Structural controls on syn-extensional subsidence, Miocene North Whipple basin, Aubrey Hills, W Arizona
- Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Geology
A thick sequence of post-18.5-Ma Miocene sedimentary and volcanic rocks in well exposed in the Aubrey Hills, western Arizona. These strata were deposited in a syn-extensional 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 rocks consist mainly of sandy conglomerate, sandstone and limestone that record deposition in medial to distal alluvial-fan and marginal-lacustrine environments. Detailed facies mapping, measured sections, and along-strike mapping of erosional surfaces reveal abrupt lateral S-to-N changes in thickness and depositional facies that provide a record of asymmetric subsidence, tilting toward the south or SE, and local erosion during ENE-WSW regional extension. These data show that initially, the basin attained a dynamic balance between asymmetric subsidence and sediment accumulation that accommodated deposition of laterally equivalent facies belts, passing from [approximately]300 meters of medial-fan facies in the south to [approximately]180 meters of lacustrine deposits in the north. Of many possible structural interpretations, there are two that best explain the data. The first involves asymmetric basin subsidence along a NW-trending, high-angle normal fault, with slip increasing substantially along strike to the SE. The second model involves synbasinal growth of an asymmetric NE-trending syncline, paired with the Whipple Mt. antiform to the south, that was oriented parallel to the direction of regional extension. The second interpretation is favored by the authors because it is consistent with independent structural data recently published by Yin and Dunn (1992), and it is a general, robust model that does not involve rigid geometric and paleographic restrictions, as does the first model.
- OSTI ID:
- 5436256
- Report Number(s):
- CONF-9305259-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARIZONA
SEDIMENTARY BASINS
GEOLOGIC HISTORY
STRATIGRAPHY
TECTONICS
GEOLOGIC FAULTS
GEOLOGIC MODELS
MIOCENE EPOCH
SEDIMENTARY ROCKS
VOLCANIC ROCKS
CENOZOIC ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
IGNEOUS ROCKS
NORTH AMERICA
ROCKS
TERTIARY PERIOD
USA
580000* - Geosciences