Joint 118th Annual Cordilleran/72nd Annual Rocky Mountain Section Meeting - 2022

Paper No. 10-8
Presentation Time: 4:05 PM


WERNICKE, Brian, Division of Geological and Planetary Sciences, California Institute of Technology, Mail Stop 100-23, Pasadena, CA 91125, AXEN, Gary, New Mexico Tech, 801 Leroy Place`, Socorro, NM 87801, POLCINO, Christina, Pasadena City College, 1570 E Colorado Blvd, Pasadena, CA 91106, SINHA, Simmi, University of Colorado, Boulder, Boulder, CO 80309, SWANSON, Erika, Los Alamos National Laboratory EES-14, P.O. Box 1663 D452, Los Alamos, NM 87545-0001 and TAYLOR, Wanda, Department of Geoscience, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Box 454010, Las Vegas, NV 89154-4010

We have completed a digital compilation of the bedrock geology of the northern part of the Cretaceous Sevier front in southern Nevada, dismembered by extension in the middle Miocene by the Mormon Peak and Tule Springs detachment systems, that includes the Tule Springs Hills, east-central Meadow Valley Mountains and Mormon Mountains. Sources include published geologic maps from three PhD theses (Axen, 1991, Harvard; 1993, GSAB); Swanson (2015, Caltech; Swanson and Wernicke, 2017 Geosphere), Wernicke (1982, MIT; Wernicke et al., 1985, Tectonics), unpublished mapping from a fourth (Olmore, 1971, Utah), and three unpublished MS theses (Skelly, 1987, NAU; Ellis, 1984, Syracuse; Taylor, 1984, Syracuse). It also includes published mapping (Anderson et al., 2010, GSA Spec. Pap. 463) and unpublished mapping in portions of the northern Mormon Mountains (Axen, Skelly, Ellis, Taylor and Wernicke, 1987) and southwestern Mormon Mountains (Polcino et al., 2019, 2022, this volume). The total area encompasses some 1700 square kilometers (670 square miles), and is viewable as a roughly 6’ x 6’ wall map at 1:24000. The region is well known as a region of primary low-angle normal faulting (Mormon Peak and Tule Springs detachments) and the controversy attending thereto, and the compilation will thus serve as an important source for further studies and debate on the system, and for class field trips. Because of the extension, the tectonics along the basal decollement of the Cordilleran foreland fold-and-thrust belt are exposed across the entire width of the system, from the base of the footwall ramp to the easternmost exposures of the allochthon where it lies on a Jurassic decollement. The basal decollement, which everywhere lies within a narrow interval of Middle Cambrian dolostone, and both overlying and underlying duplexes which include dozens of fault imbrications, are among the best exposed examples of such structures on the globe. The structures are especially well resolved owing to high stratigraphic resolution, which includes some 50 stratigraphic units within 4000-5000 m of stratigraphic section, ranging from Proterozoic basement through Neogene volcanic and sedimentary strata. The stratified rocks represent all 13 geologic periods from Cambrian through Quaternary, localized along the hinge zone of the miogeocline.