Large-magnitude Miocene extension in the central Mojave Desert: Implications for Paleozoic to Tertiary paleogeography and tectonics

Journal Article · Wed Jan 10 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB01p00557· OSTI ID:5015776

Walker, J D ^[1]; Bartley, J M ^[2]; Glazner, A F ^[3]

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1. Univ. of Kansas, Lawrence (United States)
2. Univ. of Utah, Salt Lake City (United States)
3. 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), Vol. 95:B1; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
DESERTS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
TECTONICS
AGE ESTIMATION
BASEMENT ROCK
DEFORMATION
GEOGRAPHY
GEOLOGIC FAULTS
GEOLOGIC HISTORY
LEAD ISOTOPES
LITHOLOGY
MESOZOIC ERA
METAMORPHIC ROCKS
MIOCENE EPOCH
PALEOZOIC ERA
PLUTONIC ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
TERTIARY PERIOD
URANIUM ISOTOPES
ZIRCON
ACTINIDE ISOTOPES
ARID LANDS
CENOZOIC ERA
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGY
IGNEOUS ROCKS
ISOTOPES
MINERALS
NORTH AMERICA
ROCKS
SILICATE MINERALS
USA
580000* - Geosciences