

108

6

388

114

95

1

Zircon_11_020

257

113

0.39

0.06149

0.004

0.12407

0.007

0.01473

0.000

94

1

119

7

656

117

94

1

93

1

550

232

0.38

0.05361

0.003

0.10562

0.006

0.01446

0.000

102

6

355

127

93

1

140

54

0.35

0.05121

0.004

0.10928

0.010

0.01548

0.000

99

1

105

9

250

182

99

1

Zircon_15_024

249

139

0.50

0.05324

0.003

0.11357

0.006

0.0155

0.000

99

1

109

5

339

106

99

1

Zircon_17_027

245

113

0.41

0.05985

0.003

0.12079

0.007

0.01495

0.000

96

1

116

6

598

120

96

1

Zircon_2_009

160

65

0.36

0.05619

0.004

0.11356

0.009

0.01466

0.000

94

1

109

8

460

181

94

1

Zircon_20_030

182

83

0.41

0.06693

0.004

0.14531

0.008

0.01578

0.000

101

1

138

7

836

117

101

1

Zircon_21_032

387

279

0.65

0.05131

0.003

0.10186

0.005

0.0145

0.000

93

1

98

5

255

121

93

1

Zircon_22_033

531

456

0.77

0.0469

0.002

0.15091

0.006

0.02349

0.000

150

1

143

5

44

81

150

1 2

M AN U

SC

Zircon_13_022 Zircon_14_023

859

346

0.36

0.05667

0.003

0.14652

0.007

0.01922

0.000

123

2

139

6

479

106

123

331

162

0.44

0.05198

0.002

0.10313

0.005

0.01445

0.000

92.5

1

100

4

285

109

93

1

Zircon_25_036

49

18

0.33

0.06023

0.009

0.132

0.021

0.0159

0.000

102

3

126

19

612

341

102

3

Zircon_26_038

244

124

0.46

0.0495

0.003

0.10004

0.006

0.01478

0.000

95

1

97

6

172

137

95

1

Zircon_27_039

131

65

0.44

0.05269

0.004

0.10635

0.008

0.01464

0.000

94

1

103

7

315

170

94

1

Zircon_28_040

701

481

0.61

0.05103

0.002

0.10518

0.005

0.01502

0.000

96.1

1

102

4

242

102

96

1

Zircon_29_041

817

322

0.35

0.05228

0.001

0.29134

0.007

0.04049

0.000

256

2

260

5

298

50

256

2

Zircon_3_010

102

36

0.32

0.06424

0.005

0.13495

0.011

0.01524

0.000

97

2

129

10

749

171

97

2

Zircon_30_042

955

488

0.46

0.04932

Zircon_31_044

518

267

0.46

0.05498

Zircon_33_046

2168

485

0.20

0.05187

Zircon_34_047

182

89

0.44

Zircon_35_048

289

154

0.48

Zircon_36_050

235

237

0.90

Zircon_37_051

108

22

0.18

Zircon_38_052

123

61

0.44

EP

TE D

Zircon_23_034 Zircon_24_035

0.002

0.1111

0.005

0.01637

0.000

105

1

107

4

163

93

105

1

0.002

0.17478

0.007

0.02311

0.000

147

2

164

6

411

95

147

2

0.003

1

0.005

0.01348

0.000

86

1

94

5

280

128

86

0.005

0.11925

0.010

0.01441

0.000

92

1

114

9

604

190

92

1

0.08961

0.001

3.1094

0.049

0.25144

0.002

1446

9

1435

12

1417

28

1417

28

0.09746

0.001

3.8224

0.066

0.28444

0.002

1614

12

1597

14

1576

29

1576

29

0.05936

0.005

0.12399

0.011

0.01546

0.000

99

2

119

10

580

206

99

2

0.04893

0.004

0.09971

0.008

0.01497

0.000

96

1

97

8

144

186

96

1

AC C

0.09654

0.06002

Zircon_4_011

418

312

0.67

0.05091

0.003

0.10309

0.006

0.01505

0.000

96

2

100

6

237

141

96

2

Zircon_40_054

152

86

0.50

0.05474

0.003

0.103

0.007

0.0139

0.000

89

1

100

6

402

147

89

1

Zircon_42_057

315

153

0.43

0.05074

0.003

0.09986

0.005

0.01441

0.000

92

1

97

5

229

121

92

1

ACCEPTED MANUSCRIPT

Zircon_43_058

261

97

0.33

0.06009

0.004

0.12238

0.007

0.01492

0.000

95

1

117

7

607

133

95

1

Zircon_45_060

175

81

0.42

0.05167

0.004

0.10708

0.008

0.0153

0.000

98

2

103

8

271

160

98

2

2

252

4

258

41

250

2

23

607

370

102

3

1509

683

0.40

0.05138

0.001

0.28115

0.006

0.03953

0.000

250

40

16

0.37

0.06009

0.011

0.13259

0.026

0.016

0.000

102

Zircon_49_065

225

98

0.39

0.0577

0.004

0.11782

0.007

0.015

0.000

96

1

113

7

518

128

96

1

Zircon_5_012

47

19

0.35

0.05577

0.010

0.11426

0.023

0.01486

0.000

95

3

110

21

443

367

95

3

Zircon_50_066

291

106

0.33

0.05153

0.005

0.10303

0.010

0.01484

0.000

95

1

100

9

265

196

95

1

Zircon_51_068

224

101

0.41

0.05173

0.006

0.10653

0.012

0.01475

0.000

94

1

103

11

273

222

94

1

Zircon_53_070

282

190

0.60

0.04966

0.002

0.16335

0.007

0.02387

0.000

152

2

154

6

179

86

152

2

Zircon_55_072

162

77

0.43

0.05421

0.004

0.10465

0.007

0.01426

0.000

91

1

101

7

380

147

91

1

Zircon_56_074

334

308

0.83

0.09858

0.001

3.8667

0.065

0.28419

0.002

1612

11

1607

13

1597

26

1597

26

Zircon_57_075

336

166

0.44

0.04621

0.003

0.09483

0.007

0.01481

0.000

95

1

92

6

9

138

95

1

Zircon_58_076

173

102

0.53

0.06018

0.004

0.11842

0.008

0.01433

0.000

92

1

114

7

610

130

92

1

Zircon_59_077

90

46

0.46

0.05608

0.010

0.13245

0.023

0.01641

0.000

105

3

126

20

456

335

105

3

RI PT

Zircon_46_062 Zircon_47_063

M AN U

SC

3

126

678

448

0.59

0.04844

0.002

0.0987

0.004

0.0148

0.000

95

1

96

4

121

84

95

1

230

96

0.37

0.05863

0.004

0.12102

0.010

0.01497

0.000

96

2

116

9

553

