Geochemistry of metasedimentary rocks from the Puncoviscana Complex in the Mojotoro Range, NW Argentina: Implications for provenance and tectonic setting

Journal of South American Earth Sciences 78 (2017) 250e263

Contents lists available at ScienceDirect

Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames

Geochemistry of metasedimentary rocks from the Puncoviscana Complex in the Mojotoro Range, NW Argentina: Implications for provenance and tectonic setting
lez a, *, Grony Garban b, Natalia Hauser c, Laura Gigena d Pamela A. Aparicio Gonza
pica, Consejo Nacional de Investigaciones Científicas y T
INGEISeCONICET Instituto de Geocronología y Geología Isoto ecnicas, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina b Centro de Geoquímica, Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, 3895, 1010-A, Venezuela c Laboratory of Geochronology, Instituto de Geoci^ encias, Universidade de Brasília, 70910 900 Brasília, DF, Brazil d Universidad Nacional de Salta, CP 3700 Salta, Argentina a

a r t i c l e i n f o

a b s t r a c t

Article history: Received 2 November 2016 Received in revised form 29 May 2017 Accepted 7 June 2017 Available online 15 June 2017

Low-grade metasedimentary rocks from the Lower Paleozoic Puncoviscana Complex of the Mojotoro Range in NW Argentina have been analyzed for their major and trace elements - including rare earth - in order to constrain their provenance and depositional tectonic setting. They show a moderate degree of chemical weathering with intermediate CIA (<75) values and can be classified as metawackes and metapelites. Provenance discrimination diagrams based on major element geochemistry and trace element ratios (i.e., Cr/V, Y/Ni, Th/Co, La/Sc, Th/Sc, Eu/Eu*) suggest that the sediments were derived from upper crustal, felsic source rocks. Tectonic setting discrimination diagrams based on major elements, immobile trace elements (i.e., La- Th- Sc and Th-Sc-Zr/10) and La/Yb vs. Eu/Eu* plots, support an active margin setting associated with a magmatic arc located to the east of the NeoproterozoiceCambrian Pampean Brazilian arc that formed along the margin of a Mesoproterozoic craton. © 2017 Published by Elsevier Ltd.

Keywords: Geochemistry Puncoviscana Complex Mojotoro Range Tectonic setting Provenance

1. Introduction The central and northwestern parts of Argentina (22
e33
S) were part of the tectonically active margin of Gondwana during the Late Proterozoic and early Paleozoic. This vast region is now composed of various geological provinces including the Eastern Cordillera, Puna and Famatina, and the Western and Eastern Pampeanas Range, which have as a common feature rocks with ages ranging from the Proterozoic to the Paleozoic. The outcrop pattern of the Puncoviscana Complex defines a series of narrow, north-south trending belts in the Eastern Cordillera (northwestern Argentina and southernmost Bolivia), which extends for more than 800 km parallel to the regional north-south strike over a width of circa 200 km (Fig. 1 a and b). The complex is mainly composed of a peliteegreywacke turbidite sequence, with subordinate sandstones and locally interbedded conglomerates, shelf limestones, and igneous rocks (Omarini and Baldis, 1984;

* Corresponding author. E-mail address: [email protected] (P.A. Aparicio Gonz
alez). http://dx.doi.org/10.1016/j.jsames.2017.06.003 0895-9811/© 2017 Published by Elsevier Ltd.


lez et al., 2010). Jezek, 1990; Aparicio Gonza
n, in the area of the Pampean Ranges, South of the city of Tucuma rocks of high metamorphic grade have been considered equivalents ~ olaza et al., 1988; Willner et al., to the Puncoviscana Complex (Acen 1985). In the Eastern Cordillera, this complex is overlain uncon
n formably by the Middle to Upper Cambrian siliciclastic Meso Group, which extends from southern Bolivia to northwestern Argentina (Moya, 1998; Kumpa and Sanchez, 1988; Augustsson
lez et al., 2014) (Fig. 1b). et al., 2011; Aparicio Gonza The basement to the Eastern Cordillera has been studied from different points of view, like sedimentology (Jezek, 1990; Salfity et al., 1975; Baldis and Omarini, 1984; Moya, 1998), paleontology
ngano and Buatois, 2004; Acen ~ olaza and Acen ~ olaza, 2005; (Ma
pez de Azarevich et al., 2012), structural Seilacher et al., 2005; Lo geology (Willner, 1990; Hongn, 1996), geochemistry (Do Campo and Ribeiro-Guevara, 2005; Zimmermann, 2005) and geochronology (Adams et al., 2011; Hauser et al., 2011; Escayola et al., 2011;
lez et al., 2014). These studies support different Aparicio Gonza provenance areas and tectonic environments related to sedimentation. A fore-arc basin (Kraemer et al., 1995; Keppie and Bahlburg, 1999; Zimmermann, 2005; Hauser et al., 2011; Escayola et al., 2011)


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

251

Fig. 1. a) Regional map showing the distribution of metasedimentary, sedimentary and granitic rocks of the NW Argentina basement. b) Map of the geological province. c) Local map of the Mojotoro Range with sampling areas.

or passive margin deposition (Jezek, 1990; Kraemer et al., 1995; Do ~a
n-Llamas and Simpson, Campo and Ribeiro-Guevara, 2005; Pin 2006). The Puncoviscana Complex was deformed, metamorphosed, ~
and uplifted during the Pampean orogeny (Pin an-Llamas and Simpson, 2006; Rapela et al., 2007; Ramos, 2008). The Neoproterozoic-Lower Paleozoic samples analyzed in this study are from the Mojotoro Range where Moya (1998) and
lez et al. (2010) defined three lithostratigraphic Aparicio Gonza units for the Puncoviscana Complex: the Chachapoyas, Alto de la Sierra and Guachos Formations. They represent the nucleus of the Eastern Cordillera and are well exposed (Zimmermann, 2005;


lez et al., 2010). In order to identify the proveAparicio Gonza nance areas and the tectonic setting associated with the sedimentation of these three formations, new petrographic and geochemical data are presented. These data help to better understand the evolution of the Gondwana continent in the late Neoproterozoic-Cambrian (see also McLennan et al., 1990, 1993; McLennan and Taylor, 1991; Zimmermann, 2005) (Fig. 1c). 2. Geological setting and stratigraphy The NW Argentina basement registered at least two main

252


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

~ olaza and orogenic events: the Pampean Event (550-520 Ma) (Acen Toselli, 1973) between 600 and 520 Ma (Ramos, 2008) and the ~ olaza and Toselli, 1973). Famatinian Event (490-460 Ma) (Acen In the Eastern Cordillera, the first event is well represented by the deposition of the Puncoviscana Complex, which was intruded during the Early Cambrian by the Tastil batholith (517e533 Ma, ~ ani granite (519e534 Ma, Bachmann et al., Hauser et al., 2011), Can ~ i granite (511 Ma, 1987 and Escayola et al., 2011), Nevado de Chan Zappettini et al., 2008), and Mojotoro granite (533 Ma, Aparicio Gonz
alez et al., 2011).
n Group (Turner, 1960), which is composed by Lizoite, The Meso Campanario and Chahualmayoc Formations (Turner, 1960), lies above Puncoviscana Complex in angular discordance. It is composed of the Lizoite, Campanario and Chahualmayoc formations (Turner, 1960), a set of deposits accumulated in sub- and
nchez, 1999). The age for this interetidal coastal environments (Sa group is considered middle to upper Cambrian (Adams et al., 2011; Augustsson et al., 2011; Aparicio Gonz
alez et al., 2014). The pelitic marine deposits with sandstone and limestone intercalations of the Santa Victoria Group (Turner, 1960) lie above a
n Group. further discordance (named Iruya) above the Meso The Mojotoro Range, located in the SW part of the Eastern Cordillera, represents one of the most complete stratigraphic columns for the Lower Paleozoic of NW of Argentina (Fig. 1c). This range is an anticline with N-S axis as a principal structural feature, strained by important inverse faults of submeridian strike on its eastern flank, which cause the strong asymmetry of the structure and inversion of the central section. The release of the intense compression is resolved in extensional structures generated in the anticlinal hinge. The stratigraphic core of the Mojotoro Range is the Puncoviscana Complex and it was divided into Chachapoyas, Alto de la Sierra and Guachos formations (Figs. 1c and 2).
lez et al., 2010; The Chachapoyas Formation (Aparicio Gonza
lez et al., 2014) is exposed along the western flank Aparicio Gonza of the Mojotoro Range. To the west, the sequence unconformably (Tilcara unconformity) underlies the Lizoite Fm. and to the east it is in tectonic contact with the Guachos Fm. The Chachapoyas Formation is mainly composed of green, grey and purple, laminated metapelites. Sporadically, this facies is associated with grey and green, fine- and medium-grained metasandstone which appears in discontinuous, apparently massive banks. Folding is intense, with a strong cleavage of axial planes. This tectonic characteristic makes the observation of major sedimentary attributes that would allow to discuss probable paleoenvironments, difficultealso due to the faulting that affected the stratification to varied degrees. In accordance with Hongn (1996), the dominant strike of the folded stratification varies between NE and SW, with variable dips, and cleavage of NE-SW plunge and high plunge to SE in the Mojotoro river. The Chachapoyas Formation deposits register two metamorphic foliations, at least: S1 and S2, developed under a strong compositional control. They are well represented in the metapelitic facies. In the central part of the Mojotoro Range, the unit is intruded
lez et al., 2011). by granitic rock dated at 533 ± 2 Ma (Aparicio Gonza
lez et al., 2010, The Alto de la Sierra Formation (Aparicio Gonza 2014) is characterized by layers of purple and grey sandstones, exposed in the northern part of the Mojotoro Range. On the western flank of the structure, the sequence is unconformably
n Group. Generally, it is a group of silicoclastic overlain by the Meso rocks that outcrops relatively continuously, dipping to the NE. The Alto de la Sierra Formation is a sandy unit, mainly constituted of coarse, stratified greywacke, with intercalated rare and thinly laminated metapelites. The Guachos Formation (Moya, 1998) crops out in the central part of the Mojotoro Range and is characterized by a rhythmic

