2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 2
Presentation Time: 8:00 AM-12:00 PM

DIGITAL COMPILATION OF INLAND-NORTHWEST TECTONIC AND IGNEOUS FEATURES


CLEVELAND, David1, BOOKSTROM, Arthur A.2, BOX, Stephen E.2, LEWIS, Reed3, CARLSON, Mary H.4 and LARSEN, Jeremy4, (1)Geology, Eastern Washington Univ, Cheney, WA 99004, (2)Geologic Division, U.S. Geol Survey, 904 W. Riverside, Spokane, WA 99201, (3)Idaho Geological Survey, Univ of Idaho, Moscow, ID 83844, (4)Information Systems Support, Bremerton, WA 98310, dcleveland@usgs.gov

We present maps of Inland-Northwest tectonic and igneous features, derived from a digital database, compiled from 43 geologic maps, originally made at scales of 1:100 k and 1:250 k by USGS and geological agencies of Washington, Idaho, and Montana. The compiled maps, supplemented by information from the literature, indicate important tectonic and igneous features, such as: 1) Archean gneiss, intruded by the Stillwater layered intrusive complex in the Beartooth Range; 2) the NE-trending Great Falls Tectonic Zone (GFTZ), initiated as an Early Proterozoic collisional orogen between the Archean Wyoming and Hearn Provinces; 3) the Middle Proterozoic Belt Basin, including sub-basins, early-rift and late-sag strata, axial intrusions, and WNW-trending growth faults, regarded as early manifestations of the Lewis and Clark Tectonic Zone (LCTZ); 4) Late Proterozoic Windermere strata; 5) Early Paleozoic shelf, slope and deep-water strata of southeastern Idaho and the Kootenai arc; 6a) a suture zone in northern Washington, between the Kootenai arc and the accreted Quesnellia micro-continent; 6b) a suture zone in west-central Idaho, between the North American craton and oceanic island-arcs of the Blue Mountains accreted terrane; 7a) a major NW jog in (or sinstral offset of) the Blue Mountains suture zone, along the NW projection of the Trans-Idaho Discontinuity; 7b) veins of the Coeur d’Alene Ag-Pb-Zn mining region, within the LCTZ, and possibly formed during tectonism associated with docking of accreted terranes; 8a) Cordilleran compressional folds, thrust sheets, basement-cored uplifts, and Cretaceous intermontane basin-fill deposits; 8b) the Late Cretaceous Kaniksu, Idaho, and Boulder composite batholiths, and other plutons of the Cordilleran magmatic arc; 9a) Eocene metamorphic core complexes, bounded by detachment faults, and connected by Eocene dextral faults within and parallel to the LCTZ; 9b) Eocene volcanic fields and plutons of the Challis magmatic belt, with volcano-tectonic grabens and dike swarms along the GFTZ; 10) the Rocky Mountain trench north of the LCTZ, and block-faulted basins and ranges within and south of the GFTZ; 11) Miocene flood basalts of the Columbia River basin, and 12) tectonic and bimodal volcanic features of the Snake River Plain and Yellowstone caldera.