155

96

2

Zircon_62_081

468

123

0.23

0.05447

0.002

0.11381

0.005

0.0154

0.000

99

1

109

5

391

95

99

1

Zircon_63_082

64

29

0.41

0.07264

0.020

0.14455

0.039

0.01554

0.001

99

3

137

35

1004

540

99

3

Zircon_65_084

96

38

0.35

0.05807

0.005

0.1247

0.012

0.01568

0.000

100

2

119

11

532

195

100

2

Zircon_66_086

285

118

0.37

0.05364

0.004

0.11223

0.008

0.0151

0.000

97

1

108

7

356

141

97

1

Zircon_67_087

209

129

0.55

0.04746

0.003

0.09562

0.006

0.01479

0.000

95

1

93

5

72

119

95

1

Zircon_68_088

755

219

0.26

0.04989

0.002

0.1012

0.004

0.01471

0.000

94.2

1

98

4

190

81

94

1

Zircon_7_015

57

36

0.56

0.05445

0.006

0.12132

0.014

0.01629

0.000

104

2

116

12

390

228

104

2

Zircon_71_092

780

317

0.36

0.09786

0.001

23

Zircon_72_093

207

113

0.49

0.04955

Zircon_73_094

343

178

0.46

0.0517

Zircon_75_096

251

118

0.42

0.05111

Zircon_76_098

158

68

0.38

Zircon_77_099

190

59

0.28

Zircon_78_100

226

41

0.16

TE D

Zircon_6_014 Zircon_61_080

0.048

0.23439

0.002

1357

10

1449

12

1584

23

1584

0.10303

0.006

0.0152

0.000

97

1

100

5

174

116

97

1

0.003

0.10069

0.006

0.01422

0.000

91

1

97

6

272

125

91

1

0.002

0.10565

0.005

0.01518

0.000

97

1

102

5

246

97

97

1

0.05599

0.004

0.12023

0.008

0.01575

0.000

101

2

115

8

452

142

101

2

0.04827

0.005

0.10265

0.010

0.01578

0.000

101

2

99

9

113

195

101

2

0.05456

0.002

0.187

0.009

0.02506

0.000

160

2

174

7

394

91

160

2

AC C

EP

3.1665

0.003

Zircon_79_101

259

159

0.55

0.05211

0.002

0.10539

0.005

0.01463

0.000

94

1

102

4

290

88

94

1

Zircon_80_102

190

54

0.25

0.06561

0.004

0.13849

0.009

0.01531

0.000

98

2

132

8

794

127

98

2

Zircon_81_104

249

121

0.44

0.05089

0.002

0.09953

0.005

0.0144

0.000

92

1

96

5

236

105

92

1

Zircon_82_105

268

101

0.34

0.04808

0.005

0.09512

0.009

0.01464

0.000

94

2

92

9

103

193

94

2

ACCEPTED MANUSCRIPT

Zircon_83_106

1014

715

0.63

0.05045

0.001

0.16532

0.005

0.02373

0.000

151

1

155

4

216

61

151

1

Zircon_84_107

109

45

0.36

0.05479

0.003

0.10937

0.007

0.01448

0.000

93

1

105

7

404

129

93

1

Zircon_85_108

510

217

0.38

0.05099

0.001

0.17559

0.005

0.02499

0.000

159

Zircon_86_110

74

6

0.08

0.06345

0.007

0.13044

0.015

0.01543

0.000

99

Zircon_87_111

53

22

0.37

0.06564

0.007

0.1389

0.016

0.01583

0.000

101

Zircon_88_112

192

55

0.26

0.05547

0.004

0.1141

0.008

0.01492

0.000

95

Zircon_89_113

475

178

0.34

0.05687

0.003

0.121

0.007

0.01543

0.000

99

1

4

240

61

159

1

124

164

723

229

99

2

2

132

14

795

226

101

2

1

110

8

431

153

95

1

116

6

486

106

99

1 1

13

Zircon_9_017

271

161

0.53

0.05876

0.002

0.17093

0.005

0.02077

0.000

RI PT

1

133

1

160

5

558

59

133

Zircon_90_114

556

379

0.61

0.05169

0.002

0.1042

0.004

0.01459

0.000

93

1

101

3

272

69

93

1

Zircon_91_116

207

92

0.40

0.05373

0.003

0.13649

0.009

0.0191

0.000

122

2

130

8

360

135

122

2 2

SC

2

176

92

0.47

0.052

0.003

0.10586

0.007

0.01477

0.000

94

2

102

6

285

127

94

821

608

0.66

0.04963

0.002

0.09638

0.003

0.01406

0.000

90

1

93

3

178

74

90

1

Zircon_94_119

82

47

0.52

0.06764

0.010

0.14151

0.022

0.01517

0.000

97

2

134

19

858

301

97

2

Zircon_95_120

155

92

0.53

0.05007

0.003

0.13361

0.008

0.01965

0.000

125

2

127

7

198

119

125

2

Zircon_97_123

96

36

0.33

0.0712

0.006

0.15245

0.013

0.01584

0.000

101

2

144

12

963

169

101

2

Zircon_98_124

181

73

0.36

0.04881

0.004

0.09823

0.008

0.01478

0.000

95

1

95

7

139

155

95

1

Zircon_99_125

11044

5350

0.43

0.05264

0.006

0.10388

0.012

0.01485

0.000

95

2

100

11

313

232

95

2

Zircon_96_122

-1330

-458

0.31

0.05087

0.003

0.10769

0.007

0.01542

0.000

99

1

104

6

235

132

99

1

AC C

EP

TE D

M AN U

Zircon_92_117 Zircon_93_118

ACCEPTED MANUSCRIPT

Table 3. Summary of LA-ICPMS U-Pb data of zircons from sample A79-11 (El Potrero Grande Unit). CORRECTED RATIOS ±1s

207

Pb/235U

±1s

206

Pb/238U

±1s

Zircon_1_79-11_008

300

0.42

0.0503

0.003

0.08473

0.005

0.01222

0.000

Zircon_10_018

179

234

1.25

0.05078

0.003

0.08296

0.004

0.0119

0.000

Zircon_100_126

112

81

0.69

0.05137

0.004

0.08519

0.007

0.01203

0.000

Zircon_11_020

226

325

1.37

0.06318

0.004

0.10507

0.006

0.01197

0.000

Zircon_12_021

472

201

0.41

0.05958

0.003

0.1085

0.006

0.01321

Zircon_13_022

174

207

1.13

0.06798

0.003

0.10901

0.005

0.0117

Zircon_14_023

753

388

0.49

0.04945

0.001

0.08057

0.003

0.0118

Zircon_17_027

506

187

0.35

0.05251

0.002

0.0883

Zircon_18_028

329

124

0.36

0.05374

0.002

0.08929

CORRECTED AGES (Ma)

