El Paso terrane
El Paso terrane
Permian to Cambrian
Stratigraphically and structurally complex, mostly deep-water metasedimentary and metavolcanic rocks present in the El Paso Mountains and southeastern Sierra Nevada. Rocks in the El Paso Mountains were mapped in detail by Carr and others (1997), who defined the following major units: andesite of Goler Wash (Permian: meta-andesite flows, flow breccia, and hypabyssal intrusions); metasedimentary rocks of Holland Camp (Permian: meta-argillite and calcareous metasiltstone (member D), volcanogenic meta-arkose and metaconglomerate (member C), slate and interbedded metalimestone (member B); and slate, meta-arkose, metaconglomerate, and dolomitic marble (member A)); metasedimentary rocks of Benson Well (Pennsylvanian: upper slate and quartzite member, lower metalimestone member); metasedimentary rocks of Apache Mine (Mississippian: meta-argillite, quartzite, and metaconglomerate; Robbers Mountain Formation (Mississippian: upper meta-argillite member and lower metaconglomerate member); metasedimentary rocks of Gerbracht Camp (Devonian: meta-argillite member, sandy marble member, metatuff member, and metachert member); greenstone (Devonian(?): metamorphosed basaltic rocks including pillow lava); metasedimentary rocks of Colorado Camp (Ordovician and Cambrian: meta-argillite and marble); metasedimentary rocks of El Paso Peaks (Devonian(?), Silurian(?), Ordovician, and Cambrian: calc-silicate hornfels and minor marble (upper member), schistose slate, quartzite, and pelitic hornfels (middle member), and meta-argillite, metalimestone, and orthoquartzite (lower member)); and schist, quartzite, and marble (Cambrian(?): equivalent to Mesquite schist of Dibblee, 1952). Unit ages reported by Carr and others (1997) are based on conodonts, graptolites (Ordovician), and fusulinids (Permian; Ross and Sabins, 1966). A detrital zircon study by McDonald (2016) indicates MDAs of ~256-258 Ma for member C and ~263-283 Ma for member A of the Permian metasedimentary rocks of Holland Camp. The Paleozoic metasedimentary and metavolcanic sequence is intruded by Middle Triassic to Early Permian plutonic and metaplutonic rocks of unit Gep (Carr and others, 1997; Cecil and others, 2019).
Rocks of the El Paso terrane in southeastern Sierra Nevada are composed of carbonaceous, locally phosphatic argillite and fine-grained quartz arenite in association with minor limestone, quartz arenite, basalt, stratiform barite, and conglomerate (Dunne and Suczek, 1991). These rocks are broadly equivalent to the Rockhouse Basin and Big Meadow metasedimentary belts of Ross (1995). As in the El Paso Mountains, terrane in this area is intruded by Middle Triassic to Early Permian plutonic rocks of unit Gep (Clemens-Knott and Gevedon, 2023). 
Pre-Permian detrital zircon age spectra from the El Paso terrane indicate clastic derivation from a Paleoproterozoic to Archean craton and have similar detrital sources to rocks of the Roberts Mountains allochthon to the north (Chapman and others, 2015; Attia and others, 2018; Clemens-Knott and Gevedon, 2023). Permian detrital zircons in metasedimentary rocks of Holland Camp are interpreted to have been derived from the incipient Cordilleran magmatic arc to the west (McDonald, 2016). The terrane is interpreted to be offset from the vicinity of the Roberts Mountains allochthon during left-lateral strike-slip faulting along North American continental margin in late Paleozoic time (Saleeby and Dunne, 2015) and later thrust approximately 100 km eastward onto North American Craton by about 175 Ma (Miller and others, 1995).