Ediacaran ramp depositional model of the Tamengo Formation, Brazil

Journal of South American Earth Sciences 96 (2019) 102348

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Ediacaran ramp depositional model of the Tamengo Formation, Brazil a,∗

b

T b

Rick Souza de Oliveira , Afonso César Rodrigues Nogueira , Guilherme Raffaeli Romero , Werner Truckenbrodtb, José Cavalcante da Silva Bandeirab a

Universidade Federal do Oeste do Pará (UFOPA), Instituto de Engenharia e Geociências, Rua Vera Paz, s/n, Salé, CEP: 68040255, Santarém, PA, Brazil Programa de Pós-Graduação em Geologia e Geoquímica (PPGG), Universidade Federal do Pará, Rua Augusto Corrêa, 01, Guamá, Caixa Postal 1611, CEP 66075-110, Belém, PA, Brazil

b

A R T I C LE I N FO

A B S T R A C T

Keywords: Cloudina Tamengo formation Sedimentary facies Ediacaran Carbonate ramp

The Tamengo Formation corresponds to one of the most complete records of Ediacaran carbonate deposits in South America that contains Cloudina and Corumbella calcified exoskeletons macroscopic fossils. With the objective of characterizing its paleoenvironment, a total of ten sedimentary facies indicative of a carbonate platform were identified. In the outer ramp region there are massive mudstones, massive marl to claystones, and shales. In the mid-ramp there are facies that are storm-dominated with swaley/hummocky cross-stratified grainstone, tangential cross-bedding grainstone, massive bioclastic grainstone and massive marl to claystone. Lastly, in the inner ramp portion there are massive intraclastic grainstone, massive intraclastic rudstone, massive oolitic grainstone and laminate mudstone/shale rhythmite, and microbial textures are present at the base of the rhythmites, indicative of a back-ramp environment. Faciology data indicate that the Cloudinas inhabited a protected environment between oolitic bars in the inner ramp and back-ramp. These organisms were periodically transported and reworked by waves generated by storms in the mid-ramp and outer ramp zones. The positive values for δ13C in carbonates (1,5 to 5,4‰) and δ15N (between 3,5 and 4,5‰) of deposits with Cloudina indicate a marine paleoenvironment with shallow, hot, and oxygenated waters with a high productivity of organic matter. In this context, the facies analyses and stratigraphy, aided by C, O, and N isotopes from the Tamengo Formation in outcrops from the Corumbá regions in the southwest of Brazil allows for the reconstruction of an Ediacaran carbonate ramp and inferences about the habitat of Cloudina, thus increasing understanding of this important chapter of Earth history.

1. Introduction The Ediacaran period (Knoll et al., 2004), between 635 Ma and 541 ± 1 Ma (Ogg et al., 2016) is one of the most intriguing periods known in Earth's history (Brookfield, 1994): It was the scenario of dramatic events such as the Gaskier glaciation 580 Ma (Halverson et al., 2005), accompanied by the Shuram-Wonoka negative carbon-isotope anomaly (Guerroué, 2010; Narbonne et al., 2012; Minguez et al., 2015) and the appearance of external molds and casts of non-skeletal organisms, generally associated with metazoans (Gehling, 1999; Warren et al., 2013), denominated Ediacaran Biota (Glaessner, 1958), which are present on practically all the continents. Even though MacGabhann (2014) proposed the abandonment of term “Ediacaran Biota”, the occurrence of these diverse organisms in stratigraphic sections of Ediacaran age followed by rapid extinction, demonstrates a set of bioevolutionary innovations at the end of the Precambrian Eon and gave rise to the Cambrian explosion of life in marine environments. Among the

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environmental changes, the increased levels of oxygen at the end of Ediacaran are strongly related to the rise of skeletal metazoans (Fox, 2016; Lyons et al., 2014). Fossils from the genus Cloudina stand out as they are considered to be the first metazoan organism to create a primitive exoskeleton in the form of a shell (Corsseti and Hagadorn, 2000; Knoll, 2000, Eriksson et al., 2005; Narbonne, 2005, Gaucher et al., 2009). First evidence from thin carbonate precipitates induced by biological activity are attributed to ages of approximately 2.7 Ga (Monster et al., 1979), however, the appearance of an exoskeleton represents an evolutionary advance that is so innovative that it might have been capable of acting as a trigger for the appearance of the majority of complex species that were better adapted to life in the Cambrian (Keer, 2002; Wood and Curtis, 2015; Wood et al., 2017a). In addition to possibly providing protection against the storm currents, the mineralized shell may protect the soft part of the organism from possible predators (Hua et al., 2003), and some burrows within Cloudina shells possibly indicate to the first record

Corresponding author. E-mail address: [email protected] (R.S.d. Oliveira).

https://doi.org/10.1016/j.jsames.2019.102348 Received 9 January 2019; Received in revised form 15 August 2019; Accepted 2 September 2019 Available online 06 September 2019 0895-9811/ © 2019 Elsevier Ltd. All rights reserved.

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Fig. 1. Localization of the studied section, where A: Lithostratigraphic column composed of the Corumbá Group and the Puga Formation, highlighting the Tamengo Formation (Modified after Gaucher et al., 2003); B: Main lithostratigraphic units that occur in around the City of Corumbá (Modified after Lacerda Filho et al., 2004), indicating the sections of Itaú-Saladeiro (1), Laginha (2) and Corcal (3); and C: Simplified geologic map of Tocantis Province, highlighting the Paraguay Southern Belt (Modified after Pimentel et al., 2000; Hasui, 2012).

