18 Geologic Maps and Digital Geologic Maps (Posters)

Friday, 14 March 2003
8:00 AM - 12:00 PM

DIGITAL GEOLOGIC MAP OF KNOLL BASIN, NEVADA WITH DETAILED LAYERS OF STRUCTURAL AND SEDIMENTOLOGIC DATA

Paper number: 18-2
Program: THEME SESSIONS
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Knoll basin is a half graben bounded by a west-dipping fault on the western flank of Knoll Mountain (a.k.a. HD Range) in northeastern Nevada. The northeastern corner of the basin is filled with Miocene marginal lacustrine sediment deposited, and deformed into a 4-km long NE-trending syncline in the hanging wall of a NE-trending synthetic fault, during extension. Strata in the syncline contain several mappable units that record progressive folding, valley incision, and deposition parallel to the axis of the syncline. We are analyzing the sedimentologic and tectonic origin of the syncline and incised valley. Analysis of this type of terrain necessarily requires diverse data, many of which can not be displayed on a traditional, single-layer geologic map. Consequently, we are constructing a digital geologic map that incorporates all data, including digital photos, into numerous layers so that all, or just a select few, layers of data can be viewed at any time for comparison or analysis.

The maps fundamental base layers consist of a rasterized USGS 7.5' topographic map overlain by polygons representing map units. Higher layers and sublayers include 1) attitudes of bedding; 2) faults; 3) a single layer for each formation that contains attitude data and locations of fold axes based only on attitude data from that formation, which is useful in recognizing unconformities; 4) fold axes based on attitude data from all formations; 5) structure contour maps of faults and incised valley; 6) cross sections; 7) digital photo documentation of structural and sedimentologic features; and 8) field station locations. Future layers to be added will include stereonet data, isopach maps, paleocurrent data, and additional structure contour maps. This type of compilation of diverse data facilitates and enhances the sedimentologic and tectonic analysis of the basin.