The Cerro Olivo Complex: a pre-collisional Neoproterozoic magmatic arc in Eastern Uruguay
MetadataShow full item record
The Cerro Olivo Complex is one of the few occurrences of the basement rocks in the Dom Feliciano Belt. It contains migmatitic paragneisses and orthogneisses that host granites of ca. 600–540 Ma Aiguá Batholith. The main orthogneisses are rich in orthopyroxene + Ca-plagioclase (Cerro Bori unit), but K-feldspar augen gneisses are also common (Centinela-Punta del Este unit). The paragneisses (Chafalote unit) are semi-pelitic migmatites that contain restites of metapelites, quartzites, amphibolites, and calc-silicate rocks. A clockwise pressure–temperature–time (P–T-t) path and two deformational events affected the Cerro Olivo Complex rocks. Granulitic high-pressure (HP)–high-temperature (HT) peak conditions were followed by low pressure (LP)–HT decompression. The first deformation (K1) developed an E–W gneissic foliation and westward-stretching lineations, whereas the second (K2) produced NS to NE–SW low-temperature mylonitic foliation and southward-stretching lineations. New SHRIMP U–Pb data from zircon cores in magmatic textural domains yield an intrusive age of 782 ± 7 million years for the Cerro Bori unit. The zircon rims have an age of 657 ± 7 million years, reflecting a younger partial melting event. Inherited ages in zircon xenocrysts span from 2655 to 768 million years, but are mostly ca. 1.0–1.2 thousand million years old. Bulk-rock geochemistry indicates a magmatic arc setting for the source rocks. The Cerro Bori unit represents calk-alkaline tonalitic and granodioritic rocks mixed with minor gabbros; in contrast, the Centinela unit consists of post-orogenic granites. A continental magmatic arc developed between ca. 800 and 770 Ma attending convergence of the Kalahari and Rio de la Plata palaeocontinents, but prior to their collision.
Showing items related by title, author, creator and subject.
Timing and evolution of multiple Paleoproterozoic magmatic arcs in the Tapajos Domain, Amazon Craton: constraints from SHRIMP and TIMS zircon, baddeleyite and titanite U-Pb geochronologySantos, J.; Van Breemen, O.; Groves, D.; Hartmann, L.; Almeida, M.; McNaughton, Neal; Fletcher, Ian (2004)Knowledge of the geotectonic evolution of the Tapajos Domain of the Tapajos-Parima Orogen is of major significance in the Amazon Craton, for two reasons: first, the domain lies between the Archean Central Amazon Province ...
Monazite trumps zircon: applying SHRIMP U–Pb geochronology to systematically evaluate emplacement ages of leucocratic, low-temperature granites in a complex Precambrian orogenPiechocka, A.; Gregory, C.; Zi, J.; Sheppard, S.; Wingate, M.; Rasmussen, Birger (2017)© 2017, The Author(s). Although zircon is the most widely used geochronometer to determine the crystallisation ages of granites, it can be unreliable for low-temperature melts because they may not crystallise new zircon. ...
Cavosie, Aaron; Kita, N.; Valley, J. (2009)The oxygen-isotope composition of the Earth's upper mantle is an important reference for understanding mantle and crust geochemical cycles. Olivine is the most commonly used mineral for determining the influence of crustal ...