Speleothem Palaeoclimatology in the Maya Lowlands of Northwestern Yucatán, Mexico

The sociopolitical and demographic changes in the Maya civilisation during the Terminal Classic Period (800 – 1000 CE) are increasingly thought to coincide with climate change, specifically drought. Two challenges facing interdisciplinary analysis of the complex interactions between climate and society in the Terminal Classic Yucatán Peninsula, Mexico, are the low chronological resolution of local palaeoclimate records, and the lack of quantitative reconstructions of palaeorainfall changes. I present new proxy records of climate in the Maya Classic Period from two speleothems in northwestern Yucatán which help address these issues. First, I provide a high resolution δ¹⁸O record of seasonal climate variability in the Terminal Classic. Using lamina counting and uranium series disequilibrium dating on the stalagmite Tzab06-1, I reconstruct the precise duration, timing, and relative severity of wet season droughts in the Terminal Classic. This is the first proxy record from the northern Yucatán resolved on seasonal timescales, and can be directly compared to the history of local Maya archaeological sites, as I demonstrate at Uxmal and Chichén Itzá. Secondly, I provide a multiproxy palaeoclimate record from the stalagmite HOBO-5, spanning the last 1,500 years. I use combination of the traditional stable isotopes δ¹⁸O and δ¹³C, and calcium isotopes (δ⁴⁴Ca), a novel speleothem proxy which I use to estimate semiquantitative palaeorainfall changes. As well as corroborating previous records of Terminal Classic climate, the δ⁴⁴Ca record reconstructs additional climatic variability, including a significant wet period punctuating drought events, and persistently low groundwater availability for over a century after the Terminal Classic. The assumptions in proxy interpretation in both stalagmites are tested by the establishment of monitoring at both caves of origin, and the ability of the karst system at the site of Tzab06-1 to transmit and record seasonal climate change is confirmed. This work provides new records with which spatiotemporally high-resolution analysis of human-climate-environment interactions in the Terminal Classic can be assessed to aid understanding of the complex decline of Classic Maya society, and move beyond the narrative of catastrophic collapse.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2023

Author dc:creator

• James, Daniel

Advisor dc:contributor.advisor

• Hodell, David

• Geoarchaeology
• Maya
• Palaeoclimate
• Speleothem
• Stable Isotopes

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/d0768f0d-8525-4e81-b603-cbd6e6ee9002/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.111004

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/372071