147-20 Insights into the Deglacial in Southwestern North America from a Lacustrine Record in Northeastern Arizona

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

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During the last glacial maximum, southwest North America was wetter than the present, and as deglaciation progressed, shifts in the seasonal precipitation regimes occurred. However, the relative contribution of summer and winter precipitation, as well as their underlying mechanisms and forcings remain uncertain because long continuous paleoclimate records from this region are relatively rare. Here, we present a new reconstruction of past climate changes spanning the past ca. 40,000 years from Potato Lake on the Mogollon Rim in northeast Arizona using leaf wax 𝛿D and branched glycerol dialkyl glycerol tetraethers. Paleotemperatures estimated using the MBT’5Me index show ca. 6.5˚C of cooling during the last glacial, and an early Holocene thermal maximum that is ca. 1˚C warmer than the preindustrial.  Deglacial warming occurs gradually and starts early, beginning at immediately after the last glacial maximum (LGM) at ca.21-22 ka.  A slight cooling of ca. 1˚C occurs synchronously with the Younger Dryas stadial.  In contrast, 𝛿D_wax values peak during  the LGM, but do not change significantly until ca. 16.3 ka, when they decrease abruptly. The differences between the 𝛿D_wax and temperature reconstructions suggests a decoupling between temperature and atmospheric dynamics during the deglacial, reflecting differences in the underlying processes driving precipitation and temperature changes at that time.

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

doi: 10.1130/abs/2025AM-9448

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