--> Abstract: Constraints on Extension and Subsidence Rates Along the Northern Gulf of Mexico from High-Precision GPS, by Giovanni Sella, Roy K. Dokka, and Timothy Dixon; #90914(2000)

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Giovanni Sella1, Roy K Dokka1, Timothy Dixon2
(1) Louisiana State University, Baton Rouge, LA
(2) University of Miami, Miami, FL

Abstract: Constraints on extension and subsidence rates along the Northern Gulf of Mexico from high-precision GPS

Characterizing the northern Gulf Coast as a passive plate margin based on the lack of seismicity, low relief, and geological history does not reflect all the processes that are at work. Additional processes include: gravitational loading and consequent flexure from the Mississippi deltas (and earlier rivers), compaction of thick Quaternary sediments, growth normal faulting, salt migration, and local fluid withdrawl. The net effect of these processes results in significant horizontal and vertical deformation. This deformation contributes to coastal land loss that reaches maximum rates in Louisiana of 35-40 square kilometers a year. We have established a multifunctional Global Positioning System (GPS) network, GULFNET, to investigate both horizontal and vertical movement along the northern Gulf Coast. Our network consists of 18 continuously operating stations and 25 episodic stations that are monitored once a year. The network extends from southeastern Texas across to central Alabama and from the mouth of the Mississippi river to northern Louisiana. Initial results from the continuous GPS sites provide the first limits on southward directed horizontal displacement, at a maximum rate of 8 mm/yr. Subsidence estimates from GPS generally agree with tide gauge date, measuring vertical velocities of 5 mm/yr and greater in some areas.

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