such as Sinotubulites in Califórnia and China (Grant, 1990; Conway Morris et al., 1990; Hua et al., 2003), Cloudina are directly related to the largest and last positive excursion of carbon of the Neoproterozoic (Grotzinger et al., 1995, Corsseti and Hagadorn, 2000; Amthor et al., 2003), and it is considered a fossil guide for the end of the Neoproterozoic, with a biozone characterized by U-Pb ages between 550 Ma and 542 Ma (Fig. 2) obtained from volcanic ash beds intercalated with Cloudina rich deposits (Grant, 1990; Grotzinger et al., 1995; Corsseti and Hagadorn, 2000; Amthor et al., 2003; Halverson et al., 2005; Babinski et al., 2008; Gaucher and Germs, 2009; Xiao et al., 2016; Parry et al., 2017). However, Linnemann et al. (2018) recently extended this discussion by proposing the Weesenstein-Orellana glacial event, aged 565 to 540 Ma. According to the authors, this glacial event would be younger than the Gaskiers glaciation, and would correlate in part with the Shuram-Wonoka isotopic anomaly. There exists a prolific debate regarding taxonomic affinities of the Cloudina genus in the four decades of its study (Germs, 1972; Zaine and Fairchild, 1987; Grant, 1990; Conway Morris et al., 1990; Conway-

of predator/prey trophic interaction (Wood, 2011; Wood et al., 2017b). Cloudina was first described in the Nama Group by Germs (1972), and is well represented in Brazil by fossil accumulations in the Tamengo Formation (e.g., Zaine and Fairchild, 1985; Zaine and Fairchild, 1991; Gaucher et al., 2003; Pacheco et al., 2011; Fairchild et al., 2012; Adorno et al., 2017; Becker-Kerber et al., 2017) (Fig. 1), Sete Lagoas Formation (Warren et al., 2014; Paula-Santos et al., 2017), and in diverse places around the planet (Fig. 2), such as Oman (Conway Morris et al., 1990), China (Conway Moris et al. op. cit.), Canada (Hofmann and Mountjoy, 2001), central regions of Spain (Vidal et al., 1994), Uruguay (Gaucher et al., 2003), Paraguay (Warren et al., 2011, 2017, 2019) and possibly Antarctica (Yochelson and Stump, 1977). However, Grant (1990) affirms that in the last two places cited above the taxonomy is questionable and states that this fossil occurs in the northeast of Mexico and in California and Nevada in the western United States based on fossils originally called Wyattia, Nevadatubulus and Sinotubulites (Taylor, 1966; Signor et al., 1987; McMenamin et al. 1985). In spite of being found together with other shell-producing genera 2

Fig. 2. Carbon-isotope excursions, confidence values of the Sr isotope, U-Pb age of zircons, glacial beds in the Paraguay Belt and Kalahari Craton and the occurrence of the shelled organism Cloudina in the principal Ediacaran stratigraphic sections around the world (Modified after Saylor et al., 1998). A: This paper, Gaucher et al. (2003) and Babinski et al. (2008); B: Warren et al. (2017) and Warren et al. (2019); C: Condon et al. (2005) and Zhou and Xiao (2007); D: Saylor et al. (1998) and Grotzinger et al. (1995); E: Saylor et al. (1998); F: Burns and Matter (1993) and Amthor et al. (2003); G: Vidal et al. (1994) and Herrero et al. (2011); H: Kantorovich et al. (2008); and I: Main reported occurrences of Cloudina, where the Cloudina symbol situated on the Corumbá Basin is shaded and fossils in Laurentia are dubious (Modified after Grant, 1990, Conway Morris et al., 1990 and Cortijo et al., 2010). Stratigraphic datum at the first occurrence of Cloudina.

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1978; Walde et al., 1982; Zaine and Fairchild, 1985; Hahn and Pflug, 1985; Hidalgo, 2002; Gaucher et al., 2003; Babcock et al., 2005; Pacheco et al., 2011; Tobias, 2014; Parry et al., 2017). In the Guaicurus Formation (early Cambrian) microfossils, ichnofossils and the vendotaenid Eoholynia corumbensis sp. are found, and their biostratigraphic range is still open to interpretation (Gaucher et al., 2003; Parry et al., 2017). Therefore, the Tamengo Formation represents one of the most important sedimentary records of the Late Ediacaran in South America, and the refinement of the depositional context is of fundamental importance.

Morris, 1993; Hua et al., 2003, 2005; Adorno et al., 2017), including morphology (Grant, 1990; Seilacher, 1999; Adorno et al., 2017; Mehra and Maloof, 2018), mineralogy (Grant, 1990; Brain, 2001; Hua et al., 2005; Becker-Kerber et al., 2017), paleoecology (Germs, 1972; Grant, 1990; Seilacher, 1999; Hua et al., 2005; Cortijo et al., 2010; BeckerKerber et al., 2017; Mehra and Maloof, 2018) taphonomy (Cortijo et al., 2010; Meira, 2011; Warren et al., 2012; Becker-Kerber et al., 2017, 2019; Mehra and Maloof, 2018) and extinction (Brain, 2001; Hua et al., 2003; Becker-Kerber et al., 2017). In contrast, information about the sedimentary environment in which these fossils inhabited are restricted to the Nama Group in Namibia (Germs, 1972; Seilacher, 1999; Grotzinger et al., 2000) and the central region of the Iberian Peninsula (Vidal et al., 1994). In South America, the paleoenvironment of Cloudina has been mentioned by Gaucher et al. (2003), Boggiani et al. (2010), Adorno et al. (2017), Warren et al. (2017) and Warren et al. (2019). In this context, the present study has the objective of refining the interpretation of depositional environment of the Tamengo Formation in the region of Corumbá, State of Mato Grosso do Sul (Fig. 1), using facies analysis concepts, associated with chemostratigraphy data, and thus contributing to knowledge of Cloudina macrofossil paleohabitat.