Fig. 2. Schematic stratigraphic column showing the relationship between the different stratigraphic units defined in the Eastern Cordillera and also giving the ages for the main intrusive rocks.

sequence displaying NE-SW structural trends. The contacts between this unit with Ordovician rocks of the Santa Victoria Group to the east and with the Chachapoyas Formation to the west are tectonic. The sequence is heterolithic and consists of brown to greenish-brown, shaly sandstones, characterized by the presence of Nereites ichnofacies. The depositional age of the Puncoviscana Complex is a controvertial issue. The complex has been tradition
and ally considered of Neoproterozoic-Cambrian age (Mirre ~ olaza, 1972; Acen ~ olaza and Durand, 1973; Ma
ngano and Acen ~ olaza and Acen ~ olaza, 2005; Seilacher et al., Buatois, 2004; Acen 2005; Aparicio Gonz
alez et al., 2010; Hauser et al., 2011; Escayola et al., 2011). Our detailed studies in the Mojotoro Range allowed dating of detrital zircons by U-Pb LA-ICP-MS methods that established the maximum sedimentation ages of the Chachapoyas, Alto de la Sierra and Guachos formations at 569 ± 3 Ma, 543 ± 1 Ma, and
lez et al., 2014). Several 517 ± 5 Ma, respectively (Aparicio Gonza papers about the geochemical features of the Puncoviscana Complex have been published, such as Zimmermann (2005) and Do Campo and Ribeiro-Guevara (2005). The former author defined the Puncoviscana Complex, an informal term according to the Nomenclature for Metamorphic and Sedimentary Rocks of the


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

British Geological Survey (Hallsworth and Knox, 1999). We use the
digo Argenterm Puncoviscana Complex sensu article 32 of the Co
lez et al., 2014) to comprise the tino de Estratigrafía (Aparicio Gonza entire stratigraphic core of the Eastern Cordillera. Zimmermann (2005) presented geochemical data for the stratigraphic core of the Eastern Cordillera and Pampean Ranges. The basement rocks of these two geological provinces have diverse lithology, metamorphic grades and, in some cases, different ages. For example, for the Cebila outcrops studied by Zimmermann (2005) as part of the Puncoviscana Complex, Verdecchia et al. (2007) later showed that these rocks have Ordovician ages, according to the fossil record and U-Pb geochronology on detrital zircons. Another example is from Famatina, where Collo and Astini (2008) described the Achavil Formation of upper-middle Cambrian age that was correlated with
n Group. The Achavil Formation was traditionally the Meso considered part of the Puncoviscana Complex by Zimmermann (2005). On the other hand, Do Campo and Ribeiro-Guevara (2005) studied geochemical data of samples of the Puncoviscana Complex at diverse outcrops of the Eastern Cordillera and determined a passive margin setting for the sedimentation of these metasediments. 3. Analytical methods for the geochemical analysis Twenty samples for major and trace, including rare earth, element analysis were selected from the Puncoviscana Complex at the Mojotoro Range: ten samples from the Guachos Formation (P006, P023, MLQ, RM26, CQ, CG, MR901, MP2, MG2, MP5), five samples from the Alto de la Sierra Formation (C002, C04, C005, M2a, M1), and five samples from the Chachapoyas Formation (P029, RM03, RM03A, RM04, M013). Sample locations, stratigraphic units, rock types, and mineral compositions are given in Table 1. All samples were washed with distilled water and powderized in a mill at the Universidad Nacional de Salta, Argentina. Major element analyses were obtained by X-ray fluorescence spectrometry at the University of Salta, Argentina following the procedure given by Ahmedali (1989). Sample aliquots for trace, including rare-earth, element analysis were sent to ACME Labs, Canada, where they were analyzed by ICP-MS (Table 1). Table 1 Samples analyzed for major and trace elements: location, stratigraphic units, rock type, and main minerals are referred. Mineral abbreviations after Kretz (1983). Samples

Location

Chachapoyas Formation P029 Pedrera RMO-4 Mojotoro River RMO-3 Mojotoro River RMO3 Mojotoro River MO13 Mojotoro River Alto de la Sierra Formation C002 Route 9 C04 Route 9 M-1 Route 9 M2a Route 9 C005 Route 9 Guachos Formation P006 Pedrera P023 Pedrera MLQ Quesera RML26 Mojotoro River CQ Quesera MR9-01 Route 9 CG Guachos MP2 Pedrera MG-2 Gallinato MP-5 Pedrera

Major mineral composition

Rock type

Qtz, Qtz, Qtz, Qtz, Qtz,

Kfs, Kfs, Kfs, Kfs, Kfs,

Plag, Ill, Chl, Zrn, Plag, Ill, Chl, Zrn, Plag, Ill, Chl, Zrn, Plag, Ill, Chl, Zrn, Plag,Chl, Zrn, Op

Metapelite Metapelite Metawacke Metapelite Metawacke

Qtz, Qtz, Qtz, Qtz, Qtz,

Kfs, Kfs, Kfs, Kfs, Kfs,

Plag, Plag, Plag, Plag, Plag,

Chl, Lvf, Lm, Zrn, Op Ill, Zrn, Op Chl, Zrn, Op Chl, Lvf, Lm, Zrn, Op Ill, Zrn, Op

Metawacke Metapelite Metawacke Metawacke Metapelite

Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz, Qtz,

Kfs, Kfs, Kfs, Kfs, Kfs, Kfs, Kfs, Kfs, Kfs, Kfs,

Plag, Plag, Plag, Plag, Plag, Plag, Plag, Plag, Plag, Plag,

Ill, Ill/Chl, Zrn, Op Ill, Chl, Zrn, Op Ill, Lt, Zrn, Op Ill,Ill/Chl, Zrn, Op Ill,Ill/Chl, Zrn, Op Ill,Ill/Chl, Zrn, Op Ill, Ill/Chl, Zrn, Op Ill, Ill/Chl, Zrn, Op Ill, Ill/Chl, Zrn, Op Ill, Chl, Zrn, Op

Metapelite Metapelite Metawacke Metapelite Metapelite Metapelite Metapelite Metapelite Metapelite Metapelite

Op Op Op Op

253

4. Petrography The petrographic analysis was carried out to classify the rocks, according to Folk et al. (1970), and determine the source area from minerals and clasts that compose the rocks. 4.1. Chachapoyas Formation The metapelites of the Chachapoyas Formation are characterized by alternating layers rich in phyllosilicates (white mica and chlorite) and others composed of quartz and plagioclase. In general, the contacts between grains are moderately sutured and occasionally polygonal. Two foliations can be observed (S1 and S2) that were developed under strong compositional control: they are best seen in the phyllosilicate rich bands. A preferred orientation of white mica and chlorite can be seen, whereby S1 behaves like a continuous foliation and passes into the domains rich in quartz and plagioclase. The S2 foliation is observed in some cases as an asymmetric to symmetric crenulation of S1 and is emphasized by oriented growth of white mica and chlorite. In this sample quartz veins are also observed in the concordant sandstones; and some discordant regarding S0/S1 and are distorted in folds and boudinage structures. The veins are filled by opaque minerals, with iron oxides. In general, they are characterized by continuous development, with irregular walls, variable thickness (<0,3 mme1 mm). The veins are taking advantage of the planes defined by the S1 and S2 foliations, although they are usually discordant to S1. Locally, very thin veins discordant to the S2 foliation can be recognized also composed of opaque minerals (Fig. 3a and b). The associated quartz meta-sandstones (Folk et al., 1970) show a clast-supported texture, moderately sorted, with deformation and recrystallization evidence. The matrix is scarce, 5% approximately and it is composed of very fine-grained quartz and phyllosilicates (illite and chlorite). The cement is siliceous and generally found to be in optical continuity with the quartz grains. 4.2. Alto de la Sierra Formation Samples of purple metawacke and grey metawacke have similar mineralogy, and for both facies three petrographic types are recognized, which according to Folk et al. (1970) can be classified as lithic, feldspathic and quartz metawackes. The rocks have deformation features that sometimes make mineral identification difficult. Petrographically, the reorientation of the detrital grains, intracrystalline deformation, pressure dissolution and, in some cases, recrystallization can be observed. The granulometry is predominantly medium to fine. The main minerals recognized in the samples are quartz, feldspars, lithics, mica and accessory minerals. In most of the samples, the dominant mineral is quartz at 65e90%. Feldspars account for 2e25%, lithics to 1e30%, and phyllosilicates to <10 vol%. These are illite, possibly phengite, chlorite, and white mica that is intergrown with chlorite. The most common lithics have volcanic and metamorphic origin (Fig. 3c, d and 3e). The former grains are altered and are in some cases, very difficult to differentiate at the optical scale, although they can be identified with Scanning Electron Microscopy. The acid volcanic lithics are composed of microphenocrysts of twinned plagioclase in a siliceous, undifferentiated matrix. Polycrystalline quartz clasts form mosaics of 0.4e0.5 mm size; they show, on the one hand, sutured contacts, and are thought to have been metamorphosed (Fig. 3f); and on the other hand, concave-convex contacts probably derived from plutonic rocks. Chert particles were also recognized. The accessories are tourmaline, rutile, epidote, zircon and opaque minerals.

