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The AAPG/Datapages Combined Publications Database

Williston Basin Symposium

Abstract

SKGS-AAPG

Sixth International Williston Basin Symposium, October 7, 1991 (SP11)

Pages 234 - 243

GRAVITY MODELING OF PROTEROZOIC STRUCTURES IN NORTH-CENTRAL NORTH DAKOTA.

KATHRYN C. LUTHER, Environmental Geologist, North Dakota State Department of Health and, Consolidated Laboratories, Division of Water Quality, 1200 Missouri Ave, P.O. Box 5520, Bismarck, ND 58502-5520.

ABSTRACT

During the Precambrian the core of the North American continent was formed by the collision and suturing of micro-continents. The resulting contact zone is exposed in Manitoba, and clearly marks the boundary between the Archean Superior Province and the Proterozoic Trans-Hudson Orogenic Belt. This zone includes the Thompson nickel belt and the Thompson Fault. Bouguer gravity maps of this area indicate that this boundary zone extends beneath the Phanerozoic cover in Manitoba and North Dakota.

In the study area, which is located between latitudes 48° and 49° N and longitudes 100° and 102°W, the westernmost major structure is the Thompson Fault. About 45 to 55 km (30 to 35 mi) east of this fault lies the north-south trending Superior - Trans-Hudson contact. Two-dimensional forward gravity modeling was used to determine the nature of the structures within the study area. Results indicate that (i) the Thompson Fault dips to the west and strikes about N13°E, running beneath the Minot area; (ii) the Superior-Trans-Hudson contact dips west and is slightly concave east; the dip steepens in the south; and (iii) a large circular positive gravity and magnetic anomaly centered near latitude 49° 15'N and longitude 101° W may represent a mafic pluton or a dense body of some other origin.

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