Geologic units containing felsic volcanic rock

Mineral Resources On-Line Spatial Data

Felsic volcanic rock

A light-colored, fine-grained or aphanitic extrusive or hypabyssal rock, with or without phenocrysts and composed chiefly of quartz and feldspar.

This category is also used for felsic volcanic rock (aphanitic).

California

Cretaceous marine rocks (in part nonmarine), unit 3 (Mescal Range) (Middle Jurassic to late Early Cretaceous): Undivided Cretaceous sandstone, shale, and conglomerate; minor nonmarine rocks in Peninsular Ranges
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.
Jurassic marine rocks, unit 3 (Mojave Desert) (Jurassic): Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks
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
Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains) (Jurassic): 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
Mesozoic volcanic rocks, unit 3 (Mojave Desert, Death Valley area, and Eastern Sierra Nevada) (Triassic 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
Mesozoic volcanic rocks, unit 4 (Peninsular Ranges) (Late Jurassic to Early 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
Mesozoic volcanic rocks, unit 5 (Northern Sierra Nevada and Eastern Klamath Mountains) (Late Permian(?) to Jurassic): 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
Miocene nonmarine rocks (Oligocene to Pleistocene): Sandstone, shale, conglomerate, and fanglomerate; in part Pliocene and Oligocene.
Paleozoic metavolcanic rocks, unit 1 (Eastern Klamath Mountains) (Devonian and Permian): Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks
Paleozoic metavolcanic rocks, unit 2 (Northeastern Sierra Nevada) (Devonian and Permian): Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks
Paleozoic metavolcanic rocks, unit 3 (Northwestern Sierra Nevada) (Permian to Jurassic): Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks
Paleozoic metavolcanic rocks, unit 5 (Mono Lake) (Triassic to Jurassic): Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks
Triassic marine rocks, unit 4 (West Walker River) (Triassic(?)): Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks
Undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided) (Paleozoic(?) to Mesozoic(?)): Undivided pre-Cenozoic metavolcanic rocks. Includes latite, dacite, tuff, and greenstone; commonly schistose.

Massachusetts

Felsic and mafic volcanic rocks (Proterozoic Z): Felsic and mafic volcanic rocks - Southwest of Boston Basin.