254


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

Fig. 3. a) and b) Photomicrograph of the Chachapoyas Formation metapelites with foliations S1 and S2, and crenulation cleavage. c) General view of a metawacke from the Alto de la Sierra Formation showing polycrystalline quartz (Qp), chert fragments (Lc), metamorphic lithics (Lm), and potassium feldspar (FK). d) Metawacke from the Alto de la Sierra Formation showing chert fragments (Lc) and metamorphic lithics. e) Metawacke from the Alto de la Sierra Formation showing volcanic lithic fragments (Lv) and monocrystalline quartz (Qm). f) Metawacke from the Alto de la Sierra Formation showing metamorphic lithics (Lm), polycrystalline quartz (Qp), and monocrystalline quartz (Qm). g) Mudstone facies from the Guachos Formation; the light bands represent felsic layers and the dark bands are composed of phyllosilicates. h) A metawacke from the Guachos Formation showing volcanic lithic fragments (Lv) and monocrystalline quartz (Qm).

4.3. Guachos Formation The metasandstones of this formation have quartz as the dominant mineral, which constitutes more than 90% of the rocks. Due to recrystallization, authigenic overgrowths and grain size, it is difficult to observe the original shape of the clasts. Plagioclase is more important than K-feldspar. Lithics are scarce and generally

chert. The matrix is made up of white mica and chlorite. Millimeter sized crystals of the matrix surround the quartz and plagioclase clasts. Mixtures of white mica-chlorite can be observed to follow cleavage planes. Pyrite, zircon and opaque minerals are the common accessories. Chert and felsic volcanics are the most common lithics but are low in abundance. The matrix is micaceous and abundant pseudomatrix, product of clast deformation, is observed.


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

255

(Fig. 3h). Shales are mainly composed of fine-grained white mica, white mica/chlorite intercalations, quartz, and opaque minerals (Fig. 3g). They record an occasional S1 secondary foliation, oblique to millimeter wide sedimentary lamination (S0), with alternating light quartz-rich and dark, phyllosilicate-enriched, bands. 5. Geochemical results 5.1. Major elements Major element data are compiled in Table 2. SiO2 content in the Chachapoyas Formation samples varies between 60.33 and 71.85 wt%; the highest values are recorded for the quartz metawackes and the lowest values for metapelite. The content of Al2O3 (13.0e17.9 wt%) has an average value similar to Upper Continental Crust (UCC), and samples with high Al2O3 are dominant due to the importance of metapelites in the formation. The percentage of Na2O (1.53e3.39 wt%), K2O (1.52e4.52 wt%), and Fe2O3 (4.04e6.85 wt%) matches the values calculated for the UCC by Taylor and McLennan (1985). SiO2 contents for samples from the Alto de la Sierra Formation are between 57.54 and 73.24 wt%; Al2O3 content ranges from 12.71 to 19.81 wt%; Na2O content from 0.52 to 3.6 wt%; K2O content from 2.1 to 6.93 wt%, and Fe2O3 content from 4.68 to 7.78 wt%. For all these elements the values are similar to UCC (Taylor and McLennan, 1985). The SiO2 content for the Guachos Formation samples varies between 60.87 and 72.14 wt%, and the Al2O3 content between 12.63 and 17.45 wt%; again, these are similar values as determined for the UCC. Also the contents of Na2O (1.41e2.98 wt%), K2O (2.34e5.06 wt %), and Fe2O3 (3.83e7.54 wt%) are similar to the values calculated for UCC (Taylor and McLennan, 1985). The majority of samples from the studied strata are classified as greywackes according to Herron's (1988) diagram (Fig. 4), and some samples fall into the shale field. The diagram suggests that the metamorphic processes responsible for matrix production proceeded without major changes to the bulk rock chemistry. The

Fig. 4. Geochemical classification of low-grade metasedimentary rocks from of Chachapoyas, Alto de la Sierra and Guachos formations (Puncoviscana Complex) of the Mojotoro Range using the diagram log (SiO2/Al2O3) vs. log (Fe2O3/K2O) (after Herron, 1988).

relative contents of Fe2O3 and K2O are variable, whereas the SiO2 and Al2O3 contents are more uniform.

5.2. Paleoweathering: weathering indices and A-CN-K discrimination The degree of weathering can be quantitatively assessed with the Chemical Index of Alteration (CIA) after Nesbitt and Young (1984). The CIA is defined as the ratio Al2O3/ [Al2O3 þ CaO* þ Na2O þ K2O]  100 (molar contents, where CaO* is the amount of Ca incorporated into the silicate fraction of the rock). This value allows to quantify the weathering rate and infer the dominant paleoclimate. A CIA index >92 indicates intense weathering, due to feldspar transformation to clay minerals (Potter et al., 2005). CIA values between 60 and 80 indicate intermediate weathering, and CIA <60 reflects a very low degree of chemical
bal et al., 2009). Fresh basalts weathering (Fedo et al., 1995; Aristiza

Table 2 Major oxide (SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O and K2O) and minor oxide (MnO, TiO2 and P2O5) data for samples from the Chachapoyas, Alto de la Sierra, and Guachos formations. * Measured by X-ray fluorescence spectrometry at the National University of Salta, Argentina. a Measured by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) at ACME Laboratories, Ottawa, Canada. Samples

CIA

WIP

Chachapoyas Formation P029 73.48 60.12 RMO-4* 72.84 58.98 RMO-3* 67.48 49.24 RMO3a 70.82 60.79 MO13a 70.61 50.93 Alto de la Sierra Formation C002a 67.75 55.50 C04a 72.53 68.77 M-1* 73.67 43.74 M2a* 63.30 55.58 C005a 71.42 67.23 Guachos Formation P006a 72.63 58.16 P023a 74.06 59.66 MLQa 64.37 54.83 RML26a 71.74 51.68 CQ* 72.60 55.60 MR9-01* 72.46 55.61 CG* 73.04 63.07 MP2* 73.11 62.26 MG-2* 76.67 50.37 MP-5* 73.43 58.11 UCC

SiO2 wt%

Al2O3 wt%

Fe2O3 wt%

MnO wt%

MgO wt%

CaO wt%

Na2O wt%

K2O wt%

P2O5 wt%

TiO2 wt%

LOI

60.33 61.99 75.34 64.82 71.85

17.93 16.97 11.14 16.24 13.00

6.49 6.84 4.03 5.62 4.30

0.05 0.15 0.22 0.09 0.08

2.38 2.46 1.41 1.78 1.76

0.42 0.47 0.46 0.45 0.31

1.53 1.77 3.39 2.39 2.72

4.52 4.08 1.52 3.85 2.38

0.19 0.17 0.25 0.22 0.17

0.80 0.70 0.60 0.80 0.61

5.20 4.80 1.98 3.60 2.60

72.38 58.69 71.82 73.24 57.54

12.71 19.81 13.68 12.18 18.32

4.68 6.46 4.67 4.05 7.78

0.07 0.05 0.04 0.07 0.07

1.30 1.81 1.36 1.32 2.59

0.35 0.05 0.26 1.72 0.55

3.60 0.52 0.05 3.00 1.53

2.10 6.93 4.57 2.34 5.25

0.19 0.02 0.20 0.21 0.19

0.75 0.80 0.64 0.65 0.81

1.70 4.60 2.78 1.83 5.20

61.38 61.50 72.14 68.05 66.36 66.19 60.86 62.36 62.44 61.45 66.00

16.93 17.45 12.63 14.14 15.49 15.54 17.68 17.46 17.40 17.54 15.20

6.49 6.79 3.83 5.37 6.14 6.14 7.53 7.14 7.21 6.68 4.50

0.08 0.07 0.06 0.06 0.11 0.08 0.12 0.07 0.09 0.11 0.08

2.16 2.98 1.17 2.02 2.40 2.47 2.92 2.90 2.40 2.18 2.20

0.54 0.28 1.67 0.45 0.35 0.46 0.28 0.26 0.21 0.56 4.20

1.69 1.68 2.98 2.04 1.94 1.79 1.70 1.73 0.02 1.41 3.90

4.15 4.15 2.34 3.08 3.56 3.65 4.55 4.43 5.06 4.43 3.40

0.19 0.18 0.18 0.21 0.22 0.24 0.20 0.20 0.16 0.16 0.17

0.76 0.75 0.64 0.66 0.74 0.76 0.84 0.80 0.88 0.73 0.50

5.50 3.90 2.10 3.70 3.12 3.12 3.50 3.27 5.00 4.10

256


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

have values between 30 and 45, fresh granites and granodiorites of 45e55 (Nesbitt and Young, 1984; Fedo et al., 1995). Kaolinite has a CIA value of 100 and represents the highest degree of weathering, whereas illite has a CIA value between 75 and 90, muscovite 75, and finally feldspars 50. The CIA values for the Puncoviscana Complex samples from the Mojotoro Range vary between 64 and 74, in agreement with intermediate weathering. The CIA values for the Chachapoyas Formation lie between 71 and 73; and values between 68 and 72 were obtained for samples from the Alto de la Sierra Formation and of 64e74 for samples from the Guachos Formation. This outcome is similar to results obtained by other authors (Zimmermann, 2005; ~ an Lamas & Escamillas, Do Campo & Ribeiro-Guevara, 2005; Pin 2013) for metapelites and metasandstones from the Puncoviscana Complex in other areas. In the SiO2 vs. CIA diagram, our samples plot together and indicating a CIA rate between 65 and 75 - indicating intermediate weathering, regardless of the samples’ SiO2 values. An effective way to compare the evolution of the chemical weathering degree in samples from different stratigraphic levels is the method by Bahlburg and Dobrzinski (2011). Frequently, the CIA values are also compared with the values of the Weathering Index after Parker (1970: WIP). The WIP considers the transformation of feldspars to clay minerals with respect to the mobility of major alkali and alkaline earth elements. In addition, it takes into consideration the differential mobility of the various elements, which is related to the differential strengths of oxygen bonds. The WIP is defined as (100) x [(2Na2O/0.35) þ (MgO/0.9) þ (2K2O/ 0.25) þ (CaO/0.7)], whereby the denominator values represent the strengths of the bond as a measure of the necessary energy for breaking the cation-oxygen bonds in the respective oxides. The WIP values oscillate between 100 and 0, and differ from the CIA: the lower the WIP values, the higher the weathering degree. The CIA vs. WIP diagram (Fig. 5a) shows that the samples from the three studied formations of the Puncoviscana Complex fall into the same field (WIP between 40 and 70 and CIA between 60 and 80) that corresponds to a moderate weathering degree. This allows us to interpret that the original sediments were poorly affected by chemical alteration processes. The triangular diagram Al2O3-CaO*þNa2O-K2O (A-CN-K) allows to evaluate the trend of weathering of original sediments (Fedo et al., 1995). This diagram not only allows to estimate the

