Quantification of remanent magnetization acquisition processes in speleothems

• Grant number: 23/08485-5
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2023
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Ricardo Ivan Ferreira da Trindade
• Grantee: Carolina Silveira de Moraes
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 25/02555-7 - Quantification Of Remanent Magnetization Acquisition Processes In Speleothems, BE.EP.DD 24/04142-9 - Quantification Of Remanent Magnetization Acquisition Processes In Speleothems, BE.EP.DD

Abstract

The Earth's magnetic field presents rapid variations in its direction (declination and inclination) and intensity. These variations, are currently recorded in observatories around the globe and by satellites. For periods before the last two centuries, the investigation of the magnetic field is done indirectly, based on its record in archaeological materials, sediments, and volcanic rocks. More recently, speleothems - which are formations produced by the precipitation of calcium carbonate in caves - have been intensively studied as records of recent field variations. Speleothems have several advantages when compared to other types of records due to their ability to perform continuous records, with good dating by the U-Th method and not showing the effects of post-depositional compaction. The objective of this project is to quantitatively characterize the mechanisms responsible for the acquisition of natural remanent magnetization (NRM) in speleothems. A study will be carried out of the magnetic records of synthetic stalagmites, precipitated in a similar way to the natural environment, and of stalagmites acquired in caves, in addition to the creation of numerical models of the process of acquisition of depositional remanent magnetization (DRM). The techniques used will be the acquisition of natural remanent magnetization (NRM), anhysteretic remanent magnetization (ARM) and isothermal remanent magnetization (IRM), magnetic susceptibility anisotropy (ASM), anhysteretic magnetic remanence anisotropy (AARM), remanence anisotropy isothermal (AIRM). These data will be complemented with the study of the magnetic mineralogy of both groups of speleothems, through the analysis of hysteresis curves, First-Order Reversal Curves (FORC), low-temperature thermomagnetic curves, and investigation of environmental parameters. (AU)