GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 265-3
Presentation Time: 9:00 AM-6:30 PM


MORTENSEN, Peter1, STANSELL, Nathan D.1, STEINMAN, Byron A.2, BROCARD, Gilles Y.3, SHEA, Christopher J.2 and LACHNIET, Matthew S.4, (1)Geology and Environmental Geosciences, Northern Illinois University, Davis Hall 312, Normal Rd, DeKalb, IL 60115, (2)Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, 2205 E. 5th Street RLB 205, Duluth, MN 55812, (3)School of Geosciences, The University of Sydney, Sydney, Sydney NSW, 2006, Australia; School of Geosciences, The University of Sydney, Madsen Building F09, Sydney, NSW 2006, Australia, (4)Department of Geoscience, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Box 454010, Las Vegas, NV 89154-4010,

A key impact of climate change in Central America is its effect on precipitation patterns. The isotope geochemistry of rainfall in Central America is dominated by the amount effect, with an inverse relationship existing between δ18O values of surface waters and precipitation amount. Therefore, carbonate δ18O values from lake sediments can be used to reconstruct late Holocene precipitation patterns in the region. For this study, sediment cores were collected from Lake Chichoj in central Guatemala in January of 2017, along with surface water and precipitation samples. A thinly-laminated core ~2.8 m long, spanning the past ~1000 years was obtained, and sampled for authigenic carbonates at 2 mm intervals. The carbonate samples were analyzed for δ18O values, yielding a high-resolution record of hydroclimate shifts over the past ~1000 years for the area. Sediment cores were also analyzed for bulk sediment geochemistry, loss-on-ignition, and magnetic susceptibility. These results provide further information regarding hydroclimates in Central America that are influenced by ocean-atmosphere interactions in both the Pacific and Atlantic basins, including the El Niño Southern-Oscillation (ENSO) and the North Atlantic Oscillation (NAO).