The influence of the intertropical convergence zone on the South American Summer Monsoon during the last glacial period

• Grant number: 23/14903-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: May 01, 2024
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Francisco William da Cruz Junior
• Grantee: Nathalie Melissa Martinez Medina
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 25/03747-7 - A comprehensive study of precipitation variability in convergence zones through trace elements in speleothems, BE.EP.DR

Abstract

Our current understanding of the climate systems and forcings influencing past precipitation variability in South America (SA) has drastically increased over the past decades. Yet some emerging questions need greater coverage of high-resolution continental records, especially over the region influenced by the Intertropical Convergence Zone (ITCZ) in northern SA. Since differences with the Cariaco Basin marine records has already been spotted during the Holocene, arising the question about the influence of the orbital forcing in ITCZ precipitation. As well, the mechanism driving precipitation variability under the region dominated by the South American Monsoon Summer (SAMS) in central Brazil is still not fully resolved. The lack of relationship between local insolation and tropical paleoclimatic records during a portion of the Last Glacial Period suggests that SAMS intensification was influenced by North Atlantic SSTs likely mediated by a southern ITCZ acting as a moisture conduit. Whereas other studies propose tropical South Atlantic SSTs as the main driver of precipitation changes over the SAMS. This PhD proposal aims to study speleothems collected in caves under the direct influence of both the ITCZ and SAMS in northern Venezuela and central Brazil, respectively. The comparison between the new speleothem records from these two regions will provide new insights about the ITCZ influence on the South American Convergence Zone (SACZ), a main climatic feature of SAMS, over orbital to millennial timescales during the last 120,000 years. In addition, the new record from central Brazil will provide information about local flooding events associated to the Araguaia River tributaries and provide a paleoclimate context to ancient human populations that inhabited this region thousands of years ago. (AU)