35-11 Constraints on Glacial Extent in San Pablín, Sierra Nevada del Cocuy, Colombia

Session: Ice sheets, glaciers, and landscapes, oh my! (Posters)

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Abstract:

The tropics are the primary source of heat and water vapor to the rest of the globe and play an outsized role in regulating global climate variability such as the glacial interglacial cycles of the late Pleistocene. However, there is ongoing debate whether tropical climate dynamics were independent drivers of glacial-interglacial cycles or responded to high-latitude forcings. Proxy records constraining temperature change during the Last Glacial Maximum (LGM, ~26-19 ka) and Termination 1 can help clarify the role of the tropics in high-magnitude changes in climate, but proxies in the northern high-elevation tropics are sparse. Mountain glaciers in the inner humid tropics (~10°N-10°S) respond primarily to changes in temperature, and by constraining their extent over time using glacial geomorphic mapping and cosmogenic 10Be exposure age dating, they can be used as sensitive climate proxies at high elevations.

Here, we present new surficial mapping and cosmogenic 10Be ages of past glacial extents in the Sierra Nevada del Cocuy, Colombia (6.4° N, 72.3° W).  We focus on moraines deposited downvalley of lateglacial moraines that have been mapped and dated using cosmogenic 10Be dating in prior studies. In San Pablín valley, we map three major moraine sets that mark glacial extents to ~3500 m asl.  We collected twenty boulder samples for 10Be ages from the moraine sets. Based on results from prior studies in neighboring valleys at Sierra Nevada del Cocuy constraining glacial extents in lateglacial time, we hypothesize that this set of moraines will document the LGM maximum extent of glacial cover at San Pablín and constrain the subsequent onset of Termination 1.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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