Cretaceous-Lower Tertiary Depositional Relations, Northeastern Alaska: ABSTRACT

Abstract

Analysis of depositional environments and new paleontologic data indicate the need for a revised interpretation of Cretaceous and lower Tertiary stratigraphy in northeastern Alaska. A revision is important to the understanding of these rocks in unexplored areas to the north. In the Sadlerochit Mountains area, the late Neocomian transgressive Kemik Sandstone Member and pebble shale unit of the Kongakut Formation unconformably overlie Jurassic and Triassic rocks. The unconformity, which is present throughout northernmost Alaska, apparently grades to a conformable shelf sequence to the south. In the Sadlerochit Mountains area, Upper Cretaceous organic-rich shale and bentonite of Figure the Seabee Formation overlie the pebble shale unit; the intervening Aptian and Albian strata are either absent by nondeposition or are a thin, condensed section. Subsequent deposits of Late Cretaceous and early Tertiary(?) turbidites and shale were probably derived from east-northeasterly prograding deltas that are exposed west of the Canning River. Cretaceous strata in the Sadlerochit Mountains area are about 700 m thick and contain no erosional unconformities. The comparatively thin section is attributed to the area being high (although still in deep water) relative to the Colville basin axis to the south, which was a sediment trap. End_of_Article - Last_Page 608------------