DRAINAGE BASIN MORPHOMETRY AS AN INDICATOR OF TECTONIC ACTIVITY IN THE SOUTHERN TOIYABE RANGE, GREAT BASIN NEVADA

Qualitative observations of the geomorphic characteristics of central and southern portion of the Toiyabe Range in the central Great Basin suggests that there are systematic spatial variations in the timing of tectonic uplift. The timing of tectonic uplift appears to increase from north to south parallel to the axis of the range, and the eastern side of the range appears to be more active than the western side of the range. To evaluate this hypothesis we have been using Digital Elevation Models (DEMs), satellite images, aerial photographs, and topographic maps, integrated in a GIS database to quantify the morphological characteristics of the drainage basins and the mountain fronts.

Morphometric parameters that we have measured that are commonly viewed as representative of variations in tectonic style and activity include: mountain front sinuosity, variation in the spatial distribution of drainage basin size and shape, the ratio of drainage basin area to volume of the basin, and valley floor width to height ratio. These data along with the characteristics of the longitudinal profiles and valley cross-profile morphology supports our initial hypothesis that there are systematic spatial variations in the tectonic activity of the central and southern segments of the Toiyabe Range. Although there are exceptions to the general trends, the morphometric data suggests that the mountain front is progressively more active from north to south and that the east side of the range may be more active than the west side.