* 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