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Robinson, B.E., 1989

Upper Triassic radiolarian biostratigraphy of the Glenn Shale, east-central Alaska

Bibliographic Reference

Robinson, B.E., 1989, Upper Triassic radiolarian biostratigraphy of the Glenn Shale, east-central Alaska: University of Texas, Dallas, M.S. thesis, 174 p.

Abstract

The Glenn Shale of east-central Alaska is composed of two distinct chronostratigraphic entities of significantly different tectonostratigraphic origins separated by a hiatus encompassing most, if not all, of the Jurassic. The lower portion of the Glenn Shale consists of a 174- to 240-m-thick, Middle to Upper Triassic marine carbonate unit recognized throughout east-central Alaska. Lithostratigraphic and biostratigraphic evidence suggests that the Middle to Upper Triassic portion of the Glenn Shale was deposited in response to a major transgressive event that eventually established outer shelf to slope conditions in east-central Alaska. In contrast, the upper portion of the Glenn Shale consists of a 1,600-m-thick, Lower Cretaceous deep marine to fluvial transitional unit confined to a regional foreland basin. A well preserved radiolarian assemblage occurs in the outer shelf to slope deposits of the Upper Triassic portion of the Glenn Shale.

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