206

Pb/238 U 78

207

Pb/235U

±1s

208

Pb/232Th ±1s

1

83

5

78

1

Best age (Ma) 78

76

1

81

4

75

2

76

1

77

1

83

7

76

2

77

1

77

±1s

RI PT

Pb/206Pb

±1s 1

1

101

6

75

2

77

1

0.000

85

1

105

6

82

1

85

1

0.000

75

1

105

5

76

2

75

1

0.000

75.6

0.7

79

2

75

2

76

1

SC

Th/U

207

Th (ppm) 131

M AN U

U (ppm)

0.003

0.01224

0.000

78

1

86

3

77

2

78

1

0.004

0.01207

0.000

77.3

0.8

87

3

72

2

77

1

0.011

0.0125

0.000

80

2

104

10

78

1

80

2

0.003

0.01178

0.000

75.5

0.9

83

3

74

2

76

1

0.005

0.03922

0.000

248

2

247

4

236

5

248

2

0.004

0.01225

0.000

78

1

86

4

77

3

78

1

0.007

0.01226

0.000

79

1

94

6

77

1

79

1

0.003

0.01214

0.000

77.8

1

85

3

79

2

78

1

0.003

0.01189

0.000

76.2

0.8

81

3

77

2

76

1

0.002

0.01119

0.000

71.7

1

74

2

73

2

72

1

0.07433

0.002

0.01113

0.000

71.3

0.6

73

2

71

4

71

1

0.10693

0.009

0.0124

0.000

79

2

103

8

77

2

79

2

0.08226

0.003

0.01213

0.000

77.7

0.8

80

2

76

2

78

1

70

54

0.73

0.06228

0.006

0.10733

Zircon_2_009

414

140

0.32

0.0525

0.002

0.08493

Zircon_20_030

983

679

0.66

0.05097

0.001

0.2759

Zircon_21_032

324

153

0.45

0.05246

0.003

0.08827

Zircon_22_033

334

170

0.48

0.05729

0.004

0.09682

Zircon_23_034

628

193

0.29

0.05204

0.002

0.0874

Zircon_24_035

700

171

0.23

0.05066

0.002

0.08314

Zircon_25_036

2066

345

0.16

0.04904

0.001

0.07603

Zircon_26_038

2170

12

0.01

0.04845

0.001

Zircon_28_040

138

43

0.30

0.06252

0.005

Zircon_29_041

585

292

0.48

0.04892

0.001

EP

TE D

Zircon_19_029

107

43

0.38

0.05614

0.003

0.11547

0.006

0.01484

0.000

95

2

111

6

91

5

95

2

406

216

0.51

0.04986

0.003

0.08489

0.006

0.01235

0.000

79

1

83

5

79

2

79

1

Zircon_31_044

959

784

0.78

0.05126

0.001

0.08206

0.002

0.01159

0.000

74.3

0.7

80

2

75

2

74

1

Zircon_32_045

518

366

0.67

0.05137

0.001

0.08442

0.002

0.01196

0.000

76.6

0.9

82

2

78

2

77

1

Zircon_33_046

660

353

0.51

0.05148

0.002

0.08538

0.004

0.01203

0.000

77.1

0.9

83

4

76.3

0.8

77

1

Zircon_34_047

244

341

1.33

0.05832

0.002

0.09255

0.004

0.01157

0.000

74.2

1

90

4

73

2

74

1

Zircon_35_048

268

235

0.84

0.0547

0.002

0.08893

0.003

0.01185

0.000

75.9

1

87

3

75

2

76

1

Zircon_36_050

188

312

1.58

0.05674

0.003

0.08936

0.004

0.01148

0.000

74

1

87

4

74

2

74

1

Zircon_37_051

119

193

1.54

0.06522

0.008

0.10911

0.015

0.01213

0.000

78

2

105

14

75

1

78

2

Zircon_38_052

742

307

0.39

0.04924

0.002

0.07785

0.003

0.01146

0.000

73.5

0.7

76

2

74

2

74

1

AC C

Zircon_3_010 Zircon_30_042

ACCEPTED MANUSCRIPT

236

149

0.60

0.05167

0.003

0.10148

0.006

0.01425

0.000

91

1

98

6

90

1

91

Zircon_4_011

232

89

0.37

0.05522

0.005

0.0923

0.009

0.01212

0.000

78

1

90

8

76

2

78

1

Zircon_40_054

276

141

0.49

0.05459

0.002

0.08919

0.004

0.01189

0.000

76.2

1

87

4

75

2

76

1

Zircon_41_056

198

118

0.57

0.0528

0.003

0.08873

0.005

0.01219

0.000

Zircon_42_057

194

243

1.19

0.05105

0.005

0.08907

0.010

0.01265

0.000

Zircon_43_058

725

450

0.59

0.04793

0.002

0.0781

0.004

0.01182

0.000

Zircon_44_059

680

426

0.60

0.05207

0.002

0.08435

0.004

0.01175

0.000

Zircon_45_060

356

185

0.50

0.05344

0.002

0.09027

0.003

0.01235

0.000

Zircon_46_062

209

205

0.93

0.05704

0.003

0.09285

0.005

0.01194

0.000

Zircon_47_063

391

191

0.47

0.05253

0.002

0.0863

0.003

0.01193

Zircon_48_064

113

177

1.49

0.0519

0.003

0.08667

0.006

0.01229

Zircon_49_065

579

329

0.54

0.04681

0.002

0.07505

0.004

0.01163

Zircon_5_012

146

79

0.52

0.06754

0.006

0.11155

0.010

Zircon_50_066

154

75

0.46

0.05841

0.004

0.09544

Zircon_51_068

183

115

0.60

0.06062

0.004

0.10032

Zircon_52_069

664

367

0.53

0.0473

0.002

0.0794

Zircon_53_070

293

186

0.60

0.05113

0.002

0.09817

Zircon_55_072

3291

874

0.25

0.04735

0.001

0.06645

Zircon_57_075

257

171

0.63

0.05502

0.002

Zircon_58_076

214

93

0.41

0.05194

0.003

0.08364

0.005

Zircon_59_077

301

206

0.65

0.0487

0.002

0.0793

1

1

86

5

81

3

78

1

81

2

87

10

80

2

81

2

75.7

0.9

76

4

76

2

76

1

75.3

0.7

82

3

74.4

0.7

75

1

79

1

88

3

77

2

79

1

77

1

90

5

74

2

77

1

0.000

76.5

0.8

84

3

76

2

77

1

0.000

79

1

84

6

78

2

79

1

0.000

75

1

73

4

75

2

75

1

0.01198

0.000

77

1

107

9

74

1

77

1

0.007

0.01185

0.000

76

1

93

7

74

1

76

1

M AN U

SC

78

0.007

0.01219

0.000

78

1

97

6

79

3

78

1

0.003

0.01218

0.000

78

0.8

78

3

78

1

78

1

0.004

0.01397

0.000

89

1

95

3

90

2

89

1

0.001

0.01019

0.000

65.4

0.7

65

1

