Geocrhonology and paleoenvironmental significance of clastic cave sediments of the Bahia State

• Grant number: 10/20560-2
• Support Opportunities: Regular Research Grants
• Duration: April 01, 2011 - March 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Ivo Karmann
• Grantee: Ivo Karmann
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: André Augusto Rodrigues Salgado ; Darryl Granger ; Fernando Verassani Laureano ; Francisco William da Cruz Junior

Abstract

This research proposal aims to study the stratigraphy and geochronology of clastic sediment sequences from caves in the Bahia state, based mainly on the burial ages using the cosmogenic radionuclides dating technique on quartz grains transported by underground drainages. The ages of deposition and erosion of clastic sediments in the caves will provide new insights into the understanding of the impact of Quaternary climatic events such as Heinrich and Young Dryas over the dynamics of karstic systems, which correspond to important aquifers in central Bahia. These changes in paleodischarge and water table level of underground rivers will be compared with variations of paleopluviosity revealed by the '18O records of carbonate speleothems already documented in previous research performed at the study site. The U/Th dating of calcite crusts interbedded in part of the clastic sequences will indicate ages of lower river discharge phases associated with dryer regional climate during Late Pleistocene. Furthermore, cosmogenic ages will extend the chronology of these climatic events beyond the limit of the U/Th dating technique in carbonates for the lower portion of clastic sequences that are older than 700 ky, as indicated in previous paleomagnetic studies. The chronology of the old sedimentation is a key tool to quantify the downcutting rates of underground rivers, which in turn can give precise estimates of tectonic uplifting rates within cratonic areas. This research proposal is a continuity of previous research projects funded y FAPESP (grants 96/05686-0, 96/05686-0, 99/10351-6, 06/02834-2 e 06/06761-0) with the general aim of studying paleoenvironmental records of speleothems and the dynamics of karstic systems of Brasil. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

LAUREANO, FERNANDO V.; KARMANN, IVO; GRANGER, DARRYL E.; AULER, AUGUSTO S.; ALMEIDA, RENATO P.; CRUZ, FRANCISO W.; STRICKS, NICOLAS M.; NOVELLO, VALDIR F.. Two million years of river and cave aggradation in NE Brazil: Implications for speleogenesis and landscape evolution. Geomorphology, v. 273, p. 63-77, NOV 15 2016. (10/20560-2)