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Master of Science (MS)
Housen, Bernard Arthur
Burmester, Russell F.
The Fish Creek-Vallecito basin (FCVB) is a large Plio-Pleistocene sedimentary basin in the western Salton Trough, CA. The FCVB formed during subsidence along the West Salton Detachment fault and was uplifted and tilted when slip along the West Salton Detachment fault ended and the region became dominated by strike-slip faulting. This study uses paleomagnetism and magnetostratigraphy to determine the timing and rate of rotation of the FCVB. Two hundred and one sites were sampled in the Palm Spring Group of the FCVB. Magnetite and hematite are identified as carriers of remanence, and rock magnetic measurements are consistent with a magnetite detrital remanent magnetization and hematite detrital remanent magnetization or chemical remanent magnetization. Polarity interpretation yielded nine geomagnetic polarity intervals. Correlation of the magnetostratigraphy to the geomagnetic polarity time scale at a U-Pb dated ash layer within the sampled section yields an age span of 1.78 to 3.33 Ma for the section. Comparison of the modern expected direction with mean normal and reverse-polarity directions yields 14±3° to 17±3° of clockwise rotation for the FCVB. Rotations are interpreted to be uniform for the sampled section and younger than the approximately 1.2 Ma age attributed to uplift and deformation of the FCVB. Rotation of the FCVB is attributed to slip along the Elsinore fault. Calculations of fault slip from 14±3° or 17±3° of clockwise rotation of the FCVB since 1.2 Ma produce maximum estimates of 2.1±0.3 or 2.4±0.3 mm/yr of right lateral slip along the Elsinore fault and vertical-axis rotation rates of 16±3° or 19±3° /Myr of clockwise rotation.
Western Washington University
Fish Creek Basin (Calif.); Vallecito Basin (Calif.)
Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
DeBoer, Christopher J., "Block rotation and magnetostratigraphy of the Fish Creek-Vallecito Basin, Salton Trough, CA" (2012). WWU Graduate School Collection. 230.