ABSTRACT: Sequence Stratigraphic Analysis of Plio-Pleistocene Turbidite Systems, Northern Green Canyon and Central Ewing Bank Areas, Northern Gulf of Mexico
VARNAI, PETER, and PAUL WEIMER
The Plio-Pleistocene turbidite systems were mapped in the northern Green Canyon and central Ewing Bank protraction areas. Ten depositional sequences were identified in the 5.5 Ma and younger intervals using 2560 km 2-D seismic profiles, biostratigraphic data from 22 wells and well logs from 29 wells.
The Plio-Pleistocene geologic evolution of the area is divided into four geologic intervals. Each phase differs in its seismic and geologic facies, depositional rates, nature of turbidite systems and sand content. Three turbidite elements, basin-floor fans, channel-levee systems and overbank sediments constitute most of the Plio-Pleistocene succession. Large unchannelized flows became volumetrically more significant in the younger sequences. Slides represent only small portion of the sequences.
Basin-floor fans (sheet sands) were deposited overlying sequence boundaries. Salt tectonics greatly influenced the development and the location of these fans. These sheet sands are relatively thin (100-150 m), and they consist of 15-50 m thick sand layers. The areal extent of the basin-floor fans varies between 20 and 210 km2. The size and thickness of the fans gradually decrease in the younger sequences. The basin-floor fans are reservoirs in some fields in the area, and they also have the highest reservoir potential.
The channel-levee systems are composed of up to 25 m thick channel-fill sands, which may coalesce into 60-90 m thick intervals forming stacked systems. The number and sand content of the channel systems gradually decrease upward. Coalesced channel-fill sands form the reservoirs in several fields of the area.
AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana