HR: 0800h
AN: T41D-1251    [Abstracts]
TI: Cretaceous Igneous Activity of the US Gulf Coast: Evidence for a Post-Albian Crustal Event
AU: White, G W
EM: gary_white@anadarko.com
AF: Anadarko Petroleum Corporation, 1201 Lake Robbins Circle, The Woodlands, TX 77380 United States
AU: * Bird, D E
EM: dale@birdgeo.com
AF: Bird Geophysical, 16903 Clan Macintosh, Houston, Tx 77084 United States
AU: Mentemeirer, S H
EM: samuel_mentemeier@anadarko.com
AF: Anadarko Petroleum Corporation, 1201 Lake Robbins Circle, The Woodlands, TX 77380 United States
AB: Post-Albian igneous rocks are recognized along the US Gulf Coast from South Texas to Mississippi. This alkalic suite of intrusive and extrusive rocks are characterized by a variety of structural features which include surface volcanoes, phreatic explosion craters, sills, dikes, laccoliths, and diatremes and many have associated tuffs and volcaniclastic sediments. Generally these rocks occur along crustal block boundaries that resulted from rifting in this area during the Triassic. Collectively, the compositions of these igneous rocks would suggest a deep crustal origin (depth $>$40 km). Reactivation and crustal cracking along these old block boundaries is the most likely explanation for the composition and location of the rocks. In the absence of associated large scale tectonic or thermal events, we suggest that upper Jurassic to lower Cretaceous sedimentary loading of the continental margin was followed by a "crustal event", much like the failure of a mechanical beam, which resulted in the igneous activity.
DE: 9350 North America
DE: 9609 Mesozoic
DE: 8015 Local crustal structure
DE: 8109 Continental tectonics--extensional (0905)
DE: 1219 Local gravity anomalies and crustal structure
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting