Skip to Main Content
GEOREF RECORD

Superimposed extension and shortening in the southern Salinas Basin and La Panza Range, California; a guide to Neogene deformation in the Salinian Block of the central California Coast Ranges

Joseph P. Colgan, Darcy K. McPhee, Kristin McDougall and Jeremy K. Hourigan
Superimposed extension and shortening in the southern Salinas Basin and La Panza Range, California; a guide to Neogene deformation in the Salinian Block of the central California Coast Ranges
Lithosphere (August 2012) 4 (5): 411-429

Abstract

We synthesized data from geologic maps, wells, seismic-reflection profiles, potential-field interpretations, and low-temperature thermochronology to refine our understanding of late Cenozoic extension and shortening in the Salinian block of the central California Coast Ranges. Data from the La Panza Range and southern Salinas Basin document early to middle Miocene extension, followed by Pliocene and younger shortening after a period of little deformation in the late Miocene. Extension took place on high-angle normal faults that accommodated approximately 2% strain at the scale of the approximately 50-km-wide Salinian block (oriented perpendicular to the San Andreas fault). Shortening was accommodated by new reverse faults, reactivation of older normal faults, and strike-slip faulting that resulted in a map-view change in the width of Salinian block. The overall magnitude of shortening was approximately 10% strain, roughly 4-5 times greater than the amount of extension. The timing and magnitude of deformation in our study area are comparable to that documented in other Salinian block basins, and we suggest that the entire block deformed in a similar manner over a similar time span. The timing and relative magnitude of extension and shortening may be understood in the context of central Coast Range tectonic boundary conditions linked to rotation of the western Transverse Ranges at the south end of the Salinian block. Older models for Coast Range shortening based on balanced fault-bend fold-style cross sections are a poor approximation of Salinian block deformation, and may lead to mechanically improbable fault geometries that overestimate the amount of shortening.


ISSN: 1941-8264
EISSN: 1947-4253
Serial Title: Lithosphere
Serial Volume: 4
Serial Issue: 5
Title: Superimposed extension and shortening in the southern Salinas Basin and La Panza Range, California; a guide to Neogene deformation in the Salinian Block of the central California Coast Ranges
Affiliation: U.S. Geological Survey, Menlo Park, CA, United States
Pages: 411-429
Published: 20120807
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
Number of pages: 20
References: 95
Accession Number: 2012-077188
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 1 table, sketch map
N34°30'00" - N37°00'00", W122°00'00" - W119°00'00"
Secondary Affiliation: University of California at Santa Cruz, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201240
Program Name: USGSOPNon-USGS publications with USGS authors
Close Modal

or Create an Account

Close Modal
Close Modal