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Geologic units containing diabase

Alabama

Mesozoic Intrusive Rocks; Diabase (Mesozoic)

Diabase - tholeiitic +/- olivine diabase dikes of Late Triassic and Early Jurassic age.

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)

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 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)

Middle Proterozoic sedimentary rocks (Middle Proterozoic)

Red-brown shale and sandstone, buff to orange quartzite, limestone, basalt, black shale, and sparse conglomerate. This unit includes the Grand Canyon Supergroup, Apache Group, and Troy Quartzite. These rocks were deposited in shallow marine, coastal nonmarine, and fluvial settings. (700-1300)

Proterozoic granitic rocks (Proterozoic)

Undivided Early and Middle Proterozoic granitic rocks (units Xg and Yg). (1400-1800 Ma)

California

Mesozoic volcanic rocks, unit 1 (Coast Ranges) (Jurassic to Cretaceous)

Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks

Colorado

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes (Proterozoic | Mesoproterozoic)

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes

Intrusive rocks (Phanerozoic | Paleozoic | Cambrian)

Alkalic and mafic intrusive rocks in small plutons, and diabase dikes

Connecticut

Buttress Dolerite (Middle? Jurassic)

Buttress Dolerite - Dark-gray to greenish-gray (weathers brown or gray), medium- to fine-grained, commonly porphyritic, generally massive with well-developed columnar jointing, grading from basalt near contacts to fine-grained gabbro in the interior, composed of plagioclase and pyroxene with accessory opaques and locally devitrified glass, quartz, or olivine.

Buttress Dolerite (uncertain) (Middle? Jurassic)

Buttress Dolerite (uncertain)- Dark-gray to greenish-gray (weathers brown or gray), medium- to fine-grained, commonly porphyritic, generally massive with well-developed columnar jointing, grading from basalt near contacts to fine-grained gabbro in the interior, composed of plagioclase and pyroxene with accessory opaques and locally devitrified glass, quartz, or olivine.

New Haven Arkose plus Buttress Dolerite (Upper Triassic; possibly Lower Jurassic at top plus Middle? Jurassic)

New Haven Arkose plus Buttress Dolerite - New Haven Arkose - Red, pink, and gray coarse-grained, locally conglomeratic, poorly sorted and indurated arkose, interbedded with brick-red micaceous, locally shaly siltstone and fine-grained feldspathic clayey sandstone. Buttress Dolerite (Middle? Jurassic) - Dark-gray to greenish-gray (weathers brown or gray), medium- to fine-grained, commonly porphyritic, generally massive with well-developed columnar jointing, grading from basalt near contacts to fine-grained gabbro in the interior, composed of plagioclase and pyroxene with accessory opaques and locally devitrified glass, quartz, or olivine.

West Rock Dolerite (Lower Jurassic)

West Rock Dolerite - Dark-gray to greenish-gray (weathers bright orange to brown), medium- to fine-grained, grading from basalt near contacts to fine-grained gabbro in the interior, generally massive with well-developed columnar jointing, composed of plagioclase and pyroxene with accessory opaques and locally devitrified glass, quartz, or olivine.

Georgia

Diabase (Precambrian-Paleozoic)

Diabase

Idaho

Amphibolite after gabbro, diabase, and diorite; Middle Proterozoic sill-like intrusions; southern and northern Belt provinces (Middle Proterozoic)

Younger or Intermediate Precambrian age intrusive rock undifferentiated; Intrusive rock of eastern Idaho; appears older than Cretaceous, possibly Precambrian; Highly metamorphosed rock of central Idaho; age and origin of rock questionable.

Basalt, andesite, diorite, lamprophyre intrusions; Tertiary to Cretaceous, undivided; northern Idaho, central Idaho (Cretaceous or Eocene)

Eocene intrusions including large granitic plutons and dike swarms of central Idaho

Felsic augen gneiss after porphyritic granite; Middle Proterozoic; southern Belt province (Middle Proterozoic)

Augen gneiss, amphibolite and other metamorphosed igneous rocks; possibly Precambrian.

Massachusetts

Diabase dikes and sills (Lower Jurassic)

Diabase dikes and sills.

Maryland

Diabase Sills and Dikes (Triassic)

Diabase Dikes and Sills - Sills: Greenish-gray to black, medium-grained; dikes: Greenish-gray to black, medium- to dine-grained; local contact metamorphic aureoles.