75

2

65

1

0.004

0.01158

0.000

74.2

1

85

4

71

2

74

1

0.01168

0.000

75

1

82

5

74

1

75

1

0.003

0.01187

0.000

76.1

0.8

77

3

74

2

76

1 1

TE D

0.0873

RI PT

Zircon_39_053

376

295

0.75

0.05586

0.002

0.08661

0.004

0.01116

0.000

71.5

1

84

3

71

2

72

728

351

0.46

0.04916

0.001

0.07907

0.002

0.01164

0.000

74.6

0.8

77

2

74

2

75

1

Zircon_61_080

440

194

0.42

0.05117

0.002

0.08606

0.005

0.0122

0.000

78.2

0.8

84

4

77.5

0.8

78

1

Zircon_62_081

208

91

0.41

0.0573

0.009

0.01186

0.000

76

1

91

8

74

1

76

1 1

EP

Zircon_6_014 Zircon_60_078

0.005

0.0937

208

691

3.16

0.06143

0.003

0.09975

0.005

0.0119

0.000

76

1

97

4

71

2

76

226

105

0.44

0.06007

0.002

0.11407

0.004

0.01384

0.000

89

1

110

4

92

3

89

1

Zircon_66_086

1244

467

0.36

0.05028

0.001

0.07759

0.002

0.01122

0.000

71.9

0.6

76

2

71

2

72

1

Zircon_67_087

112

174

1.48

0.0563

0.004

0.09524

0.006

0.01246

0.000

80

1

92

6

76

2

80

1

Zircon_68_088

662

159

0.23

0.05126

0.002

0.08099

0.003

0.01146

0.000

73.5

0.6

79

2

73

2

74

1

Zircon_69_089

138

164

1.13

0.0672

0.005

0.11877

0.009

0.01308

0.000

84

1

114

8

86

2

84

1

Zircon_7_015

173

92

0.50

0.05036

0.003

0.08804

0.005

0.01261

0.000

81

2

86

5

83

4

81

2

Zircon_70_090

286

144

0.48

0.05771

0.002

0.09798

0.004

0.01244

0.000

79.7

1

95

4

80

2

80

1

Zircon_71_092

350

502

1.37

0.05875

0.008

0.09485

0.014

0.01171

0.000

75

1

92

13

73

2

75

1

AC C

Zircon_63_082 Zircon_65_084

ACCEPTED MANUSCRIPT

95

59

0.59

0.06246

0.008

0.10339

0.015

0.01201

0.000

77

2

100

14

74

2

77

2

914

582

0.61

0.05373

0.001

0.08224

0.002

0.01111

0.000

71.2

0.6

80

2

73

2

71

1

Zircon_77_099

666

244

0.35

0.05049

0.002

0.07782

0.004

0.01118

0.000

71.7

0.7

1

Zircon_78_100

77

59

0.73

0.06492

0.007

0.11815

0.014

0.0132

0.000

Zircon_79_101

221

163

0.70

0.05489

0.003

0.08661

0.004

0.01151

0.000

Zircon_8_016

177

129

0.69

0.05586

0.003

0.11111

0.006

0.01447

0.000

Zircon_80_102

220

174

0.75

0.05289

0.002

0.08199

0.004

0.01123

0.000

Zircon_81_104

411

219

0.51

0.05288

0.005

0.09214

0.010

0.01264

0.000

Zircon_82_105

223

517

2.20

0.06352

0.003

0.10283

0.005

0.01188

0.000

Zircon_84_107

893

383

0.41

0.04958

0.001

0.07917

0.002

0.01157

4

71.1

0.8

72

85

2

113

13

81

2

85

2

74

1

84

4

75

2

74

1

93

2

107

6

91

4

93

2

72

1

80

4

72

2

72

1

81

2

89

9

80

2

81

2

76

1

99

5

76

2

76

1

0.000

74.2

0.8

77

2

76

2

74

1

0.000

71.6

1

73

2

78

2

72

1

0.000

75.9

0.7

82

3

75.2

0.6

76

1

SC

76

RI PT

Zircon_73_094 Zircon_74_095

2311

379

0.16

0.04835

0.001

0.07444

0.002

0.01117

Zircon_86_110

1334

484

0.35

0.05175

0.002

0.08456

0.003

0.01185

Zircon_87_111

398

198

0.47

0.05032

0.002

0.07918

0.003

0.01142

0.000

73.2

0.7

77

3

76

2

73

1

Zircon_88_112

407

149

0.35

0.04957

0.003

0.09122

0.005

0.01331

0.000

85

1

89

5

85

3

85

1

Zircon_9_017

147

169

1.09

0.06199

0.004

0.10443

0.006

0.01221

0.000

78

1

101

6

71

2

78

1

Zircon_90_114

743

389

0.50

0.0474

0.001

0.07483

0.002

0.01153

0.000

73.9

0.6

73

2

74

2

74

1

Zircon_91_116

317

134

0.40

0.0508

0.002

0.08243

0.003

0.01175

0.000

75.3

0.8

80

3

75

2

75

1

Zircon_92_117

144

84

0.55

0.05268

0.003

0.10325

0.006

0.01421

0.000

91

1

100

6

90

1

91

1

Zircon_93_118

151

116

0.73

0.05326

0.003

0.09015

0.006

0.01241

0.000

80

1

88

6

75

3

80

1

Zircon_94_119

762

190

0.24

0.0512

0.002

0.08216

0.003

0.01165

0.000

74.7

0.8

80

2

74

2

75

1

Zircon_95_120

540

317

0.56

0.04936

0.002

0.07842

0.003

0.0115

0.000

73.7

0.7

77

3

74

2

74

1

Zircon_97_123

69

164

2.25

0.05212

0.004

0.08367

0.006

0.01199

0.000

77

2

82

6

71

2

77

2

Zircon_98_124

215

321

1.43

0.04999

0.004

0.07985

0.007

0.01158

0.000

74

1

78

7

74

1

74

1

Zircon_99_125

741

426

0.55

0.05146

0.007

0.08302

0.012

0.0117

0.000

75

2

81

11

74

5

75

2

Zircon_15_024

158

187

1.13

0.06136

0.004

0.11737

0.010

0.01359

0.001

87

5

113

9

73

2

87

5

Zircon_16_026

767

191

0.24

0.09733

0.001

3.3345

0.057

0.24854

0.002

1431

13

1489

13

1309

25

1574

24

Zircon_54_071

252

79

0.30

0.06577

0.003

0.13632

0.009

0.01516

0.001

97

4

130

8

102

7

97

4

Zircon_83_106

283

129

0.43

0.09521

0.002

2.7643

0.063

0.21057

0.002

1232

9

1346

17

1212

9

1532

36

AC C

EP

TE D

M AN U

Zircon_85_108

ACCEPTED MANUSCRIPT

Table 4. WR 40Ar/39Ar analytical data from the andesitic sample JR10 (El Potrero Grande Unit) eastern Sonora, Arivechi region.

JR10 Can/Pos

Mineral

J

WR

± (1s)

0.004 0.000006

% error

Int Age (Ma) ± (2 s) with ± in J

0.16

212.73

0.92

1.13

221/JR10 AOR13-11

IsoPlot PA--> IsoPlot CA-->

Decay corrected true ratios Step no

Power

40Ar/39Ar

Plateau Age ± (2s)

±

38Ar/39Ar

±

37Ar/39Ar

36Ar/39Ar

±

±

40Ar*/39Ar(K)

with ± in J

RI PT

Sample no

MSWD % 39Ar

261.93

1.35

1.57

8.43

35.95

na

na

na

na

na

Probability Initial Ratio Initial Ratio Error na

na

na

261.90

1.80

na

0.80

28.59

0.45

280.80

5.30

±

40Ar*

Cumulative

Age

±

Ca/K

±

Cl/K

±

(%)

(Ma)

(1 s)

1

3.5

553.458

8.710

1.265

0.030

2.803

0.455

1.822

0.033

15.389

5.079

2.8

0.39

98.59

31.67

5.14

0.87

0.2095

0.02

2

4.5

162.443

1.943

0.597

0.013

2.666

0.371

0.509

0.010

12.324

2.239

7.6

1.10

79.38

14.11

4.89

0.72

0.1124

0.01

3

5.5

81.315

0.494

0.391

0.006

3.946

0.139

0.238

3.54

74.09

4.35

7.24

0.42

0.0767

0.01

4

6.5

59.549

0.314

0.330

0.004

4.991

0.123

0.157

5

8.0

56.574

0.273

0.255

0.003

6.447

0.131

0.131

6

9.5

47.233

0.281

0.387

0.004

8.646

0.142

0.078

7

11.0

48.846

0.229

0.998

0.008

3.348

0.058

0.047

8

12.5

53.740

0.231

1.054

0.006

2.577

0.054

0.034

9

14.5

51.733

0.294

1.115

0.008

2.218

0.067

0.032

10

18.0

47.458

0.236

1.000

0.008

2.043

0.074

11

22.0

45.944

0.158

1.332

0.007

2.271

12

27.0

49.101

0.169

1.329

0.007

13

31.0

47.629

0.165

0.857

0.005

14

35.0

35.845

0.108

0.682

0.004

2.077

(1 s)

(1 s)

M AN U

(1 s)

(1 s)

(1 s)

11.485

0.689

14.1

0.002

13.721

0.577

23.0

6.35

88.16

3.62

9.17

0.48

0.0661

0.01

0.002

18.530

0.423

32.6

10.14

118.07

2.61

11.85

0.60

0.0500

0.00

0.001

25.147

0.367

52.9

14.43

158.43

2.21

15.92

0.78

0.0830

0.01

0.001

35.357

0.274

72.2

21.37

218.98

1.60

6.14

0.30

0.2248

0.02

0.001

43.969

0.271

81.7

29.12

268.52

1.54

4.72

0.24

0.2382

0.02

0.001

42.569

0.326

82.2

34.98

260.56

1.86

4.07

0.23

0.2524

0.02

0.030

0.001

38.871

0.335

81.8

38.57

239.36

1.93

3.74

0.22

0.2258

0.02

0.061

0.026

0.000

38.586

0.196

83.9

48.66

237.71

1.13

4.16

0.22

0.3024

0.03

2.466

0.047

0.023

0.001

42.576

0.210

86.6

59.82

260.60

1.20

4.52

0.23

0.3020

0.03

2.007

0.044

0.019

0.000

42.365

0.192

88.8

71.00

259.39

1.09

3.68

0.19

0.1933

0.02

0.037

0.022

0.000

29.506

0.147

82.2

100.00

184.53

0.87

3.81

0.19

0.1528

0.01

TE D

0.003

EP

(1 s)

AC C

(%)

SC

(1 s)

39Ar (%)

ACCEPTED MANUSCRIPT San Luis Río Colorado

Upper Cretaceous-Cenozoic plutonic rocks (granite and granodiorite).

115° 114°

AR IZ SO ONA NO RA

32°

113°

Upper Cretaceous volcano-sedimentary rocks.

Sonoyta ?

RI PT

112°

Puerto Peñasco

109°

110°

111°

Agua Prieta

Nogales

75

31° Cananea 1000

29°00´

?

Im

?

Caborca

Esqueda

SC

## Santo Tomas

2000

Ma

Altar

CABORCA

Santa Ana Nacozari Arizpe

0

1500

1000

1000

Banámichi

o 3030°

30° 69

1

M AN U

2000

60 0

113 o

C. ZOROPUCHI

1000

31°

1

+

250

Moctezuma

00

10

C. LA BEBELAMA

C. PEÑASCO BLANCO

C. LA SATA C. EL MOGOLLON

1000

C. LAS CONCHAS

Las Conchas

C. COLORADO

29°

65 0

Arivechi

Tarachi

C. EL VOLANTIN Guisamopa

112 o

C. EL PALMAR

Yecora 5

## Bámori

250

1500

El Potrero Grande

Sahuaripa

HERMOSILLO

29 o

1500

ÑA DA DE

TA RA CH I

TE D

CA

C. EL SANTISIMO

C. EL ENCINAL

Tepache

Ures L

### Arivechi #

28 o28°

28°

Guaymas

500

250

C. SAN MIGUEL

Cd. Obregón

1000

Navojoa 27°

5

C. LA GOMILLA

0

AC C

R

## Valle de Tacupeto

1000

EP

500

study area

San Miguel

scale 0

20

40

60

kilómeters 0

2 kilometers

-109°20´

28°45´ -109°00´

Figure 1. Location of the study area to the east of Arivechi, Sonora, Mexico and outcrops of Upper Cretaceous rocks.