magnitude of chemical weathering, but it is possible to evaluate and correct for post-depositional alteration effects, such as potassic metasomatism, and what is more, it allows to obtain information about the original rock composition that provided the sediments (Fedo et al., 1995). In many weathering profiles, the ideal trend for weathering (no post-depositional alterations) can be followed by drawing a line parallel to the A-CN line of the ternary diagram (Nesbitt and Young, 1984). The extension of the intersection of the shown tendencies by the analyzed samples (coincident with lines parallel to A-CN) and the feldspar join allows to obtain the ratio between plagioclase and K-feldspar in the original, presumed fresh rock, (Fedo et al., 1995). The A-CN-K diagram (Fig. 5b) shows that the majority of samples from the Guachos, Alto de la Sierra and Chachapoyas formations falls into the field of intermediate weathering, with some samples plotting in the weak weathering field (metagraywackes M2A and MLQ from the Alto de la Sierra and Guachos formations, respectively). Samples from all three formations form a distinct array that is quite different from the inferred ideal weathering trends (dashed-line arrow), with a general trend toward illitemuscovite compositions (solid-curve arrow). This could suggest that some potassium metasomatism (Fedo et al., 1995) affected this sample set. Another possibility to explain this data configuration (intersection of the ideal weathering trend with the feldspar join, and the cluster of data) could be that the Puscoviscana Complex samples are derived from granodioritic and/or granitic-rhyolitic sources. 5.3. Trace elements In order to evaluate the effect of sediment recycling, the Th/Sc vs. Zr/Sc diagram (McLennan et al., 1993) was used as a tool to deduce mineral selection and sediment recycling for clastic rocks. Th/Sc and Zr/Sc ratios show a strong positive correlation in sedimentary rocks - the products of the initial sedimentary cycles; however, for clastic rocks that result from strong mineral selection and sediment recycling (multiple sedimentation cycles), the Zr/Sc ratio increases more strongly than the Th/Sc ratio that does not vary significantly (McLennan et al., 1993) (compare our Table 3). In Fig. 6 it can be seen that the samples of the three analyzed formations plot far from the magmatic compositional variation trend of rocks, with a trend toward zircon concentration (high Th

Fig. 5. a) Relationship between two weathering proxies, CIA (Nesbitt and Young, 1984) and WIP (Parker, 1970), for metasedimentary samples from the Chachapoyas, Alto de la Sierra, and Guachos formations (Puncoviscana Complex). b) A-CN-K and CIA diagram (after Fedo et al., 1995) showing the weathering trend for the studied samples. Dashed-line arrows represents the predicted weathering trend for different, typical igneous rocks. Values for the AGV-2, BCR-2 and RGM-2 reference materials from the USGS Certificate of Analysis Fact Sheet (http://crustal.usgs.gov/geochemical_reference_standards/).


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

257

Table 3 Trace element data for samples from the Chachapoyas, Alto de la Sierra, and Guachos formations. Eu* PAAS. Eu** chondrite. Chachapoyas Formation

Alto de la Sierra Formation

Guachos Formation

UCC

P029

RMO3

Mo13

C04

COO5

COO2

P006

P023

MLQ

RM26

Sc ppm V ppm Ba ppm Sr ppm Y ppm Zr ppm Cr ppm Co ppm Ni ppm Cu ppm Zn ppm Ga ppm Rb ppm Nb ppm Cs ppm La ppm Ce ppm Pr ppm Nd ppm Sm ppm Eu ppm Gd ppm Tb ppm Dy ppm Ho ppm Er ppm Tm ppm Yb ppm Lu ppm Hf ppm Ta ppm Pb ppm Th ppm U ppm

18 112 392 42.8 33.2 165.4 0.011 19.7 31 23.8 100 25.4 191.3 17.6 9.3 42.6 89.8 10.83 44.2 7.93 1.43 6.85 1.09 5.95 1.16 3.36 0.56 3.48 0.53 5.2 1.3 16.4 15.8 3.2

15 94 386 62.4 31.9 243 0.011 21.5 33 20.5 90 21.1 158.4 17.3 7.9 42.4 89.6 10.94 44.5 7.92 1.47 6.98 1.11 5.94 1.15 3.35 0.51 3.37 0.5 7.3 1.2 4.2 15.2 2.8

11 69 257 56.1 21.2 155.9 0.008 41.7 31 25 73 14.5 98.6 13.9 5.3 30.9 66 7.81 31.2 5.58 0.99 4.66 0.74 3.76 0.77 2.27 0.36 2.4 0.34 4.8 1 15.9 10.9 2.1

21 120 851.4 24 33.3 184.3 0.011 12.8 31 57 52 28.4 273.9 18.8 12.9 29.5 60.6 8 30.1 5.73 1.12 5.42 0.95 5.65 1.08 3.36 0.53 3.61 0.58 5.8 1.4 7.2 17.6 3.9

19 117 756.4 47.1 38.7 183 0.011 19.5 43 12.5 101 23.9 190.6 18.2 11.5 43.7 86.2 11.51 46.8 8.64 1.65 7.8 1.29 6.85 1.43 4.12 0.61 3.81 0.57 5.6 1 13.7 16.2 3.1

9 87 307 73.9 24.4 298.3 0.012 44.4 44 5.1 53 18.9 81.6 13.5 3.3 32.5 64.7 8.27 30.2 5.51 1.09 4.83 0.78 4.68 0.86 2.58 0.41 2.69 0.41 8.3 0.8 6.4 11.7 2.4

15 106 361 54.4 30.7 150.7 0.17 22.7 66 17.3 96 29.5 185.1 16 9 37.8 79.9 9.72 37.2 7 1.28 6.1 1.03 5.19 1.14 3.33 0.51 3.02 0.49 4.8 1.2 11.9 14.8 3.2

17 104 362.4 33.1 31.8 164.1 0.011 30.3 28 22.2 115 24.5 177.8 16.9 8.9 38.3 82.6 9.81 40.2 7.14 1.31 6.41 1.02 5.63 1.12 3.21 0.5 3.32 0.47 5.2 1.1 49.5 14.9 3.1

9 63 409 363 27.7 318.6 0.008 73.9 24 3.9 45 13.9 89.1 13.7 5.2 36.2 76.2 9.16 37.9 6.37 1.35 5.87 0.92 5.14 0.99 2.86 0.43 2.86 0.43 8.9 0.9 12.7 10.6 2.4

13 79 307.3 55.9 30.4 206.9 0.008 28.2 32 13.2 86 18.5 133.5 15.4 7.8 35.2 75.4 9 37.3 6.74 1.17 6.18 0.98 5.76 1.12 3.24 0.48 3.03 0.45 6.3 1 4 12.8 2.8

Th/Sc Zr/Sc La/Th La/Sc Eu/Eu* Eu/Eu**

0.88 9.19 2.69 2.37 0.91 0.58

1.01 16.2 2.79 2.83 0.93 0.59

0.99 14.17 2.83 2.81 0.91 0.58

0.84 8.78 1.68 1.4 0.94 0.61

0.85 9.63 2.7 2.3 0.95 0.6

1.3 33.14 2.78 3.61 0.99 0.63

0.97 10.04 2.55 2.52 0.92 0.59

0.88 9.65 2.57 2.25 0.91 0.58

1.18 35.4 3.42 4.02 1.04 0.66

0.98 15.91 2.75 2.71 0.85 0.54

Total REE

219.77

219.74

157.78

156.23

224.98

159.51

193.71

201.04

186.68

186.05

13.6 107 550 350 22 190 83 17 44 25 71 112 12 4.6 30 64 7.1 26 4.5 0.88 3.8 0.64 3.5 0.8 2.3 0.33 2.2 0.32 5.8 1 17 10.7 2.8

The Puncoviscana Complex samples from the Mojotoro Range have Th/Sc ratios between 0.84 and 1.3, and the Zr/Sc ratios vary between 8.8 and 35, whereby the highest values were obtained for samples from the Alto de la Sierra and Guachos formations. These data are concordant with the high concentrations of zircon grains
lez found in the metasandstones of these units (Aparicio Gonza et al., 2014). These findings allow to infer that, in spite of the possible effect of diverse sedimentation cycles, the sediments were mainly altered by mechanical weathering, with a moderate effect of chemical alteration (Fig. 6).

