Magnesium in subaqueous speleothems as a potential palaeotemperature proxy.

Area of Science:

• Paleoclimatology
• Geochemistry
• Speleothem Science

Background:

• Limited paleoclimate archives exist outside polar regions for multi-cycle temperature reconstructions.
• Developing a coherent global picture of past temperatures is hampered by data scarcity.

Purpose of the Study:

• To investigate Mg concentrations in subaqueous speleothems as a proxy for regional sea-surface temperatures.
• To reconstruct past temperatures over multiple glacial-interglacial cycles using a novel archive.

Main Methods:

• Analysis of Mg concentrations in a subaqueous speleothem from an Italian cave.
• Correlation of Mg data with established paleoclimate records to validate temperature proxy.

Main Results:

• Speleothem Mg concentrations successfully tracked regional sea-surface temperatures over the last 350,000 years.
• Higher Mg values correlated with warm intervals, and lower values with cold stages.
• Temperature, rather than rainfall, was identified as the primary driver of Mg variability.

Conclusions:

• Subaqueous speleothems provide a reliable archive for multi-cycle paleotemperature reconstructions.
• The unique depositional setting enhances temperature sensitivity of Mg partitioning.
• This method offers a valuable tool for understanding long-term climate dynamics beyond polar regions.