Tectonic, climatic and paleogeographic characteristics, genesis and preservation of pre-cenozoic glacial deposits in Brazil

• Grant number: 91/00546-2
• Support type: Research Projects - Thematic Grants
• Duration: January 01, 1992 - December 31, 1995
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal researcher: Antonio Carlos Rocha-Campos
• Grantee: Antonio Carlos Rocha-Campos
• Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The proposed project refers to the study of the action of tectonic, climatic and paleogeographic factors on the characteristics, genesis, and preservation of pre-cenozoic glacial sediments in Brazil. The primary objectives of the project are the development of concepts and models of sedimentation useful for the discernment of the effects of the different factors and of the causal relationships between tectonics, geological aspect and glacial stratigraphs, in different glaciated basins or under glacial influence. It is intended, in this way, for example, through the description of the character and arrangement of the sedimentary aspects preserved in these basins, to develop criteria for the distinction between the deposits of mountain glaciations and those of continental icecaps; the identification of controls of retreats and advances of ice sheets and their relationships with the glacio-isostatic and glacio-eustatic variations. Secondarily, the aim is to design and characterize glacial sequences and their potential for preservation, under different tectonic conditions; to contribute to the elaboration of a genetic classification of the glaciated basins, in the context of plate tectonics; for the understanding of the relationships between paleogeography and climate; for the identification of problematic glaciogenetic aspects etc. The approach to be used involves sedimentological and stratigraphic studies of "type areas”, probably representative of different sets of tectonic, paleoclimatic and paleogeographic conditions and among them probable Cenozoic and recent analogues. To this end, 4 "type areas” were selected, representing basins with glacial sedimentation from the Pre-Cambrian (Proterozoic) and Neopaleozoic in Brazil (Paraná basin). The Cenozoic glacial deposits of the Gulf of Alaska, USA, pleistocenic of the Basin of the Irish Sea, Ireland and recent glacio-marine sediments of Admiralty Bay, South Shetland Islands, Antarctica were selected as most suitable analogues of the deposits of the pre-cenozoic glaciated basins of Brazil. In counterpart to the present-day analysis, the project could contribute to the solution of several problems of Cenozoic glacial sedimentation (for example, the sedimentary record of the end (final deglaciation) of glaciation in ancient glacial sequences. The participating team is composed of researchers from Brazil and abroad, from varying backgrounds (Sedimentology, Stratigraphy, Glaciology, Regional Geology of folded Pre-Cambrian seams), with broad experience in different aspects of the study of glacial sedimentology in basins of different nature and conditioning (intracratonic; coverings and folded seams of the Pre-Cambrian; active and passive continental margin). Multidisciplinary teams led by the most experienced researcher will develop field and laboratory work relating to each area. A rotating system in the constitution of the teams will enable an interaction of the participants. The coordination of the work will be handled through joint field work; regular evaluation meetings, revision and planning; the preparation of reports; and the presentation of papers. These activities will occur, whenever possible, in conjunction with national and international scientific events. A final meeting is envisaged for planning of the final report and presentation of results, open to the participation of other interested researchers. Postgraduate students are participating in the team, which should include undergraduates, through scientific initiation grants. The results of the proposed project are of interest to at least three international and Brazilian projects (PICG 260: InQUA; PROANTAR). (AU)