Seismic, Stratigraphic, and Structural Analysis of Northeast Campeche Escarpment, Gulf of Mexico: ABSTRACT

Multifold reflection seismic profiles and DSDP core holes allow a detailed structural and stratigraphic analysis of the northeast Campeche Escarpment. The escarpment, in the central Gulf of Mexico, marks the northern edge of the massive Campeche carbonate platform. A major middle Cretaceous unconformity occurs within the sedimentary section both on the platform and in the deep gulf and represents a major change in sedimentation rate and type. Pre-middle Cretaceous sedimentary rocks in the deep gulf are characterized by weakly developed halokinetic structures (salt pillows and associated faulting), suggesting evaporites in the section. Lower Cretaceous (carbonate-prone) sedimentary rocks overlie these evaporites and are deep-water equivalents of the Lower Cretaceous bank sediments. Sedimentary rocks overlying the middle Cretaceous unconformity consist mainly of Pleistocene turbidites, hemipelagics, or laminites which represent the distal part of the Mississippi fan complex. On the platform, Lower Cretaceous bank sediments are shallow-water carbon te rocks while the post-middle Cretaceous is composed mainly of pelagic sediments, foraminiferal nannofossil oozes and chalks. The seismic reflection data indicate that the northeast Campeche Escarpment is a fault-controlled feature probably related to the early rifting of the Gulf of Mexico. It trends northeast-southwest for approximately 500 km and is modified by local slumping, secondary faulting, and current erosion. The major structural feature on the bank proper is normal faulting, an expression of regional extensional forces. Differential movement between major adjacent fault blocks controlled local sedimentation style. End_of_Article - Last_Page 726------------