T216 Evolving Perspectives of the Precambrian World: Using Combined Theoretical and Applied Approaches to Tackle Problems at the Intersection of Geology, Geobiology, and Geochemistry

Tuesday, 6 November 2018
1:30 PM - 5:30 PM
Room 242

GEOLOGICAL EVOLUTION OF THE BOLIVIAN PRECAMBRIAN SHIELD, SW AMAZONIAN CRATON: U-PB ISOTOPIC CONSTRAINTS

Paper number: T216-7
Program: Technical Sessions
Time: 2:55 PM – 3:10 PM

Authors

  • Ramiro Matos Presenting Author
    Instituto de Investigacones Geologicas y del medio Ambiente (IGEMA), La Paz

Abstract

The tectonic evolution of the Bolivian Precambrian shield extends from the Paleo- to the Mesoproterozoic; it can be related with the magmatic and metamorphic events in the Rondonian - San Ignacio (1.56-1.30 Ga) and Sunsás (1.25-1.00 Ga) provinces. Geochronological data and geological mapping allow to separate three temporally distinct granite suites before the San Ignacio orogeny (1.37-1.30 Ga):

  1. a) The Correreca granite from 1.92 to 1.89 Ga (Pb-Pb evaporation) and Santo Corazon granite, this last one yielding 1850 Ma. It is suggested that the area of Correreca and Santo Corazon granites - which crop out in the southeastern of the Precambrian shield - could be part of the Apa Block and it could be collided to the Paraguá Terrane during Sunsas orogeny.
  2. b) The Yarituses Granitoid Suite of 1.67 to 1.62 Ga - which crops out in the area of San Javier - is intruded into the San Ignacio Schist group and correspond to volcanic arc granite.
  3. c) The San Ramon granodiorite – which yields an age of 1.43 Ga - could be considered as a pre-kinematic pluton associated to the Pensamiento Granitoid Complex of the San Ignacio orogeny. The magmatism, deformation and metamorphism of the San Ignacio orogeny with sin- to late-kinematic and late to post-kinematic plutons have crystallization ages of 1373 - 1340 and 1347-1275 Ma respectively. This orogeny represents a continental accretionary arc that built the architecture of the Rondonian-San Ignacio province (1.56-1.30 Ga) by the collision of the Paragua Terrane against the Rio Negro -Juruena province (1.78-1.60 Ga).
  4. d) The evolution ends with the formation of the Sunsás collisional belt which produced sin- to late and late to-post-kinematic plutonism. The allochthonous and collisional nature of the Sunsás orogeny is marked by tectonic fronts converging towards the Paraguá Terrane.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-321494

© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.