Unraveling Gulf Coast Paleo-rainfall Variability Using Climate Proxies Archived in Alabama Stalagmites

Joshua Vanlandingham and William Lambert
[email protected]

"Variability in moisture flux from the Gulf of Mexico to Gulf Coast states is a significant concern as the region is highly dependent on rainfall throughout the year. With uncertainty of how future global climate change will affect regional rainfall patterns, researchers have turned to paleoclimate records archived in geologic materials to better understand natural climate cycles. In the Southeast (SE), widespread karst terrain serves as an archive of past rainfall variability needing only to be unraveled by careful examination of preserved rainfall proxies. Unfortunately, high-resolution paleo-rainfall records for the SE derived from cave deposits (i.e., stalagmites) are few in number and are not yet verified. DeSoto Caverns (Childersburg, AL) represents one of few SE cave systems that has been the focus of paleoclimate research over the past decade. Variability in ?¹⁸O of spelean CaCO₃, as well as hiatuses in stalagmite growth, suggest significant changes in SE rainfall between 31.9-11.3 ka and 5.8 ka to present. Of particular interest, the well-known Younger Dryas cooling event is expressed as an ~1000 year hiatus in deposition, likely attributed to changing rainfall patterns. In an attempt to increase confidence in paleo-rainfall interpretations from SE cave deposits, we are investigating stalagmites from nearby Cathedral Caverns (Grant, AL). Here we will present preliminary results from a 70-cm long stalagmite, which based on initial examination, displays growth patterns similar to DeSoto Caverns stalagmites. The investigation will include standard petrographic techniques to identify growth hiatuses, a preliminary age model based on U-series dating techniques, and stable isotope profiles along the central growth axis of the stalagmite."

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63^rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013