--> Abstract: Characterizing Deep Water Basin-Floor Channels Using Seismic, Logs, and Cores, by J. S. Hewlett and J. H. McGowen; #91012 (1992).

Datapages, Inc.Print this page

ABSTRACT: Characterizing Deep Water Basin-Floor Channels Using Seismic, Logs, and Cores

HEWLETT, JAMES S., ARCO Oil and Gas Co., Houston, TX, and JOSEPH H. MCGOWEN, ARCO Oil and Gas Co., Plano, TX

Recent studies in postrift passive margin (North Sea), forearc (California), and foreland (North Slope, Alaska) basins have defined deep water basin-floor channels that exhibit similar seismic geometries and well log character. These channels truncate adjacent basin-floor marine shales, have locally steep channel walls, exhibit laterally accreting stratal patterns, and are filled with sandy gravity-flow or density-underflow deposits. Despite similar two-dimensional expressions, paleotopographic reconstructions from seismic sequence analysis and facies interpretations from well data indicate these channels evolved in slightly different depositional settings.

Basin-floor channels in the Eocene, North Sea, and the Cretaceous, North Slope, Alaska, each lie seaward of local, high-relief delta slopes and extend for tens of kilometers seaward and parallel to the shelf edge. Unconfined turbidite systems were not recognized downdip from these channels. Seismic geometries and depositional facies from core suggest the channels were filled by turbidity flows initiated on the slope and by density underflow currents traveling downslope and considerable distances within the basin-floor channel.

In contrast to the previous examples, the depositional profile for middle Miocene turbidites in the San Joaquin Valley, California, consisted of a ramp sloping into bathyal water depths. High-density turbidity currents confined to channels on this deep water ramp fed downdip to an unconfined sand-rich turbidite system.

The Valencia Valley, offshore Spain, and the North Atlantic Mid Ocean Channel provide possible analogs to these ancient basin-floor channels.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)