26 Paleoclimatology/Paleoceanography (Posters)

Sunday, 4 November 2012
9:00 AM - 6:30 PM
Hall B

PALEOTEMPESTOLOGY OF SOUTHWEST FLORIDA: POTENTIAL GEOLOGIC PROXIES IN DETERMINING PAST HURRICANE LANDFALLS

Paper number: 26-25
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Since 1995, the number of tropical storms has increased, in particular the number of major hurricanes (category 3-5) in the Atlantic Ocean and Gulf of Mexico (GOM). Recently, scientists have debated this increase; some interpreting it as a result of global warming, while others attribute the increase to natural multidecadal variability. In addition, researchers continue to investigate possible interactions between hurricane frequency and El-Nino Southern Oscillation (ENSO). Unfortunately, in the absence of a longer observational record, the effects of greenhouse gases or ENSO on the frequency of major hurricanes are difficult to detect. In this context, studying past hurricane events in the geologic record, a research field known as paleotempestology, has become greatly important in extending the known record of hurricane landfalls.

To date, paleotempestology research in the GOM has focused on the northern shoreline. Our research is focused on the underrepresented Southwest Florida region and the sediment sources and processes related to storm overwash deposits. This study identified overwash deposits in sediment cores taken from back barrier lagoons in three locations. Cores were analyzed for water content, inorganic content, organic carbon and carbonate content, and percent grain size. Interpreted tempestites were then analyzed for marine fossil indicators. In addition, we collected beach profile and sediment sample data from the shoreline in front of our coring sites 24 hours before and after tropical storm Debby passed SW Florida in July 2012. This helps us to better understand modern sediment movement and deposition during tropical storms in Southwest Florida. Our results show that proxies such as moisture content, inorganic content, grain size, and calcium carbonate best characterize tempestite layers in our cores. Furthermore, identifying marine fossils adds additional strength to our interpretation of tempestites.

This study provides scientists with potential proxies for paleotempestology research in Southwest Florida. By accomplishing this, we can feel more confident in paleotempestology records and the information they provide on past hurricane dynamics in Southwest Florida.