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Geologic units containing serpentinite

Arkansas

Olistoliths of Metagabbro and Soapstone-Serpentine (Phanerozoic | Paleozoic)

Olistoliths of Metagabbro and Soapstone-Serpentine - Altered peridotite

Arizona

Early Proterozoic metavolcanic rocks (Early Proterozoic)

Weakly to strongly metamorphosed volcanic rocks. Protoliths include basalt, andesite, dacite, and rhyolite deposited as lava or tuff, related sedimentary rock, and shallow intrusive rock. These rocks, widely exposed in several belts in central Arizona, include metavolcanic rocks in the Yavapai and Tonto Basin supergroups. (1650 to 1800 Ma)

Middle Miocene to Oligocene volcanic rocks (Oligocene to Middle Miocene)

Lava, tuff, fine-grained intrusive rock, and diverse pyroclastic rocks. These compositionally variable volcanic rocks include basalt, andesite, dacite, and rhyolite. Thick felsic volcanic sequences form prominent cliffs and range fronts in the Black (Mohave County), Superstition, Kofa, Eagletail, Galiuro, and Chiricahua Mountains. This unit includes regionally extensive ash-flow tuffs, such as the Peach Springs tuff of northwestern Arizona and the Apache Leap tuff east of Phoenix. Most volcanic rocks are 20-30 Ma in southeastern Arizona and 15 to 25 Ma in central and western Arizona, but this unit includes some late Eocene rocks near the New Mexico border in east-central Arizona. (11-38 Ma)

Orocopia Schist (Late Cretaceous to Early Tertiary)

Mostly gray, fine-grained quartz-feldspar-mica schist, with sparse metabasalt and metachert. The unit is exposed in tectonic windows in the southwestern corner of Arizona. It is interpreted as metamorphosed marine sandstone that was tectonically emplaced beneath southwestern Arizona during early Tertiary subduction of Pacific Ocean sea floor. (65-165 Ma)

California

Franciscan Complex, unit 1 (Coast Ranges) (Jurassic to Cretaceous)

Franciscan complex: Cretaceous and Jurassic sandstone with smaller amounts of shale, chert, limestone, and conglomerate. Includes Franciscan melange, except where separated--see KJfm.

Schist of various types and ages, unit 2 (Southern and West-central California) (Late Cretaceous to Eocene)

Schists of various types; mostly Paleozoic or Mesozoic age; some Precambrian.

Ultramafic rocks, chiefly Mesozoic, unit 1 (Trinity Ophiolite) (Ordovician)

Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 1

Ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains) (Late Proterozoic(?) to Early Jurassic)

Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 2

Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains) (Middle to Late Jurassic)

Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 3

Undivided pre-Cenozoic metavolcanic rocks, unit 1 (Southwestern Sierra Nevada) (Ordovician(?) to Permian(?))

Undivided pre-Cenozoic metavolcanic rocks. Includes latite, dacite, tuff, and greenstone; commonly schistose.

Connecticut

Ultramafic rock (Ordovician or older)

Ultramafic rock - Ultramafic rock, originally composed of olivine and pyroxene, now generally altered to tremolite, talc, chlorite, or serpentine.

Delaware

Serpentine (Paleozoic)

Serpentine - serpentine

Idaho

Metavolcanic and metasedimentary rocks, diorite, trondhjemite, and migmatite; Cretaceous to Jurassic quartz dioritic plutons in Mesozoic to Permian greenschist-facies rocks; western Idaho, Blue Mountains island-arc complex (Cretaceous to Permian)

Triassic and possibly Permian submarine metavolcanic rocks of west-central Idaho.

Massachusetts

Cobble Mountain Formation (Middle Ordovician)

Cobble Mountain Formation - Serpentinite and/or talc rock, interpreted as large clasts.

Mount Mineral Formation (Proterozoic Z)

Mount Mineral Formation (Probably correlates with Poplar Mountain Gneiss but is more aluminous) - Lenses of partially serpentinized harzburgite containing abundant veins of anthophyllite.

Serpentinite and/or talc rock (Precambrian to Phanerozoic)

Serpentinite and/or talc rock - Interpreted as tectonic slivers.

Serpentinized peridotite stocks (Ordovician to Proterozoic Z)

Serpentinized peridotite stocks - Intrudes Yw and Ygg.

Maryland

Georgetown Mafic Complex (Late Precambrian (?) - Early Paleozoic )

Georgetown Mafic Complex - Poorly exposed complex of tonalite, dark quartz diorite, gabbro, amphibolite, and undifferentiated basic rocks.

Ultramafic and Gabbroic Rocks (Early Paleozoic (?))

Ultramafic and Gabbroic Rocks - Mixed metagabbro, serpentinite, metapyroxenite, and actinolite-, chlorite-, and epidote-bearing schists.

Ultramafic Rocks (Early Paleozoic - Late Precambrian (?))

Ultramafic Rocks - Chiefly serpentinite with partly to completely altered dunite, peridotite, pyroxenite, and massive to schistose soapstone; talc-carbonate rock and altered gabbro are common in some bodies.

