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Table of Contents - Special Paper 475

High Geologic Slip Rates since Early Pleistocene Initiation of the San Jacinto and San Felipe Fault Zones in the San Andreas Fault System, Southern California, USA

By Susanne U. Janecke, Rebecca J. Dorsey, David Forand, Alexander N. Steely, Stefan M. Kirby, Andrew T. Lutz, Bernard A. Housen, Benjamin Belgarde, Victoria E. Langenheim, and Tammy M. Rittenour

Abstract		2
Introduction		3
Structural Geology of Dextral Fault Zones in the Western Salton Trough		6
	San Jacinto Fault Zone	6
	Clark Fault Zone     Right Slip across the Clark Fault Zone in Crystalline Rocks     Right Slip across the Clark Fault Zone in Sedimentary Rocks	7
	Coyote Creek Fault Zone     Displacement near Coyote Mountain     Displacement near Borrego Mountain	17
	San Felipe Fault Zone     Structural Geometry     Displacement	21
	Folds within the Dextral Fault Zones	26
	How Robust Are the New Slip Estimates?	26
Basin Analysis and Fault Activity		27
	Structural Setting of the Study Sites 27	6
	Stratigraphy of Pleistocene and Holocene Deposits	27
	Dating Initiation of the San Jacinto and San Felipe Fault Zones in the Western Salton Trough	31
Changes after Initiation of the San Jacinto and San Felipe Fault Zones		32
	Early San Jacinto Fault Zone     Formation of the San Felipe Anticline within the Early San Jacinto Fault Zone	32
	Clark Fault     Santa Rosa Segment of the Clark Fault     Initial Blind Slip on the Tarantula Wash Segment of the Clark Fault	32
	Coyote Creek Fault     Coyote Ridge Segment of the Coyote Creek Fault     Borrego Badlands and Borrego Mountains Segments and Their Possible Precursors	33
	San Felipe Fault Zone	34
	Insights into Structural Reorganizations from Lithology, Provenance, Paleocurrents, and Depositional Environment of Basinal Deposits	35
	Younger Deformation	35
Discussion		36
	Summary of Results from the Western Salton Trough	36
	Total Slip and Age of the San Jacinto Fault Zone	36
	Comparison to the Northwestern San Jacinto Fault Zone	37
	Lifetime and Interval Fault Slip Rates     Clark Fault     Lifetime Slip Rate     Interval Slip Rate     Coyote Creek Fault     Lifetime Slip Rate     Interval Slip Rates     San Felipe Fault Zone	37
	Total Lifetime Slip Rate across the San Jacinto Fault Zone	38
	Comparison of Slip Rates	40
	Variation of Slip Rates in Time and Space?     Implications for the Southern San Andreas Fault System	41
Conclusions		42
Acknowledgments		43
References Cited		43