Hydroclimate variability in Central America during the Holocene inferred from lacustrine sediments in Lake Izabal, eastern Guatemala
"Holocene hydroclimate reconstructions have contributed to our understanding of the mechanisms controlling precipitation in Central America. Recent hydroclimate proxy records from the region, however, have revealed considerable spatiotemporal complexity in precipitation variability. This complexity is hypothesized to result from the interaction between multiple oceanic-atmospheric processes that converge in the region. This project analyzed three sediment cores from Lake Izabal, eastern lowland Guatemala, with the goal of understanding changes in precipitation, lake productivity, and lake water chemistry during the Holocene. Our proxy results indicate that precipitation in the region increased from the early to the middle Holocene, when Lake Izabal became a meromictic lake following a marine incursion. Anoxic bottom waters lasted ~3,500 years, preserving 2,186 mm-scale dark and light laminae couplets that are distinctly different in color, composition, and texture. At ~4,800 calibrated years before present (cal yr BP), Lake Izabal became a polymictic lake, and precipitation in the region stabilized, remaining high until ~1,200 cal yr BP, with an abrupt decrease in precipitation thereafter. Our findings indicate that Lake Izabal is highly sensitive to changes in Caribbean sea level and Caribbean sea-surface temperatures, the former controlling lake water chemistry and the latter controlling precipitation. Our results also add to new hydroclimate proxy data from the region, highlighting the complexity in precipitation variability in the area. Additional paleoclimate proxy records from Central America are needed to improve our understanding of how global warming will affect environmental conditions and regional hydroclimate variability"--Abstract, page iv.
Central America, Elemental abundances, Lake Izabal, Precipitation, Sea surface temperatures, Varves, Geology
Missouri University of Science and Technology
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