Large-magnitude Miocene extension in the central Mojave Desert: Implications for Paleozoic to Tertiary paleogeography and tectonics
- Univ. of Kansas, Lawrence (United States)
- Univ. of Utah, Salt Lake City (United States)
- Univ. of North Carolina, Chapel Hill (United States)
The main Cenozoic extensional structure in the central Mojave Desert is the Waterman Hills detachment fault, which places brittely deformed synorogenic Miocene rocks on ductilely and cataclastically deformed footwall rocks. The mylonitic fabric in the lower plate was formed at 23 Ma, based on a zircon U/Pb age from a synmylonitic intrusion. Upper plate strata consist of rhyolite flows overlain by sedimentary rocks that were apparently deposited during extensional faulting. These strata were tilted, folded, and intruded by synkinematic rhyolite plugs that are cut off at the detachment fault. Potassium metasomatism of the rhyolitic rocks is pervasive. Upper plate detrital sediment was derived from the rhyolitic rocks and from metamorphic and plutonic basement rocks not present in the area. The probable source of the exotic basement clasts is the Alvord Mountain area, presently located 35 km east-northeast of the Waterman Hills area. This source was probably much nearer to the Waterman Hills during deposition of the synorogenic deposits and has been subsequently shifted by extensional deformation. Distinctive Mesozoic plutonic rocks provide a possible tie between upper and lower plate rocks. Similar poikilitic gabbro bodies in the Goldstone area and the Iron Mountains suggest slip on the Waterman Hills detachment fault to be about 40-50 km. This is also consistent with other offset markers, such as the western edge of a Mesozoic dike swarm. When 15-20 km( ) of Tertiary extension is restored, Paleozoic eugeoclinal rocks are placed structurally above their miogeoclinal counterparts. Combined with the distribution of Triassic and Jurassic rocks, this implies post-Early Triassic and pre-Late Jurassic stacking of these lithologies.
- OSTI ID:
- 5015776
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B1; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ACTINIDE ISOTOPES
AGE ESTIMATION
ARID LANDS
BASEMENT ROCK
CALIFORNIA
CENOZOIC ERA
DEFORMATION
DESERTS
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOGRAPHY
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
IGNEOUS ROCKS
ISOTOPES
LEAD ISOTOPES
LITHOLOGY
MESOZOIC ERA
METAMORPHIC ROCKS
MINERALS
MIOCENE EPOCH
NORTH AMERICA
PALEOZOIC ERA
PLUTONIC ROCKS
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
STRATIGRAPHY
TECTONICS
TERTIARY PERIOD
URANIUM ISOTOPES
USA
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