80

100

27°

ACCEPTED MANUSCRIPT 100

9::::

U/Pb Zircon Chrontours for the northern Peninsular Ranges of Alta and Baja California

90

110 120

Zircon Chrontours (Ma) 90 U/Pb Sample site

33° 135

115

USA ME XIC O

90 100 120

107

110

32°

90

110

Agu

a Bla

A

90

nca

lif Ca

Fau

lt

orn

RI PT

US

100

f lf o

Gu

120

97 +4/-1

110

80 70 60

ia

31°

120

Pa

140

100

ic cif

50

ea Oc

n

b

115°

SC

110 100

90

109 139

15

101 104

140

102 103

116°

117°

80

14

40

Ar/39Ar Hornblende Chrontours for the northern Peninsular Ranges of Alta and Baja California 90 40Ar/39Ar Hornblende Chrontours (Ma)

12

120

23

17

18

10

19

8

9

110

111

9::::

7

112

99

105

6

33°

116

114 113

9

4

121

119

125

126 124

120

10

60

12

70

115

130 131

136

15

122

11

130 14

17

148 147

142

21

140

22

120

120

137 138 134

145

141

50

USA ME XIC O

132 133

13 130

80

7

135 300

5

128 127129

117

144

130 23

39

28 96

25

24

90

26

100

40

34

49

44

50 48

43

38

105

42

110

58

35

80

58

52

37 45

36

100

46 47

78

62

32°

69 73

40

41

94

42

45 46

66

95 94 93

48

92

TE D EP

orn

5 4 3

53 2

1

81

9 40

8 8

6 1 2 4 6

82

93 9 18

10

25 23 55

80

16

an 79 77

90 100

73

110

c

120

117°

100 120 110

90

15

115°

116°

80

70

40

Ar/39Ar Biotite Chrontours for the northern Peninsular Ranges of Alta and Baja California

12

60

23 11 17 18 21

10

20

22

24 19

8 9

25

24

7

80 40Ar/39Ar Biotite Chrontours (Ma)

10

5

23

9

20

8

4

22

21

107

18

19 17

115 116 16

33°

2

114 113

1

7

1

15 6

8

5

12

14

4

13

3

7

2 3

121

119

6

125 126 123 124

120

130

11

3

117

131

USA ME XIC O

122

11

133

60

17 16

145 141

143

18

148

146

2

142

20 21

22

30

19

144

29

149

23

39

24

31

28 96

25

9::::

32

27 26

70

58 33

57

49 44

110

50 48

43

59

42 35

60

53

41

58

59

54

37

51 45

36

120

100

46

55

56 56

80

100

62 98

63

32°

68

64

74

61

71

90

41

64

42

lf Gu

40

80

63

73

70

94

80

79

62

72

69

77

44

67

60

61

57

47

46

66

75

47

81

88

96 95

89 88

90

86

94 93

48

49

cif

50 51

ca

91 90

52

Fault

70

5 4

40

3

53 54

1

2

25

9 6 81

82

1 2 4

93

92

8 10

18 17

Oc

23 55

24

80

16

n ea

60

ia

ic

100

orn alif

Blan

Pa

31°

60

89

Agua

of C

AC C

91 90

52

Fault

74

118

70 80 90

50 51

ca

ce

120

89

Blan

84 83

alif

85

cO

110

49

Agua

87 86

72

16

140

fC

85 84

cifi

31°

120

88

47

96

91 90

88

82 83

Pa

140

a

43

67

65

lf o

110

72

68

64

Gu

100 90

61

74 98

63

ia

M AN U

106

108

50

80 79 78

76

110

d

117°

116°

120

100

90

115°

Figure 10. (a) Palinspatic reconstruction for western Mexico before opening the Gulf of California in the Mesozoic and U-Pb chrontours for plutons of the Mesozoic western arc for the Peninsular Ranges. (b) Zircon U-Pb chrontours; (c) Hornblende 40Ar/39Ar plateau and K/Ar chrontours; (d) Biotite 40Ar/39Ar plateau and K/Ar dates chrontours for the Peninsular Ranges Batholith. Modified from Ortega-Rivera (2003). arrows indicate the likely direction of provenance of some detrital zircons in the study area.

ACCEPTED MANUSCRIPT

Volcanics rocks SMO angular unconformity

Limestone, Unknown age Conglomerate, Unknown age

EL POTRERO GRANDE UNIT

Limestone, shale, sandstone (Lower Cretaceous)

Limestone (Mississippian, Paleozoic) Dolomite (Proterozoic) Quartzite (Proterozoic)

d

M AN U

Block of igneous Permian rocks 40 39 Ar/ Ar 261±1.8 Ma

e

RI PT

Conglomerate, sandstone, siltstone (Permo-Triassic)

SC

Monoliths

Tuff (Permian)

Tuff

Trachydacite

Limolita Shale

Sandstone

e

Siltstone

Large megablock of possible Permian-Triassic rocks Large megablocks of Paleozoic and exotic rocks Shear zones Large megablock of possible Permian-Triassic rocks

c

AC C

EP

c

TE D

Conglomerate

d

CAÑADA DE TARACHI UNIT

UPPER CRETACEOUS

Granite (Upper Cretaceous)

b

Large megablocks of sedimentary Precambian rocks

b

Megablocks of sedimentary Precambian rocks

Megablock of conglomerate unknown age Large megablocks of Paleozoic rocks

a

Large megablocks of Lower Cretaceous rocks 40

Ar/39Ar KSP 69.57±0.48 Ma U-Pb Zircon 76.00±2.00 Ma

a

angular unconformity ?

Figure 2. Schematic stratigraphic column, without scale, that shows relationships between the Cañada de Tarachi and El Potrero Grande units in the Arivechi area and the interpreted monoliths in the Cañada de Tarachi and the El Potrero Grande units. a) The megablocks are separated by shear zones. Intense shearing between Paleozoic rocks and underlying Lower Cretaceous rocks around Cerro Las Conchas. b) Block constituted by conglomerate of unknown age in the Cañada de Tarachi stream. The block is surrounded by conglomerate of possible Triassic age. c) Megablock constituted by Paleozoic rocks exposed along the Arivechi-Tarachi road. d) and e) Blocks of Precambrian rocks along the Cañada de Tarachi stream. The block of figure e contains stromatolites that indicate the Precambrian age.

