Geologic units containing anorthosite

Earth material > Plutonic rock > Gabbroid

Anorthosite

A plutonic rock defined in the QAPF diagram as having Q between 0 and 5, P/(A+P) greater than 90, and M less than 10. A group of monomineralogic plutonic igneous rocks composed almost entirely of plagioclase feldspar...

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Arizona - California - Idaho - Michigan - Minnesota - Montana - New York - Oklahoma - Pennsylvania - Tennessee - Virginia - Wisconsin - Wyoming

Arizona

Early Proterozoic granitic rocks (Early Proterozoic): Wide variety of granitic rocks, including granite, granodiorite, tonalite, quartz diorite, diorite, and gabbro. These rocks commonly are characterized by steep, northeast-striking foliation. (1600-1800 Ma)
Middle Proterozoic diabase (Middle Proterozoic): Dark gray to black sills (intrusions mostly parallel to bedding) in strata of the Apache Group and irregular to sheet-like intrusions in other rocks. Present in east-central and southeastern Arizona. Some sills are more than 100 m thick. Exposures are extensive north of Globe. (1050-1150 Ma)

California

Precambrian granitic rocks, unit 1 (Eastern Mojave Desert) (Early Proterozoic to Miocene): Precambrian granite, syenite, anorthosite, and gabbroic rocks in the San Gabriel Mountains; also various Precambrian plutonic rocks elsewhere in southeastern California
Precambrian granitic rocks, unit 2, (San Gabriel Mountains Anorthosite) (Middle Proterozoic): Precambrian granite, syenite, anorthosite, and gabbroic rocks in the San Gabriel Mountains; also various Precambrian plutonic rocks elsewhere in southeastern California
Precambrian igneous and metamorphic rock complex (Early Proterozoic to Miocene): Complex of Precambrian igneous and metamorphic rocks. Mostly gneiss and schist intruded by igneous rocks; may be Mesozoic in part.

Idaho

Anorthosite (folded sill-like intrusive or metasomatic bodies); Middle Proterozoic; northern Idaho, Boehls Butte metamorphic core complex (Middle Proterozoic): Highly metamorphosed, probably Precambrian, intrusive rock; anorthosite common

Michigan

Gabbroic rocks of Keweenawan affinity (Middle Proterozoic): Gabbroic rocks of Keweenawan affinity - gabbro, anorthosite, granite, peridotite

Minnesota

Anorthosite, gabbroic anorthosite, and anorthositic gabbro of the Mentor mafic intrusive complex in Polk County (Late Archean): Anorthosite, gabbroic anorthosite, and anorthositic gabbro of the Mentor mafic intrusive complex in Polk County
Duluth Complex; Anorthositic series (Middle Proterozoic): Duluth Complex; Anorthositic series - Plagioclase-rich gabbroic cumulates and related rocks
Post-tectonic intrusions of the Penokean orogen (Early Proterozoic): Post-tectonic intrusions of the Penokean orogen - Small stocks of olivine pyroxenite in Morrison County; small plutons of hornblende-rich diorite and gabbro that contain layers and lenses of nelsonite, pyroxenite, and anorthosite in Todd County.
Post-tectonic mafic intrusions (Late Archean): Post-tectonic mafic intrusions - Gabbro, peridotite, pyroxenite, and their metamorphic equivalents. Unit also includes small intrusive complexes of anorthosite, gabbroic anorthosite, and anorthositic gabbro. Generally characterized by pronounced magnetic signatures.

Montana

Stillwater complex (Archean Proterozoic(?) preCambrian-Proterozoic(?) preCambrian(?) Phanerozoic | Paleozoic(?) Mesozoic(?) Cenozoic | Cambrian(?) Ordovician(?) Silurian(?) Devonian(?) Carboniferous(?) Permian(?) Triassic(?) Jurassic(?) Cretaceous(?) Tertiary): Stillwater complex: consists chiefly of ultrabasic intrusive rocks and metamorphic rocks not yet named or subdivided.

