Speleothem magnetism from the Last Glacial Maximum to the Holocene in South America

• Grant number: 19/06709-8
• Support type: Scholarships abroad - Research Internship - Doctorate
• Effective date (Start): June 24, 2019
• Effective date (End): March 19, 2020
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal researcher: Ricardo Ivan Ferreira da Trindade
• Grantee: Plinio Francisco Jaqueto
• Supervisor abroad: Joshua Moser Feinberg
• Home Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Research place: University of Minnesota (U of M), United States
• Associated to the scholarship: 16/24870-2 - Environmental significance of speleothem magnetism, BP.DR

Abstract

Magnetic enhancement in soils depends on water availability and its evolution through time. In karst environment these changes depend on the amount of rainfall and water transport in the aquifer system activated by the recharge (mainly storm events). Recent work has shown that magnetic minerals present in stalagmites are usually originated in the soil and sediments above the cave and are transported through cracks in the karst sys-tem before being deposited at the stalagmites. The amount and type of magnetic minerals present in the speleothem can be therefore linked to the soil dynamics and the long-term precipitation changes. South America presents antiphase climatic regimes recorded in ox-ygen isotope records in stalagmites, where the Northeast experiences humid condition on low insolation and aridity on high insolation, whereas central and southwest Brazil expe-rience the opposite relationship. The objective of this project is twofold. First, through a set of samples from different karst environments in Brazil comprising stalagmites, bed-rock and soil above the cave, a rock magnetic database will be constructed to better under-stand the origin of magnetic minerals in different settings and their relation to the bedrock and to the soil dynamics. Second, using four selected stalagmites covering the Holo-cene until the Last Glacial Maximum, a high-resolution record of magnetic properties will enable comparison with classical isotopic and geochemical proxies in order to infer the significance of millennial-scale variations in speleothem magnetism.