Utah Geological Association Publication 30.Pub
Utah Geological Association Publication 30 - Pacific Section American Association of Petroleum Geologists Publication GB78 239 CENOZOIC EVOLUTION OF THE NORTHERN COLORADO RIVER EXTEN- SIONAL CORRIDOR, SOUTHERN NEVADA AND NORTHWEST ARIZONA JAMES E. FAULDS1, DANIEL L. FEUERBACH2*, CALVIN F. MILLER3, 4 AND EUGENE I. SMITH 1Nevada Bureau of Mines and Geology, University of Nevada, Mail Stop 178, Reno, NV 89557 2Department of Geology, University of Iowa, Iowa City, IA 52242 *Now at Exxon Mobil Development Company, 16825 Northchase Drive, Houston, TX 77060 3Department of Geology, Vanderbilt University, Nashville, TN 37235 4Department of Geoscience, University of Nevada, Las Vegas, NV 89154 ABSTRACT The northern Colorado River extensional corridor is a 70- to 100-km-wide region of moderately to highly extended crust along the eastern margin of the Basin and Range province in southern Nevada and northwestern Arizona. It has occupied a criti- cal structural position in the western Cordillera since Mesozoic time. In the Cretaceous through early Tertiary, it stood just east and north of major fold and thrust belts and also marked the northern end of a broad, gently (~15o) north-plunging uplift (Kingman arch) that extended southeastward through much of central Arizona. Mesozoic and Paleozoic strata were stripped from the arch by northeast-flowing streams. Peraluminous 65 to 73 Ma granites were emplaced at depths of at least 10 km and exposed in the core of the arch by earliest Miocene time. Calc-alkaline magmatism swept northward through the northern Colorado River extensional corridor during early to middle Miocene time, beginning at ~22 Ma in the south and ~12 Ma in the north.
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