The proposed work would conduct a detailed geophysical survey of the Laguna de Tota, a large tectonic lake in the Eastern Cordillera of the Colombian Andes. The survey would determine the thickness and layout of the bottom sediment layers, and allow the researchers to better understand the type of materials available for a possible later expedition to extract samples by drilling for cores. The proposed geophysical work involves an international team of U.S. and Colombian geoscientists, which will strengthen international collaboration and provide training for U.S. and Colombian graduate students. Drs. Bird and Escobar will engage local communities that rely on Tota's water resources by giving lectures about the geophysical and drilling project at community centers. They will also speak at Colombian universities to increase awareness about Andean water resources and climate change.
The location of the lake is important, because as South America's third largest lake, it is well removed to the North from the other two (Lakes Titicaca and Junin, in Bolivia and Peru). A sediment core from the Laguna de Tota could potentially contain climate data recording temperatures and lake process history over the last several hundred thousand years, and include several glacial/inter-glacial climate signals, including that of the South American Summer Monsoon, whose details are poorly understood.
Using a small, high-resolution single-channel airgun seismic reflection system and a CHIRP sub-bottom profiler the team would map Tota's bathymetry, determine the thickness of lacustrine sedimentary sequences, locate depositional centers and identify lake-level transgression-regression sequences. Littoral sediment cores collected from Tota in 2013 suggest that the lake's sediment archive contains detailed climatic information, including evidence of past lake level changes. The team would characterize Tota's sediment archive and assess its potential for developing a long-term paleoclimate record. Despite near certainty that Tota's sediment archive spans at least several hundred thousand years, no known geophysical or paleoclimate work has been conducted on the lake previously. The proposed work therefore represents a unique opportunity to investigate a site that has tremendous potential for containing a long, continuous record of Northern Hemisphere South American Pleistocene climate. This work is in its initial phases, but has potential to transform our understanding of tropical climate change. As such, this work is appropriate for the EAGER funding mechanism that is designed to support "high risk-high pay off" exploratory work in its early stages.
The funding is requested for ¾ of a summer month for the lead PI, 1 month for his graduate student, as well as travel for 3 PIs and 2 U.S. graduate students. Airfreight for the coring equipment from LacCore and its return, per diem in the Tota vicinity, and boat and truck rental are also requested.