3. Methods The facies and geochemical data were collected along the active mining front of limestone quarries around the town of Corumbá, State of Mato Grosso do Sul, on the border between Brazil and Bolivia (Fig. 1). These three outcrops were chosen because they represent the best sites where the Tamengo Formation is exposed and which contains Cloudina fossils. The facies analysis was performed with the creation of photo mosaics (Wizevich, 1991; Arnot et al., 1997), and lithostratigraphic profiles in outcrops wherein sedimentary structures, stratigraphic surfaces, geometry, lithologic variability, and vertical and lateral distribution could be identified. Subsequently, the facies were refined according to the classification proposed by Flügel (2004), modified from Phanerozoic models of Wilson (1975) and Burchette and Wright (1992). Special attention was given to the occurrence of Cloudina fossils, which after being positioned along the profile, were characterized macroscopically considering their orientation, relation with sedimentary structures and number of individual specimens. In thin sections, orthogonal and transverse measurements were made along the shell and quantified the number of individuals per square centimeter. Siliciclastic lithologies were classified according to Folk (1974). For carbonates, the lithological classification was based on Dunham (1962) adopting the modifications added by Embry and Klovan (1971). Differentiation between types of calcite and dolomite was conducted through staining thin sections with a slightly modified mixture of Friedman (1959), Dickinson (1965) and Evamy (1969), composed of 1 g of potassium ferricyanide and 0.1 g of alizarin red S in 50 ml 2% HCl. The fabric and textures were classified according to Folk (1965, 1974), Friedman (1965), Logan and Seminiuk (1976) and Sibley and Gregg (1987). The mineralogical identification of the pelitic fractions was conducted using X-ray diffraction analysis (XRD) using a X'Pert Pro PANalytical diffractometer (40 kV and 40 mA) equipped with a copper tube (Cu Kα, λ = 1,54 Å) in the Laboratory of Mineral Characterization in the Federal University of Pará. For identification of the groups of clay minerals, the < 2 μm fraction was used applying the following treatments: air-dried samples, saturated with ethylene glycol and heated at 550 °C for 1 h. The carbon isotope ratios for the primary carbonate substrate (δ13Ccarb), associated kerogen (δ13Corg), and oxygen in the primary carbonate substrate (δ18Ocarb) were measured using between 1 and 10 mg of powdered sample that was reacted in a high-vacuum line with H3PO4 at 25 °C for 4 h to extract the CO2 from the calcite and then at 80 °C for 2 h to extract the CO2 from the dolomite according to the technique described by Swart et al. (1991). The amount of extracted CO2 and its carbon and oxygen isotopic compositions were measured using a helium continuous-flow mass spectrometer (AP-2003) at IPGP laboratory (Paris, France). The reproducibility of the δ13C and the δ18O measurements is 0.1 and 0.2‰, respectively. The samples were calibrated using a laboratory standard associated with an international standard V-PDB (Viena Pee Dee Belemnites), and the results were recorded using the conventional notation delta (δ) in per-mille (‰). For the isotopic analysis of nitrogen present in the kerogen-associated

2. Geological setting The Corumbá Basin occurs within the Southern Paraguai Belt, specifically on the eastern margin of the Rio Apa Block between the Serra da Bodoquena and the Tucavaca Aulacogen, (Fig. 1). This basin (Alvarenga and Trompette, 1992; Boggiani, 1997; Walde et al., 2015) has approximately 400 km of extension in the NW-SE direction (Gaucher et al., 2003) and up to 600 m of sedimentary thickness (Boggiani et al., 2010). The basin was developed in a set of grabens that resulted from the Rodinia rifting process, approximately 590 Ma ago (Trompette et al., 1998; Tohver et al., 2006; Li et al., 2008; Piacentini et al., 2013), with its depositional filling represented essentially by the Corumbá Group (Fig. 1), as a result of a complete rift-to-drift tectonic evolution (Boggiani et al., 2010; Alvarenga et al., 2000). The depositional succession was initiated during the rift phase, with alluvial deposits of the Cadiueus Formation that are overlaid by the diamictites of the Puga Formation (Maciel, 1959) and separated by an unconformity, followed by quartz sandstones, arkose, and transgressive shales of the Cerradinho Formation (Almeida, 1965). Then, during the drift stage, the Bocaina Formation was deposited at 555.18 ± 0.3 Ma (Parry et al., 2017), formed by limestones and dolomites rich in phosphate and related to a tidal flat environment, followed by the Tamengo Formation at 543 ± 3 Ma according to Babinski et al. (2008) or 542.3 ± 3 Ma according to Parry et al. (2017), represented by limestones, shales and marls deposited in a shallow marine environment, and by the Guaicurus Formation, represented by shales on a strongly passive margin, delineating the end of deposition in this basin (Almeida, 1965; Boggiani, 1997; Trompette et al., 1998; Alvarenga et al., 2000; Gaucher et al., 2003; Spangenberg et al., 2013). A few correlations, principally based on fossils, were presented between the Tamengo Formation and the Itapucumi Group in Paraguay, (Boggiani and Gaucher, 2004; Warren et al., 2017, 2019), the Arroyo del Soldado Group in Uruguay (Gaucher et al., 2003), Murciélago Formation in Bolivia (Jones, 1985; Boggiani, 1997; Trompette et al., 1998) and consequently, with deposits that contain Cloudina around the world (Fig. 2). The first fossil record occurs at the top of the Cerradinho Formation, represented by organic-walled microfossils (Gaucher et al., 2003), while in the Bocaina Formation, fossil occurrence is restricted to Titanotheca coimbrae and microbialites (Gaucher et al., 2003; Romero et al., 2016). However, the majority of occurrence of fossils in the Corumbá Group refers to microfossils in the Tamengo Formation, ichnofossils and also in macrofossils of Corumbella werneri and Cloudina (e.g. Fairchild, 4

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Table 1 Summary of facies, processes and facies associations of the Tamengo Formation outcrops in the region of Corumbá, Mato Grosso do Sul. FACIES

DESCRIPTION

PROCESSES

ASSOCIATION

Massive mudstone (Mm).

Flat and laterally continuous layers, with a tendency for inclination at low angles indicating tempestite. Grey to dark in color, intensly neomorphic and with up to 5% terriginous material. Thick bedding, red coloured, with up to 40% calcite. Hummocky/swaley cross-stratification. Has approximately 5% terriginous grains. Has Cloudina shell, with 0.9 mm of diameter and up to 1 cm in length. Locally, it occurs as wackestone. Tabular cross-stratification with low angles (< 10°), with Cloudina fossil. Thick layers of incipient parallel laminations, abundant in Cloudina macrofossils. Thick bedding and red coloured.

Deposition in a moderate energy environment through oscillatory flux.

FA1 – THIN BEDDED OUTER RAMP DEPOSITS

Massive marl to claystone (MCm) Swaley cross-stratification/ hummocky cross stratification grainstone (Gsh) Tangential cross-bedding grainstone (Gc) Bioclastic grainstone (Gb) Massive marl to claystone (MCm) Massive intraclastic grainstone (Gi)

Massive intraclastic rudstone (Rm) Massive oolitic grainstone (Go)

Laminate mudstone/shale rhythmite (MSl)

Massive shale (Sm)

Tabular layers that are laterally continuous for tens of meters. Formed by rounded intraclasts de micrite and oolitic grainstone. And rare terriginous grains. Angular clasts up to4 cm in diameter composed of oolites in a sparry matrix. Tabular layers that are laterally continuous and up to 1 m in thickness. Composed of simple and compound ooids with 0.4 mm of average diameter, cemented by calcite in fringes and in blocks. Rare presence of oolitic intraclasts. Lamination oriented in flat planes with sets varying from 5 to 10 cm in thickness. Bituminous. Diverse occurrence of macrofossils, microfossils and thrombolites (?). Cloudina occurs with an intact body and no vestiges of reworking. Tabular layers with sets between 1 and 3 m, in the majority bituminous.

