Reconstitution of Rainfall in Northeast Brazil During the Holocene: The Oxygen Isotope Record in Stalagmites from Jerônimo Cave

• Grant number: 24/20290-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2025
• End date: December 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Francisco William da Cruz Junior
• Grantee: Camila Sayuri Kinoshita
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/08359-7 - Interhemispheric monsoon precipitation patterns under different warming backgrounds in the past 140 KA and the anthropocene epoch, AP.PFPMCG.R

Abstract

The Intertropical Convergence Zone (ITCZ) and the South American Monsoon System (SAMS) are the primary drivers of convection over the tropical region of South America. According to previous research, atmospheric dynamics between the ITCZ and SAMS have shifted over the last millennia across Northeast Brazil (NEB), causing unexpected climate fluctuations in certain areas. The research hypothesis is that changes in atmospheric circulation over NEB have resulted in distinct precipitation patterns between S-NEB (SAMS region) and N-NEB (ITCZ region), with eastern Amazon potentially acting as an intermediary axis between these regions-sometimes in phase with N-NEB and at other times with S-NEB.Stalagmites from Jerônimo Cave (Uauá, Bahia - S-NEB) form part of a speleothem collection housed at IGc-USP, with previous results covering the last 8,000 years. In this research project, it will be possible to document the entire Holocene period using samples that have already been precisely dated through the uranium-thorium decay series method, though they still need to be analyzed to obtain stable isotope data for carbon and oxygen. These samples will enable the reconstruction of paleoprecipitation patterns in northern Bahia to better understand its variability and main drivers over the past 11,700 years. Additionally, the findings can be compared with available NEB data and other South American records to gain further insight into the relationship between SAMS and ITCZ during the studied period.