Michigan

Menominee Group; Negaunee Iron-formation (Early Proterozoic)

Menominee Group; Negaunee Iron-formation - Highly metamorphosed banded iron-formation. Principal iron-formation in Marquette trough and nearby areas. Includes abundant metadiabase sills.

Minnesota

Logan Intrusions (Middle Proterozoic)

Logan Intrusions - Diabase, porphyritic diabase, gabbro, and related felsic sills and dikes.

Mille Lacs Group and related rocks of the Penokean fold-and-thrust belt; Metabasalt, metadiabase, and metasedimentary rocks metamorphosed to lower amphibolite facies (Early Proterozoic)

Mille Lacs Group and related rocks of the Penokean fold-and-thrust belt; Metabasalt, metadiabase, and metasedimentary rocks metamorphosed to lower amphibolite facies - Includes fragmental volcanic rocks, mafic hypabyssal intrusions, graphitic argillite, and oxide iron-formation

Mille Lacs Group and related rocks of the Penokean fold-and-thrust belt; Metadiabase, undivided (Early Proterozoic)

Mille Lacs Group and related rocks of the Penokean fold-and-thrust belt; Metadiabase, undivided

North Carolina

Diabase (Jurassic)

Diabase - dikes, gray to black

Diabase (Jurassic)

Diabase - dikes, gray to black.

Diabase (Jurassic)

Diabase - dikes, gray to black.

Diabase (Jurassic)

Diabase - dikes, gray to black.

Diabase (Jurassic)

Diabase - dikes, gray to black.

Diabase (Jurassic)

Diabase - dikes, gray to black.

Newark Supergroup, Chatham Group; Diabase (Jurassic)

Diabase - dikes and sills, gray to black.

New Hampshire

Gabbro and diabase (Middle Ordovician)

Gabbro and diabase - Foliated to nonfoliated and coarse- to fine-grained; includes mafic dikes tentatively correlated with Chickwolnepy intrusions.

New Jersey

Diabase (Early Jurassic)

Diabase - Fine-grained to aphanitic dikes; medium- to coarsegrained, subophitic discordant stock-like intrusions of dark-greenish-gray to black diabase; and plugs of dark gray, concordant to discordant sheetlike, medium- to coarse-grained, quartz-rich to albite-rich granophyre (map unit Jg). The chilled margins of diabase masses are aphanitic to very fine grained. Diabase is dense, hard, and sparsely fractured. It is composed mostly of plagioclase (An50-70), clinopyroxene (mostly augite) and magnetite +/- ilmenite. Accessory minerals include apatite, quartz, alkali feldspar, hornblende, titantite, and zirocon. Olivine is rare. Within about 200 m (655 ft) above and 150 m (490 ft) below the large diabase sheets, red mudstones are typically metamorphosed into indurated, bluish-gray hornfels commonly with clots or crystals of tourmaline or cordierite, whereas argillitic siltstone is metamorphosed into brittle, black, very fine grained hornfels, Sheetlike intrusions are as much as 360 to 400 m (1,180-1,310 ft) thick. Dikes range in thickness from 3 to 15 m (10-50 ft) and several kilometers (miles) long. Thickness of the stocklike bodies is unknown.

Diabase (Jurassic)

Diabase - Concordant to discordant, predominantly sheet-like intrusions of medium- to fine-grained diabase and dikes of fine-grained diabase; dark-greenish-gray to black; subophitic texture. Dense, hard, sparsely fractured rock composed mostly of plagioclase (An50-70), clinopyroxene (mostly augite), and magnetite-ilmenite. Orthopyroxene (En75-80) is locally abundant in the lower part of the sheets. Accessory minerals include apatite, quartz, alkali feldspar, hornblende, sphene, zircon, and rare olivine. Diabase in the map area was derived primarily from high-titanium, quartz-tholeiite magma. Sedimentary rocks within about 300 m (984 ft) above and 200 m (656 ft) below major diabase sheets are thermally metamorphosed. Red mudstone is typically altered to indurated, bluish-gray hornfels with clots or crystals of tourmaline or cordierite. Gray argillitic siltstone is typically altered to brittle, black, very fine grained hornfels. Sills are 365 to 400 m (1,197-1,312 ft) thick. Dikes range in thickness from 3 to 10 m (10-33 ft) and are many kilometers long.