ACCEPTED MANUSCRIPT

109°09´

109°03´ 28°57´

9

Tv

EXPLANATION

22

1000

1100

38 49

33

40

26

Tgr

Pz

C. PEÑASCO BLANCO 72

SC

Tba

C. LAS CONCHAS

Las Conchas

Ksgr

Pz

Ki

A82-11

Pz

A78-11

58

52 58

38

Tgr

49 33 de da Tarachi 15 ña a C 65 81

50

24 5

35

57

35

15 30

35

75

40

30

20

Conglomerate, sandstone, shale, tuff, siltstone, andesite and megaliths

0

42

12

A79-11

39

C. EL BATAMOTE

40

40

42

25

34

45

Pc

Ks1

67

33

TR

35

C. EL VOLANTIN

48

El Potrero Grande

130

0

50

C. EL PALMAR

TE D

1300

Pc

C. LAS TIERRITAS

Tcg

Ks2

140

28

43

30

78

Ksgr

50

20

Granite

Pz

38

30

41

Tuff

Tgr

Andesite

Ks2

Pz

55

Pz

Tcg

51

Tv

C. COLORADO

M AN U

15

28°53´

TR

Basalt

PALEOGENE

C. LA BEBELAMA

31

Tba

RI PT

Ks2

Conglomerate, sandstone

Ks2

55

Conglomerate, sandstone,siltstone, andesite, tuff, monoliths

Ksgr Granite

Ki Limestone, shale

TR Conglomerate, sandstone, siltstone, shale, andesite

Pz

C. LA AGUJITA

74

EP 32

AC C

25

C. LA AGUJA

Pc

oyo

TR

Sa

31

C. LOS HORCONES

l

SIMBOLOGY 20

60

strike and dip normal fault strike-slip fault lineament megaliths

C. SAN MIGUEL

anticlinal

44

Mina Los Horcones

1000

35

?

San Miguel

Ks2

20

Arr

angular unconformity

40

c

Tcg

35

32

el igu

nM

Pc Quartzite, dolomite

0

1 Kilometers

28°50´

0

90

18

Limestone, andesite

1400

C. ZAPALUPA

El Potrero Grande Unit

Ks1

18

Tcg

NEOGENE

C. MOSIBOPA C. MOSIBOPA

syncline road sample locality

Figure 3. Geologic map showing the main synsedimentary megablocks of the Arivechi area. The map is modified from Rodríguez-Castañeda et al. (2015). The new interpretation (this work) includes the Permo-Triassic rocks in the study area.

Cañada de Tarachi Unit

Vinateria 43

42

UPPER CRETACEOUS

Tcg

Zoropuchi

MONOLITHS

59

C. ZOROPUCHI

ACCEPTED MANUSCRIPT

RI PT

Cerro Zoropuchi

b

M AN U

SC

a

d

f

AC C

e

EP

TE D

c

g

h

Figure 4. The Cañada de Tarachi conglomerate in the Cerro Zoropuchi (a and b) locality). Clasts are limestone of Paleozoic and Cretaceous ages. Conglomerates exposed along the Arivechi-Tarachi road (c, d, e and f) show sedimentary clasts with angular shapes, whereas, in the Cañada de Tarachi stream conglomerates (g and h) show well-rounded volcanic clasts. Sedimentary clasts are composed of quartzite, sandstone, chert and mudstone, whereas the volcanics clasts are mainly andesite and some tuffs.

70

14

a

A78-11

A78-11

n = 100

60

ACCEPTED MANUSCRIPT

data-point error ellipses are 2σ

0.12

A78-11

Intercepts at 262±12 & 1441±16 [±17] Ma MSWD = 5.5

n=8

12

0.10

10

2

0 400

a

600

800

1000

1200

1400

1600

1800

100

150

80

200

40

b n = 100

A82-11 n = 93

35

30

40 30

20 15

20

10

10

5 0

0 0

400

800

1200

50

1600

100

150

10

60

A79-11

EP

c

A79-11 n = 100

20 238

A82-11

0.12

Intercepts at 88.8±4.7 & 1589±160 Ma MSWD = 22

0.10

0.08

0.06

200 0.04 200

250

0

300

20

40

60 238

A79-11

n = 98

Intercepts at 70.5- 2.3 & 1832- 190 Ma MSWD = 11.7

40

20

Pb/206Pb

Number

30

0.08

207

AC C

Number

0.10 Relative probability

Relative probability

60

600

0.06 20

100

data-point error ellipses are 2σ

0.12

40

80

U/206 Pb

50 80

30

U/206 Pb data-point error ellipses are 2σ

Age, Ma

Age, Ma

100

TE D

50

25

Number

Number

Relative probability

60

200

0

300

Relative probability

M AN U

70

b

250

Age, Ma

Age, Ma

A82-11

600

0.04

50

SC

200

1000 0.06

0 0

0.08

Pb/206Pb

4

207

20

Pb/206Pb

6

1400

207

8

RI PT

30

Relative probability

40

Number

10

Relative probability

Number

50

10

200 0

c

0 0

400

800

Age, Ma

1200

1600

50

100

150

200

Age, Ma

250

300

0.04 0

20

40

60 238

U/206 Pb

Figure 5. U-Pb detrital zircon age-probability plots and the Concordia diagrams for (a) sample A78-11, (b) sample A82-11, and (c) sample A79-11. The second set of diagrams displays the younger populations in more detail.

80

100

120

ACCEPTED MANUSCRIPT

box heights are 2σ

Plateau steps are magenta, rejected steps are cyan

0.004

SC

Age = 261.9±1.8 Ma 40 36 Initial Ar/ Ar = 280.8-5.3 MSWD = 0.80

0.002

36

M AN U

Ar/40Ar

200

100

0

20

60

40 39

Cumulative Ar Percent

80

EP

0

TE D

0.001

100

0.000 0.000

0.004

0.008

0.012 39

0.016

0.020

Ar/40Ar

Figure 6. 40Ar/39Ar step-heating age spectrum and isotope correlation diagram of whole-rock sample JR10 from the block found in the El Potrero Grande unit.

AC C

Age (Ma)

0.003

data-point error ellipses 2σ

RI PT

300

0.024

ACCEPTED MANUSCRIPT

114°

l rie ab G ce n vin Sa Pro

Pina

l Pro

Sonoyta

?

UN MÉ

vinc

e

NEW MÉXI CO

S

32°

Douglas

TE D

Nogales

CHIUAHUA

SONORA

30°

)

ks

AC C

Caborca Block 1.8 - 1.7 Ga rock

D X I C S TAT E O

oc

EP

Pinal Province 1.7 - 1.6 Ga rock

ITE

R a rc ck talline bo Blo ic Crys Ca rca erozo bo f Prot Ca (Limit o

ia

orn

alif

fC

lf o

Gu Individual sample localities

San Antonio Basin

SC

ARIZONA

M AN U

BAJA CALIFORNIA

Localities of crystalline rocks of Precambrian age (ages established by means of isotopic studies of cogenetic zircon suites)

RI PT

Yavapai Province

Yuma

109°

110°

112°

HERMOSILLO

0

100 Km

Figure 7. Tectonostratigraphic terranes in northern Sonora and southern Arizona . The Pinal Province extends through Sonora and Arizona (modified from Anderson and Silver, 2005).

