NSFGEO-NERC: Collaborative Research: MexiDrill: Developing a 350,000 year record of climate and environmental change in tropical North America

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The primary scientific objective of this joint NSF-GEO/NERC proposal is to obtain a continuous, high-resolution record of past changes in climate and volcanism in the Mexico City region over the last 350,000 years. We will analyse a recently recovered ~350 metre-long core from the Lake Chalco basin on the southern outskirts of Mexico City. This sediment sequence will be among the longest archives of climate, environment, and biota from a region presently lacking such records. Information obtained from these cores will help understand the mechanisms that caused past climate shifts, which is critical for evaluating impacts of ongoing and future climate change. Mexico is projected to become drier in the coming decades-centuries in response to ongoing climate change, and these anthropogenic changes will be superimposed on natural variability in climate systems that are not fully understood. This project will extract information on the temperature and precipitation over the last 350,000 years to evaluate the drivers of the climate. The Chalco sedimentary sequence also provides a unique record of the explosive volcanism in the Mexico City region, with ash from more than 150 volcanic eruptions preserved. These volcanic ash layers are likely to be from the major stratovolcanoes that surround Mexico City and the extensive monogenetic field situated in the southern part of the city. We will use these eruption deposits to obtain a chronology for the core and establish the magnitude and frequency of past eruptions. This information on the long-term history of these volcanoes will be invaluable for hazard and risk assessments for this densely populated region.