Quantification Of Remanent Magnetization Acquisition Processes In Speleothems

• Grant number: 25/02555-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: June 01, 2025
• End date: October 15, 2025
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Ricardo Ivan Ferreira da Trindade
• Grantee: Carolina Silveira de Moraes
• Supervisor: Roger Fu
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Harvard University, United States
• Associated to the scholarship: 23/08485-5 - Quantification of remanent magnetization acquisition processes in speleothems, BP.DD

Abstract

The Earth's magnetic field varies rapidly in its direction (declination and inclination) and intensity. Currently, global observatories and satellites record these variations. For periods before the last two centuries, the study of directional and magnetic field intensity data is carried out indirectly through records in archaeological materials, sediments, and volcanic rocks. Recently, speleothems have been increasingly used to study the record of recent variations in the magnetic field. They offer advantages such as continuous records, exceptionally precise U-Th dating, and a lack of post-depositional effects. However, the magnetic remanence acquisition process in speleothems still needs to be fully understood. The main aim of this project is to investigate the mechanisms of acquisition of remanent magnetization in speleothems. Therefore, we will precipitate artificial stalagmites using a calcium carbonate solution with added cave sediments. The stalagmites will be constructed in a climate box, which allows to control parameters such as temperature, relative humidity, and pCO2. The stalagmites will be precipitated with sediments from different caves, varying the intensities of the ambient magnetic field. The sediments used have already been characterized by their magnetic mineralogy and have previously been implemented in experiments purchasing synthetic stalagmites with sodium thiosulfate. Additionally, we will conduct experimental data acquisition using the Quantum Diamond Microscope (QDM). We will characterize the magnetization direction and intensity information on micrometric scales of experimentally constructed speleothems and samples precipitated in a cave environment. The results of this project will contribute to a deeper understanding of the behavior of data acquisition with QDM, potentially improving information on DRM acquisition in speleothems, taking into account the properties of sediments from caves and the shape of calcite crystals.