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Preliminary isostatic residual gravity anomaly map of Paso Robles 30 x 60 minute quadrangle, California

Open-File Report 2011-1104

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Abstract

This isostatic residual gravity map is part of an effort to map the three-dimensional distribution of rocks in the central California Coast Ranges and will serve as a basis for modeling the shape of basins and for determining the location and geometry of faults within the Paso Robles quadrangle. Local spatial variations in the Earth\'s gravity field, after accounting for variations caused by elevation, terrain, and deep crustal structure reflect the distribution of densities in the mid- to upper crust. Densities often can be related to rock type, and abrupt spatial changes in density commonly mark lithological or structural boundaries. High-density rocks exposed within the central Coast Ranges include Mesozoic granitic rocks (exposed northwest of Paso Robles), Jurassic to Cretaceous marine strata of the Great Valley Sequence (exposed primarily northeast of the San Andreas fault), and Mesozoic sedimentary and volcanic rocks of the Franciscan Complex [exposed in the Santa Lucia Range and northeast of the San Andreas fault (SAF) near Parkfield, California]. Alluvial sediments and Tertiary sedimentary rocks are characterized by low densities; however, with increasing depth of burial and age, the densities of these rocks may become indistinguishable from those of older basement rocks.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Preliminary isostatic residual gravity anomaly map of Paso Robles 30 x 60 minute quadrangle, California
Series title:
Open-File Report
Series number:
2011-1104
Year Published:
2011
Contributing office(s):
Western Region Geology and Geophysics Science Center
Description:
1 Map Sheet: 55 inches x 30 inches; Appendix A folder
Online Only (Y/N):
Y
Additional Online Files(Y/N):
Y