Structural evolution of the Frampton growth fold system, Atwater Valley-Southern Green Canyon area, deep water Gulf of Mexico

The Frampton growth anticline is part of the Atwater Valley-Southern Green Canyon frontal fold belt in the deep-water northeastern Gulf of Mexico. The anticline is located basinward of the allochthonous Sigsbee Salt sheet near the Sigsbee Escarpment. The timing and mechanisms of the formation of the frontal fold have been investigated using palinspatically restored depth sections and by the analysis of the growth stratal architecture preserved on fold limbs. The Frampton anticline is cored by autochthonous Middle Jurassic Louann salt and its western limit is bounded by the Green Knoll diapir. The fold geometry varies along strike, from a symmetric box-fold in the east, to a breached detachment fold in the west. Small-wavelength salt pillows formed during the Late Jurassic-Cretaceous in response to an early contractional deformation. These precursor structures controlled the geometry of Tertiary age folding. The Green Knoll diapir, west of the Frampton anticline, influenced deformation, leading to complex interactions between segments of the fold system and associated thrust faults. A landward-vergent thrust fault accommodated shortening adjacent to the diapir whereas folding was the main mechanism of deformation in the eastern part of Frampton anticline. Analysis of growth strata indicates that the detachment anticline developed according to a progressive limb rotation kinematic model with minor hinge migration. The fold evolution model proposed in this study could be used as an analogue for less well imaged, hydrocarbon-bearing growth folds in the deep-water province of the Gulf of Mexico, particularly those that are partially obscured by overlying allochthonous salt sheets. (C) 2004 Elsevier Ltd. All rights reserved.