Paleoclimate of Pleistocene Epoch Costa Rica: Grain Size, AMS, and MAR Analyses That Explore the Behavior of the Intertropical Convergence Zone (ITCZ), Prevailing Winds, and Ocean Circulation Over the Last Two Million Years
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Paleoclimate studies enable us to understand the past climate of Earth and, in turn, help us understand present-day climate. In addition, paleoclimate studies can help us predict future climate in a world with ever increasing air and ocean CO2 levels. Ocean Drilling Program (ODP) Leg 202 retrieved oceanic cores off the Pacific coast of South America and Central America. By studying samples from ODP Site 1242, which is located off the coast of present day Costa Rica, it is possible to gain insight into the behavior of the Intertropical Convergence Zone (ITCZ) over the last two million years. Hemipelagic nannofossil clays and clayey nannofossil oozes are characteristic of this site. Sediment eroded from the continents and deposited in the oceans can reflect climatic changes through time in both atmospheric and oceanic systems. To obtain this terrigenous portion of the sediment, the oceanic samples were processed through five chemical extraction steps to remove biogenic carbonate and silicate components, and to dissolve any oxy-hydroxy coatings. The sediment was sieved in order to remove any grains larger than 63 µm. AMS was analyzed on a KLY4S-Kappabridge to measure the induced magnetic field within the sample which offers clues to the direction and strength of ocean flow. Deposition rates, indicated by our MAR values, may be influenced by changes in precipitation on land and/or changes in prevailing wind or oceanic circulation patterns.
Buczek, Catherine R., "Paleoclimate of Pleistocene Epoch Costa Rica: Grain Size, AMS, and MAR Analyses That Explore the Behavior of the Intertropical Convergence Zone (ITCZ), Prevailing Winds, and Ocean Circulation Over the Last Two Million Years" (2017). Environmental Studies Summer Fellows. 5.