--> --> ABSTRACT: Cretaceous Strata in North Dakota, by Sidney B. Anderson; #91002 (1990).

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ABSTRACT: Cretaceous Strata in North Dakota

Sidney B. Anderson

Cretaceous strata in North Dakota represent both nonmarine and marine facies. Maximum aggregate thickness of the cretaceous strata totals 5270 ft. Cretaceous stages in North Dakota are represented by strata of Aptian, Albian, Cenomanian, Turonian, Coniacian, Santonian, Campanian, and Maestrichtian. Most of the data on Cretaceous strata in North Dakota is obtained from geophysical borehole logs (re: electric and radioactivity logs) and from samples and cores. A few data have been obtained from very limited outcrops of the Turonian Carlile, the Coniacian Niobrara, and the Campanian Pierre Formations from outcrops in eastern North Dakota where glacial deposits cover the surface. In the unglaciated area in southwestern North Dakota, more data have been obtained from outcrops f the Maestrichtian Fox Hills and Hell Creek formations along with some data from the Campanian Pierre Formation in extreme southwestern North Dakota.

Initial Cretaceous deposition began with the nonmarine fluvial Aptian to Albian Inyan Kara Formation. Marine deposition appears to have begun near the close of the Inyan Kara. Marine conditions continued through the deposition of the Colorado and Montana groups. The Colorado Group is represented by the Cenomanian Bell Fourche, the Cenomanian to Turonian Greenhorn, the Turonian Carlile, and the Coniacian Niobrara Formations. The Montana Group is represented by the Santonian through Campanian Pierre and Maestrichtian Fox Hills formations. Nonmarine conditions returned during deposition of the Maestrichtian Hell Creek Formation.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990