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Geologic units containing Biotite gneiss

Biotite gneiss
A granitic gneiss in which the dominant mafic mineral is biotite
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Colorado - Connecticut - Georgia - Massachusetts - Maryland - North Carolina - Rhode Island - South Carolina - Virginia - Vermont - Washington

Colorado

Connecticut

Middletown Formation (Middle Ordovician)
Middletown Formation ( = Ammonoosuc Volcanics of New Hampshire) - Heterogeneously interlayered dark- to light-gray, generally medium grained gneiss and granofels, ranging from quartz-biotite gneiss through felsic amphibole gneiss to amphibolite and characteristically containing anthophyllite or cummingtonite with or without hornblende. Also layers of calc-silicate rock and of biotite gneiss with quartz-sillimanite nodules.
Shelton Member [of Trap Falls Formation] (Middle or Lower Ordovician)
Shelton (white gneiss) Member [of Trap Falls Formation] - White, light-gray, or buff, fine- to medium-grained, generally well foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and garnet (in tiny almost ubiquitous grains), also commonly minor biotite; generally interlayered with mica schist, biotite gneiss, and calc-silicate rock. Thought to be metavolcanic equivalent of unit Og. Shelton Member of Trap Falls Formation (Rodgers, 1985) is here referred to as Shelton muscovite granite. On the basis of field and laboratory studies, Ansonia, Beardsley, Pumpkin Ground, and Shelton gneisses, previously considered stratigraphic units, are reinterpreted as plutonic. Shelton is a foliated, medium-grained, garnet-bearing muscovite leucogranite with a conspicuous white color and abundant garnets. Age of crystallization determined from U-Pb garnet analysis is 380+/-3 Ma (Middle Devonian). Southeast margin of the Shelton is in contact with the Trap Falls Formation (Sevigny and Hanson, 1993).
Upper member [of Middletown Formation] (Middle Ordovician)
Upper member [of Middletown Formation] - Light-gray, generally rusty weathering, well-layered gneiss and granofels, composed of oligoclase, quartz, biotite, and amphibole (cummingtonite, anthophyllite, gedrite, or hornblende, or several of these), also garnet and chlorite. Many layers of amphibolite and biotite gneiss throughout.

