Integrated approach to diamond exploration in the north-central United States

A Diamond Exploration Geoscientific Information System (DEGIS) has been developed as the underpinning for three independent diamond exploration models that are used to examine the potential of the north-central United States for economic kimberlite and lamproite occurrences. Information from the three models in turn is combined to produce an integrated model that shows considerable promise for diamond exploration. The DEGIS database is raster format with 4 km grid cells--180,276 cells of geology, geochemistry, geophysics, and remote sensing data for a ;The empirical diamond exploration model correlates the distributions of geologic attributes that world-wide are thought to be important for the emplacement, preservation, and detection of economic primary diamond deposits. The attributes include age of Precambrian basement, lithospheric and crustal thicknesses, and presence or absence of sedimentary bedrock and glacial cover. The stacked model registers linear and point features that may focus kimberlite and lamproite intrusions, or are associated in some way with them--features such as the presence of geomorphic lineaments and basement faults and their intersections, the presence of anomalous cobalt and nickel in stream sediments, and the presence of cryptoexplosion structures, plus occurrences of in situ and alluvial diamonds. The proximity model ranks grid cells based on their positions with respect to linear and point features that are associated with kimberlite and lamproite bodies, and crustal upwarps that are evident as positive relief in the earth's surface and in the Precambrian basement surface.;The integrated diamond exploration model incorporates factors from all three of the independent exploration models, and it has highlighted four areas of the study region that are permissive for economic kimberlite and lamproite intrusions: (1) Wisconsin-Upper Peninsula of Michigan, (2) southeastern Wyoming, (3) northeastern North Dakota-northern Minnesota-southwestern Ontario, and (4) northwestern Iowa. Prospective locations within these areas are grid cells that most likely contain kimberlite and lamproite bodies, based on anomalous proximity scores and(or) the presence of stacked attributes that favor primary diamond deposits.