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B. A. Kososki

Publications and source records attributed to B. A. Kososki.

6 recordsLinked to original sources
USGS1978

A gravity study of the northern part of the Arctic National Wildlife Range, Alaska

Interpretation of all publicly available onshore gravity data provides a basis for outlining regional elements of the basement and overlying structure in the northern part of the Arctic National Wildlife Range. Major post-Carboniferous sedimentary basins whose centers lie offshore on the Beaufort Shelf extend onshore in the northern part of the study area. There is strong evidence that dense basement rocks beneath these onshore extensions rise to relatively shallow depths along the northeast Alaskan coast. Geologic studies and interpretation of the gravity data indicate that the gross structural and stratigraphic framework of this area is similar to that of the Prudhoe Bay region to the west. A high potential for petroleum accumulation in the Wildlife Range is indicated by the surface presence of oil seeps, oil sands, and outcrops of reservoir and source rocks along the southern margins of the onshore basinal areas. Present data suggest that the greatest potential for onshore accumulations of hydrocarbons lies in the area south and east of Barter Island and that possibilities exist there for commercially substantial reserves. The potential of this area cannot be fully assessed, however, until the subsurface extent of several major unconformities is known. Unfortunately, gravity data alone are of little use in such determinations. South of the mountain front, large granitic intrusions are marked by a sharply defined gravity minimum. The subsurface distribution of these bodies could probably be mapped by detailed gravity surveys. Detailed aeromagnetic surveys should serve equally well for such a purpose.

Alaska↗
USGS1975

Geologic framework of the Alaskan Continental Terrace in the Chukchi and Beaufort seas

Seismic, magnetic and gravity data indicate that the Chukchi and Beaufort epicontinental seas off northern Alaska overlie three sedimentary basins, or provinces, separated by structural highs of regional extent. The basins trend west to northwest and become increasingly marine from south to north. The Chukchi-Beaufort continental margin is similar to those of Atlantic type. Hope basin, in the southern Chukchi Sea, overlies strongly deformed Paleozoic to mid-Cretaceous rocks of the Brooks Range orogen. The basin is inferred to contain nonmarine and marine clastic sedimentary rocks in a 1-km-thick Upper Cretaceous(?), a 1 1/2-km-thick Paleogene(?), and a 3/4-km-thick Neogene(?) sequence. A large anticline and many faults and smaller folds disrupt mainly the older sequences. The Hope basin sedimentary units onlap Herald arch, which trends northwest from Cape Lisburne in the central Chukchi Sea. At the Herald fault zone Brooks Range rocks in the arch are thrust east or northeast over Mississippian to Jurassic shelf carbonate and clastic rocks of the Arctic Alaska (Ellesmerian) basin and overlying Cretaceous flysch and molasse of the Colville geosyncline. These Mississippian to Cretaceous rocks underlie the northeast Chukchi Sea and reportedly are about 10 km thick near the Herald fault zone on the Lisburne Peninsula. The great Chukchi syntaxis in western Brooks Range rocks and structures is thought to result from intersection of the west-trending Brooks Range orogen by the northwest-trending Herald fault zone. The Mississippian to Jurassic shelf sequence thins northward, and onlaps the Barrow arch, which trends northwest from Point Barrow to 161° W.long., thence west-southwest to the Herald fault zone. The Colville geosyncline sequence oversteps both the pre-Cretaceous rocks and. the Barrow arch to form the North Chukchi basin west of 161°W. long. and the progradational Beaufort continental terrace east of it. The North Chukchi basin may contain about 6 km of section, probably Cretaceous and Tertiary and possibly deltaic. Diapirs (of Cretaceous shale?) pierce the gently northward-dipping strata of this basin, in places reaching the sea floor. Thick Tertiary marine and nonmarine clastic rocks of the Camden basin overlie the Cretaceous rocks of the North Slope and inner Beaufort continental terrace east of the Colville River delta. These rocks dip gently seaward west of 146°W. long. but are thrown into long, high-amplitude, east-northeast-striking folds to the east.

Alaska↗