147-14 Phreatic Overgrowths on Speleothems from the Yucatán Peninsula Reveal Past Stable Sea Levels in the Caribbean.

Session: Climate, Ocean and Environmental Changes Through Earth History: From Marine and Terrestrial Proxies to Model Assessments (Posters)

Poster Booth No.: 181

Presenting Author:

Emma Hughes

Authors:

Hughes, Emma Kathryn¹, Polyak, Victor James², López Martínez, Rafael Antonio³, Valera-Fernández, Daisy⁴, Sosa, Erick⁵, Mitrovica, Jerry X⁶, Asmerom, Yemane⁷, Onac, Bogdan P⁸

(1) School of Geociences, University of South Florida, Tampa, FL, USA, (2) Earth & Planetary Sciences, University of New Mexico, Albuquerque, NM, USA, (3) Carbonates and Karst Laboratory, Institute of Geology, National Autonomous University of Mexico, Mexico City, Mexico, (4) Carbonates and Karst Laboratory, Institute of Geology, National Autonomous University of Mexico, Mexico City, Mexico, (5) Servicios Ambientales Especializados, BIOMA, Quintana Roo, Mexico, (6) Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA, (7) Dept Earth & Planetary Sciences, Univ New Mexico, Albuquerque, NM, USA, (8) School of Geosciences, University of South Florida, Tampa, FL, USA,

Abstract:

Reconstructing past sea level, and understanding the implications for ice sheet stability, has become increasingly important in the face of accelerating sea-level rise in our progressively warming world. The Yucatán Peninsula, like most coastal landforms in the Caribbean Sea region, is vulnerable to sea-level rise due to its low elevation. In addition to this vulnerability, the Caribbean region is understudied with respect to past relative sea level (RSL). The Yucatán Peninsula’s low hydrologic gradient and long-term tectonic stability make it a prime location for reconstructing precise regional sea-level histories, especially following the recent discovery of phreatic overgrowths on speleothems (POS) in the region. This study presents new RSL estimates based on POS, which form at the air-water interface in littoral caves during periods of stable sea level. POS morphology and elevation preserve mean sea level at the time of precipitation, making them high-precise indicators for paleo sea-level reconstruction. 

Samples were collected within 7 km of the coast and dated using U-series methods to Marine Isotope Stage (MIS) 9 (~353-290 kyr), MIS 7 (~245-200 kyr), and MIS 5 (~130-80 kyr). POS from MIS 9 were collected at 5 meters below present sea level (mbpsl). Three POS likely corresponding to MIS 7e or 7c comes from 1 meter above present sea level. The ages of three additional samples collected at 5 and 14 mbpsl suggest they formed during MIS 5, although large dating uncertainties prevent precise identification of the specific substage at this point. Ongoing U-series analysis will extend the current record and provide tighter constraints on past RSL for the Yucatán Peninsula and the broader Caribbean region. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7608

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