Diabase dikes (Late Proterozoic) (Late Proterozoic)

Diabase dikes (Late Proterozoic) (Ratcliffe, 1987; Puffer and others, 1991) - Medium- to dark greenish-gray, aphanitic to fine-grained dikes that are dense and hard. Contacts are typically chilled and sharp against enclosing country rock. Tholeiitic to alkalic composition; hypersthene a normative mineral. Composed principally of plagioclase (labradorite to andesine), augite, and ilmenite and (or) magnetite. Locallly occurring pyrite blebs are ubiquitous. Dikes range from a few cm to 20 m (an inch to 65 ft. wide) and as much as 5 km (3 mi) long. Occur throughout the Highlands, but intrude only Middle Proterozoic rocks.

Nevada

Conglomerate, limestone, meta-andesite, phyllite, and shale (Devonian to Mississippian)

CONGLOMERATE, LIMESTONE, META-ANDESITE, PHYLLITE, AND SHALE-Includes Grossman, Banner, Nelson, and Mountain City Formation. Northern Elko County

New York

Ladentown diabase and baslatic lava (Upper Triassic)

Ladentown diabase and basaltic lava

Lamprophyre, diabase, and albite-basalt dikes (Jurassic - Lower Cretaceous)

Lamprophyre, diabase, and albite-basalt dikes - not shown in Proterozoic terrane.

Palisade Diabase (Early Jurassic)

Palisade Diabase

Oregon

Intrusive gabbroic rocks (Oligocene and Eocene) (Eocene to Oligocene)

Sills and dikes of basalt, diabase, gabbro, and granophyric gabbro; locally albitized and zeolitized (Snavely and others, 1976a, b)

Mafic and intermediate intrusive rocks (Miocene) (Miocene)

Dikes, plugs, and sills of basalt, diabase, gabbro, and lesser andesite that fed many of the Miocene basalt and andesite flows in unit Tc. Some intrusions are rootless and are invasive into sedimentary sequences; includes related breccia and peperite. Includes Depoe Bay and Cape Foulweather dikes, sills, and plugs in the Coast Range (Snavely and others, 1976a, b; Wells 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

Pennsylvania

Diabase (Jurassic)

Diabase - Medium- to coarse-grained, quartz-normative tholeiite; composed of labradorite and various pyroxenes; occurs as dikes, sheets, and a few small flows. Includes the dark-gray York Haven Diabase (high titanium oxide) and the slightly younger Rossville Diabase (low titanium oxide). In chilled margins, the Rossville is distinguished from the York Haven by its lighter gray color and distinctive, sparse, centimeter-sized calcic-plagioclase phenocrysts.

Rhode Island

diabase (Triassic?)

diabase - Greenish-gray to gray-black, fine-grained, commonly porphyritic, generally massive dike rock composed of plagioclase, augite, opaque minerals, olivine pseudomorphed by serpentine and chlorite minerals, and sparse quartz.

Tennessee

Bakersville Gabbro (Precambrian)

Bakersville Gabbro - Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses.

Texas

Mundy Breccia and Castner Limestone, undivided (preCambrian-Proterozoic)

Mundy Breccia and Castner Limestone, undivided

Virginia

Diabase (Jurassic)

Diabase

Washington

Mesozoic-Tertiary volcanic rocks, undivided (Oligocene to Eocene)

Altered basalt, pillow lavas, and flow breccia of inner volcanic belt of Olympic Peninsula; includes minor interbedded red limy argillite and associated manganese ore.

Permian rocks (Permian-Triassic)

Conglomerate, graywacke, siltstone, argillite and interbedded fossiliferous limestone, greenstone, and minor angular conglomerate in northwestern Stevens and Ferry Counties. Impure quartzite, sandstone, graywacke, greenstone, ribbon chert, chert breccia, and limestone in Snohomish County and on San Juan Island. Lower Permian limestone on Black Mountain in northwestern Whatcom County. Middle Permian rocks in northeastern Washington.

Wyoming

Rhyolite to diabase porphyry dikes (Proterozoic | Mesoproterozoic)

RHYOLITE TO DIABASE PORPHYRY DIKES (1,400 Ma).