Showing papers in "Journal of South American Earth Sciences in 2011"

TL;DR: The Borborema Province of Brazil has three major subprovinces: the central subprovince consists of a tectonic collage of various blocks, terranes, or domains ranging in age from Archean to Neoproterozoic as discussed by the authors.

TL;DR: In this paper, recent provenance data based on LA-ICPMS U-Pb ages of detrital zircon grains from several of these units, are reviewed and their significance for the age of deposition of the original sediments and tectonic evolution of the Brasilia Belt are discussed.

TL;DR: The Southern Andes have been built through stacking of crustal sheets in discrete periods during the last 100my as discussed by the authors, where rather anhydrous subducted slabs generated a discontinuous arc emplaced in the foreland area at the time of mountain building.

TL;DR: In this article, it was shown that the Puncoviscana Formation rocks older than 530 ǫ are deposited in the arc-trench gap of the west-facing Pampean arc and/or the associated trench, whereas the rocks younger than 530ǫ were deposited in a syn-collision foreland basin.

TL;DR: The detrital zircon ages of the Ollantaytambo Formation range from 2013-Ma to 445-Ma as discussed by the authors, and the older ones correspond to major orogenic cycles recorded on the southwestern Amazonia craton, the Rondonia-San Ignacio, Sunsas, and Brasiliano orogenies.

TL;DR: In this article, the four periods of rock-forming events discussed here (Siderian, Rhyacian, Orosirian, Statherian) are mainly recorded and recognizable for most of the cratonic domains of the continent.

TL;DR: The Andrelândia Nappe System as discussed by the authors is a pile of nappes that records the Neoproterozoic history of the subduction and collision between passive and active margins, respectively belonging to the Sao Francisco and Paranapanema Plates.

TL;DR: A petrological and geochronological study of Cordilleran granitoid intrusions in the Bariloche area (Argentina) point to a complex time-compositional evolution of magmatic processes in relation with oblique subduction of the Phoenix plate below the South America active margin during Jurassic times as mentioned in this paper.

TL;DR: In this paper, it was shown that these augen gneisses do not differ significantly from the metaplutonic rocks of the basement complex regarding their nature and emplacement age of the primary magmas.

TL;DR: In this article, it is suggested that the Brusque Group initially evolved in an independent peri-cratonic basin setting separated from the Florianopolis- Pelotas-Aigua magmatic arc by the Adamastor ocean.

TL;DR: In this article, the authors developed the needed stratigraphy for the areas in the Pisco Formation where most of the vertebrate paleontological research is occurring, using GPS locations, maps of the marker beds on aerial photographs, and outcrop photographs allowing field determination of the stratigraphic positions of study areas.

TL;DR: Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene.

TL;DR: U-Pb SHRIMP dating of zircons from two orthogneisses and one metasedimentary migmatite from the Tahami Terrane (core of the Central Cordillera, Colombian Andes) indicate that regional metamorphism took place in Late Triassic times as mentioned in this paper.

TL;DR: The Sierra de Velasco contains three main types of Early Ordovician granitoids that are mineralogically and geochemically distinct, but generally conform a continuous high-K, magnesian and calc-alkalic magmatic series.

TL;DR: In this paper, the ages for post-collisional granites from the central Ribeira belt (Rio de Janeiro State, southeast Brazil) are reported for I-type, megaporphyritic and equigranular leucogranite plutons and dykes intruded high-grade metasedimentary units, orthogneisses, and migmatites within the root zone of the deeply eroded Neoproterozoic-Cambrian ribeira orogen.

TL;DR: In this article, sedimentological, paleocurrent, and sandstone petrographic results from Cenozoic type localities are presented to provide insights into the tectonic history of the northern Middle Magdalena Valley Basin of Colombia.

TL;DR: In this article, detrital zircon age populations in late-Paleozoic accretionary prisms formed after its collision along the Pacific margin of Gondwana were examined, which may have incorporated sediments derived from the erosion of the Chilenia basement.

TL;DR: In the Sao Felix do Xingu region, southern portion of Amazonian craton, voluminous well-preserved Late Paleoproterozoic volcanic and plutonic rocks are grouped in the Sobreiro and Santa Rosa formations.

TL;DR: In this article, the authors developed an evolutionary stratigraphic and tectonic model, based on the characterization of depositional sequences, internal flooding surfaces, depositional systems arrangement and paleoflow directions.

TL;DR: The Baquero Group holds a rich fossil flora including macrofloristic and palynological remains that characterize the Early Cretaceous vegetation of Argentina as mentioned in this paper, but there have been no reliable age constraints for the fossil assemblages.

TL;DR: The Tabira, Itapetim and Timbauba granitoids are intruded into metasedimentary sequences and Cariris Velhos (Tonian) orthogneisses from the Central Domain of the Borborema Province, NE Brazil as discussed by the authors.

TL;DR: In this article, the authors examined the origin and behavior of the main components of the two groups of waters and compared them with each other in the south and the north of Chile.

TL;DR: A new investigation of the Guarani Aquifer System (SAG) in Sao Paulo state is presented in this paper, where sedimentary data were acquired about sedimentary framework, flow pattern, and hydrogeochemistry.

TL;DR: The southern side of the Ponta Grossa Arch (PGA), a prominent NW-SE-trending tectonic feature extending over 600 km, was the site of important alkaline and alkaline-carbonatitic magmatic activity in Early and Late Cretaceous times.

TL;DR: Lu-Hf isotope data for dated Permian zircon grains from six samples of the latest Palaeozoic to Jurassic low-grade metasedimentary rocks of western Patagonia and the northern Antarctic Peninsula, as well as from potential source rocks in the North Patagonian Massif were presented in this article.

TL;DR: In this article, a petrographic study combined with conventional and pseudosection thermobarometry led to deducing a short prograde metamorphic evolution within migmatite blocks.

TL;DR: In this paper, five new U-Pb zircon dating and corresponding Nd isotope data for felsic granulites from the south Itabuna-Salvador-Curaca Block (ISCB), in the Sao Francisco Craton, Brazil.

TL;DR: In this paper, the behavior of C and O isotopes, major and trace element chemistry have been examined in core drill carbonate samples from three drill holes (Poty Quarry, Olinda and Itamaraca).

TL;DR: In this article, the authors present an analysis of the North Patagonian Massif based on the analysis of Sm-Nd systematics and conclude that it is a crustal block with bulk crustal average ages between 2.1 and 1.6 ǫ T DM (Nd) and at least three metamorphic episodes could be identified in the Paleozoic rocks of the NPM.

TL;DR: Fossils of terrestrial mammals preserved in the submarine environment have been recorded in several places around the world, including Brazil as discussed by the authors, where the fossils encompass several groups of both extinct and extant mammals, and exhibit several distinct taphonomic features related to the marine environment.