1,721,722 research outputs found
The Precambrian to Paleozoic crustal growth of South America: From collisional to accretionary tectonics
No full textSouthern South America hosts a vast geologic record of Precambrian to Paleozoic geodynamic and tectonic processes, particularly related to the assembly and crustal growth of Western Gondwana. This special volume comprises 24 novel contributions focused on the Precambrian to Paleozoic tectonic evolution of southern South America, focused on different tectonostratigraphic domains of southeastern Brazil, Uruguay, Argentina and Chile (Figs. 2, 3). Papers also cover a wide temporal frame, including Archean to Tonian processes of pre-Brasiliano basement inliers; the tectonometamorphic, magmatic and sedimentary record of the late Neoproterozoic Brasiliano Orogeny, particularly related to the Dom Feliciano Belt; and Paleozoic accretionary systems of the proto-Pacific margin (Fig. 4).Fil: Oriolo, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Hueck, Mathias. Universidade de Sao Paulo; BrasilFil: Oyhantcabal, Pedro. Universidad de la República; UruguayFil: Siegesmund, Siegfried. Universität Göttingen; Alemani
The significance of rock fabrics for the geological interpretation of geophysical anisotropies
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The Río de la Plata Craton of Argentina and Uruguay
No full textThe geology and the tectonic evolution of the Río de laPlata Craton is reviewed, taking into account geochronological,isotopic and geophysical data. The craton consistsof voluminous granite-gneissic terrains (2.2?2.1 Ga) thatrepresent magmatism during the accretional stage of theorogeny. Coeval volcano-sedimentary basins are preservedas relics of supracrustal rocks, deformed andmetamorphosed during a collisional event that occurred atca. 2.1 Ga. Sm?Nd and Hf model ages between 2.7 and2.2 Ga, and positive to slightly negative eNd(t) valuesindicate a Neoarchean to Paleoproterozoic juvenile crustwhich underwent a short period of crustal recycling.Undeformed granitoids, gabbros and dolerite swarms withcalc-alkaline signature intruded at ca. 2.07 Ga correspondto the late- to post-tectonic stages of the orogeny.Exhumation, cooling and cratonization occurred duringthe Orosirian (2050?1800 Ma) and later anorogenicextension is recorded in tholeiitic dyke swarms intrudedat ca. 1.8 Ga in Uruguay and at ca. 1.6 Ga in the BuenosAires province of Argentina. There is no evidence ofMeso- or Neoproterozoic orogenic reworking and onlyone shallow granite intrusion in Uruguay andlow-temperature hydrothermal alteration in theNeoproterozoic cover of the Tandilia System can beascribed to far-field effects of the Brasiliano orogeny.Fil: Oyhantçaba, Pedro. Universidad de la República; UruguayFil: 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; ArgentinaFil: Wemmer, Klaus. Georg-August-Universität Göttingen; AlemaniaFil: Siegesmund, Siegfried. Georg-August-Universität Göttingen; Alemani
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