8 Precambrian Geology of the Midcontinent: Celebrating the Career of W.R. Van Schmus

Monday, 12 April 2010
8:30 AM - 12:00 PM
Cooper Creek 2

AN OVERVIEW OF THE AMAZONIAN CRATON EVOLUTION: INSIGHTS FOR PALEOCONTINENTAL RECONSTRUCTION (THE UNITED PLATES OF SOUTH AMERICA)

Paper number: 8-8
Program: Theme Sessions
Time: 10:40 AM – 11:00 AM

Authors

Abstract

Supercontinent assemblages developed at several times in the Earth history and major tectonic events. Based on geochronologic, structural and paleomagnetic evidence paleocontinental reconstructions of the Amazonian craton.have been proposed for Archaean to younger times. The oldest highly speculative continent (Ur) had joined five Achaean cratonic areas where 3.0-2.8 Ga shallow-water supracrustals assemblages are observed. Coeval sediments of Agua Clara formation may suggest the participation of the Achaean rocks of the Carajás region in the Ur landmass.

Supercontinental 2.45 Ga Kenorland amalgamation is indicated by paleomagnetic data including Laurentia (Superior and Wyoming cratons), Baltica (Karelia craton), Australia (Yilgarn craton), and Kalahari and Kaapvaal cratons. From 1.83 Ga to 1.25 Ga Columbia supercontinent including Amazonian craton was proposed. Paleomagnetic and tectonic data indicate NE portion of the Amazonian craton had connection with West Africa and Kalahari cratons at that time.

Reconstructions of the Rodinia supercontinent show Amazonia joined to Laurentia-Baltica as result of 1.1 Ga to 1.0 Ga fusion of the Sunsas-Aguapei, Greenville and Sveconorueguian belts. The 750-520 Ma Gondwana assembly included most of the continental fragments rifted apart during the break-up of Rodinia at the beginning of the Neoproterozoic. Successive collision and plate indentation processes occurred during this global event. The configuration of the South America platform was defined during the Gondwana amalgamation where the Amazonian craton was bordered by the Neoproterozoic belts.

The Amazonian craton margins were not involved in the collisional processes during Pangea (230-180 Ma) because it was probably embebed within Neoproterozoic mobile belt rocks. As a consequence, Amazonian craton borders have no record of the orogenic processes responsible for the Pangea amalgamation.