Post-Ellesmerian depositional sequences of central North Slope subsurface
Detailed electrical-log correlations of bedding in the Mesozoic to recent intervals define nearly time-equivalent stratigraphic units. Basinal depositional minima separate them into depositional cycles of 15 to 40-m.y. duration, and sequences of similar cycles correspond to the major episodes of Arctic tectonism. The close of the Sag River cycle in Pleinsbachian time ended the Ellesmerian sequence of accretionary tectonics and northerly continental provenance. Long,oscillating uplift to the northwest during the Jurassic Kingak cycle, and five or more subcycles of emergence along an ancestral Barrow arch rift shoulder during the Lower Cretaceous Kup River cycle show that the Barrovian sequence accompanied Arctic rifting. The Brookian sequence records a time of Arctic seafloor spreading coincident with underthrusting of the North Slope block toward a convergent Pacific margin. A series of major overthrusts onto the block from this margin were sources for Lower Torok, Nanushuk, Schrader Bluff, Prince Creek, and Franklin Bluffs cycles. The lower Torok source was in a distant westerly direction, and those of the following cycles became progressively closer and more southerly, ending near the present position of the central and western Brooks Range. A collision between Alaska and Siberia in mid-Tertiary time initiated the Eurekan sequence of circum-arctic compressional tectonics. The North Slope block was tilted northeast, and the Nuwok cycle was derived from the resulting regional erosion. Similar tilting and erosion beginning in the Pleistocene started the Gubik cycle that is still being deposited.
- Research Organization:
- Marathon Oil Co., Anchorage, AK
- OSTI ID:
- 5961780
- Report Number(s):
- CONF-8505215-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 69:4; Conference: AAPG-SEPM-SEG Pacific section meeting, Anchorage, AK, USA, 22 May 1985
- Country of Publication:
- United States
- Language:
- English
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