153 Paleoclimatology/Paleoceanography I: Proxy Evaluations

Tuesday, 24 October 2006
1:30 PM - 5:30 PM

POTENTIAL FOR PALEOTEMPESTOLOGY AND OTHER PALEOENVIRONMENTAL RECONSTRUCTION IN COASTAL LAKES OF THE DOMINICAN REPUBLIC

Paper number: 153-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

The emerging field of paleotempestology is aimed at reconstructing the long-term history of tropical cyclone landfalls through geological proxies, most often overwash deposits in coastal lakes and marshes. Most published work so far has focused on the Atlantic and Gulf coasts of the United States. A major gap in research exists in the eastern Caribbean region. We recovered cores from several lakes on the eastern and southwestern Dominican Republic coasts during a pilot study (Nov. 2005) to assess potential for paleotempestology and other paleoenvironmental reconstructions from sediments in this area. We report on our ongoing analysis of sediments from three lakes: two on Isla Saona (Laguna Los Flamencos and an unnamed pond; ~18.14°N, 68.75°W), situated on an uplifted terrace of Pleistocene reef, and Laguna Alejandro (informally named, 18.31°N, 71.03°W) in the arid Enriquillo Valley region.

Sediments from the Isla Saona lakes were shallow (~40–50 cm to bedrock) and composed of silts and sands. Loss on ignition indicated high carbonate content (30–40%) and low organic content (ave. 12.6%) for both lakes. The 195-cm L. Alejandro core was more organic (ave. 21.0%) with lower carbonate fractions and contained several organic deposits, mainly plant material. Visual observations suggest three large overwash deposits of coarse material, each about 2 cm in depth, in the Alejandro core. Changes in the stratigraphy of the Saona cores are more subtle upon visual inspection. Lithological variations were measured at 1-cm intervals with a GEOTEK© multi-sensor core logger and color changes recorded by a GEOSCAN color line scan camera. These data, along with upcoming x-radiography, will help to identify overwash deposits and other stratigraphic changes not easily detectable by eye. Chronologies for the lakes are in process (AMS dating of organics by Beta Analytic) and will be presented. Preliminary results indicate good potential for paleotempestology and other paleo-studies.