5.4. Provenance

Fig. 6. Th/Sc vs. Zr/Sc diagram after McLennan et al. (1993), indicating recycling, sedimentary sorting, and upper crustal input. Th/Sc > 0.79 (solid-line) reflects provenance of samples from the upper continental crust. High Zr/Sc ratios in some samples from the Alto de la Sierra and Guachos formations suggest a higher degree of reworking.

and Zr). This indicates obvious sedimentary sorting and recycling (McLennan et al., 1993).

In agreement with the data previously discussed, the geochemistry of the metasedimentary rocks of the Puncoviscana Complex can reflect, in a consistent way, the characteristics and nature of the rocks that originated the sediments of these units. The analyzed rocks suffered low to intermediate weathering, have a low chemical maturity, and have been affected by a very low metamorphic grade (Do Campo & Ribeiro-Guevara., 2005; Aparicio
lez et al., 2010). They represent recycled material. In this Gonza section we examine the likely provenances for these rocks.

258


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

5.4.1. Evidence from major elements Previous studies have demonstrated the effective use of contrasting values in the major element composition as a tool to determine the sediment provenance (Roser and Korsch, 1988; Fedo et al., 1995; Girty et al., 1996; Meinhold et al., 2007). With the objective to establish diagrams for the determination of sediment source type, Roser and Korsch (1988) generated discriminating functions using major elements. In their discriminating binary diagram using the DF1 vs. DF2 functions (see legend in Fig. 7a), the analyzed samples from the three studied formations fall into a field of igneous-felsic provenance, with an intermediate igneous trend (Fig. 7a). Taking into account the A-CN-K diagram (Fig. 5b), the sediment source for the Puncoviscana Complex samples is in accordance with an igneous-felsic (granite-rhyolite) to a felsicintermediate (granodiorite) heritage. Girty et al. (1996) found that sediments from a mafic source show Al2O3/TiO2 < 14 values, while for felsic sources, the ratio is between 19 and 28. For the Guachos Formation samples, the Al2O3/TiO2 ratio is between 20 and 14, whereas it is between 17 and 23 for the Alto de la Sierra Formation and between 18 and 24 for the Chachapoyas Formation. This, too, indicates that the sediment source for the three formations had predominantly felsic composition, with a minor input from intermediate source rock.

5.4.2. Evidence from trace elements Hiscott (1984) and McLennan et al. (1993) used Cr/V vs. Y/Ni ratios to evaluate the provenance of ophiolitic sources. The parameter Cr/V ratio acts as a monitor of the Cr enrichment over the other ferromagnesian, whereas the Y/Ni ratio tracks the behavior of a ferromagnesian trace element (Ni) over Y (incompatible element of the HFSE type). This ratio is used as an indicator of the presence of HREE (Heavy Rare Earth Elements) in felsic rocks (McLennan et al., 1993). In this way, the sediment sources of maficultramafic composition show high values in the Cr/V ratio and low values in the Y/Ni ratio, whereas sediments with intermediate to felsic sources show low Cr/V ratio and high Y/Ni ratio. In the Cr/V vs.Y/Ni diagram, the analyzed samples from the three units of the Puncoviscana Complex clearly fall into a zone that represents a felsic composition (granitic and/or metamorphic) (Fig. 7b). Furthermore, Cullers (2002) used the Th/Co and La/Sc ratios to discriminate sediments from basic sources from those of felsic composition. Values of Th/Co > 0.3 and La/Sc > 0.7 are characteristic of sediments from felsic sources, whereas La/Sc < to 0.4 is related to mafic sources. The analyzed samples of the three formations fall in this diagram into the field for felsic sources (Fig. 7c), in agreement with the major element results. Floyd and Leveridge (1987) developed the La/Th vs. Hf ratio diagram to discriminate input from an arc system source (tholeiitic,

Fig. 7. a) Discrimination diagram for sedimentary provenance (after Roser and Korsch, 1988). DF1 ¼ 30.638 TiO2/Al2O3 - 12.541 Fe2O3/Al2O3 þ 7.329 MgO/Al2O3 þ 12.031 Na2O/ Al2O3 þ 35.402 K2O/Al2O3 - 6.382. DF2 ¼ 56.5 TiO2/Al2O3e10.879 Fe2O3/Al2O3 þ 30.875 MgO/Al2O3e5.404Na2O/Al2O3 þ 11.112 K2O/Al2O3e3.89. b) Cr/V vs. Y/Ni diagram for sedimentary provenance (after Hiscott, 1984). Upper and lower curves represent the mixing lines of ultramafic (Cr/V z 45; Y/Ni z 0.001), felsic metamorphic (Cr/V z 1.23; Y/ Ni z 1.02), and granitic (Cr/V z 0.25; Y/Ni z 2.33) rocks (Dinelli et al., 1999). c) Th/Co vs. La/Sc diagram for provenance discrimination (after Cullers, 2002). d) Comparative diagrams of samples from the Mojotoro Range and samples of Zimmermann (2005). La/Th vs. Hf diagram after Floyd and Leveridge (1987). Fields indicate the compositions of sedimentary rocks deposited in different tectonic settings. Most samples from the Puncoviscana Complex plot into the field for an acidic arc source.


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

andesitic and felsic sources). Plotting the analyzed samples of Puncoviscana Complex in this discrimination diagram (Fig. 7d), it can be seen that the samples come predominantly from a felsic arc source, with a minor influence from passive margin components. This is in good agreement with the results obtained by Zimmermann (2005) (Fig. 7d). Between the different trace elements used as sediment provenance indicators, the REE have the advantage of not being significantly fractionated by sedimentary processes, and thus remaining a reflection of the original source composition for siliciclastic rocks (McLennan, 1989; Dou et al., 2010; Um et al., 2013). The majority of felsic rocks show subtle variations in the magnitude of the negative Eu anomaly (displayed as C1 chondrite normalized Eu/Eu* ratios < 1), whereas for mafic or ultramafic rocks the negative Eu anomaly disappears altogether. The REE patterns of our samples (normalized to C1 chondrite, after McDonough and Sun, 1995) show strong LREE enrichment over HREE (Fig. 8a), as reflected by the C1 normalized (La/Yb) ratios. For the Chachapoyas Formation (Fig. 8a) these values fall into the 8.2e8.7 interval, and the samples of the Alto de la Sierra and Guachos formations have values between 5.5-8.2 and 7.8e8.6, respectively. Our samples show significantly negative Eu anomalies, evidenced by values of (Eu/Eu*)nC1 between 0.54 and 0.66 (Chachapoyas Formation ¼ 0.58e0.59; Alto de la Sierra Formation ¼ 0.60e0.63; Guachos Formation ¼ 0.54e0.66). These REE characteristics (enriched in LREE, with a moderate slope along

Fig. 8. a) Chondrite-normalized REE patterns for samples from the Chachapoyas, Alto de la Sierra and Guachos formations (Puncoviscana Complex). b) Eu/Eu* (chondritenormalized) vs. Th/Sc plot showing the distribution of Puncoviscana Complex samples into fields for stream sediments derived from mafic and felsic igneous sources (after McLennan et al., 1990; Cullers, 2002).

259

the MREE-HREE section of patterns, and strong negative Eu anomaly) are typical for sediments from felsic sources (Cullers, 1995). Combining the Th/Sc evidence (Th is enriched in felsic rocks, whereas Sc is enriched in mafic rocks - McLennan et al., 1990) with the findings regarding Eu anomalies, it is possible to generate discriminating diagrams for establishing the original composition of sediment sources (Jorge et al., 2013). In the (Eu/Eu**)vs. Th/Sc diagram (Fig. 8b) plotted for the Puncoviscana Complex samples, data cluster in the field corresponding to a source of evolved felsic composition, which is in fine agreement with our other results. 5.5. Tectonic setting The chemical composition of clastic rocks is significantly controlled by the tectonic setting of a sedimentary basin, and the nature of the original sediment source. Consequently, clastic rocks of different tectonic settings will show the particular geochemical features of the terrain where they were formed. In this way, the geochemistry of sedimentary rocks has been widely used as an effective tool in the determination of tectonic settings in which sedimentation occurred (Bhatia, 1983, 1985; Roser and Korsch, 1988; Floyd and Leveridge, 1987; McLennan and Taylor, 1991). 5.5.1. Evidence from major elements Bhatia (1983) applied the weight percentage (wt%) of TiO2 and the (Fe2O3þMgO) ratios to distinguish four possible tectonic settings: a) Passive Margins (PM); b) Active Continental Margin (ACM); c) Continental Island Arc (CA); and d) Oceanic Island Arc (OIA). This relationship eliminates the possible effect of SiO2 mobilization by post-depositional processes and allows to investigate the dispersion of sample distribution. Our results show that the data favor the field corresponding to Island Arc tectonic settings, but the Guachos Formation samples plot into the Contiental Island Arc field (Fig. 9a). The discriminate function diagram proposed by Bhatia (1983) and Roser and Korsch (1988) makes use of the Al, Ti, Fe, Mg, Ca, Na and K oxide data. In the DF1 vs. DF2 diagram (Bhatia, 1983), the Puncoviscana Complex samples fall into the fields for Island Arcs (continental and oceanic), with some samples from the Guachos and Alto de la Sierra formations dispersed into the Active Continental Margin field (Fig. 9b). The dispersion for the samples from the different formations can be partially attributed to the mobility of species such as K and Na, which are integrated into the calculation of the discriminating functions, during feldspar weathering and/or the effect of potassium metasomatism. 5.5.2. Evidence from trace elements The use of discriminating diagrams for the determination of tectonic settings based only on the geochemistry of major elements can bear a high degree of uncertainty, due to the possible mobility of species as a result of weathering or alteration processes (e.g., Basu et al., 2016). It is, thus, recommended to complement the interpretation of major element data with trace element evidence, because of their low mobility during sedimentary processes (Bhatia, 1983, 1985; Taylor and McLennan, 1985; Bhatia and Crook, 1986; McLennan et al., 1993). Especially Th, Y, REE, Zr, Hf, Nb, Sc and Co are useful towards the discrimination of provenance and tectonic settings due to the low mobility of these species during sedimentary processes, and their short residence times in sea water (Holland, 1978: Bhatia and Crook, 1986). These elements are transported quantitatively during the weathering and transportation cycle and, thus, would reflect signatures of the parent material (McLennan et al., 1983; Bhatia and Crook, 1986). Trace element characteristics for greywacke samples from different tectonic sites allowed Bhatia and Crook (1986) to obtain a

