El Paso intrusive suite
El Paso intrusive suite
Middle Triassic to Early Permian, ~239-274 Ma
Intrudes Paleozoic metamorphic rocks of the El Paso terrane (unit EPS) in the southeast Sierra Nevada and El Paso Mountains. North of the Garlock fault in the El Paso Mountains, this unit consists of Late Permian Weiss Mountain gneiss (granodiorite), Early to Late Permian unnamed foliated granite, non-deformed, unnamed, Late Permian-Early Triassic quartz monzonite and tonalite stocks (too small to show), the Early-Middle Triassic Burro Schmidt (quartz monzonite to quartz diorite), and Last Chance Canyon (granodiorite to tonalite) plutons (Carr and others, 1997; Cecil and others, 2019). The Permian foliated unnamed granite and Weiss Mountain pluton are coeval with volcaniclastic and volcanic rocks in the El Paso terrane (Permian andesite of Goler Gulch of Carr and others, 1997) consisting of volcaniclastic sandstone, and andesite formed in a continental-margin volcanic arc (Carr and others, 1997). In the southeastern Sierra Nevada this unit consists of highly deformed Permian to Middle Triassic granitic plutons intruded into the Kern Plateau shear zone bordering metasedimentary rocks of the El Paso terrane (Clemens-Knott and Gevedon, 2023). Rock types are chiefly medium- to fine-grained hornblende quartz diorite, tonalite, hornblende granodiorite, hornblende-biotite granite, and leucocratic granite. This unit has zircon U-Pb ages of ~239-274 Ma in the El Paso Mountains (Cecil and others, 2019), and ~249-274 Ma in the southeastern Sierra Nevada (Clemens-Knott and Gevedon, 2023). Zircons in some plutons display Precambrian and early Paleozoic inheritance (Saleeby and Dunne, 2015). This unit in southeast Sierra Nevada also yields a reset hornblende K-Ar date of ~86 Ma and biotite K-Ar date of ~74 Ma (Evernden and Kistler, 1970). In the El Paso Mountains, on the other hand, this unit has hornblende K-Ar ages of ~224-246 Ma and biotite K-Ar ages of ~146-230 Ma (Carr and others, 1997). This granitoid suite records initiation of subduction and arc magmatism along the southwestern margin of the North America craton.