Skip to main content
U.S. flag

An official website of the United States government

Middle Tertiary plutonism in the Santa Catalina and Tortolita Mountains, Arizona

January 1, 1976

Recent reconnaissance geologic mapping in the Santa Catalina and Tortolita Mountains of southeastern Arizona, supplemented by new and published potassium-argon and fission-track ages, suggests that a large middle Tertiary (about 25 m.y.) composite batholith crops out extensively in both mountains. More than two-thirds of the batholith and the contiguous wallrocks are gneissic, the gneissosity comprising strong cataclasis and mylonitization, penetrative planar and linear structures, and crystallization of muscovite and biotite in the foliation planes. New radiometric ages indicate the deformation followed the crystallization of the batholith so closely that the K-Ar dating method cannot distinguish a difference, whereas previously published ages from the gneisses indicate a short time interval between the two events.

Publication Year 1976
Title Middle Tertiary plutonism in the Santa Catalina and Tortolita Mountains, Arizona
DOI 10.3133/ofr76262
Authors S. C. Creasey, Norman G. Banks, R. P. Ashley, Ted G. Theodore
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 76-262
Index ID ofr76262
Record Source USGS Publications Warehouse