SGER Award-Exploratory Work in Rondonia - the Laurentia-Amazonia Connection

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Most Rodinia plate reconstructions propose juxtaposition of the western Amazon craton with some segment of the 3000 km long Grenville margin of Laurentia. This connection is based on linking similarly aged (ca. 1.2-0.95 Ga) mobile belts across ancient continental margins. However, poor understanding of the metamorphic and structural history of the western Amazon block has prevented a test of these Laurentia-Amazonia configurations. This proposal requests funding for exploratory work in recently exposed field areas to document the deformational history of the western Amazon craton using structural mapping, metamorphic petrology and geochronology. Preliminary mapping and sample collecting of two key regions in the western Brazilian state of Rondonia, located on the margin of the Amazon craton, will be undertaken in collaboration with the Brazilian Geological Service (CPRM). The laboratory portion of this project will focus on pressure and temperature (P-T) conditions and geochronology (using 40Ar/39Ar and U/Pb systems) for the timing of peak metamorphism and deformation. These data will test the feasibility of a larger project in the area toward a firm understanding of Laurentia-Amazonia interactions in late Proterozoic times.