ABSTRACT: Multiple-Stage Deformation along the Southern Flank of the North Chukchi High, Chukchi Sea, Alaska

Peter P. Johnson

Structural and stratigraphic relations along the southern edge of the North Chukchi high provide insights into the timing and mechanics of Late Cretaceous and Cenozoic tectonic events in the northern Chukchi Sea. In this area, the easternmost strand of the north-trending Hanna wrench fault zone is deflected to the northeast and terminates in a series of reverse faults along the southern edge of the high. Areas east of the Hanna fault zone were characterized by tectonic stability during this period of time. Within the fault zone, east-west-trending box folds and reverse faults accompanied uplift of the North Chukchi high and erosion of the entire Ellesmerian sequence along its southern margin. Stratigraphic and structural relations indicate that this compressional deformat on began during the Early Cretaceous (Albian?) but ceased prior to the Late(?) Cretaceous.

During the early Cenozoic(?), the northern part of the Hanna fault zone was reactivated as an extensional systems which controlled the development of a local basin. Some faults which showed an early history of reverse displacement were reactivated as normal faults during this late-stage tectonic event.

This data is consistent with a model for Early Cretaceous impingement of adjacent blocks at a constrained corner near the North Chukchi high during the rift opening of the North Chukchi basin. The compressional deformation ceased prior to the Cenozoic when the opposing blocks in the constrained corner finally escaped past each other. Continued rifting and subsidence of the North Chukchi basin resulted in late-stage extensional overprinting of earlier compressional structures.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990