Deposition by suspension. Deposition by combined flow that is dominantly oscillatory through storm waves.

FA2 – STORM REWORKING MID-RAMP DEPOSITS

Migration of bed forms under unidirectional flux in a transitional to superior regime. Deposition under a superior flow regime. Deposition by suspension associated with chemical precipitation. Erosion, abrasion, and resedimentation through tractive and oscillatory flow.

FA3 – INNER RAMP SAND SHOALS

Erosion, abrasion, and resedimentation through high-energy flow. Carbonate precipitation and migration of sand flats under the action of flow dominated by waves in a high-energy environment. Rhythmic alternance between chemical precipitation and terrigenous grain deposition through suspension in a low-energy environment. Deposition through suspension. Concentration of organic matter.

FA4 – INNER TO OUTER RAMP DEPOSITS

Table 2 Isotopic values for carbonate facies of the Tamengo Formation in which the Cloudina fossil occurs with better preservation. The samples denominated “Lar” correspond to the Laginha quarry, and the sample “C1” was obtained in the Corcal quarry. Sample

Carbonate (Wt.%)

δ13Ccarb (‰)

δ13Corg (‰)

Δ13C (‰)

δ18 Ocarb (‰)

δ15Norg (‰)

TOC %

Lar 1 Lar 2 Lar 6 Lar 7 C1

85.0 89.0 97.0 81.0 97.0

4.4 5.2 1.5 5.4 3.9

−24.6 −23.5 −25.9 −24.5 −23.5

−29.0 −28.7 −27.4 −29.9 −27.4

−7.6 −7.7 −7.0 −7.5 −8.4

4.8 3.4 3.2 3.9 3.2

0.33 0.29 0.30 0.41 0.74

(δ15Norg), combustion using a CaO-Cu furnace was used followed by subsequent analysis on a mass spectrometer with a triple static vacuum collector connected directly to the extraction line at IPGP laboratory, which allowed for reporting measurements in nanomoles of N2, with uncertainty levels around 0.5‰. Total organic carbon (TOC) was obtained by the removal of CaCO3 from a dried sediment sample by treatment with H3PO4. The solid residue was then analyzed for total carbon by instrumental CHN microanalysis and the acidic supernatant is analyzed for acid-soluble organic carbon by a dissolved organic carbon method. The sum of the two determinations equals the organic carbon content of the sediment. The results in ppm were converted to %. A summary of analyzed samples can be found in Table 2.

4.1.1. Thin bedded outer ramp deposits (FA1) FA1 occurs at the quarries Corcal and Itaú-Saladeiro (Fig. 3). It has tabular layers, forming a deepening upward cycle of approximately 25 m in thickness, composed of massive mudstone (Mm) and massive marl to claystone (MCm) facies (Table 1). The laterally continuous disposition of these layers, which persists for tens of meters or more, indicates a general flat and wide morphology for the depositional environment (Fig. 4 B). Nonetheless, the thinning and thickening of the layers and the low angle inclination between them suggests the presence of tempestites (Handford, 1986), even though these layers are rarely present in internal ripples or hummocky cross-stratification. The abrupt intercalation with no indication of dissolution events between the black carbonate facies and the yellow clay facies indicates that the eventual interruptions in carbonate precipitation are primarily related to a greater load of terrigenous materials. In the Laginha quarry, the interruptions in carbonate sedimentation are related to a change in the depositional regime where mudstones (Mm) are succeeded by shales (Sm) in a deepening upward context (Fig. 4 A). X-ray diffraction tests in seven samples in the Corcal quarry indicate marl as the original composition for the pelites, with predominance of calcite and quartz surrounded by a base of clay composed principally of interstratified illite/smectite, and in a lesser proportion by illite and kaolin (Fig. 4 E). The marl with thin-bedded limestone facies are interpreted as deep-

4. Results 4.1. Facies associations A total of three outcrops in mining fronts were analyzed which resulted in a total of ~124 m of carbonates and pelites (Fig. 3), including ten sedimentary facies grouped into four facies associations (FA), representing outer ramp (FA1 and FA2), mid-ramp (FA3) and inner ramp (FA4) sedimentary environments. The principal characteristics, processes, and interpretations are shown in Table 1. 5

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Fig. 3. Columnar sections of the Tamengo Formation in the region of Corumbá, with sedimentary structures, sampling, occurrence of Cloudina fossils, geochemical data, sedimentary facies, and facies associations. 1: Itaú-Saladeiro quarry, 2: Laginha quarry and, 3: Corcal quarry.

neomorphism (Fig. 5). The FA2 is formed by a succession that initiates with swaley crossstratification and hummocky cross-stratification, grainstones with wave lengths between 50 cm and 1 m, and heights ranging from 10 to 15 cm at the base, giving rise to tangential cross-stratification with an angle inferior to 10°, and finalizing with unstratified layers (Fig. 3). This succession forms amalgamated sets of up to 7 m in thickness, interspersed with thin marl (Fig. 4 D). The isotropic form of the hummocky cross-stratifications in the Corcal quarry is consistent with a scour and drape scenario in an oscillatory combined flow process (Cheel and Leckie, 1993; Myrow and Southard, 1996) situated between a storm wave base and a fair-weather wave base (Burchette and Wright, 1992), and in the Laginha quarry the carbonates were deposited in shallower conditions, as shown by the predominance of swaley crossstratification (Dumas and Arnott, 2006) in Fig. 3. The deposition of marl indicates eventual interruptions of the storm waves movement during a depositional null. The highest concentration of fossils of the genus Cloudina are found

water outer ramp deposits similar to the deposits found in the Upper Muschelkalk of the Catalan Basin (Calvet and Tucker, 1988), where the marl is the principal sediment and the limestones are interpreted as distal storm deposits. In short, the group AF1 is interpreted as thin bedded with outer ramp deposits situated below the storm wave base, where tempestites were deposited in an environment with moderated energy in an oscillating flux, interbedded with thin layers of pelite deposited by suspension. 4.1.2. Storm reworking mid-ramp deposits (FA2) The FA2 group consists of facies defined as swaley and hummocky cross bedding grainstone (Gsh), tangential cross-bedding grainstone (Gc), massive bioclastic grainstone (Gb), and as in FA1, massive marl to claystone (MCm) (Table 1). The FA2 occurs with 6 m of thickness in the Corcal quarry and with 3 m of thickness in the Itaú-Saladeiro quarry (Fig. 3). In thin sections, the carbonates have up to 3% quartz grains the size of silt, and a xenotopic calcite texture resulting from intense 6

