100 Marine/Coastal Science Geology (Posters)

Monday, 1 November 2010
8:00 AM - 6:00 PM
Hall D

HIGH-RESOLUTION RECONSTRUCTION OF PALEO-HURRICANE STRIKES FROM THE BLUE HOLE OF LIGHTHOUSE REEF, BELIZE

Paper number: 100-2
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

Sediment cores (to 6 m long) collected from the famous Blue Hole of Lighthouse Reef provide a near-annual record of hurricane activity along the coast of Belize, spanning the past ca. 1500 years. These cores consist of undisturbed biogenic carbonate muddy laminae (apparently annual) interbedded with what are interpreted to be overwash deposits produced by tropical storms and hurricanes, deposited into the anoxic bottom waters of the Blue Hole. High-resolution digital imaging, lightness profiles, and grain-size analysis were used to distinguish hurricane deposits from normal background sedimentation and AMS C-14 dating was preformed to obtain absolute ages for events. From this, a chronology and return period of hurricane events has been developed for the Blue Hole.

Preliminary results indicate a hyperactive period of hurricane activity prior to ~1000 y BP. During that time frame, the return period for hurricanes depositing overwash sediments into the Blue Hole is estimated to be approximately 7 y. In comparison, between 1000 yr BP and present day, the return period for comparable events is estimated to be approximately 11 y. The temporal clustering of hurricanes observed in this study has also been observed in cores collected along the southern coastline of Belize (McCloskey and Keller, 2008). These records support the hypothesis that the migration of the hurricane belt is (climatically) controlled by large-scale shifts in atmospheric pressure conditions such as the position of the Bermuda High high pressure system over the North Atlantic Ocean.