Geologic map of the Little Harquahala Mountains, west-central Arizona

The Little Harquahala Mountains of west-central Arizona contain major Mesozoic thrust faults that juxtapose a complex assemblage of Mesozoic sedimentary and volcanic rocks, Paleozoic cratonic strata, and Jurassic and Precambrian crystalline rocks. The structurally lowest rocks, referred to as the Harquar plate, consist of a Jurassic volcanic and volcaniclastic sequence depositionally overlain by primarily sedimentary rocks of the Jurassic and/or Cretaceous McCoy Mountains Formation. The Hercules thrust separates these rocks from the structurally overlying Hercules plate, which is composed of a variety of crystalline rocks of Precambrian (?) and Jurassic (?) age. The structurally higher Centennial thrust places Precambrian, Paleozoic, and Mesozoic sedimentary rocks of the Centennial plate over the Hercules plate. Crystalline rocks in the southern part of the range, referred to as the Sore Fingers assemblage, are structurally below the Centennial plate, but their structural relationship to the Hercules and Harquar plates is uncertain. Lithologic similarity of the Sore Fingers assemblage to rocks of the Hercules plate suggests that the two packages of rocks are related and probably continuous as depth beneath the Centennial plate. (20 pages)Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu