LiDAR Digital Elevation Model and Topographic Cross-Sectional Analysis of Wetumpka Impact Structure, Alabama

The Wetumpka impact structure (near the town of Wetumpka, Alabama) has a semi-circular crystalline rim that is ~ 5 km in diameter. This well-exposed, marine-target impact structure developed in both poorly consolidated, water-saturated sediments and underlying crystalline basement. Our previous studies have described a semi-circular, crystalline rim, an interior structure-filling unit, and an exterior disturbed area developed within the sedimentary target sequence outside the southwestern part of the central, basement crater. Based on field and drill-core observations, we recognize the following specific structural and lithological impact-related terrains: overturned crystalline rim flap; slumped interior megablock terrain; central polymict breccia (originating as near-field ejecta); interior marine chalk deposits and reworked glauconitic sands (formed by resurge and post-impact deposition); and a collapsed southern part of the rim with overturned flap (mainly developed within the sedimentary target rocks). In this paper, we examine what we know of these terrains so far and review how using new LiDAR data (sub-meter resolution) has given us new insights into the nature and origin of these impact-related terrains and their post-impact erosional history.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California