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Fig. 4. Facies succession of the Tamengo Formation dominated by storms, where A: Panoramic section of the Itaú Saladeiro quarry, with cycles of deepening marked by interspersion between the facies of massive mudstone (Mm) and massive shale (Sm); B: Layers of laterally continuous tempestites from the Corcal quarry (1.5 m); C: Detail of the hummocky cross-stratification with up to 15 cm of length of waves (Gsh) in the Corcal quarry; D: Levels of massive marl to claystone (MCm) intercalated with massive bioclastic grainstones (Gb) in the Corcal quarry and E: DRX in the whole sample (above) and the clay fraction (below) of the MCm facies of the Corcal quarry (sample C8), where Q = quartz, C = calcite, I/S = interstratified illite-smectite, I = illite and K = kaolin.

fossils considered as integers and without evidence of fragmentation in the shell structure, the longitudinal section for each individual reached a size ranging from 2 mm to 3 mm, while in cross sections, the average size ranging from 850 μm to 1500 μm and wall thickness ranging from 50 μm to 100 μm. Compatible with the dimensions reported by Zaine and Fairchild (1987) and Adorno et al. (2017) for Cloudina lucianoi

in FA2 (Fig. 5), often generating accumulations of up to 4 specimens per square centimeter, suggesting an analogy, in terms of the hydrodynamic regime, to carbonate rocks rich in mollusks of Phanerozoic age that are informally called “coquinas” (e.g. Thompson et al., 2015). These principally occur at the peak of storm cycles, with no defined orientation related to reworking through oscillatory combined flow (Fig. 3). In 7

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Fig. 5. Occurrence of shells of Cloudina fossils reworked in a matrix of bioclastic grainstone with a xenotopic texture (A); intense neomorphism of the bioclastic grainstone facies (B); Swaley cross-stratification/hummocky cross stratification grainstone with an accumulation of fragmented shells (C) and intercrystalline cement between the walls of Cloudina (rectangle) in the Gb facies (D). All images are in plane-polarized light, except B. All images are representative of the Corcal quarry, with C1, C6 and C9 corresponding to samples shown in Fig. 3.

composition, peloidal intraclasts, and rounded intraclasts from oolitic packstones with a peloidal matrix (Fig. 6 B and C). These allochemical constituents are always cemented by an early phase, represented by calcite fringes, and a late phase, represented by sparry calcite with a xenotopic habit, and fine to medium granulation (Fig. 6 C). In general, the intraclasts have an average size of 500 μm and can be larger than 2 mm. The ooids of the Go facies have a nucleus formed by crystalline limestone fragments and are, on average, about 250 μm, and can be larger than 500 μm when they are composed by the junction of two or more ooids thus forming compound ooids (Fig. 6 C). A majority part of the simple ooids with a dimension of up to 200 μm were completely substituted by sparry calcite, creating as a result “ghosts” that preclude their identification by conventional petrography (Fig. 6 D). The rudstones of the Rm facies are formed by pebbles that are generally angular, compounds made of oolitic intraclasts of up to 10 cm on its largest axis, and are configured in a closed arrangement of grains, texturally analogous to intraformational breccia (Fig. 6 D). Apparently, this facies is a continuation of the reworking of the Gi facies, representing a progressive increase in energy of the depositional system from the base of Gi to the top of Rm. Understanding of the origin and depositional context of these carbonate breccias is complicated due to the absence of diagnostic fossils (Madden et al., 2017). However, the pebbles with evidence of short transport, the composition of the parent material and of pebbles is similar to the adjacent oolitic/intraclastic layers, and the abrupt superior and inferior contacts suggest that there is a tectonic origin for these deposits. The top of these facies is marked by ripple-type structures, which could explain the rounding of the edges of some of the pebbles. Boggiani et al. (2010) attributed the formation of these breccias to glacioeustatic sea level fall, however these authors do not exclude a purely tectonic origin. The expressive presence of ooids (Go) together with rudstones (Rm)

(Buerlen and Sommer, 1957) in the Tamengo Formation. However, Mehra and Maloof (2018) have shown that morphological analyzes in 2D sections produce orientation errors of the order of 180° and lead to erroneous interpretations of eccentricity and curvature. In some specimens, surface imbrication and funnel morphology were identified, with openings filled with early cement (Fig. 5 D) similar to that reported by Cortijo et al. (2010) and Becker-Kerber et al. (2017). The occurrence of fragmented fossil specimens together with nonfragmented fossils like in the GSh facies have also been reported by Adorno et al. (2017), being common in stormy environments (Brett and Baird, 1986) and resemble each other through affinity, with a taxonomic degree of “D” Brandt (1989). Even in the Gb facies the Cloudina shells are fragmented, indicating that in spite of apparently being massive facies, this was also deposited through action of storms and its sedimentary structures might have been obliterated through remobilization inherent to the deposition process of sedimentation by storms or destroyed by neomorphic processes during diagenesis. Therefore, AF2 is interpreted as mid-ramp subject to storm wave action interspersed with brief moments of calm, which resulted in deposition of interbedded tempestites and pelites.

4.1.3. Inner ramp sand shoals (FA3) The FA3 occurs exclusively in the Laginha quarry (Figs. 1 and 6), where it reaches a total thickness of 65 m (Fig. 3). It is composed of grey-black carbonates of the massive intraclastic rudstone (Rm), massive intraclastic grainstone (Gi) and massive oolitic grainstone (Go) facies, the principal characteristics and processes of which are summarized in Table 1. With the exception of supercritical ripples that occur at the top of the Gi facies, the FA3 group is primarily massive, formed by ooids, compound ooids (~grapestones), pebbles of an intraclastic 8