New York

Hybrid rock: anorthositic and metasedimentary rock (Middle Proterozoic): Hybrid rock: anorthositic and metasedimentary rock - ranges from anorthositic rock with local blocks, shreds or layers of undifferentiated metasediment, to mappable roof pendants and/or xenoliths of metasediment in anorthositic rock.
Hybrid rock: mangeritic to charnockitic gneiss (Middle Proterozoic): Hybrid rock: mangeritic to charnockitic gneiss - with xenocrysts of calcic andesine and, locally, xenoliths of anorthosite; with increasing percentage of anorthosite component, passes gradationally into anorthositic rocks.
Interlayered gabbroic or noritic metanorthosite (Middle Proterozoic): Interlayered gabbroic or noritic metanorthosite - mangerite or charnockite, and the Yach lithology.

Oklahoma

Raggedy Mountain Gabbro Group (Phanerozoic | Paleozoic | Cambrian-Early): LAWTON- Gabbro, anorthosite, and diorite; thickness, as much as 10,000 feet (3,000 m).

Pennsylvania

Anorthosite (Probably lower Paleozoic): Anorthosite - Medium to coarse grained, light to dark bluish gray, predominantly plagioclase; local alteration minerals.
Anorthosite (Precambrian): Anorthosite - Medium to coarse grained, light to dark bluish gray, predominantly plagioclase; local alteration minerals.

Tennessee

Bakersville Gabbro (Precambrian): Bakersville Gabbro - Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses.
Mount Rogers Group including Bakersville Gabbro, Beech Granite, Cranberry Granite, and Roan Gneiss (Precambrian): Mount Rogers Group - Metavolcanics, typically purplish and reddish; massive lavas and tuffs, altered rhyolites and quartz latites; strongly foliated; interbedded arkose, shale, and conglomerate. Thickness 1,000 to 3,000 feet; Includes Bakersville Gabbro - Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses; Beech Granite - Granite, porphyritic, light-gray to reddish; coarse potash feldspar crystals and clustered interstitial mafics (chloritized biotite and hornblende) give spotted appearance; includes Max Patch Granite; Cranberry Granite - Complex of intertonguing rock types including migmatite, granitic gneisses, monzonite, quartz diorite, greenstone, mica and hornblende schists, abundant granitic pegmatite; and Roan Gneiss - Layered hornblende and garnet gneiss and granitic migmatite with zones of mica schist and amphibolite, foliation commonly contorted; contains numerous granitic and gabbroic dikes.

Virginia

Montpelier Metanorthosite (Proterozoic Y): Montpelier Metanorthosite - Anorthosite
Roseland Anorthosite (Proterozoic Y): Roseland anorthosite - Anorthosite

Wisconsin

Gabbroic rocks of Keweenawan affinity (Middle Proterozoic): Gabbroic rocks of Keweenawan affinity - gabbro, anorthosite, granite, peridotite
Layered metagabbro (Late Archean): Layered metagabbro - Interlayered gabbro, mafic accumulates, gabbroic anorthosite and anorthosite (Cummings, 1984) in Eau Claire River (T. 27 N., R. 8 W.). Age uncertain, but interpreted as Archean (Sims, 1990).
Wolf River Batholith; Anorthosite (Middle Proterozoic): Wolf River Batholith; Anorthosite- Gray, coarse-grained (1-20 cm) plagioclase-rich (An45-53) rock containing interstitial orthopyroxene, clinopyroxene, Fe-Ti oxides, and apatite.

Wyoming

Laramide Anorthosite Complex--anorthosite and norite (Proterozoic | Mesoproterozoic): LARAMIE ANORTHOSITE COMPLEX--Anorthosite and norite. In Laramie Mountains.
Laramide Anorthosite Complex--pyroxene and hornblende syenite (Proterozoic | Mesoproterozoic): LARAMIE ANORTHOSITE COMPLEX--Pyroxene and hornblende syenite--Age 1,435 Ma. In Laramie Mountains.

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