John Lopez¹
(1) N/A, Slidell, LA

Abstract: Survey of active Tectonic Elements of the U. S. Gulf Coast Basin

The U.S. Gulf Coast Basin is actively prograding southward into the Gulf of Mexico. Modern tectonism principally occurs along the present margin and slope. The present basin has evolved from the active ‘unstable progradational margin’ phase of instability to a later stage diminished activity. A surprising array of active tectonic elements are present along the Texas and Louisiana coasts and shelf.

Active fault systems have been proposed in six regions including three in Louisiana and three in Texas. Five active salt domes have relief above the delataic plain in the Atchafalaya Basin in Louisiana. Offshore Louisiana domes have no bathymetric relief, but can have evidence of recent movement by faulting or doming of the Holocene. 17 seismic events have been documented in the Coastal areas of Louisiana since 1840 and 27 events in Texas since 1847. In Texas most of these earthquakes are related to active faults or fault systems.

Relative Sea level rise in south Louisiana is 2 to 5 times greater than eustatic rise and demonstrates the significance of subsidence. Subsidence in Louisiana is generally attributed to compaction of the Holocene, but a tectonic overprint is present that may reverse or accelerate subsidence. Subsidence is a principal concern to the coastal restoration effort of Louisiana, and research is underway to decipher the magnitude, variability and causes of subsidence along the Louisiana coast.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana