Asymmetric basin subsidence and horizontal-axis block rotations in the Miocene North Whipple Basin, SE California and W Arizona
- Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Geology
A thick, faulted sequence of post-18.5-Ma Miocene sedimentary and volcanic rocks is well exposed in the Aubrey Hills, W Arizona, and the northeastern Whipple Mountains, SE California. These strata were deposited in alluvial fans and playa lakes of a syntectonic sedimentary basin (North Whipple Basin), which evolved in the upper plate of the Whipple detachment fault on the north flank of the growing proto-Whipple Mountains. Sedimentary deposits reveal substantial lateral changes in thickness and depositional facies (lacustrine to proximal-fan) that provide a record of asymmetric basin subsidence and upper-plate block rotations during strong regional extension. Final uplift, exhumation and unroofing of lower-plate rocks occurred during this time, as evidenced by sandstone-petrographic and conglomerate clast-count studies. Two horizontal orthogonally oriented axes of synbasinal crustal rotation are recognized: extension-perpendicular (NW-SE), and extension-parallel (NE-SW). Rotation about extension-perpendicular axes occurred by displacements on NW-striking normal faults that formed classic half-graben basins in the extending upper plate. Evidence for rotation about an extension-parallel axis is seen in pronounced lateral thickening and coarsening of sedimentary lithofacies toward the SE in the Aubrey Hills. This was likely controlled by synbasinal growth of an extension-parallel syncline, which formed on the NW flank of the Whipple Mountain extension-parallel antiform.
- OSTI ID:
- 5588826
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tertiary basin development and tectonic implications, Whipple detachment system, Colorado River extensional corridor, California and Arizona
Sedimentation in detachment-dominated extensional orogens: Examples from the Mojave extensional belt, California