297 Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology (Posters)

We welcome submissions on the biogeochemistry, astrobiology, and historical records in of caves and karst features.

Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Reconstructing Paleoclimate from 44 -11 kya in the Philippines Using the Geochemistry of a Stalagmite Sample

Paper number: 297-2
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

In an era of rapid anthropogenic climate change, it is imperative to understand past and current climate trends as a means to constrain future hydroclimate changes. As such, periods of past rapid climate change and deglaciation are important to target for investigation. Further, tropical regions are severely understudied for both past and current studies of climate variability, despite being specifically vulnerable to anthropogenic influence on Earth's climate system. Climate archives such as speleothems preserve geochemical proxies that reflect past rainfall amounts present at the time of their formation. By studying proxies that contain information about these fluctuations, we can create models that reconstruct climate variations from the late Pleistocene to early Holocene. In this study, we reconstruct a multi-proxy speleothem paleoclimate record from the Philippines, a tropical island nation that relies heavily on annual monsoonal rainfall in order to replenish their minimal groundwater reservoirs. 

Speleothem sample PPUR-GP-3, is a broken stalagmite that was collected on the island of Palawan, Philippines, from the Puerto Princesa Subterranean River National Park (10.1926° N, 118.9266° E). PPUR-GP-3 is 16 cm in length and grew between 43,839 ± 748 to 11,220 ± 135 years B.P. (± 2𝜎). This sample grew during several key climate periods including Heinrich Events 1 through 4, the Younger Dryas, and the last deglaciation. Powders for geochemical analyses were drilled at a 250 µm spatial resolution. Preliminary stable isotope (δ18O), (δ13C), and trace element (Mg/Ca, Ba/Ca, Sr/Ca) data were analyzed every 1mm with a temporal resolution of ~272 years. Fluctuations in trace element data suggest preliminary results of drying trends through time, represented by an increase in Mg/Ca, and a decrease of Sr/Ca. Results from the stable isotope analyses will help constrain rainfall conditions present at the time of formation. Comparing our geochemical record with additional regional speleothem records from Sulawesi, Sumatra, Northern Borneo, and Palawan will provide insight into the tropical climate response to periods of global climate change. Future implications of these results provide new information pertaining to past climate variability in the Philippines that can be utilized for risk management of infrastructure and water resources.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413446

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