Maine

Cambrian Jim Pond Formation, felsic volcanic rocks (Cambrian): Cambrian Jim Pond Formation, felsic volcanic rocks Volcanic and metasedimentary rocks of the ophiolite sequence in central-western Maine are here named the Jim Pond Formation. It consists of a basal chlorite-albite-epidote-actinolite greenstone member with minor metagraywacke, 150 to 500 m thick. Northwest of the Squirtgun fault it is divided into lower and upper units by a metadacite member in the east, 0 to >500 m thick, and a metagraywacke member in the west. The metadacite member is closely associated with hematitic chert iron-formation members. Greenstone is thickly layered with pillowed and massive flows. Patches of altered amphibolite are in contact with the southeastern belt of tonalite of the Boil Mountain Complex. (ME075) Unit description from USGS GEOLEX website (ME078).
Cretaceous mafic to felsic volcanic rocks (Cretaceous): Cretaceous mafic to felsic volcanic rocks
Devonian Eastport Formation mafic to felsic volcanic member (Devonian): Devonian Eastport Formation mafic to felsic volcanic member
Devonian Hedgehog Formation (Devonian): Devonian Hedgehog Formation
Devonian - Silurian Castine Formation (Devonian - Silurian): Devonian - Silurian Castine Formation
Mesozoic mafic to felsic volcanic rocks (Mesozoic): Mesozoic mafic to felsic volcanic rocks
Ordovician Ammonoosuc Volcanics (Ordovician): Ordovician Ammonoosuc Volcanics
Ordovician - Cambrian Cookson Formation mafic to felsic volcanic rocks (Ordovician - Cambrian): Ordovician - Cambrian Cookson Formation mafic to felsic volcanic rocks
Ordovician - Cambrian unnamed volcanic rocks (Ordovician - Cambrian): Ordovician - Cambrian unnamed volcanic rocks
Ordovician Lobster Mountain volcanic complex (Ordovician): Ordovician Lobster Mountain volcanic complex
Ordovician Munsungun Lake Formation (Ordovician): Ordovician Munsungun Lake Formation
Ordovician - Precambrian Z Columbia Falls Formation (Ordovician - Precambrian Z): Ordovician - Precambrian Z Columbia Falls Formation
Ordovician Quimby formation (Ordovician): Ordovician Quimby formation
Ordovician tuff of the Depot Mountain sequence (Ordovician): Ordovician tuff of the Depot Mountain sequence
Ordovician unnamed felsic volcanic rocks (Ordovician): Ordovician unnamed felsic volcanic rocks
Ordovician unnamed volcanic and sedimentary rocks (Ordovician): Ordovician unnamed volcanic and sedimentary rocks
Ordovician unnamed volcanic rocks (Ordovician): Ordovician unnamed volcanic rocks
Silurian Dennys Formation mafic to felsic volcanic rock member (Silurian): Silurian Dennys Formation mafic to felsic volcanic rock member
Silurian Edmunds formation (Silurian): Silurian Edmunds formation
Silurian Leighton Formation mafic to felsic volcanic rock member (Silurian): Silurian Leighton Formation mafic to felsic volcanic rock member
Silurian - Ordovician Dunn Brook formation (Silurian - Ordovician): Silurian - Ordovician Dunn Brook formation
Silurian - Ordovician unnamed volcanic rocks (Silurian - Ordovician): Silurian - Ordovician unnamed volcanic rocks
Silurian - Ordovician Vassalboro Formation volcanic rocks (Silurian - Ordovician): Silurian - Ordovician Vassalboro Formation volcanic rocks
Silurian Quoddy Formation mafic to felsic volcanic rock member (Silurian): Silurian Quoddy Formation mafic to felsic volcanic rock member
Silurian unnamed volcanic and sedimentary rocks (Silurian): Silurian unnamed volcanic and sedimentary rocks
Undifferentiated mafic to felsic volcanic rocks (Devonian - Ordovician): Undifferentiated mafic to felsic volcanic rocks
Unnamed volcanic rocks (Devonian - Silurian): Unnamed volcanic rocks

Minnesota

Felsic to intermediate volcanic and volcaniclastic rocks, mica schist, phyllite, and granitoid rocks (Late Archean): Felsic to intermediate volcanic and volcaniclastic rocks, mica schist, phyllite, and granitoid rocks - Variably and cataclastically deformed. Unit forms aeromagnetic "quiet zone" and probably contains some rocks of Paleoproterozoic age.
Logan Intrusions (Middle Proterozoic): Logan Intrusions - Diabase, porphyritic diabase, gabbro, and related felsic sills and dikes.
Unnamed schistose, volcanic, and hypabyssal rocks of mafic composition and volcanic, volcaniclastic, and intrusive rocks of felsic composition (Early Proterozoic): Unnamed schistose, volcanic, and hypabyssal rocks of mafic composition and volcanic, volcaniclastic, and intrusive rocks of felsic composition - May be correlative with rocks of the Wisconsin magmatic terranes.

New Hampshire

Ironbound Mountain Formation, Felsic volcanic member (Lower Devonian): Ironbound Mountain Formation, Felsic volcanic member.
Perry Mountain Formation, Volcanic facies in Piermont allochthon (Lower? - Middle? Silurian): Perry Mountain Formation, Volcanic facies in Piermont allochthon.