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Fig. 6. Principal characteristics of the facies that occur in the Laginha quarry. A: Intercalation between massive rudstone (Rm), rhytimite mudstone/shale (MSl) and oolitic grainstone (Go); B: Grainstone from the Gi facies with intraclasts of oolitic packstone (O), peloidal intraclasts (P) and ghosts of ooids generated by neomorphism (arrows); C: Grainstone of the Go facies, formed by simple (So) and compound (Co) ooids, highlighted in the red rectangles, early (a) and late (b) cementation; D: Intraclastic Rudstone (Rm), with clasts of up to 10 cm and E: Clotted microbial texture of the MSl facies associated with carbonate precipitation through bacterial activity. B and C in crossed polarizers and E in parallel polarizers. B and C represents the sample LN4a in Fig. 3, and E represents the sample LN1. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

4.1.4. Inner to outer ramp deposits (FA4) The FA4 facies was found in the Itaú-Saladeiro quarry (Fig. 4 A) where it reached 7 m (Fig. 3), and is formed by laminate mudstone/ black shale rhythmite (MSl) and massive black shale (Sm) facies (Table 1).

and intraclastic grainstones (Gi), indicates a deposition in the context of sand shoals in a high-energy environment, subject to constant reworking by waves (Tucker and Wright, 1992; Burchette and Wright, 1992), situated in the fair-weather wave base in an inner ramp context.

9

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frameworks for global correlation of neoproterozoic succession (Knoll et al. 1986, 1995; Narbonne et al., 1994; Kaufman and Knoll, 1995; Kaufman et al., 1997; Saylor et al., 1998; Jacobsen and Kaufman, 1999; Knoll, 2000), isotopic studies of carbon, oxygen, and nitrogen were conducted in sedimentary facies MSl and Gsh, where fossils of Cloudina are found (Fig. 3, Table 1 and Table 2). Additionally, TOC and carbonate content were obtained with the aim of characterizing the level of marine production of the waters of the proterozoic ocean in this portion of South America during the Ediacaran Period. In the MSl facies of the Laginha quarry (Fig. 3), the isotopic values of δ13Ccarb varied between 1.5 and 5.4‰, with an average of 4.1‰ and are compatible with the values obtained by Gaucher et al. (2003), Boggiani et al. (2010) and Spangenberg et al. (2013) for the Tamengo Formation. The δ13Corg values obtained from organic matter varied between −23.5 and −25.9‰, with an average of −24.6‰ and are also similar to the values obtained by Spangenberg et al. (2013). The values of Δ13C, that represents the difference between δ13Ccarb and δ13Corg are limited between −27.4 and −29.9‰, with an average of −28.7‰ (Table 2). In the Tamengo Formation, the δ18Ocarb values varied between −7 and −7.7‰, with an average of −7.4‰ and are in agreement with data obtained by Boggiani et al. (2010). The δ15Norg varied between 3.2 and 4.8‰, with an average of 3.8‰ (Table 2). In the GSh facies (Fig. 3), where Cloudina fossils accumulate through reworking due to storm wave action, the values were δ13Ccarb of 3.9‰, δ13Corg of −23.5‰, Δ13C of −27.4‰, δ18Ocarb of −8.4‰ and δ15Norg of 3.2‰. The carbonate content for the non-clay facies of the MSl facies association varied between 97 wt% and 81 wt%, indicating that the rhythmic intercalation of these sedimentary facies are composed of variations of carbonates, clay carbonates, and shales. In the Gsh facies, the percent carbonate was approximately 97% confirming the depositional regime as being one of high energy restrictive to the deposition of clays associated with carbonate. TOC values for the MSl facies varied between 0.29 and 0.41%, with an average of about 0.33%, and for the Gsh facies, the value was 0.74%.

Fig. 7. Depositional model proposed for the sedimentary succession of the Tamengo Formation, indicating the distribution of the main facies from the back ramp to the outer-ramp settings, with the approximate location of the studied sections represented by 1: Itaú-Saladeiro, 2: Laginha and 3: Corcal. Not to scale. Inspired after the models of Read, 1985, Grotzinger, 1989 and James, 1983, with modifications.

This facies occurs in layers with a tabular geometry, laterally continuous and in abrupt contact with the Mm (Fig. 4 A), Rm and Go (Fig. 6 A) facies. In the Laginha quarry, AF4 showed a rhythmic interbedded every 15–20 cm between shale and mudstone, while in the Itaú-Saladeiro quarry these intercalations are rare and give rise to a predominance of shale. Internally, the lithotypes present a flat lamination and fissility typical of bituminous shale. This facies association contains the principal occurrence of fossils of the Tamengo Formation (Cf. Hidalgo, 2002; Gaucher et al., 2003; Boggiani et al., 2010) with carapaces of Cloudina standing out among the fossils found here, and which occur with complete specimens with no vestiges of reworking. Thin sections of the sample Larg 1 (Fig. 3) collected from a thin lamina of the MSl facies revealed a clotted texture (Fig. 6 E) similar to that found in thrombolites (Cf. Aitken, 1967; Kennard and James, 1986; Shapiro, 2000; Riding, 2011). The occurrence of Cloudina associated with colonies of cyanobacteria seems to be somewhat diverse as records are found amid thrombolites in Namibia (e.g., Grotzinger et al., 2000; Penny et al., 2014; Wood et al., 2017b) and Paraguay (Warren et al., 2011; Warren et al., 2017), stromatolites in Namibia (Seilacher, 1999; Grotzinger et al., 2000), laminite incrustations in the Tamengo Formation (Becker-Kerber et al., 2017) and China (Cai et al., 2014) and even with MISS - Microbially Induced Sedimentary Structure in Paraguay (Warren et al., 2011). The FA4 is interpreted as being a product of alternating chemical precipitation and deposition events of siliciclastic material through suspension in a low-energy environment. It occurs interspersed between oolitic bars (Go) of FA3 association possibly being related to a lagoon and tidal flat environment, or interspersed with tempestites (Mm) from FA1, in an inner ramp context. Part of the Sm facies could even be associated with distal mud tempestites in outer ramp conditions (Burchette and Wright, 1992).