ACCEPTED MANUSCRIPT

N

0

Phoenix Buckeye Hills Maricopa Mountains San Tan Mountains Sierra Estrella

Webb Peak

Tank Mountains

Gila Bend Mountains

Zapata Wash

115´00° 116´00° CA LIF OR NIA NI A BA JA CA LIF OR

Yuma

115°

bou

Jhonny Lions Hills

Rincon Mountains

113°00´

32°

ry o

Sonoyta

97

f th eE

AR IZ S O O N A 112°00´ NO RA

.

.

.

.

.

.

.

.

.

.

108 ± 1.2 Ma 107 ± 1.8 Ma 102 ± 1.6 Ma 110 ± 1.6 Ma 97 + 4/-1 Ma

31°

69 64

Mo

jav

Caborca

96 ± 4 Ma

e-S

75

on

ora

Im

nA

nto

Sierra Buenos

Lo

SC

GU

ult

ar

LF OF CA

Nochebuena

s

Ajo 75.7+0.30/-0.70 Arizpe Nacozari sf 71.7±1.7 au lt 70.02±1.5 75 73.56±1.3 74.64±1.5 73.8±1.6 75.10±1.2 Bánamichi 74.30±1.3 69 69.1±2.4

OR

Moctezuma

72.20+1.60/-1.20 75.75+0.55/-0.85

A

CE

NI

CO AN

69.4±1.2

Isla Tiburón

29°00´

Ures

Tepache

62

72.0±1.2

75.9±0.8 HERMOSILLO 70.8±1.8 81.4±0.8 90.1±1.1 84.1±1.0 74.0±0.7

90.6 95.2

60 65

Mazatan

88.7 Sahuaripa

TE D

29°00´

Arivechi

.

Tarachi

.

72-70 90

Guisamopa

72 Yecora

89-70

kilómetros

28°00´

30°00´

Opodepe

M AN U

IFI

LIF

C PA

75

30°

31°00´

Esqueda

i Aires Magdalena o fa

he

79

95 ± 1 Ma

as

Cerros Mesteñas

Cananea

Sa

n

me

g Santa Ana

80

30°00´

Sierra Los Ajos

75 31°

Agua Prieta

Nogales

.

Puerto Peñasco

109°00´

110°00´

111°00´

Puerto Peñasco

92

150

PR

ABF

Dos Cabezas Mountains Little Dragoons Mountains

Tucson

Los Alacranes

nda

32°00´

Piñaleno Mountains

John The Baptist Mountains

Yuma

San Luis Río Colorado 114°00´ 84 Sierra 97

RI PT

117´00°

28°00´

scale

0

SO

AL

IF

O

R

N

IA

50 kilometers

EP

C

RA

JA

NO

BA

pre-Cenozoic reconstruction of Baja and Sonora

AC C

BAJA CALIFORNIA

Upper Cretaceous granitoids

Upper Cretaceous sedimentary rocks

Triassic-Jurassic metamorphic rocks Paleozoic sedimentary rocks

Overlap of magnetite and ilmenite series (magnetite-ilmenite boundary)

ABF = Agua Blanca Fault

100

Guaymas 500

Cd. Obregón

Navojoa

27°00´

27°00´

SONORA Upper Cretaceous and Cenozoic intrusives (Granite and granodiorita)

ARIZONA Anorogenic granitoids

Upper Cetaceous volcanosedimentary rocks. Anorogenic granitoids (circles)

84.1±1.0 U-Pb Zircon date 65, 90 U-Pb Zircon date

Figure 8. Map showing the 1) Eastern and Western Peninsular Ranges Batholith of Baja California (modified from Kimbrough et al., 2001; Ortega_Rivera, 2003; Geology from the Carta Geológica-Minera del Estado de Baja California, scale 1:500,000, Servicio Geológico Mexicano, 2008). 2) Outcrops of 1400 Ma anorogenic granites in Sonora (circles) and Arizona and their relationship with the major geologic structures in Sonora (modified from Carta Geológica-Minera del Estado de Sonora, scale 1:500,000, Servicio Geológico Mexicano, 2008; and Meijer, 2012); and 3) Exposed batholiths in Sonora (geology Carta Geológica-Minera del Estado de Sonora, scale 1:500,000, Servicio Geológico Mexicano, 2008). U-Pb data compiled from the literature (Anderson and Silver, 1969; Ortega-Rivera, 2003; Ramos-Velázquez et al., 2008; McDowell et al., 2001; Pérez-Segura, 2006; González-León, 2011). Inset square shows pre-Cenozoic reconstruction of Baja California and Sonora.

ACCEPTED MANUSCRIPT

PE

215-230 Ma

RM

UTAH COLO

N A R AD FO I EV AL C

TR IA

CHINLE FORMATION

IC

IA

SS 240-260 Ma

MOJAVE

Flagstaff

SC

36°

RI PT

N

O-

ARIZONA NMX

Barstow

240-250 Ma

C

San Bernardino

34°

O

R

D IL 210-225 Ma LE

Blythe

R

A

N

California ia Baja Californ

San Luis Río Colorado

TE D

32°

M AN U

DESERT

260-270 Ma .

.

.

.

.

.

30°

AC C

Triassic rocks

Sonoyta

M

AG

0

50

.

.

119°

ARIZONA Nogales SONORA .

.

.

.

.

AT I

C

Magdalena Santa Ana

AR

117°

116°

Nacozari

C Moctezuma

HERMOSILLO

Sahuaripa Arivechi

100

118°

Agua Prieta

Cananea

Caborca

Triassic plutons

29°

M

EP

31°

Puerto Peñasco

Tucson

Kilometers

115°

114°

113°

112°

111°

274-247 Ma 110° 109°

Figure 9. Map of southwestern North America and northern Sonora showing location of the Permo-Triassic Cordillera Magmatic Arc that can be extended to the Arivechi region. Modified from Riggs et al. 2013.

ACCEPTED MANUSCRIPT

Highlights Large-scale mass-gravity megablocks are characteristic feature of Upper Cretaceous rocks. U-Pb detrital zircon and 40Ar/39Ar ages reveal Permo-Triassic and Cretaceous sediments.

RI PT

We constrain the age of exposed Upper Cretaceous rocks.

AC C

EP

TE D

M AN U

SC

We provide new insights into the geological evolution of northwestern México.