Constraints on the tectonics of the Mule Mountains thrust system, southeast California and southwest Arizona

Journal Article · Sat Nov 10 04:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB12p20025· OSTI ID:5319645

Tosdal, R M ^[1]

---

1. Univ. of California, Santa Barbara (USA)

The Mule Mountains thrust system crops out discontinuously over a 100-km-strike length in the Blythe-Quartzsite region of southeast California and southwest Arizona. Along the thrust system, middle and upper crustal metamorphic and plutonic rocks of Proterozoic and Mesozoic age are thrust north-northeastward (015{degree} to 035{degree}) over a lower plate metamorphic terrane that formed part of the Proterozoic North American craton, its Paleozoic sedimentary rock cover, overlying Mesozoic volcanic and sedimentary rocks, and the intruding Jurassic and Cretaceous granitic rocks. Stratigraphic, petrologic, and Pb isotopic ties for Jurassic granitoids and for Jurassic( ) and Cretaceous sedimentary rocks across the various parts of the thrust system indicate that related crustal blocks are superposed and preclude it from having large displacements. The thick-skinned thrust system is structurally symmetrical along its length with a central domain of synmetamorphic thrust faults that are flanked by western and eastern domains where lower plate domains where lower plate synclines underlie the thrusts. Deformation occurred under low greenschist facies metamorphic conditions in the upper crust. Movement along the thrust system was probably limited to no more than a few tens of kilometers and occurred between 79{plus minus}2 Ma and 70{plus minus}4 Ma. The superposition of related rocks and the geometry of the thrust system preclude it from being a major tectonic boundary of post-Middle Jurassic age, as has been previously proposed. Rather, the thrust system forms the southern boundary of the narrow zone of Cretaceous intracratonic deformation, and it is one of the last tectonic events in the zone prior to regional cooling.

• OSTI ID: 5319645
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B12; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ARIZONA
CALIFORNIA
CONSTRAINTS
CRETACEOUS PERIOD
DEFORMATION
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGY
IGNEOUS ROCKS
ISOTOPES
JURASSIC PERIOD
LEAD ISOTOPES
MESOZOIC ERA
METAMORPHIC ROCKS
METAMORPHISM
MOUNTAINS
NORTH AMERICA
PETROLOGY
PLUTONIC ROCKS
PRECAMBRIAN ERA
ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
TECTONICS
USA
VOLCANIC ROCKS