Geologic framework, hydrocarbon potential, and environmental conditions for exploration and development of proposed oil and gas lease sale 87 in the Beaufort and northeast Chukchi Seas: A summary report

Quaternary acoustic stratigraphy between the Colville River and Prudhoe Bay, Beaufort Sea Shelf, Alaska

“…The Maquire In two boreholes located in Stefansson Like deposits that underlie the Stefansson oreholes located seaward of the barrier which is consistent with the erosional f the islands (Wolf et al, 1985). Holocene rrelate with the acoustic sequence above Uiit Ice-bonded subsea permafrost exists in the Osterkamp andHarrison, 1978a and1978b;Sellmann, 1984;Vralsted, 1986) as do gas-bean ig and Thrasher, 1982;Grantz et al, 1982). Gas complicate acoustic stratigraphic interpretation nificant reflection coefficients because of their large gas confined by stratigraphy enhances reflectors horizons may be misinterpreted as stratigraphi conform to stratigraphy.…”

“…Gas-bearing sediments may appear as high amplitude reflectors, velocity pulldown, or attenuated (acoustically turbid) zones on acoustic profiles. Gas-enhanced reflectors and acoustically turbid zones occur on the middle and outer Beaufort shelf (Grantz et al, 1982). On the inner shelf, high amplitude reflectors, high frequency attenuation, and reflector pulldown imply that shallow gas occurs.…”

Structure and stratigraphy of the Hanna Trough, U.S. Chukchi Shelf, Alaska

“…Previous investigations of the Chukchi Shelf and the contiguous Arctic continental shelves were carried out primarily by Arthur Grantz and colleagues of the U.S. Geological Survey. These pioneer studies, speciµcally those of Grantz et al (1975Grantz et al ( , 1981Grantz et al ( , 1982aGrantz et al ( , 1982bGrantz et al ( , 1990Grantz et al ( , 1994, , May (1983, 1987), and Eittreim and Grantz (1979), established the basic geologic framework for the Shelf, Alaska featuring a southern segment, an hypothesized northern segment (axis location unknown-obscured beneath North Chukchi Basin), and a transform fault or rift jump that links the two segments. The axis of the southern segment of Hanna Trough south of Burger well is drawn along a gravity high mapped by Herman and Zerwick (1994) and shown in Figure 4.…”

Geological evolution and analysis of confirmed or suspected gas hydrate localities

“…These rocks generally mark the acoustic basement of the region due to their alteration. Due to the heat and pressure that these rocks experienced in Cambrian to Mississippian time they are generally considered overmature with respect to hydrocarbon generation, and thus also constitute the economic basement of the region (Grantz et al, 1980;Grantz et al, 1982a).…”

“…Lisburne group sediments progressively onlapped exposed basement north of the depositional limit of the Endicott Group (Craig et al, 1985). In addition to limestone and dolomite, marine sandstone, shale, and chert have been recognized in the Lisburne Group (Grantz et al, 1982a). Sea level drop and epeiric uplift in Late Pennsylvanian to Early Permian time eroded the Lisburne Group and produced yet another recognized unconformity (Craig et al, 1985).…”