New Mexico

andesites and basaltic andesites (Phanerozoic | Cenozoic | Tertiary): Upper Oligocene andesites and basaltic andesites (26-29 Ma); includes La Jara Peak Basaltic Andesite, Uvas Basalt, the basaltic andesite of Poverty Creek, and Squirrel Springs Andesite, the Razorback, Bear Springs Canyon, Salt Creek, Gila Flat, and Middle Mountain Formations, and the Alum Mountain Group; locally includes more silicic flows
felsic shallow-intrusive rocks (Phanerozoic | Cenozoic | Tertiary): Middle Tertiary felsic shallow-intrusive rocks; phonolites and trachytes of northeastern N.M.; includes the rhyolite of Ash Mountain
silicic flows and massess and associated pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary): Upper Oligocene silicic (or felsic) flows and masses and associated pyroclastic rocks; includes Taylor Creek, Fanney, and Rocky Canyon Rhyolites
silicic flows, domes, and associated pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary): Lower Oligocene silicic (or felsic) flows, domes, and associated pyroclastic rocks and intrusions; includes Mimbres Peak Formation
silicic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary): Lower Oligocene silicic pyroclastic rocks (ash-flow tuffs); includes Hell's Mesa, Kneeling Nun, lower part of Bell Top Formation, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump and Tadpole Ridge Tuffs, the tuffs of the Organ cauldron, Treasure Mountain Tuff (now known as Chiquito Peak Tuff), Bluff Creek Tuff, Oak Creek Tuff, tuff of Steins Mountain, tuff of Black Bill Canyon, tuff of Farr Ranch, Woodhaul Canyon, Gillespie and Box Canyon Tuffs, Cooney Tuff, and other volcanic and interbedded fluvial and pumiceous units; (31-36.5 Ma)
silicic to intermediate volcanic rocks (Phanerozoic | Cenozoic | Tertiary): Silicic to intermediate volcanic rocks; mainly quartz latite and rhyolite Neogene; may locally include flows interbedded with Santa Fe Group
Valles Rhyolite (Phanerozoic | Cenozoic | Quaternary): Valles Rhyolite; Jemez Mountains area only

Nevada

Continental sedimentary rocks (Late Cretaceous to Early Miocene): CONTINENTAL SEDIMENTARY ROCKS-Clark County
Horse Spring Formation (Late Oligocene to Middle Miocene): HORSE SPRING FORMATION-Tuffaceous sedimentary rocks, southern Nevada
Tuffaceous sedimentary rocks (Late Eocene to Late Miocene): TUFFACEOUS SEDIMENTARY ROCKS-Locally includes minor amounts of tuff

Oregon

Sedimentary rocks (Jurassic) (Late Jurassic ): Black and gray mudstone, shale, siltstone, graywacke, andesitic to dacitic water-laid tuff, porcelaneous tuff, and minor interlayers and lenses of limestone and fine-grained sediments metamorphosed to phyllite or slate. Locally includes some felsite, andesite and basalt flows, breccia, and agglomerate. Marine invertebrate fauna indicates age range from Early Jurassic (Hettangian) to early Late Jurassic (Oxfordian). In Klamath Mountains of southwest Oregon, includes Galice Formation (Wells and Peck, 1961) and unnamed, hornblende- and (or) pyroxene-bearing clastic rocks of Jurassic age (Smith and others, 1982)
Volcanic rocks (Jurassic) (Late Jurassic): Lava flows, flow breccia, and agglomerate dominantly of plagioclase, pyroxene, and hornblende porphyritic and aphyric andesite. Includes flow rocks that range in composition from basalt to rhyolite as well as some interlayered tuff and tuffaceous sedimentary rocks. Commonly metamorphosed to greenschist facies; locally foliated, schistose or gneissic. Includes the Rogue Formation and volcanic rocks commonly assigned to the Galice Formation (Wells and Walker, 1953; Wells and Peck, 1961). Considered to be accreted island-arc terrane

Rhode Island

Esmond Igneous Suite - felsic volcaniclastic rock (Late Proterozoic): Esmond Igneous Suite - felsic volcaniclastic rock - Light-colored to dark-gray ash flow tuff, ignimbrite, and felsite; may include some shallow-level intrusive rock. Phenocrysts of quartz, orthoclase, and plagioclase in a fine-grained matrix of quartz, feldspar, biotite, and opaque minerals. Some varieties contain fiamme and lithic fragments. Includes rock mapped formerly as Pennsylvanian felsite at Diamond Hill.