Georgia

Massachusetts

Biotite gneiss near New Bedford (Proterozoic Z)
Biotite gneiss near New Bedford - Layered feldspathic gneiss.
Collinsville Formation (Middle Ordovician or older)
Collinsville Formation - Homogeneous garnetiferous biotite gneiss containing chlorite as clots and halos around garnet.
Fourmile Gneiss (Ordovician, Cambrian, or Proterozoic Z)
Fourmile Gneiss - Layered to massive biotite-feldspar gneiss and amphibolite.
Intimately interfolded Littleton and Partridge Formations (Lower Devonian and Middle Ordovician)
Intimately interfolded Littleton and Partridge Formations - In areas of poor exposure and incomplete mapping.
Marlboro Formation (Ordovician, Cambrian, or Proterozoic Z)
Marlboro Formation - Thinly layered amphibolite, biotite schist and gneiss, minor calc-silicate granofels and felsic granofels.
Monson Gneiss (Ordovician, Cambrian, or Proterozoic Z)
Monson Gneiss - Layered to massive biotite-plagioclase gneiss, amphibolite, microcline augen gneiss.
Nashoba Formation (Ordovician or Proterozoic Z)
Nashoba Formation - Sillimanite schist and gneiss, partly sulfidic, amphibolite, biotite gneiss, calc-silicate gneiss and marble. Nashoba Formation occurs in Nashoba zone of eastern MA. Consists of interlayered sillimanite-bearing, partly sulfidic schist and gneiss, calc-silicate gneiss, and subordinate quartzite and marble. Protoliths were probably volcanogenic sediments interlayered with limy marine sediments. Bell and Alvord (1976) divided Nashoba into 10 members on basis of lithology. Amphibolite is most abundant near presumed base, namely in Boxford Member. Skehan and Abu-Moustafa (1976) divided Nashoba into 30 members based on section in Wachusett-Marlborough tunnel. Although Bell and Alvord's and Skehan and Moustafa's sections contain similar lithologies, Bell and Alvord's is much thicker, and Boxford Member is not readily identified in Skehan and Abu-Moustafa's. Subdivision of Nashoba is conjectural south of Marlborough and Shrewsbury. On MA State bedrock map (Zen and others, 1983) only Boxford Member is separated out from the rest of the Nashoba because this unit was the only member clearly recognized in several area. A definite sequence of members probably does not exist anywhere in the Nashoba because of lenticularity of assemblages and repeated rock types, both of which could be accounted for by either sedimentary or tectonic processes. Although Castle (1965) considered Fish Brook to be either a premetamorphic intrusive rock or a core gneiss of intrusive or sedimentary ancestry, Bell and Alvord (1976) considered it to be volcanic or volcaniclastic in origin. Zircons in Fish Brook are certainly volcanic in origin and yield a date of 730 +/-26 Ma (Olszewski, 1980). If the rock were a core gneiss, that date would apply only to the Fish Brook and not to surrounding rocks; but, Bell and Alvord (1976) believe Fish Brook to be part of the Marlboro Formation-Nashoba Formation sequence and therefore the date does apply to the sequence. In addition, a 1500 Ma date for Shawsheen Gneiss [reference not given] helps bracket age of Marlboro-Nashoba sequence. An upper limit for the sequence was established from the 430 +/-5 Ma age of intruding Sharpers Pond Diorite and 450 +/-23 Ma age of the intruding Andover Granite (Zartman and Naylor, 1984). Although age on MA State bedrock map is shown as Proterozoic Z or Ordovician (due to uncertainty regarding actual rocks sampled by Olszewski and a strong belief that rocks of Nashoba zone correlated with Ordovician rocks to the west), author now feels that rocks of Nashoba zone (except for Tadmuck Brook Schist) are all Proterozoic, but that they are unlike the Proterozoic rocks of neighboring Milford-Dedham zone. [no formal age change made in this report] (Goldsmith, 1991).
Nashoba Formation (Ordovician or Proterozoic Z)
Nashoba Formation - Boxford Member - Thin bedded to massive amphibolite, minor biotite gneiss. Of the 10 members of the Nashoba Formation defined by Bell and Alvord (1976), only amphibolitic Boxford Member, at the presumed base of Nashoba is separated out on MA State bedrock map of Zen and others (1983) because it is the only member clearly identified in several locations. Although age on MA State bedrock map is shown as Proterozoic Z or Ordovician (due to uncertainty regarding actual rocks sampled by Olszewski and a strong belief that rocks of Nashoba zone correlated with Ordovician rocks to the west), author now feels that rocks of Nashoba zone (except for Tadmuck Brook Schist) are all Proterozoic, but that they are unlike the Proterozoic rocks of neighboring Milford-Dedham zone. [No formal age change is made in this report.] (Goldsmith, 1991).
Partridge Formation (Middle Ordovician)
Partridge Formation (includes Brimfield Schist of Emerson, 1917) - Biotite gneiss.
Partridge Formation (Middle Ordovician)
Partridge Formation (includes Brimfield Schist of Emerson, 1917) - Biotite gneiss of volcanic derivation, minor amphibolite and sulfidic schist.
Poplar Mountain Gneiss (Proterozoic Z)
Poplar Mountain Gneiss (Probably correlates with Mount Mineral Formation but is more feldspathic) - Biotite gneiss where mapped separately.
Poplar Mountain Gneiss (Proterozoic Z)
Poplar Mountain Gneiss (Probably correlates with Mount Mineral Formation but is more feldspathic) - Dark biotite gneiss containing white microcline megacrysts and beds of quartzite.
Quinebaug Formation (Ordovician, Cambrian, or Proterozoic Z)
Quinebaug Gneiss - Amphibolite, biotite and hornblende gneiss, felsic gneiss, and calc-silicate gneiss.
Tatnic Hill Formation (Ordovician or Proterozoic Z)
Tatnic Hill Formation - Sulfidic sillimanite schist, sillimanite schist and gneiss, biotite gneiss; minor amphibolite, calc-silicate gneiss and marble.
Undifferentiated Poplar Mountain and Dry Hill Gneisses (Proterozoic Z)
Undifferentiated Poplar Mountain and Dry Hill Gneisses .

