Late Mesozoic and Cenozoic Palinspastic Restoration: Interplay of Halokinetics and Sedimentation, Northwestern Gulf of Mexico

Abstract

In the northwestern Gulf of Mexico, Cenozoic halokinetics (salt tectonics) of thick sequences of Callovian evaporites heavily influenced accommodation and deposition of overlying strata. Using a long two-dimensional (2D) seismic line (597 km) from Canyon Lake, Texas through East Breaks and Alaminos Canyon to the Sigsbee Escarpment, we examined the relationship between sedimentation and salt evacuation from the Middle Jurassic to the present. GulfSPAN regional 2D seismic reflection profile 2450 was fully interpreted and a full line-length kinematic reconstruction in 12 time steps from the Holocene to the Middle Jurassic was conducted using 2D Move restoration software. The results of the restoration were used to calculate extension in each respective time period. According to work from previous authors, the majority of Cenozoic fluvial input to the area is derived from the Rio Grande fluvial axis up to the Middle Miocene when a large deposode is associated to the Guadalupe fluvial axis. Our calculations of sedimentation ratios from the Holocene to Early Cretaceous revealed rates that show generally low rates in the Cretaceous increasing at the time of deposition of the Midway and Wilcox groups in a deltaic environment supplied by the Rio Grande fluvial input axis. Increased sedimentation ratios can be tied to increased halokinetics. Our observations confirm that salt extrusion is younger (Eocene) in the western Gulf of Mexico than in the Central Gulf of Mexico (Cretaceous). Large allochthonous salt bodies develop during the Oligocene and a second detachment forms. The majority of accommodation space creation is a result of salt withdrawal and utilizes pre-existing areas of evacuation. Salt kinematics through time is an important element for petroleum systems models, due to the high heat conductivity of salt. Also, palinspastic restorations of the 2D line allow for better interpretation of the seismic data, especially in the higher signal to noisy older sequences.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018