Texas

Bofecillos volcano volcanic rocks, including units 1-8 of Rawls Formation and lava flows in upper part of Fresno Formation (Phanerozoic | Cenozoic | Tertiary | Oligocene): Bofecillos volcano volcanic rocks, including units 1-8 of Rawls Formation and lava flows in upper part of Fresno Formation
Eocene intrusive rocks (Phanerozoic | Cenozoic | Tertiary | Eocene): Eocene intrusive rocks
Oligocene intrusive rocks (Phanerozoic | Cenozoic | Tertiary | Oligocene): Oligocene intrusive rocks
Quitman Mountains caldera volcanic rocks and volcanic rocks of sneed (Cox) Mountain and west of Victorio Peak (Phanerozoic | Cenozoic | Tertiary | Oligocene): Quitman Mountains caldera volcanic rocks and volcanic rocks of sneed (Cox) Mountain and west of Victoria Peak
Wiley Mountain caldera volcanic rocks (Phanerozoic | Cenozoic | Tertiary | Eocene): Wiley Mountain caldera volcanic rocks

Virginia

Chopawamsic Formation - Foliated felsite (Cambrian): Chopawamsic Formation - Foliated felsite
Felsic Volcanic and Volcaniclastic Rocks (Proterozoic Z): Felsic volcanic and volcaniclastic rocks.
Felsic Volcanic Rocks (Proterozoic Z): Felsic volcanic rocks.
Interlayered Mafic and Felsic Metavolcanic Rocks - Foliated felsite (Cambrian): Interlayered Mafic and Felsic Metavolcanic Rocks - Foliated felsite
Mount Rogers Formation - Porphyritic felsite (Proterozoic Z): Mount Rogers Formation - Porphyritic extrusive felsite
Robertson River Igneous Suite; Battle Mountain Alkali Feldspar Granite - felsite (Proterozoic Z): Robertson River Igneous Suite - Battle Mountain Alkali Feldspar Granite - felsite
Ta River Metamorphic Suite (Cambrian): Ta River Metamorphic Suite - Amphibolite gneiss

Wisconsin

Volcanic rocks, undivided (Early Proterozoic): Volcanic rocks, undivided - Mafic to felsic flows, pyroclastic rocks, impure quartzite, and conglomerate in Eau Claire River, Eau Claire and northern Clark Counties. Rhyolite has zircon ages of 1,858 +/- 5 Ma. Possibly correlative with Milladore Volcanic Complex.

Wyoming

Absaroka Volcanic Supergroup: Sunlight Group (Phanerozoic | Cenozoic | Tertiary | Eocene): ABSAROKA VOLCANIC SUPERGROUP: SUNLIGHT GROUP--including Trout Peak Trachyandesite, Wapiti Formation (andesitic volcaniclastic rocks), Crescent Hill Basalt, and Mount Wallace Formation (felsic and mafic volcaniclastic rocks).
Absaroka Volcanic Supergroup: Thoroughfare Creek and Sunlight Groups (Phanerozoic | Cenozoic | Tertiary | Eocene (44-49 Ma)): ABSAROKA VOLCANIC SUPERGROUP: THOROFARE CREEK GROUP (AGE 44 TO 49 Ma)--Light-colored volcaniclastic strata, andesite lava flows, and dark-brown breccia AND SUNLIGHT GROUP--including Trout Peak Trachyandesite, Wapiti Formation (andesitic volcaniclastic rocks), Crescent Hill Basalt, and Mount Wallace Formation (felsic and mafic volcaniclastic rocks).
Absaroka Volcanic Supergroup: Washburn Group (Phanerozoic | Cenozoic | Tertiary | Eocene): ABSAROKA VOLCANIC SUPERGROUP--WASHBURN GROUP: includes Sepulcher Formation (andesitic and dacitic volcaniclastic rocks), Lamar River Formation (andesitic lava and volcaniclastic rocks), and Cathedral Cliffs Formation (light-colored andesitic volcaniclastic rocks).
Caldwell Canyon volcanics (Phanerozoic | Cenozoic | Tertiary | Miocene Pliocene): CALDWELL CANYON VOLCANICS--Dacitic volcanic rocks; obsidian gravel at base.