Maryland

North Carolina

Amphibolite and Biotite Gneiss (Cambrian/Late Proterozoic)
Amphibolite and Biotite Gneiss - interlayered; minor layers and lenses of hornblende gneiss, metagabbro, mica schist, and granitic rock.
Ashe Metamorphic Suite and Tallulah Falls Formation; Biotite gneiss (Late Proterozoic)
Biotite gneiss - interlayered with biotite-garnet gneiss, biotite-muscovite schist, garnet-mica schist, and amphibolite.
Ashe Metamorphic Suite and Tallulah Falls Formation; Metagraywacke (Late Proterozoic)
Metagraywacke - foliated to massive, locally conglomeratic; interlayered and gradational with mica schist, muscovite-biotite gneiss, and rare graphitic schist.
Biotite Gneiss and Schist (Cambrian/Late Proterozoic)
Biotite Gneiss and Schist - inequigranular and megacrystic; abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.
Biotite Gneiss and Schist (Cambrian/Late Proterozoic)
Biotite Gneiss and Schist - inequigranular and megacrystic; in places contains garnet; interlayered and gradational with mica schist and amphibolite; includes small masses of granitic rock.
Biotite Gneiss and Schist (Cambrian/Late Proterozoic)
Biotite Gneiss and Schist - inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.
Biotite Gneiss and Schist (Cambrian/Late Proterozoic)
Biotite Gneiss and Schist - (Located in the Lilesville granite aureole) inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.
Coweeta Group; Biotite Gneiss (Middle/Late Proterozoic)
Biotite Gneiss - migmatitic; interlayered and gradational with biotite-garnet gneiss and amphibolite; locally abundant quartz and alumino-silicates. Stratigraphic position uncertain.
Felsic Mica Gneiss (Cambrian/Late Proterozoic)
Felsic Mica Gneiss - interlayered with biotite and hornblende gneiss and schist.
Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic)
Fine-grained Biotite Gneiss - massive to strongly foliated; minor layers of amphibolite and muscovite schist.
Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic)
Fine-grained Biotite Gneiss - strongly foliated; minor layers of amphibolite and muscovite schist.
Fine-grained Biotite Gneiss (Cambrian/Late Proterozoic)
Fine-grained Biotite Gneiss - strongly foliated; minor layers of amphibolite and muscovite schist.
Inequigranular Biotite Gneiss (Cambrian/Late Proterozoic)
Inequigranular Biotite Gneiss - weakly foliated to massive, contains plagioclase megacrysts and, rarely, larger megacrysts of quartz and feldspar.
Injected Gneiss (Cambrian/Late Proterozoic)
Injected Gneiss - biotite gneiss and schist intruded by numerous sills and dikes of granite, pegmatite, and aplite; minor hornblende gneiss.
Megacrystic Biotite Gneiss (Cambrian/Late Proterozoic)
Megacrystic Biotite Gneiss - poorly layered to massive; megacrysts of microcline and quartz; local mica schist, amphibolite, and biotite gneiss
Mica Schist (Cambrian/Late Proterozoic)
Mica Schist - contains garnet, staurolite, kyanite, or sillimanite; includes lenses and layers of quartz schist, micaceous quartzite, biotite gneiss, amphibolite, and phyllite.
Mica Schist (Cambrian/Late Proterozoic)
Mica Schist - Garnet, staurolite, kyanite, or sillimanite occur locally; lenses and layers of quartz schist, micaceous quartzite, calc-silicate rock, biotite gneiss, amphibolite, and phyllite.
Migmatitic Granitic Gneiss (Ordovician/Cambrian)
Migmatitic Granitic Gneiss - foliated to massive, granitic to quartz dioritic; biotite gneiss and amphibolite common.
Phyllite and Schist (Cambrian/Late Proterozoic)
Phyllite and Schist - includes phyllonite and interlayered biotite gneiss.