260


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

Fig. 9. Comparative diagrams of samples from the Mojotoro Range and samples of Zimmermann (2005) a) Plot of Fe2O3 þ MgO vs. TiO2 to discriminate tectonic settings (after Bhatia, 1983). b) The major element compositions for the metasedimentary rocks from the Puncoviscana Complex on the tectonic setting discrimination diagram (after Bhatia, 1983). DF1: 0.421 SiO2 þ 1.988 TiO2 e 0.526 Al2O3 e 0.551 Fe2O3 e 1.610 FeO þ 2.720 MnO þ 0.881 MgO e 0.907 CaO e 0.177 Na2O e 1.840 K2O þ 7.244 P2O5 þ 43.57. DF2: e0.0447 SiO2 e 0.972 TiO2 þ 0.008 Al2O3 e 0.267 Fe2O3 þ 0.208 FeO e 3.082 MnO þ 0.140 MgO þ 0.195 CaO þ 0.719 Na2O e 0.032 K2O þ 7.510 P2O5 þ 0.303. c) La-Th-Sc and Th-Sc-Zr/10 plot for the metasedimetary rocks from the Puncoviscana Complex in the Mojotoro Range for tectonic setting discrimination (after Bhatia and Crook, 1986). PM¼ Passive Margin; ACM ¼ Active Continental Margin; CA¼ Continental Island Arc; OIA¼ Oceanic Island Arc. Most of the Puncoviscana Complex data are consistent with a derivation from a continental island arc. d) Lan/Ybn vs. Eu/Eu* diagram after McLennan et al. (1990) and Cingolani et al. (2003) for tectonic setting discrimination. Most of the Puncoviscana Complex data are consistent with a continental arc derivation.

general trend of increase of LREE (La, Ce, Nd), Th and Nb concentrations and a progressive V and Sc decrease when moving from an Oceanic Island Arc to a Continental Island Arc-Active Continental Margin-Passive Margin setting. In the La-Th-Sc and Th-Sc-Zr/10 triangular diagrams (Fig. 9aed), the analyzed samples plot clearly into the Continental Island Arc field (CA), in agreement with the findings based on major elements (Fig. 9 c and d). 5.6. Source area characterization The determination of the geotectonic environment that hosted the source rocks for our sedimentary strata gave coherent results, irrespective of which data sets - geochemical (mobile and immobile elements), petrographic, or geochronologicaleare considered. By using the classic Roser and Korsch (1988) y Bhatia (1983) diagrams, it is observed that the rocks are projected into the Active Continental Margin-Continental Island Arc fields, showing a clear

association with a magmatic arc. The chemical index of alteration (CIA) of the studied rocks indicates that the original material endured a moderate degree of weathering, as the determined values are near or slightly below the ones corresponding to illite. Thus, it is suggested that they are mixtures of primary and secondary detrital components. On the other hand, the discriminating diagrams for tectonic environments using trace elements show an affinity with source areas of felsic to intermediate composition. Corresponding to this observation, the La/Th vs. Hf diagram suggests that the Puncoviscana Complex sediments in the Mojotoro Range come from sources that are compatible with an arc of felsic composition, with low sedimentary cortical recycling. The relationships between traditional trace elements that are considered good indicators of tectonic environment, such as Th/Sc, Zr/Hf, La/Th, La/Sc, plot these samples into a Continental Island Arc or Active Continental Margin environment.


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

If our new data are compared with the results by Zimmermann (2005) for the Eastern Cordillera, it is noted in the La/Th vs. Hf diagram (Fig. 7 d) that the samples analyzed by Zimmermann (2005) from Pedrera and their Corralito River samples (COR) plotted as average values have the same geochemical behavior as the samples from the three lithostratigraphic units reported on here. In contrast, the average geochemical values for their samples from the Toro (TOR), Seclant
as (SEC), Molinos (MOL), and Choromoro (CHO) areas are associated with a Passive Continental Margin. This discrepancy seems to be caused by the fact that Zimmermann (2005) studied the stratigraphic core of the eastern Cordillera by integrating samples of different lithology, metamorphic grade and ages. In the diagrams of Fig. 9, the results by Zimmermann (2005) and reported here do not show significant differences. The majority of data are located in the Continental Island Arc field, except for Zimmermann's TOR samples that in the TiO2 vs Fe203 þ MgO diagram (Fig. 9a) plot near the Passive Continental Margin field. Petrographic analysis of the Alto de la Sierra and Guachos formation samples showed the presence of volcanoclastic grains and
lez et al., 2010). The presence of felsic tuff lithics (Aparicio Gonza volcanoclastic and tuff level derived material in Puncoviscana Complex samples was described from other sites in the Eastern Cordillera as well (Jezek, 1990; Zimmermann, 2005; Escayola et al., 2011) and is also consistent with a volcanic arc source. In some samples the grain proportion is low due to presence of a weathered and dissolved pseudo-matrix (Zimmermann, 2005; Aparicio Gonz
alez et al., 2010). The provenance studies on detrital zircons made for the Alto de la Sierra and Guachos formations (Aparicio Gonz
alez et al., 2014) allowed to identify idiomorphic zircons that kept the original acicular pyramidal morphology, meaning that they were little transported from a tuff source. These grains gave maximum ages of sedimentation of 534 ± 1 Ma and 517 ± 5 Ma, respectively, which was interpreted as indicating that this zircon type from tuffs can be linked to a magmatic arc. The existence of major magmatic and detrital sources from exhumed Mesoproterozoic basement (Lucassen et al., 2000; Steenken et al., 2006; Escayola et al., 2007; Schwartz and Gromet, 2004; Rapela et al., 2007; Siegesmund et al., 2010; Drobe et al., 2009, and references therein) and volcanic, plutonic rocks to the east of the Puncoviscana Complex is consistent with the volcanicarc geochemical signatures observed in our samples. The Arequipa-Antofalla massif in the Sierras Pampeanas (Lucassen et al., 2000; Steenken et al., 2006; Escayola et al., 2007; Collo et al., 2009) or the Kalahari craton and its vicinity (Schwartz and Gromet, 2004; Rapela et al., 2007; Siegesmund et al., 2010; Drobe et al., 2009 and references therein) have been proposed as possible Mesoproterozoic sources for the Puncoviscana Complex and related metasedimentary rocks.

6. Conclusions Based on major and trace element records for sedimentary samples from the Puncoviscana Complex in the Mojotoro Range, a derivation of the detrital material from felsic and intermediate rocks on the upper continental crust is postulated. It is inferred that the sediment sources are related to the magmatic arc located to the east of the complex and belonging to the Neoproterozoic-Cambrian Pampean Brazilian arc that formed along the margin of a Mesoproterozoic craton. Paleo-weathering proxies such as the CIA (Chemical Index of Alteration), WIP (Weathering Index of Parker), and A-CN-K discrimination diagram indicate that the source rocks were affected by a weak to moderate weathering history.

261

Acknowledgements The authors acknowledge with special thanks the reviews of Dr. Victor Ramos, Dr. Maximiliano Naipauer and Dr. Uwe Reimold. References ~ olaza, F.G., Durand, F., 1973. Trazas fo
siles del basamento cristalino del noroeste Acen
rdoba 1, 45e55. argentino. Bol. Asoc. Geol. Co ~ olaza, F.G., Miller, H., Toselli, A.J., 1988. The Puncoviscana Formacio
n (Late Acen Precambrian-Early Cambrian). Sedimentology, tectonometamorphic history and age of the oldest rocks of NW Argentina. In: Bahlburg, H., Breitkreuz, Ch, Giese, P. (Eds.), The Southern Central Andes, Lecture Notes in Earth Sciences, vol. 17, pp. 25e37. ~
ficas y tecto
nicas sobre Acenolaza, F.G., Toselli, A.J., 1973. Consideraciones estratigra el Paleozoico inferior del Noroeste Argentino. Memorial del II Congreso Latin
s, vol. 2. Ministerio de Minas e Hidrocarburos, oamericano de Geología, Caraca
n de Geología, Caracas, pp. 755e764. Direccio ~ olaza, F.G., Acen ~ olaza, G., 2005. La Formacio
n Puncoviscana y unidades estraAcen
ficas vinculadas en el Neoproterozoico-Ca
mbrico Temprano del Noroeste tigra Argentino. Lat. Am. J. Sedimentol. Basin Anal. 12, 65e87. ~ olaza, F.G., Toselli, A.J., Griffin, W.L., 2011. The Pacific Adams, C.J., Miller, H., Acen Gondwana margin in the late Neoproterozoic early Paleozoic: detrital zircon UPb ages from metasediments in northwest Argentina reveal their maximum age, provenance and tectonic setting. Gondwana Res. 19, 71e83. Ahmedali, S.T. (Ed.), 1989. X-ray Fluorescence Analysis in the Geological Sciences: Advances in Methodology, vol. 7, p. 297. Geological Association of Canada where published. Short Course Notes.
lez, P.A., Moya, M.C., Impiccini, A., 2010. Estratigrafía del basamento Aparicio Gonza
mbrico, Sierra de Mojotoro, Cordillera Oriental Argentina. Neoproterozoico-Ca Lat. Am. J. Sedimentol. Basin Anal. 17, 65e83.
lez, P.A., Pimentel, M., Hauser, N., 2011. Datacio
n U-Pb por LA-ICP-MS Aparicio Gonza de diques graníticos del ciclo Pampeano, Sierra de Mojotoro, Cordillera Oriental Argentina. Rev. la Asoc. Geol. Argent. 68, 33e38.
lez, P., Pimentel, M., Hauser, N., Moya, M.C., 2014. UePb LA-ICP-MS Aparicio Gonza geochronology of detrital zircon grains from low-grade metasedimentary rocks (NeoproterozoiceCambrian) of the Mojotoro Range, northwest Argentina. J. S. Am. Earth Sci. 49, 39e50.
bal, E., Roser, B., Yokota, S., 2009. Patrones e
Indices de Meteorizacio
n quíAristiza
sitos de vertientes y rocas fuentes en el Valle de Aburr
mica de los depo a Boletín de Ciencias de la Tierra, vol. 5, pp. 27e42. Augustsson, C., Rüsing, T., Adams, C.J., Chmiel, H., Kocabayoglu, M., Büld, M., Zimmermann, U., Berndt, J., Kooijman, E., 2011. Detrital quartz and zircon combined: the production of mature sand with short transportation paths along the Cambrian West Gondwana margin, northwestern Argentina. J. Sediment. Res. 81, 284e298. Bachmann, G., Grauert, B., Kramm, U., Lork, A., Miller, H., 1987. El magmatismo del
mbrico medio-C
Ca ambrico Superior en el basamento del noroeste Argentina;
picas y geocronolo
gicas sobre los granitoides de los cominvestigaciones isoto ~ ani. Actas del Congr. Geol. Argent. plejos intrusivos de Santa Rosa de Tastil y Can 4, 125e127. Bahlburg, H., Dobrzinski, N., 2011. A review of the Chemical Index of Alteration (CIA) and its application to the study of Neoproterozoic glacial deposits and climate transitions. In: Arnaud, E., Halverson, G., Shields, A. (Eds.), The Geological Record of Neoproterozoic Glaciations. The Geological Society London, Memoir, vol. 36, pp. 81e92.
mbrico-Ca
mbrico) en la Baldis, B.A., Omarini, R., 1984. El Grupo Lerma (Preca ~ a y su posicio
n en el borde pacífico americano. In: comarca central salten
gico Argentino, vol. 1, pp. 64e78. Bariloche, S.C. (Ed.), Acta 9
Congreso Geolo Basu, A., Bickford, M., Deasy, R., 2016. Inferring tectonic provenance of siliciclastic rocks from their chemical composition: a dissent. Sediment. Geol. 336, 26e35. Bhatia, M., Crook, K., 1986. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contributions Mineralogy Petrology 92, 181e193. Bhatia, M., 1983. Plate tectonics and geochemical composition of sandstones. J. Geol. 91, 611e627. Bhatia, M., 1985. Rare earth element geochemistry of Australian Paleozoic graywackes and mudrocks: provenance and tectonic control. Sediment. Geol. 45, 97e113. Cingolani, C., Manassero, M., Abre, P., 2003. Composition, provenance, and tectonic setting of Ordovician siliciclastic rocks in the San Rafael block: southern extension of the Precordillera crustal fragment, Argentina. J. S. Am. Earth Sci. 16, 91e106.
n Achavil: una unidad diferenciable dentro Collo, G., Astini, R.A., 2008. La Formacio
rfico de bajo grado del Famatina en la regio
n pampeana del basamento metamo de los Andes Centrales. Rev. la Asoc. Geol. Argent. 63, 344e362. Collo, G., Astini, R.A., Cawood, P.A., Buchan, C., Pimentel, M., 2009. U-Pb detrital zircon ages and Sm-Nd isotopic features in low-grade metasedimentary rocks of the Famatina belt: implications for late Neoproterozoic-early Palaeozoic evolution of the proto-Andean margin of Gondwana. J. Geol. Soc. Lond. 166, 303e319. Cullers, R., 1995. The controls on the major-and trace-element evolution of shales, siltstones, and sandstones of Ordovician to Tertiary age in the Wet Mountains

262


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza

region, Colorado, USA. Chem. Geol. 123, 107e131. Cullers, R., 2002. Implications of elemental concentrations for provenance, redox conditions, and metamorphic studies of shales and limestones near Pueblo, CO, USA. Chem. Geol. 191, 305e327. Dinelli, E., Lucchini, F., Mordenti, A., Paganelli, L., 1999. Geochemistry of OligoceneeMiocene sandstones of the northern Apennines (Italy) and evolution of chemical features in relation to provenance changes. Sediment. Geol. 127, 193e207. Dou, Y., Yang, S., Liu, Z., Clift, P., Shi, X., Yu, H., Berne, S., 2010. Provenance discrimination of siliciclastic sediments in the middle Okinawa Trough since 30 ka: constraints from rare earth element compositions. Mar. Geol. 275, 212e220. Do Campo, M., Ribeiro-Guevara, S.R., 2005. Provenance analysis and tectonic setting of late Neoproterozoic metasedimentary successions in NW Argentina. J. S. Am. Earth Sci. 19, 143e153.
pez de Luchi, M.G., Steenken, A., Frei, R., Naumann, R., Wemmer, K., Drobe, M., Lo Siegesmund, S., 2009. Provenance of the late Proterozoic to early Cambrian metaclastic sediments of the Sierra de San Luis (Eastern Sierras Pampeanas) and Cordillera Oriental, Argentina. J. S. Am. Earth Sci. 28, 239e262. Escayola, M.P., Pimentel, M.M., Armstrong, R., 2007. Neoproterozoic back-arc basin: sensitive high-resolution ion microprobe U-Pb and Sm-Nd isotopic evidence from the Eastern Pampean Ranges, Argentina. Geology 35, 495e498. Escayola, M.P., van Staal, C., Davis, W.J., 2011. The age and tectonic setting of the Puncoviscana Formation in northwestern Argentina: an accretionary complex related to Early Cambrian closure of the Puncoviscana Ocean and accretion of the ArequipaeAntofalla block. J. S. Am. Earth Sci. 32, 438e459. Fedo, C.M., Nesbitt, H.W., Young, G.M., 1995. Unraveling the effects of potassium metasomatism in the sedimentary rocks and paleosols with implications for paleoweathering conditions and provenance. Geology 23, 921e924. Floyd, P., Leveridge, B., 1987. Tectonic environment of the Devonian Gramscatho basin, south Cornwall: framework mode and geochemical evidence from turbiditic sandstones. J. Geol. Soc. Lond. 144, 531e542. Folk, R.L., Andrew, P.B., y Lewis, D.W., 1970. Detrital sedimentary rock classification and nomenclature for use in New Zealand. J. Geol. Geophys. 13, 937e968. Girty, G., Ridge, D., Knaack, C., Johnson, D., Al-Riyami, R., 1996. Provenance and depositional setting of Paleozoic chert and argillite, Sierra Nevada, California. J. Sediment. Res. 66, 107e118. Hallsworth, C.R., Knox, R.W.O.’B., 1999. BGS rock classification scheme. British Geological Survey. In: Classification of Sediments and Sedimentary Rocks, vol. 3, pp. 1e44. Research Report, RR 99-03. Hauser, N., Matteini, M., Omarini, R.H., Pimentel, M.M., 2011. Combined U-Pb and Lu-Hf isotope data on turbidites of the Paleozoic basement of NW Argentina and petrology of associated igneous rocks: implications for the tectonic evolution of western Gondwana between 560 and 460 Ma. Gondwana Res. 19, 100e127. Herron, M.M., 1988. Geochemical classification of terrigenous sand and shales from core or log data. J. Sediment. Res. 58, 820e829. Hiscott, R., 1984. Ophiolitic source rocks for Taconic-age flysch: trace-element evidence. Geol. Soc. Am. Bull. 95, 1261e1267. Holland, H., 1978. The Chemistry of the Atmosphere and Oceans. Wiley, New York, p. 451.
n (C
Hongn, F.D., 1996. La Estructura Pre-Grupo Meso ambrico) del Basamento del Valle de Lerma, Provincia de Salta. Acta 13
cong. Geol. Argent. 137e145.
lisis Sedimentolo
gico de la Formacio
n Puncoviscana entre Jezek, P., 1990. Ana ~ olaza, F.G., Miller, H. y, Toselli, A.J. (Eds.), El Ciclo Tucum
an y Salta. In: Acen Pampeano en el Noreste Argentino. Facultad de Ciencias Naturales e Instituto
n Geolo
gica. Tucum
Miguel Lillo. Instituto Superior de Correlacio an. Serie
n Geolo
gica, vol. 4, pp. 9e36. Correlacio Jorge, R., Fernandes, P., Rodrigues, B., Pereira, Z., Oliveira, J., 2013. Geochemistry and provenance of the carboniferous baixo alentejo flysch group, south Portuguese zone. Sediment. Geol. 284/285, 133e148. Keppie, J.D., Bahlburg, H., 1999. Puncoviscana Formation of northwestern and central Argentina. In: Ramos, V.A., Keppie, J.D. (Eds.), Laurentia-gondwana Connections before Pangea, vol. 336. Geological Society of America, pp. 139e143.
tesis sobre la evolucio
n tecKraemer, P.E., Escayola, M.P., Martino, R.D., 1995. Hipo
rdoba (30
40'e32
40'). tonica neoproterozoica de las Sierras Pampeanas de Co Argent. Rev. la Asoc. Geol. Argent. 50, 47e59. Kretz, R., 1983. Symbols for rock-forming minerals. Am. Mineralogist 68, 277e279. Kumpa, M., Sanchez, M.C., 1988. Geology and sedimentology of the cambrian grupo
n (NW Argentina). In: Bahlburg, H., Breitkreuz, C., Giese, P. (Eds.), The Meso Southern Central Andes, vol. 17, pp. 39e53. Lecture Notes in Earth Sciences.
pez de Azarevich, V., Acen ~ olaza, F.G., Omarini, R., Azarevich, M., 2012. La Cuenca Lo Neoproterozoica y Eoc
ambrica en el NOA: sedimentología y ambientes de
sito de secuencias con icnofo
siles, nuevas perspectivas. In: XIII Reunio
n depo Argentina de Sedimentología, Relatorio, pp. 119e132. Lucassen, F., Becchio, R., Wilke, H.G., Franz, G., Thirlwall, M.F., Viramonte, J., Wemmer, K., 2000. Proterozoic ePaleozoic development on the basement of the Central Andes (18-26
S)ea mobile belt of the South America Craton. J. S. Am. Earth Sci. 13, 697e715. McDonough, W.F., Sun, S., 1995. Composition of the earth. Chem. Geol. 120, 223e253.
ngano, M.G., Buatois, L.A., 2004. Integracio
n de estratigrafía secuencial, sedMa
lisis cronoestratigr
imentología e icnología para un ana afico del Paleozoico inferior del noroeste argentino. Rev. la Asoc. Geol. Argent. 59, 273e280.
, J.C., Acen ~ olaza, F.G., 1972. El hallazgo de Oldhamia sp. (Traza fo
sil) y su valor Mirre


mbrica para el supuesto Preca
mbrico del borde como evidencia de edad ca occidental del Aconquija, provincia de Catamarca. Ameghiniana 9, 72e78. € ner, A., 1983. Geochemical evolution of archean shales McLennan, S., Taylor, S., Kro from South Africa I. The Swaziland and pongola supergroups. Precambrian Res. 22, 93e124. McLennan, S., 1989. Rare Earth Elements in Sedimentary Rocks: Influence of Provenance and Sedimentary Process, vol. 21. Mineralogical Society of America, pp. 169e200. Reviews in Mineralogy. McLennan, S., Taylor, S., McCulloch, M., Maynard, J., 1990. Geochemical and NdeSr isotopic composition of deep-sea turbidites: crustal evolution and plate tectonic associations. Geochimica Cosmochimica Acta 54, 2015e2050. McLennan, S., Taylor, S., 1991. Sedimentary rocks and crustal evolution: tectonic setting and secular trends. J. Geol. 99, 1e21. McLennan, S., Hemming, S., McDaniel, D., Hanson, G., 1993. Geochemical approaches to sedimentation, provenance, and tectonics. In: Johnson, M., Basu, A. (Eds.), Processes Controlling the Composition of Clastic Sediments, vol. 284. Geological Society of America Special Paper, pp. 21e40. Meinhold, G., Kostopoulos, D., Reischmann, T., 2007. Geochemical constraints on the provenance and depositional setting of sedimentary rocks from the islands of Chios, Inousses and Psara, Aegean Sea, Greece: implications for the evolution of Palaeotethys. J. Geol. Soc. Lond. 164, 1145e1163. Moya, M.C., 1998. El Paleozoico inferior en la sierra de Mojotoro, Salta-Jujuy. Rev. la Asoc. Geol. Argent. 53, 219e238. Nesbitt, H., Young, G., 1984. Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic consideration. Geochimica Cosmochimica Acta 48, 1523e1534. Omarini, R.H., Baldis, B.A., 1984. Sedimentología y mecanismos deposicionales de la
n Puncoviscana (Grupo Lerma, Prec

mbrico) del noroeste Formacio ambrico-Ca argentino. 9
Congr. Geol. Argent. Acta 1, 384e398 (S. C. Bariloche). Parker, A., 1970. An index of weathering for silicate rocks. Geol. Mag. 107, 501e504. ~a
n-Llamas, A., Simpson, C., 2006. Deformation of Gondwana Margin Turbidites Pin during the Pampean Orogeny, vol. 118. Geological Society of America Bulletin, north-central Argentina, pp. 1270e1279. ~ an Lamas, A., Escamillas, Casas, J., 2013. Provenance and tectonic setting of Pin Neoproterozoic to Early Cambrian metasedimentary rocks from the Cordillera Oriental and Eastern Sierras Pampeanas, NW de Argentina. Bol. la Soc. Geol. Mex. 65, 373e375. Potter, P.E., Maynard, J.B., y Depetris, P., 2005. Mud and Mudstones Introduction and Overview. Springer Science and Business Media, New York, p. 296. Ramos, V.A., 2008. The basement of the central andes: the arequipa and related terranes. Annu. Rev. Earth Planet. Sci. 36, 289e324. Rapela, C.W., Pankhurst, R.J., Casquet, C., Fanning, C.M., Baldo, E.G., Gonz
alesCasado, J.M., Galindo, C., Dahlquist, J., 2007. The Río de la Plata craton and the assembly of SW Gondwana. Earth Sci. Rev. 83, 49e82. Roser, B., Korsch, R., 1988. Provenance signatures of sandstonee mudstone suites determined using discriminant function analysis of major-element data. Chem. Geol. 67, 119e139.
rrez, W., 1975. Consideraciones sobre la Salfity, J.A., Omarini, R.H., Baldis, B., Gutie
n geotecto
nica del Preca
mbrico y Paleozoico Inferior del Norte de evolucio

mica, vol. 4, Argentina. In: Acta 2 Congreso Iberoamericano de Geología Econo pp. 341e361.
nchez, M.C., 1999. Sedimentología y Paleogeografía del Grupo Meso
n (C
Sa ambrico).
lez Bonorino, G., Omarini, R., y Viramonte, G. (Eds.), “Geología del In: Gonza

gico Argentino, pp. 126e133. noroeste argentino”, Relatorio 14 Congreso Geolo Seilacher, A., Buatois, L.A., M
angano, M.G., 2005. Trace fossils in the EdiacaranCambrian transition: behavioral diversification, ecological turnover and environmental shift. Palaeogeogr. Palaeoclimatol. Palaeoecol. 227, 323e356. Schwartz, J.J., Gromet, L.P., 2004. Provenance of a late Proterozoic-early Cambrian
rdoba, Argentina. Precambrian Res. 129, 1e21. basin, Sierras de Co Siegesmund, S., Steenken, A., Martino, R.D., Wemmer, K., Lopez de Luchi, M., Frei, R., Presnyakov, S., Guereschi, A., 2010. Time constraints on the tectonic evolution of the eastern Sierras Pampeanas (central Argentina). Int. J. Earth Sci. 99, 1199e1226.
pez de Luchi, M.G., Frei, R., Wemmer, K., 2006. Steenken, A., Siegesmund, S., Lo Neoproterozoic to Early Palaeozoic events in the Sierra de San Luis: implications for the Famatinian geodynamics in the Eastern Sierras Pampeanas (Argentina). J. Geol. Soc. Lond. 163, 965e982. Taylor, S.R., McLennan, S.M., 1985. The Continental Crust: its Composition and Evolution; an Examination of the Geochemical Record Preserved in Sedimentary Rocks. Blackwell, Oxford, p. 312. Turner, J.C.M., 1960. Estratigrafía de la Sierra de Santa Victoria y adyacencias, vol. 41.
rdoba, pp. 163e196. Boletín Academia Nacional de Ciencias Co Um, I., Choi, M., Bahk, J., Song, Y., 2013. Discrimination of sediment provenance using rare earth elements in the Ulleung Basin, East/Japan Sea. Mar. Geol. 346, 208e219. Verdecchia, S.O., Baldo, E.G., benedetto, J.L., Borghi, P.A., 2007. The first shelly fauna
bila Formation, Sierra from metamorphic rocks of the Sierras Pampeanas (La Ce de Ambato, Argentina): age and paleogeographical implications. Ameghiniana 44, 493e498. Willner, A.P., Miller, H., Jezek, P., 1985. Geochemical features of an Upper Precambrian-lower Cambrian greywacke/pelite sequence (Puncoviscana trough) from the basement of the NW-Argentine Andes. Neues Jahrb. für Geol. Paleontol. 8, 498e512.
n tectometamo
rfica del Basamento del Noroeste ArgenWillner, A.P., 1990. Divisio ~ olaza, F., Miller y, H., Toselli, A.J. (Eds.), El Ciclo Pampeano en el tino. In: En Acen


lez et al. / Journal of South American Earth Sciences 78 (2017) 250e263 P.A. Aparicio Gonza
n Geolo
gica, vol. 4, pp. 113e159. Noroeste Argentino. Serie de Correlacio
n Chan ~ i: un Zappettini, E.O., Coira, B., Santos, J.O., 2008. Edad U/Pb de la Formacio
tico Tilc
granito del arco magma arico. XVII Congr. Geol. Argent. Jujuy 2, 248e249. Zimmermann, U., 2005. Provenance studies of very low to low-grade

263

metasedimentary rocks of the Puncoviscana Complex, northwest Argentina. In: En Vaughan, A.P.M., Leat, P.T y, Pankhurst, R.J. (Eds.), Terrane Processes at the Margins of Gondwana, vol. 246. Geological Society, London, Special Publications, pp. 381e416.