Skip to main content
U.S. flag

An official website of the United States government

Structural superposition in fault systems bounding Santa Clara Valley, California

January 1, 2015

Santa Clara Valley is bounded on the southwest and northeast by active strike-slip and reverse-oblique faults of the San Andreas fault system. On both sides of the valley, these faults are superposed on older normal and/or right-lateral normal oblique faults. The older faults comprised early components of the San Andreas fault system as it formed in the wake of the northward passage of the Mendocino Triple Junction. On the east side of the valley, the great majority of fault displacement was accommodated by the older faults, which were almost entirely abandoned when the presently active faults became active after ca. 2.5 Ma. On the west side of the valley, the older faults were abandoned earlier, before ca. 8 Ma and probably accumulated only a small amount, if any, of the total right-lateral offset accommodated by the fault zone as a whole. Apparent contradictions in observations of fault offset and the relation of the gravity field to the distribution of dense rocks at the surface are explained by recognition of superposed structures in the Santa Clara Valley region.

Citation Information

Publication Year 2015
Title Structural superposition in fault systems bounding Santa Clara Valley, California
DOI 10.1130/GES01100.1
Authors Russell W. Graymer, Richard G. Stanley, David A. Ponce, Robert C. Jachens, Robert W. Simpson, Carl M. Wentworth
Publication Type Article
Publication Subtype Journal Article
Series Title Geosphere
Index ID 70187389
Record Source USGS Publications Warehouse
USGS Organization Geology, Minerals, Energy, and Geophysics Science Center