Geologic units containing Peridotite

A plutonic rock with M equal to or greater than 90 and ol/(ol+opx+cpx) greater than 40%

California - Kentucky - Massachusetts - Maryland - Michigan - Minnesota - New York - Oregon - Pennsylvania - Tennessee - Virginia - Vermont - Washington - Wisconsin - Wyoming


Gabbro and ultramafic rocks associated with granitic plutons (Cretaceous and Jurassic) (Late Jurassic and Early Cretaceous)
Predominantly hornblende gabbro, gabbro, and olivine gabbro, but includes pyroxenite, hornblende pyroxene, and minor peridotite, dunite, and serpentinite (Smith and others, 1982)
Ultramafic and mafic intrusive rocks and serpentinized equivalents (Triassic and Paleozoic) (Paleozoic to Triassic)
Peridotite, pyroxenite, gabbro, and norite. Light-green, gray, and black serpentine, mostly derived from peridotite; commonly highly sheared; in places includes some metavolcanic rocks and metamorphosed inclusions of keratophyre and chert. Includes ultramafic and mafic phases of the ophiolitic Canyon Mountain Complex of Thayer (1963; 1977) and Brown and Thayer (1966), alpine mafic rocks of Wolff (1965), gabbro of Ashley (1967), and serpentinite-matrix melange of Brooks and others (1983) and Ferns and others (1983):
Ultramafic and related rocks of ophiolite sequences (Jurassic) (Paleozoic(?), Triassic(?), and Jurassic)
Predominantly harzburgite and dunite with both cumulate and tectonite fabrics. Locally altered to serpentinite. Includes gabbroic rocks and sheeted diabasic dike complexes. Comprises Josephine ophiolite of Harper (1980), ophiolites of Onion Mountain, Sexton Mountain, Pearsoll Peak, Rogue River, and Riddle areas (Smith and others, 1982) and Coast Range ophiolite and serpentinite melange of M.C. Blake, Jr. and A.S. Jayko (unpublished data, 1985). In southwest Oregon, locally includes small bodies of early Mesozoic or late Paleozoic serpentinized and sheared ultramafic rocks, mostly in shear zones. Locally, volcanic and sedimentary rocks shown separately