ABSTRACT

Active volcanism has played a significant role in the development of the Gulf Coastal Province. The recognition of areas and formations in which significant quantities of detritus occur is of considerable importance to Gulf Coast petroleum geologists. The presence of volcanic detritus in a formation increases the potential for damage during drilling and stimulation. Diagenesis of volcanic-rich sediments results in the rapid development of a wide variety of pore-fill minerals (clays, zeolites, carbonates), and well-bore fluids must be tailored to avoid unfavorable reactions with these minerals.

Two volcanic regions may be recognized: 1) the Mississippi embayment, including the region immediately offshore of the present Mississippi delta; and 2) the Rio Grande embayment. Explosive eruptions contributed pyroclastic debris to Gulf Coast sediments nearly continuously since Late Cretaceous (Gulfian) time. The most prolific volcanic activity occurred during the Late Cretaceous and late Oligocene-Miocene. In both style and composition, Gulf Coast volcanism appears similar to that observed in aulacogens such as the present day Benue trough, western Africa.