Schist, quartzite, marble, skarn, and mafic gneiss; Jurassic to Mississippian amphibolite-facies rocks; southwestern Idaho, western accreted island-arc complex (IDJMwm;0)

State	Idaho
Name	Schist, quartzite, marble, skarn, and mafic gneiss; Jurassic to Mississippian amphibolite-facies rocks; southwestern Idaho, western accreted island-arc complex
Geologic age	Jurassic to Mississippian
Original map label	PZm
Comments	JMm consists of interbedded schist, quartzite, and marble lenses, undivided. Age is given as probably Paleozoic (ID001), pre-Cretaceous (ID127), and unknown (ID112, ID176). JMm is intruded by granitic rocks of the Idaho batholith, dated 87 +/- 3 Ma (ID177). JMm lies just west of Sr isotopic initial ratio 0.706 line (ID177), along the Western Idaho Suture Zone (ID161). Scattered blocks of hornblende gabbro and quartzite, suggest a tectonic melange with an oceanic-crustal component (James Evans, oral commun., 2005). The age of the accreted terrane is pre-Cretaceous, probably Jurassic to Mississippian, like western accreted terranes to the north in Idaho and Oregon, and to the southwest, in northern Nevada, as indicated by the metamorphic-terrane map in ID176.
Primary rock type	schist
Secondary rock type	quartzite
Other rock types	marble; skarn; mafic gneiss
Lithologic constituents	Major Metamorphic > Schist (Amphibolite)quartz, biotite, hornblende, muscovite, graphite, garnet varieties Minor Metamorphic > Marblelenses of massive, fine-grained marble locally replaced by skarn Metamorphic > Quartzite (Amphibolite)interlayered with schist Incidental Igneous > Plutonic > Gabbroic > Gabbroamphibole-gabbro blocks in possible tectonic melange Metamorphic > Skarn (Amphibolite)hedenbergite, ilvaite, diopside, garnet, tremolite, ore minerals
Map references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000.
Unit references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000. Idaho Bureau of Mines and Geology, undated, Geology of the Jordan Valley quadrangle, Oregon-Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, scale 1:250,000. Ekren, E.B., McIntyre, D.H., Bennett, E.H., and Malde, H.E., 1981, Geologic map of Owyhee County, Idaho, west of longitude 116o W.: U.S. Geological Survey Miscellaneous Investigations Series, Map I-1256, 1:125,000 scale. [http://pubs.er.usgs.gov/publication/i1256] Silberling, D.L., Jones, D.L., blake, M.C., Jr., and Howell, D.G., 1987, Lithotectonic terranes of the western conterminous United States: U.S. Geological Survey map MF-1874-C, 1:2,500,000 scale, with pamphlet, 20 p. [http://pubs.er.usgs.gov/publication/mf1874C] Armstrong, R.L., Taubeneck, W.H., and Hales, P.O., 1977, Rb-Sr and K-Ar geochronometry of Mesozoic granitic rocks and their Sr isotopic composition, Oregon, Washington, and Idaho: Geological Society of America Bulletin, v. 88, p. 397-411.
Geographic coverage	Owyhee