--> --> Mapping of the Miocene-Quaternary deformation of Nellis Dunes Recreational Area using GIS, Processed Aster and QuickBird images and field mapping

AAPG Pacific Section and Rocky Mountain Section Joint Meeting

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Mapping of the Miocene-Quaternary deformation of Nellis Dunes Recreational Area using GIS, Processed Aster and QuickBird images and field mapping

Abstract

Nellis Dunes Recreational Area (NDRA) lies north of Frenchman Mountain, adjacent to the city of Las Vegas, Nevada. While a popular site for recreation, some active seismic epicenters were detected in NDRA. Detailed geologic understanding of the area has been hampered by a lack of deformational mapping of the area. The NDRA and its surrounding area are believed to have deformed by pull-apart basin extension between the Las Vegas Valley Shear Zone (LVVSZ) and the Munitions Fault. Previous large-scale mapping failed to show this interaction, instead suggesting that it was deformed by only LVVSZ. This study makes use of remotely sensed imagery and field mapping for geospatial analysis within a GIS in order to produce a more detailed deformational understanding for NDRA. This study uses Aster level 1B data to create detailed geological map for NDRA using VNIR and SWIR channels. Minimum Noise Fraction (MNF) is used to show variation between bands in an image and to reduce the computational requirements for subsequent processing. Secondly, this study uses Principal Components Analysis (PCA) to derive a subset of new bands that highlight uncorrelated data bands; PC 1, PC 2, and PC 3. Supervised classification based on these bands then facilitated the classification of different rock units at NDRA based on field mapped training sites. Results of this study show that NDRA confines the Muddy Creek Formation along with some Quaternary deposits. Large scale mapping (1:8,000) and kinematic analysis showed that different geometries and orientations of folds, thrust faults and normal faults developed in different areas in NDRA. Kinematic analysis showed a change in tectonism through time. First, The NW-striking LVVSZ developed in Miocene-Pliocene in the central part of the area and stopped moving before the Quaternary. In the Quaternary, a NE- oriented left-lateral accommodation zone developed in the central part of the area overprinting the LVVSZ deformation. Lately, The northern end of the Frenchman Mountain fault curves to the NE forming a left-lateral fault splay in the southern part of NDRA.