2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 82-8
Presentation Time: 10:25 AM


LUZZADDER-BEACH, Sheryl, Geography and the Environment, University of Texas at Austin, CLA Bldg. Rm. 3.306, A3100, 305 E. 23rd Street, Austin, TX 78712, KRAUSE, Samantha M., University of Texas at Austin, Austin, TX 78712, BEACH, Timothy, Geography and Environment, UT Austin, 305 E. 23rd Street, Austin, TX 78712 and ESHLEMAN, Sara, 301 ICC, 37th and O Streets, NW, Washington, DC 20056, beacht@austin.utexas.edu

This paper compares the sediment records of three floodplain wetlands with intensive ancient Maya impacts over the Late Holocene: the BOP wetlands in the Rio Bravo, the Ojo de Agua wetlands in the Booth’s River, and the Lamanai wetlands in the New River. We gathered data from water chemistry around the sites, excavations to 3 m depth, and multiple cores. Our goals are to understand late Holocene wetland formation during times of high human disturbance, climate change, and full tropical forest. We found that all water sources had high dissolved loads of calcium and sulfate that precipitate gypsum during the dry season, which adds to the more usual alluvial aggradation. Each system has slow rates of deposition and paleosol formation before the Maya Preclassic, starting about 3000 bp. After the Maya Preclassic, sedimentation increased, and pollen, phytolith, and δ13C evidence shows the expansion of cultigens like maize, cassava, and fruit trees. The Maya built field and canal systems in these wetlands over periods of drought and rising water tables in the Late to Terminal Classic, and the canals became traps for sedimentation after Maya abandonment about 1000 bp. Based on a series of AMS and 210Pb dates we estimate sedimentation rates for before, during, and after Maya intensive uses of this tropical wetland in the Late Holocene.