Petrography descriptions and U-Pb zircon datasets from the Archean Pavas Block, Precambrian of Uruguay

Relacionado con el artículo: 10.1016/j.jsames.2021.103364This database is a geological and geochronological compila- tion made to study a small Archean/Paleoproterozoic block located in the centre of the Precambrian rock exposition of Uruguay. Petrographic and field outcrops data supporting the samples from which the zircons for textural analysis and U-Pb dating (LA-ICP-MS) come are presented at first with their descriptions. The first table (1) contains the new U- Pb isotopic data. The second table (2) presents a correlation of textures from different zircon samples. The last table (3) contains an inventory of different U-Pb ages found in an- tecedents. All these data are associated with the paper en- titled: “The Archean Pavas Block in Uruguay: extension and tectonic evolution based on LA-ICP-MS U-Pb ages and air- borne geophysics".CSIC: 2015 C-60

The Tonian Embu Complex in the Ribeira Belt (Brazil) : revision, depositional age and setting in Rodinia and West Gondwana

Funding: Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq, grants 443439/2014-1 and 305074/2015-6, the Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP, grant 2015/04487-7, and the Australian Research Council, grant FL160100168.The Embu Complex in the Neoproterozoic Ribeira Belt of Brazil provides a record of sedimentation associated with the Rodinia supercontinent and its subsequent deformation and metamorphism during assembly of West Gondwana. It is composed of a succession of variably migmatized pelitic schists and paragneisses, as well as minor calcsilicate rocks with quartzite intercalations, and orthogneiss. Detrital zircon U-Pb (LA-ICP-MS and SHRIMP) determinations for key samples of the Embu Complex in its type-area (West and Southwest of São Paulo City), and samples from neighboring units (Votuverava and São Roque groups) indicate distinct provenance histories and in combination with other data, discrete times of sediment accumulation. Detrital zircons from the Embu Complex are characterized by ages in the range 1500-1000 Ma and 2000-1700 Ma, with a very minor number of older ages. The youngest detrital grain is dated at 974 ± 12 Ma. Metamorphic zircon overgrowths range from 850 to 570 Ma with age peaks at ca. 820-790 and 650-570 Ma. Thus, the depositional age of the Embu Complex is constrained to 970-850 Ma. The detrital zircons of the Votuverava and São Roque groups are dominated by ages in the range 2200-2000 Ma, along with minor Paleoproterozoic and Archean ages. The youngest detrital grains are ∼1400 Ma (Votuverava Group) and ∼1750 Ma (São Roque Group). Metamafic rocks from the Votuverava Group have crystallization ages of ca. 1300 Ma, with a higher metamorphic grade amphibolite showing a range of discordant ages with upper and lower intercepts of 1300 Ma and ∼800 Ma, respectively. These results demonstrate that the Embu Complex was probably accreted to the Apiaí Terrane during a Tonian (820-790 Ma) orogenic event, prior to final development of the Ediacaran Ribeira belt arc-related magmatism and a transcurrent shear zone system. The main source area for detrital zircons of the Embu Complex is likely to be the Grenville-Sveconorwegian-Sunsás orogen or time-equivalent regions rather than the central portions of the neighboring cratons. The Embu Complex geological context is consistent with accumulation on the margin of the Rodinia supercontinent.PostprintPeer reviewe

Reassessing the polyphase neoproterozoic evolution of the Punta del Este terrane, Dom Feliciano Belt, Uruguay

Some recent models challenge the position and extension of the assumed oceanic basins formed through the break-up of Rodinia, and the tectonic processes involved in the Gondwana assembly, making the investigation of the Early Neoproterozoic record of great relevance. Within the South-American Atlantic margin, the Punta del Este Terrane (PET) of the Dom Feliciano Belt (DFB) comprises a unique Tonian to Ediacaran record, and has a strategic position to reconstruct spatio-temporal relationships with the southern African orogenic belts. Novel zircon U–Pb and Lu–Hf data from the PET basement orthogneisses display Tonian magmatic ages (805–760 Ma) and Hf isotopic signatures indicative of mainly crustal/metasedimentary sources, (Nd TDM ages: 2.2–1.9 Ga, and εHf(t): −12 to −4). The basement paragneisses yielded late Paleoproterozoic to Neoproterozoic U–Pb ages, but dominantly positive εHf(t) values. The presented results confrm the correlation of the PET with the Coastal Terrane of the Kaoko Belt, and discard the idea of the Nico Pérez Terrane as a source. Detrital zircon U–Pb and Lu–Hf data from the Rocha Formation yielded a main peak at ca. 660 Ma, with the Neoproterozoic grains showing a εHf(t) between+1 and+14. The deposition age of the Rocha Formation is constrained by the youngest detrital zircon age peak (660 Ma), and the beginning of the deposition of the Sierra de Aguirre Formation (580 Ma). The data indicate common sources with the Marmora Terrane, and it is thus proposed that the Rocha Formation belongs to the Gariep Belt, and it was juxtaposed during the Ediacaran to the DFB

Provenance and paleogeography of the Devonian Durazno Group, southern Parana Basin in Uruguay

A succession of Devonian cover rocks occurs in outcrop and in the subsurface of central-northern Uruguay where they were deposited in an intracratonic basin. This Durazno Group comprises three distinct stratigraphic units, namely the Cerrezuelo, Cordobés and La Paloma formations. The Durazno Group does not exceed 300 m of average thickness and preserves a transgressive-regressive cycle within a shallow-marine siliciclastic shelf platform, and is characterized by an assemblage of invertebrate fossils of Malvinokaffric affinity especially within the Lower Devonian Cordobés shales. The sedimentary provenance of the Durazno Group was determined using petrography, geochemistry, and morphological studies of detrital zircons as well as their U-Pb ages. Sandstone petrography of Cerrezuelo and La Paloma sequences shows that they have a dominantly quartz-feldspathic composition with a minor contribution of other minerals. Whole-rock geochemical data indicate that alteration was strong in each of the three formations studied; chondritic-normalized REE patterns essentially parallel to PAAS, the presence of a negative Eu-anomaly, and Th/Sc and La/Hf ratios point to an average source composition similar to UCC or slightly more felsic. Within the Cerrezuelo Formation, recycling of older volcano-metasedimentary sources is interpreted from Zr/Sc ratios and high Hf, Zr, and REE concentrations. U-Pb detrital zircon age populations of the Cerrezuelo and La Paloma formations indicate that the principal source terranes are of Neoproterozoic age, but include also minor populations derived from Mesoproterozoic and Archean-Paleoproterozoic rocks. A provenance from the Cuchilla Dionisio-Dom Feliciano, Nico Pérez and Piedra Alta terranes of Uruguay and southern Brazil is likely. This study establishes an intracratonic extensional tectonic setting during Durazno time. Considering provenance age sources, regional paleocurrent distributions and the established orogenic history recorded in SW Gondwana, we suggest that the basin fill was derived from paleohighs located in what is currently SE Uruguay.Fil: Uriz, Norberto Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División geología; ArgentinaFil: Cingolani, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División geología; ArgentinaFil: Basei, M.A.S.. Universidade de Sao Paulo; BrasilFil: Blanco, G.. Universidad de la República; UruguayFil: Abre, P.. Universidad de la República; UruguayFil: Portillo, N.S.. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División geología; ArgentinaFil: Siccardi, Aron. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División geología; Argentin