Optically Stimulated Luminescence in Corals and Speleothems: From the Construction of Specific Reading Equipment to the Operating Principles of the Indicator

• Grant number: 25/06449-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: October 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Vinícius Ribau Mendes
• Grantee: Raquel de Carvalho Gradwohl
• Host Institution: Instituto do Mar (IMar). Universidade Federal de São Paulo (UNIFESP). Campus Baixada Santista. Santos , SP, Brazil
• Associated research grant: 22/02957-0 - Effects of the South Atlantic warming over South American precipitation, AP.PNGP.PI

Abstract

There are dozens of climate archives on Earth, and within this wide range of archives, there are various indicators that make it possible to retrieve information such as changes in vegetation, soil or water temperature, precipitation shifts, among others. Within this scenario of multiple possibilities, two types of archives stand out due to their ability to provide high temporal resolution results: on land, we have stalagmites, which allow for the reconstruction of continental precipitation variations, and in the ocean, certain species of corals enable the reconstruction of variations in water temperature and salinity. Both records are primarily composed of calcium carbonate, and many of the indicators used in these materials are based on the analysis of carbon and oxygen isotopes.The development of the first luminescence scanner within the context of the project "PI - Effects of South Atlantic Warming on South American Precipitation", to which this grant proposal is related, enabled the unprecedented analysis of optically stimulated luminescence (OSL) in stalagmites and corals. Preliminary analyses indicate a strong correlation between luminescence values and oxygen isotopes. If this correlation is confirmed, luminescence could be used as an alternative method for reconstructing variations in sea surface temperature (in corals) and precipitation (in stalagmites).To confirm the validity of this correspondence between carbonate luminescence and oxygen isotopes, it will be necessary to adapt the reading equipment to scan both stalagmites and corals, and tests will be required to evaluate which intrinsic property of calcium carbonate causes the luminescence signal to change. If validated, this method will allow for a significant increase in the number of samples analyzed, thanks to its low operational cost and high data acquisition speed.