North Carolina

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentinite, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite, local peridotite; serpentinite, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite, local peridotite, serpentinite, soapstone, and other ultramafic rock. Only larger bodies shown.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic)

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

New Jersey

Serpentinite (Cambrian and Late Proterozoic)

Serpentinite - Light-yellowish-green to dark-green, fine-grained, massive serpentinite containing locally abundant magnetite where fresh. Contains a variety of serpentine minerals and alteration products where sheared or weathered. Exposed only along the Hudson waterfront in Hoboken but present elsewhere in boring logs.

Nevada

Diorite (Jurassic to Cretaceous)

Serpentinite (Late Devonian to Early Triassic)

SERPENTINITE (Paleozoic)-Mineral, northwestern Nye, and eastern Humboldt counties

New York

Serpentinite (Lower Ordovician)

Serpentinite.

Oregon

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)

Melange (Jurassic) (Jurassic)

Structurally complex mixture of basaltic rocks, serpentinite, chert, argillite, conglomerate, silty sandstone, and lenses of marble composing the melange of the Takilma area of Smith and others (1982)

Melange of Dutchmans Peak (Triassic or Paleozoic) (Paleozoic(?) to Jurassic(?))

Heterogeneous mixture of interlayered metasedimentary and metavolcanic rocks metamorphosed to upper greenschist and (or) almandine-amphibolite facies, and serpentinite, gabbro, and metagabbro (Smith and others, 1982)

Mixed rocks (Mesozoic and Paleozoic) (Paleozoic to Mesozoic)

Intermingled, commonly highly sheared metasedimentary, metavolcanic, and igneous rocks. Includes serpentinite, altered gabbro, chert, siliceous phyllite, greenstone, and limestone

Otter Point Formation of Dott (1971) and related rocks (Upper Jurassic) (Late Jurassic)

Highly sheared graywacke, mudstone, siltstone, and shale with lenses and pods of sheared greenstone, limestone, chert, blueschist, and serpentine. Identified as melange by some investigators

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

Pennsylvania

Ultramafic rocks (Probably lower Paleozoic)

Ultramafic rocks - Includes serpentine, steatite, and other products of alteration of peridotites and pyroxenites.

Rhode Island

Blackstone Group - greenstone, amphibolite, serpentinite (Late Proterozoic? or older?)

Blackstone Group - greenstone, amphibolite, serpentinite - Dark-green, massive to foliated metamorphosed gabbroic and basaltic rock interlayered with epiclastic rock; local pillow-structures preserved. Consists primarily of epidote, actinolite, chlorite, and plagioclase. Includes rock mapped formerly as Hunting Hill Greenstone.

South Carolina

Hammett Grove Meta-igneous Suite - ultramafic rocks (Paleozoic or Neoproterozoic)

Hammett Grove Meta-igneous Suite - ultramafic rocks: metamorphosed ultramafic rocks: hornblendite, pyroxenite, serpentinite and talc schist

South Dakota

Metagabbro (Proterozoic | Paleoproterozoic)

Dark-green sills of amphibolite, actinolite schist, greenstone, and serpentine. Thickness of sills variable, up to 1,000 ft (305 m).

Texas

Coal Creek Serpentinite (preCambrian-Proterozoic)

Coal Creek Serpentinite

Virginia

Metaperidotite, Metapyroxenite, and Hornblende Metagabbro (Proterozoic Y)

Metaperidotite, Metapyroxenite, and Hornblende Metagabbro - Serpentinite is metaperidotite, Hornblende metagabbro

Piney Branch Complex (Proterozoic Z-Cambrian)

Piney Branch Complex - Metamorphosed mafic and ultramafic rocks

Vermont

Ultramafic Rocks (Ordovician)

Ultramafic Rocks - Serpentinite, carbonate rock, talc-carbonate rocks and steatite.

Ultramafic Rocks (Ordovician)

Ultramafic Rocks - Dunite, peridotite, and serpentinite

Washington

Basic intrusive rocks, undivided (Jurassic in central Cascades; Oligocene to Eocene in northern Cascades)

Predominantly gabbro; includes some serpentine. Age undetermined.

Pre-Tertiary sedimentary and metasedimentary rocks, undivided (Mostly Early Cretaceous to Middle Jurassic, possibly includes minor Eocene rocks)

Graywacke, argillite, phyllite, chert, talc, and graphite schist; some faulted-in blocks of serpentinite and greenstone. Includes minor limestone on San Juan Island.

Pre-Tertiary ultrabasic intrusive rocks (Late-Jurassic)

Peridotite and pyroxenite; generally altered partly or completely to serpentine. Includes serpentinite and saxonite on Sumas Mountain, Whatcom County.

Pre-Tertiary volcanic rocks, undivided (Probably mostly Jurassic)

Andesite and basalt flows, and greenstone; includes minor interbedded limestone, arkose, quartzite, and chert beds.

Tertiary dunite intrusive rocks (Late Cretaceous)

An intimate mixture of saxonite and dunite, partly serpentinized; Twin Sisters mountain area of Whatcom and Skagit Counties. Predominantly dunite and associated serpentinite in Jumbo Mountain area of central Snohomish County.