Rhode Island

South Carolina

Virginia

Vermont

Ammonoosuc Volcanics (Ordovician)
Ammonoosuc Volcanics - Fine-grained chloritic and biotitic gneiss and greenstone in areas north of Bellows Falls; biotite gneiss and amphibolite south of Bellows Falls. (Southeastern Vermont).
Cavendish Formation, Bull Hill Gneiss (Cambrian?)
Cavendish Formation, Bull Hill Gneiss - Quartz-plagioclase-microcline-biotite gneiss characterized in many areas by augen of microcline as much as 2 inches long; fine- to medium-grained quartz-plagioclase-biotite or biotite-muscovite gneiss. Cardinal Brook Intrusive Suite is here named in the cores of the Chester-Athens dome and Rayponda-Sadawga dome in the eastern and southern Green Mountains, VT, and the northern part of the Berkshire massif, MA. Includes the Stamford Granite of Hitchcock (1861), the Somerset Reservoir Granite (new name), the Harriman Reservoir Granite (new name), and the Bull Hill Gneiss of Richardson (1929-30). Because of uncertainty regarding the geologic position of the Bull Hill, it is restricted to the Chester and Athens domes and the original definition of Richardson is retained. Rocks mapped as Bull Hill in the Jamaica area are assigned to the Somerset Reservoir Granite and those in the Rayponda-Sadawga dome are assigned to the Harriman Reservoir Granite. Structural position is unclear. U-Pb zircon age is Middle Proterozoic (960-950 Ma). . [GNU Staff note--This report mistakenly uses the phrasing "Bull Hill Gneiss of Richardson (1929-30)" which would normally imply that the unit has not been adopted for use by the U.S. Geological Survey (USGS) because of inadequate definition by Richardson or successive workers in the area. However, in this report, the phrasing simply means that Richardson's definition and use are preferred over the usage on the VT State Geologic Map of Doll and others (1961) and that the unit meets the requirements for formal usage by the USGS.] (Ratcliffe, 1991).
Missisquoi Formation, Barnard Volcanic Member (Ordovician)
Missisquoi Formation, Barnard Volcanic Member - Fine- to medium-grained biotite gneiss, hornblende gneiss, and amphibolite.
Missisquoi Formation, Whetstone Hill Member (Ordovician)
Missisquoi Formation, Whetstone Hill Member - Carbonaceous black to light gray phyllite and schist containing porphyroblasts of biotite and garnet; beds of gray micaceous quartzite, fine-grained biotite gneiss and amphibolite.
Mount Holly Complex (Precambrian)
Mount Holly Complex - Mainly fine- to medium-grained biotitic gneiss, locally muscovitic, and in western areas chloritic; massive and granitoid in some localities, fine-grained or schistose and compositionally layered in others; also abundant amphibolite and hornblende gneiss, and minor beds of mica schist, quartzite, and calc-silicate granulite; includes numerous small bodies of pegmatite and gneissoid granitic rock. Includes a suite of metatonalites, metatrondhjemite, and possible metadacite with chemical characteristics of a calc-alkaline volcanic-plutonic suite. Mappable units are College Hill Granite Gneiss and 10 unnamed subdivisions including several varieties of gneiss as well as schist, amphibolite, and quartzite. U-Pb zircon upper intercept ages of 1.35 to 1.30 Ga have been determined and interpreted as age of crystallization (Ratcliffe and others, unpub. data). Cores of abraded zircon obtained from College Hill Granite Gneiss of Mount Holly Complex have a U-Pb upper intercept age of 1245 +/-14 Ma, interpreted as crystallization age for that granite (Aleinikoff and others, 1990). Dust collected by abrasion of zircons, thought to represent migmatitic overgrowth, has a Pb-Pb age of approx 1100 Ma. These data suggest that College Hill Granite Gneiss was intruded at 1245 Ma and migmatized at 1100 Ma. On north and south slopes of College Hill, College Hill Granite Gneiss grades outward into migmatitic biotite granite gneiss of Mount Holly Complex. College Hill is discordant to contacts and folds in paragneiss units of Mount Holly Complex. Dacitic metavolcanics are found within Washington Gneiss of Berkshire massif of MA (Ratcliffe and Zartman, 1968). They are interbedded with thick succession of rusty-weathering, quartz-pebble gneisses, calc-silicate rocks and garnet-sillimanite schist similar to, but much thicker than, the rusty-weathering gneiss and schist unit of Mount Holly Complex exposed in Green Mountains of VT. It is possible that the metadacitic and metatrondhjemitic suite of VT constitutes a lateral, south-to-north facies of the Washington Gneiss of MA (Ratcliffe, in press).
Mount Holly Complex, quartzite and schist (Precambrian)
Mount Holly Complex, quartzite and schist - Quartzite, locally in massive beds as much as 30 ft thick, micaceous quartzite, and quartz-mica schist that commonly contains garnet or pseudomorphs (largely chlorite) after garnet; schists are locally rusty weathered and contain conspicuous flakes of graphite; also includes amphibolite and minor hornblende gneiss, biotite gneiss, and pegmatite.
Orfordville Formation, Post Pond Volcanics (Ordovician)
Orfordville Formation, Post Pond Volcanics - Greenstone, green chloritic schist interbedded with schistose felsite, quartz-feldspar-sericite schist; fine-grained chloritic, biotitic gneiss, all west of Ammonoosuc fault; mainly amphibolite east of the Ammonoosuc fault.
Partridge Formation, Volcanics (Ordovician)
Partridge Formation, Volcanics - fine-grained biotite gneiss and amphibolite. (Southeastern Vermont).
Stamford Gneiss (Precambrian)
Stamford Gneiss - Granitic biotite gneiss with megacrysts of microcline. A dike-like feature of Stamford Granite, found near eastern margin of Green Mountain massif near locality 1 on this map (represented by sample 172), was incorrectly referred to as a probable Late Proterozoic diabase dike by Ratcliffe on his section of the Bedrock Map of Massachusetts (Zen and others, 1983). U-Pb zircon dates from Karabinos and Aleinikoff (1988, 1990) yield an age of 959+/-4 Ma. Unpublished data from Harding and Mukasa yield a U-Pb zircon date of about 950 Ma (Ratcliffe and others, 1993).

Washington