5. Discussion 5.1. Depositional model The Tamengo Formation was deposited in a carbonate platform (Fig. 7) constituted by an outer ramp of deposits (FA1), storm reworking mid-ramp deposits (FA2), inner ramp sand shoals (FA3) and inner to outer ramp deposits (FA4). In the outer ramp, the predominance of massive mudstones and marl denotes a null environment, below the storm zone, which is represented by the mid-ramp deposits constituted by bioclastic grainstones with hummocky and swaley cross stratifications. Just above the storm zone are the oolitic inner ramp and intraclastic carbonate deposits, which form a natural protection against high energy wave breaks, generating refuges capable of allowing the deposition of thrombolites and rhythmites in the outer ramp zone. The abundance of carbonate ramps during the neoproterozoic (Grotzinger and James, 2000), the tabular deposition character with ample lateral continuity as well as the absence of detritus flux turbidites and olistolites suggests deposition on a gentle slope, probably associated with a storm-dominated carbonate ramp-barrier-bank (Read, 1985). However, from a conservative point of view, the term “carbonate platform”, can be applied in this case, according to the concept described by Burchette and Wright (1992), due to the scarcity of outcrops that limit adequate recognition of the transition between the large belts of facies necessary to make the distinction between ramp and shelf. Additionally, a portion of the studied sections present intense neomorphism and absence of sedimentary structures making microfaciologic and hydrodynamic interpretation difficult. In the FA3, for example, stylolites are common even though the petrographic analysis indicates that loss of sections due to dissolution events is minimal and

4.2. Isotopic geochemistry of C, O and N, TOC and carbonate content Considering that isotopic variation of ocean water is used as a paleoenvironment proxy, and in elaboration of chemostratigraphic 10

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influenced by storms. The interstratified illite-smectite, and kaolin clays (Fig. 4E) in the facies MCm suggest a predominantly warm climate during deposition, with occasional relatively humid periods (Weaver 1958, 1989). Such climatic conditions are compatible with that described by Adorno et al. (2017), which propose a tropical climate for these deposits. The presence of kaolin and expansive clay minerals can be explained by the increase of oxygen during the Ediacaran-Cambrian transition, which in turn caused an increase in weathering and a decrease in K2O/Al2O3 ratios (Cox et al., 1995; Kennedy et al., 2006; Och and Shields-Zhou, 2012). On the other hand, it is possible that these clay minerals were modified by the thermal events as reported by Walde (1987), Trompette et al. (1998), Gaucher et al. (2003) and Tobias (2014), however the mineralogical assemblage and the crystallinity of the minerals are compatible with a primary origin.

no vestige of Cloudina fossils were found in this facies association, probably due to the difficulty in preserving them in an environment of intense reworking and diagenesis. Although the carbonates from the end of the Neoproterozoic have, in the majority, an important association with metazoan organisms and calcifying metaphytes that mark the transition from a predominantly abiotic depositional context to more modern patterns of production and accumulation of carbonates (Cozzi et al., 2004), the difficulty of correlation is common in carbonate deposits of a Neoproterozoic age around the planet (Chakraborty, 2004), mainly due to the absence of a diversity of guide fossils. In spite of the scarcity of fossils in the Corumbá Formation, the stratigraphic correlation between the profiles could be inferred from analysis of the Cloudina fossils (Fig. 3) supported by the zoning proposed by Adorno et al. (2017). The existence of a Clymene Ocean that separated the Amazon Craton from the São Francisco Craton and the Rio de Plata Craton during the Late Ediacaran to the Early Cambrian is still controversial (Scotese and McKerrow, 1990; Tohver et al., 2010, 2012; Cordani et al., 2013; Tohver and Trindade, 2014; Warren et al., 2014; Arrouy et al., 2016). However, the correlation between the Corumbá Group and the Arroyo del Soldado Group (Gaucher et al., 2003) suggests a cratonic origin for the Tamengo Formation (Boggiani et al., 2010; Tohver et al., 2012; Warren et al., 2014), and could be indicative that there was probably, at least, an epicontinetal sea that inundated central portions of South America during the Late Ediacaran. Similarly, in spite of there being diverse paleogeographic models for the Ediacaran/Cambrian transition based on paleomagnetism, fossil occurrence and isotopic data (McKerrow et al., 1992; Li and Powell, 2001; Aceñolaza et al., 2002; Astini and Rapalini, 2003; Rapela et al., 2007; Li et al., 2008, 2013; Trindade et al., 2006; Torsvik and Cocks, 2013; Tohver and Trindade, 2014), it's plausible to state, independently of the adopted paleogeographic reconstruction model, that the position of the Corumbá Basin in the (proto) Gondwana is compatible with the interpretation of a carbonate ramp (Fig. 8). In this sense, the deepening of the basin in the southeast in the direction of the city of Bonito and Serra da Bodoquena during the deposition of the Tamengo Formation as proposed by Boggiani et al. (1993) and Gaucher et al. (2003), can be extended to the northeast with the slope of the carbonate ramp is near to 45° azimuth, indicating that the entire eastern region presents a tendency of deepening in a gradual form and without a marked break in slope. The absence of Cloudina fossils to the east also reinforces the hypothesis that these organisms inhabited shallow waters. In FA2 the fossils are accumulated without apparent orientation and surrounded by tempestites, probably from FA4, where they proliferated in what was probably a low-energy marine environment or a tidal flat, protected from the action of storm waves by ramp sand shoals of FA3 (Fig. 7). In this way, Cloudina occurs in the Tamengo Formation in paleoenvironmental conditions analogous to those described by Vidal et al. (1994) for Iberia, where the refuges that served as habitat for Cloudina would have been associated with oolitic shoals. In FA4, interspersed between oolite and intraclastic facies, there is a reduction in the energy of the depositional system, which facilitated the rhythmic intercalation between mudstone and organic shale represented by the facies MSl (Fig. 3). In this facies, Cloudina shells occur whole, isolated and locally associated with thrombolytic carbonates. The occurrence of Cloudina associated with microbialites could indicate an ecological relationship between the metazoan and colonies of cyanobacteria in a shallow marine environment or a tidal flat during deposition of this sedimentary facies. This interpretation is compatible with those proposed by Seilacher (1999), Grotzinger et al. (2000), Penny et al. (2014) and Wood et al. (2017a,b) for the Nama group in Namibia and by Warren et al. (2011, 2017) for the Itapucumi Group in Paraguay, that associate the occurrence of Cloudina to reefs of microbialites in a tidal flat environment, and Gaucher et al. (2003) and Boggiani et al. (2010) that associate the occurrence of this fossil to a generally shallow marine context

