Stacy A. Smith¹

(1) Texaco Worldwide Exploration, Bellaire, TX

ABSTRACT: Cretaceous to Quarternary Structural Development in the Central Walker Ridge Area, Northern Gulf of Mexico

Sub-salt structures in Walker Ridge may hold as much exploration potential as the trend of oil - bearing structures already found to exist nearby in the southeast Green Canyon and southwest Atwater Valley areas of the Gulf of Mexico. 3D seismic data has been used to establish a current day structural framework for over 1000 square miles in central Walker Ridge. Important kinematic and stratigraphic relationships can be demonstrated from the integration of regional structure / isopach maps and time-step reconstructions.

Examination of this data shows a major pre-autochthonous salt (Jurassic) structural lineament, which trends northwest-southeast and appears to be coincident with the depositional limits of thick Louann salt. North of this 'basement' lineament lies a salt stock-canopy system with deep welded autochthonous salt evacuation basins (Miocene in age) and overlying tabular allochthonous salt with 'Roho' basins (Pleistocene in age). Locally thick autocthonous salt was progressively loaded with Miocene sediments from the North towards the South. This pattern generated turtle structures and forced many of the early salt-cored folds North of the 'basement' lineament to break out. These salt stock piercements extruded and coalesced to form the present day Sigsbee salt canopy.

South of the major 'basement' lineament, deformation due to autochthonous salt movement is much less dramatic. Low relief salt-cored buckle folds in this area have had very little horizontal shortening since mid - Cretaceous. These salt features were rejuvenated with minor active diapirism during the Oligocene and lower Miocene - primarily due to the redistribution of autochthonous salt from deep evacuation areas North of the 'basement' lineament. Subtle readjustments occurred as folds were blanketed by upper Miocene to recent sediments.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado