* Denotes speaker other than senior author.

FRITSCHE, A. EUGENE, LENI G. FIELD*, FRANK E. DENISON, MARY S. STECHESON, JESSE F. HOLT, MARK O. KRUGER, and LEMUEL DE PAULA
Department of Geological Sciences, California State University, Northridge, CA

Abstract: Mid-Tertiary Pre-Rotation Orientation of the Western/Eastern Transverse Ranges of California

The pre-San Andreas fault juxtaposition of the western and eastern Transverse Ranges is well documented on the basis of stratigraphic evidence. Initial palinspastic reconstructions of these two presently separated portions of the Transverse Ranges on the basis of paleomagnetic evidence have portrayed the Transverse Ranges as a series of straight, north-trending, fault-bounded panels that rotated clockwise into their present orientation by right slip along the panel-bounding faults. A recent palinspastic reconstruction has shown that the western portion of the Transverse Ranges, rather than being straight, had an originally curved aspect that straightened into its present east-west trend during rotation. The eastern Transverse Ranges were not considered in this recent reconstruction. Paleomagnetic evidence from the eastern Transverse Ranges shows that they were rotated clockwise the same amount as the eastern portion of the western Transverse Ranges. Palinspastic reconstruction, therefore, requires that the entire Transverse Ranges block rotated as a single entity around a pivot point at the eastern end of the eastern Transverse Ranges. It is clear that this tectonic rotational event preceded and was mostly completed before movement on the San Andreas fault separated the eastern and western portions of the Transverse Ranges.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California