Lateral Displacement of Upper Miocene Rocks and the Neogene History of Offset along the San Andreas Fault in Central California

Research Article| October 01, 1972 Lateral Displacement of Upper Miocene Rocks and the Neogene History of Offset along the San Andreas Fault in Central California O F. HUFFMAN O F. HUFFMAN Department of Geology and Geophysics, University of California, Berkley, California 94720 PRESENT ADDRESS: GULF RESEARCH AND DEVELOPMENT COMPANY, P.O. DRAWER 2038, PITTSBURGH, PENNSYLVANIA 15230 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1972) 83 (10): 2913–2946. https://doi.org/10.1130/0016-7606(1972)83[2913:LDOUMR]2.0.CO;2 Article history received: 13 Aug 1971 rev-recd: 01 May 1972 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation O F. HUFFMAN; Lateral Displacement of Upper Miocene Rocks and the Neogene History of Offset along the San Andreas Fault in Central California. GSA Bulletin 1972;; 83 (10): 2913–2946. doi: https://doi.org/10.1130/0016-7606(1972)83[2913:LDOUMR]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Late Miocene strata occur on both sides of the San Andreas fault for several hundred miles in central California. The unlike facies and contrasting paleogeographic situations which are found across the fault along much of this distance must have been brought together by large-scale strike-slip movement on the fault. Clastic deposits west of the San Andreas need granitic-volcanic sources east of the fault, but the only such sources are to the southeast—in one probable case, more than 110 mi away. Likewise, voluminous coarse conglomerate beds east of the fault in the southern Temblor Range require the presence of a large, highly elevated granitic and metamorphic source immediately west of the fault during the later upper Miocene. The northern Gabilan Range, about 150 mi (240 km) to the northwest, was probably the only such basement area exposed at the time; the granitic and metamorphic bedrock here is very similar to the type of gravel found within the conglomerate of the southern Temblor Range. Thus, the Temblor Range clastic rocks were deposited adjacent to the Gabilan bedrock, and the two areas subsequently have been offset by about 150 mi (240 km) of right-slip on the San Andreas fault. The Gabilan source appears to have moved northwestward along the fault during the upper Miocene; together with tentative correlations between parts of the source and parts of the clastic deposits, this suggests post-Miocene offset of 145 ± 5 mi (234 ± 8 km), post-early upper Mohnian offset of 158 ± 3 mi (254 ± 5 km), and thus 5 to 21 mi (8 to 34 km) of slip during the later upper Miocene.Work in progress by several investigators, including the writer, indicates about 185 to 190 mi (300 km) of displacement for rocks 22 m.y. old. Comparison of the 145- to 158-mi and 185- to 190-mi offsets reveals that movement on the San Andreas in central California included at least one change of rate in the last 22 m.y. Although this conclusion and the indicated offsets restrict the possible histories of displacement somewhat, faulting may have proceeded at widely varying rates, and movement may have been episodic, continuously accelerating, or, if motion on this segment of the fault began only 12 ± 4 m.y. ago, constant. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.