Sequence Stratigraphy, Geologic Evolution, and Hydrocarbon Prospectivity of Northern Antarctic Peninsula Continental Shelf

John B. Anderson, Peter G. Pope, Mark A. Thomas

During the United States Antarctic program 1988 cruise, 3,200 km of seismic profiles were collected on the continental shelf of the northern Antarctic Peninsula. These data, plus the results of land-based studies (mostly work of Polish scientists) and ocean drilling (DSDP Leg 35), were used to reconstruct the evolution of the shelf and to assess hydrocarbon prospectivity for the region.

The study area has evolved from an active to a passive margin as the Aluk spreading center was gradually subducted at the Antarctic plate boundary. The timing of ridge subduction (based on sea-floor magnetic data) proceeds from south to north (oldest to youngest) along the margin, and five major oceanic fracture zones segment the shelf tectonically and sedimentologically. These differences are manifested in the degree of deformation of pretectonic and syntectonic shelf sequences, as well as the thickness and extent of passive margin sequences.

Besides the obvious tectonic controls, major changes in shelf sedimentation also took place due to climatic changes during the Cenozoic. The main climatic events affecting the style of shelf sedimentation include (1) gradual destruction of dense vegetation on the continent and gradual elimination of streams and rivers (late Paleogene), (2) establishment of an extensive ice cap in the peninsula area as subpolar to polar conditions were established and subsequently the change from fluvial/fluvial-deltaic/coastal sedimentation to glacial/glacial-marine sedimentation, (3) overdeepening of the continental shelf by glacial erosion (middle-late Miocene), and (4) intensification of oceanic circulation and subsequent increase in biogenic sedimentation (late Miocene).

The results of this study indicate that hydrocarbon prospectivity on the continental shelf of the Antarctic Peninsula increases southward mainly because the potential for suitable reservoirs increases in that direction. Hydrocarbon potential is very low north of the Hero fracture zone, moderate between the Hero and Tula fracture zones, and good south of the Tula fracture zone.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.