5.2. Isotopic signature The MSl facies of the Tamengo Formation showed low variation in the values of Δ13C, as well as low correlation between δ13Ccarb and δ18Ocarb with a R2 equal to 0.19, what indicate that the carbon isotopic values were not affected by diagenesis (neomorphism and dolomitization), metamorphism and/or percolation of fluids of an atmospheric origin (Kaufman and Knoll, 1995; Jacobsen and Kaufman, 1999), and therefore reflect an isotopic composition of coeval sea water. The constant values of δ13Ccarb are compatible with an environment that is shallow or a tidal flat for the MSl facies, and the positive values suggest an important consumption of 12C compatible with the proliferation of organisms since the biota preferentially consumes lighter isotopes of carbon (Narbonne et al., 1994; Saylor et al., 1998, Corsseti and Hagadorn, 2000). In this context, the δ13C values and the fractionation range showed by Δ13C are compatible with an increase in primary biological activity that resulted from the occurrence of microbialites and Cloudina, with the proliferation of biota of the Ediacaran in FA4 (Hidalgo, 2002; Gaucher et al., 2003) and are similar to data obtained for depositions near the limit between the Ediacaran and Cambrian around the planet (Fig. 2). The values of TOC also confirm this increasing production of organic matter, as shown by sample C1 and Lar 7. Isotopic records of the associated organic matter reflect oceanic productivity, the quantity of CO2 in the superficial waters, the input of material derived from the continent, and the action of diagenesis (Maslin and Swann, 2005). The negative values of δ13Corg in the Tamengo Formation suggest that there was a contribution of bacterial biomass to the accumulation of organic matter derived from the primary production of the Neoproterozoic Ocean. Furthermore, the values for Δ13C = 28 ± 2‰ were empirically determined by Knoll et al. (1986) for Neoproterozic sequences of eastern Greenland and Spitsbergen (Svalbard, Norway) while values of Δ13C = 33 ± 2‰ have been considered representative of pre-Marinoan deposits, and are, therefore, much older. The isotopic values are also different from those reported for the late Neoproterozoic Araras carbonate platform, in the Southern Amazon Craton, and southwestern-most part of the Amazon craton (e.g., Nogueira et al., 2007; Sial et al., 2016; Gaia et al., 2017). In this way, the values obtained for the Tamengo Formation reinforce that this portion is chronologically inserted in the transition from the preCambrian to the Phanerozoic. Since nitrogen is an essential nutrient for the maintenance of marine life, its availability has the potential to limit biological production over large regions of the oceans (Maslin and Swann, 2005). Stable isotope records for sedimentary nitrogen have been used to trace the origin of organic matter, infer superficial conditions during primary production, and reconstruct environmental and paleographic features (Peters et al., 1978; Sweeney et al., 1978; Rau et al., 1987; Altabet and Francois, 1994; Tesdal et al., 2013) and are directly related to the balance between nitrification and denitrification (Wada et al., 1975; Beaumont and Robert, 1999; Galbraith et al., 2008; Montoya, 2009). Negative values of δ15N suggest a metabolic isotopic fractionation in anoxic 11

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Fig. 8. Global paleogeographic reconstruction proposed for the Upper Ediacaran (550 Ma), according to (A) Tohver and Trindade (2014); (B) Trindade et al. (2006) and (C) Li et al. (2008). Paleogeographic reconstruction for the Upper Ediacaran (540 Ma) according to Li et al. (2013) (D) and Torsvik and Cocks (2013) through (E) true polar wander reconstruction and (F) paleomagnetic reconstruction. The red rectangle represents the approximate location of the area studied in this paper. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

water. Shales interbedded with carbonates with microbial textures (MCl) were protected by the oolitic sand shoals, and this denotes a restricted depositional context associated with a back-ramp. The facies data permit the identification of intervals that have the presence of Cloudina accumulated by storms and facies with indications that this species lived in a protected environment between oolitic bars in the Inner Ramp and Back-Ramp. Isotopic data for C and N, and geochemical percentages indicate that this macrofossil lived in an oxic environment and without perturbation of the nitrogen cycle which permitted an intense proliferation of this species and the accumulation of reasonable levels of organic matter due to relative organic productivity. In synthesis, this study provides an integrated vision of the processes that were responsible for the deposition of carbonates during the Proterozoic-Paleozoic interval in the southwestern part of Gondwana and adds information to the comprehension of one of the most enigmatic fossils of the history of the Earth.

conditions with microorganisms using reduced forms of nitrogen (N2, NH4+). However, the positive isotopic data for nitrogen varied between +3.2 and +4.8‰ in the AF4 and AF2 associations, indicating the presence of an atmosphere already rich in oxygen during this deposition, which would allow for an expressive biological production of NO3− and its use as a source for organic nitrogen, probably related to the action of cyanobacteria (Fig. 6E). This affirmation is in agreement with data for δ13C, with respect to the ratio between δ13C versus δ15N in dispersion and with a positive tendency. 6. Conclusion The facies analysis in the carbonatic and pelitic successions of the Tamengo Formation allowed for the individualization of ten sedimentary facies grouped into four associations of facies (Table 2) that represent outer ramp, mid-ramp and inner ramp sedimentary environments (Fig. 7). The outer ramp deposits are marked by the presence of distal tempestites interspersed with marls and shales. The mid-ramp is characterized by grainstones with hummocky cross-stratification, swaley cross-stratification and tangential cross-bedding deposited between the storm wave base and the fair-weather wave base. Finally, the inner ramp deposits are basically composed of oolitic rudstones and grainstones which were deposited in a context of shallow, agitated

Acknowledgments The authors thank the Brazilian Research Council for Science and Technology (CNPq), that financed this research through the projects Universal 481978/2004-6 and Universal/CT-Petro - 485902/2007/9, the 12

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Instituto Nacional de Ciência e Tecnologia de Geociências da Amazônia (INCT – GEOCIAM) for support, and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the masters research scholarship granted to the first author. Additionally, the authors thank the Programa de Pós-Graduação em Geologia e Geoquímica da Universidade Federal do Pará (PPGG-UFPA) and Magali Ader of the Laboratoire de Géochimie des Isotopes Stables of Université de Paris for logistical support. We also thank Professor Dr. François Gauthier-Lafaye of the Laboratoire d'Hydrologie et de Geochimie de Strasbourg of Université de Strasbourg and Dra. Renata Hidalgo for help and valuable discussions during the field campaigns. The authors are grateful to the companies Calcário Corumbá Ltda., Itaú Cimentos - Votorantim and the management of the Corcal and Laginha quarries for help and the access offered during field work. A special thanks to Prof. Dr. Troy Patrick Beldini of the Universidade Federal do Oeste do Pará (UFOPA) and the anonymous reviewers for their careful review and suggestions that greatly improved the final version of the manuscript.

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