Crustal-scale tilting of the central Salton block, southern California

Geosphere
University of Oregon
By:  and 

Links

Abstract

The southern San Andreas fault system (California, USA) provides an excellent natural laboratory for studying the controls on vertical crustal motions related to strike-slip deformation. Here we present geologic, geomorphic, and gravity data that provide evidence for active northeastward tilting of the Santa Rosa Mountains and southern Coachella Valley about a horizontal axis oriented parallel to the San Jacinto and San Andreas faults. The Santa Rosa fault, a strand of the San Jacinto fault zone, is a large southwest-dipping normal fault on the west flank of the Santa Rosa Mountains that displays well-developed triangular facets, narrow footwall canyons, and steep hanging-wall alluvial fans. Geologic and geomorphic data reveal ongoing footwall uplift in the southern Santa Rosa Mountains, and gravity data suggest total vertical separation of ∼5.0–6.5 km from the range crest to the base of the Clark Valley basin. The northeast side of the Santa Rosa Mountains has a gentler topographic gradient, large alluvial fans, no major active faults, and tilted inactive late Pleistocene fan surfaces that are deeply incised by modern upper fan channels. Sediments beneath the Coachella Valley thicken gradually northeast to a depth of ∼4–5 km at an abrupt boundary at the San Andreas fault. These features all record crustal-scale tilting to the northeast that likely started when the San Jacinto fault zone initiated ca. 1.2 Ma. Tilting appears to be driven by oblique shortening and loading across a northeast-dipping southern San Andreas fault, consistent with the results of a recent boundary-element modeling study.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Crustal-scale tilting of the central Salton block, southern California
Series title Geosphere
DOI 10.1130/GES01167.1
Volume 11
Issue 5
Year Published 2015
Language English
Publisher Geological Society of America
Publisher location Boulder, CO
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 19 p.
First page 1365
Last page 1383
Country United States
State California
Other Geospatial Southern California
Online Only (Y/N) N
Additional Online Files (Y/N) N