Geologic units containing Granodiorite

A plutonic rock defined in the QAPF diagram as having Q between 20 and 60% and P/(A+P) between 65 and 90%

Alabama - Arizona - California - Colorado - Delaware - Idaho - Massachusetts - Maryland - Maine - Michigan - Minnesota - North Carolina - New Hampshire - New Jersey - New Mexico - Nevada - New York - Oregon - Pennsylvania - Rhode Island - South Carolina - Texas - Utah - Virginia - Vermont - Washington - Wisconsin - Wyoming


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 metamorphic rocks (Early Proterozoic)
Undivided metasedimentary, metavolcanic, and gneissic rocks. (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)
Early Tertiary to Late Cretaceous granitic rocks (Late Cretaceous to Early Tertiary)
Porphyritic to equigranular granite to diorite emplaced during the Laramide orogeny. Larger plutons are characteristically medium-grained, biotite +/- hornblende granodiorite to granite. Smaller, shallow-level intrusions are typically porphyritic. Most of the large copper deposits in Arizona are associated with porphyritic granitic rocks of this unit, and are thus named 'porphyry copper deposits'. (50-82 Ma)
Jurassic granitic rocks (Jurassic)
Granite to diorite, locally foliated and locally alkalic; includes Triassic(?) granitoids in the Trigo Mountains. This unit includes two dominant assemblages of igneous rocks. The Kitt Peak-Trigo Peaks superunit includes, from oldest to youngest: dark, foliated or gneissic diorite, medium-grained equigranular to porphyritic granodiorite, and small, irregular intrusions of light-colored, fine-grained granite. The Ko Vaya superunit, limited to south-central Arizona, includes texturally heterogeneous K-feldspar-rich granitic rocks. (150-180 Ma)
Middle Miocene to Oligocene granitic rocks (Oligocene to Middle Miocene)
Granite to diorite representing solidified magma chambers that were the likely source of overlying and nearby volcanic rocks of map unit Tv. The granitic rocks are typically equigranular and fine- to medium-grained. (14-26 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)
Middle Proterozoic granitic rocks (Middle Proterozoic)
Mostly porphyritic biotite granite with large microcline phenocrysts, with local fine-grained border phases and aplite. Associated pegmatite and quartz veins are rare. This unit forms large plutons, including the Oracle Granite, Ruin Granite, granite in the Pinnacle Peak - Carefree area northeast of Phoenix, and several bodies west of Prescott. (1400-1450 Ma)
Proterozoic granitic rocks (Proterozoic)
Undivided Early and Middle Proterozoic granitic rocks (units Xg and Yg). (1400-1800 Ma)
Tertiary to Early Proterozoic gneissic rocks (Early Proterozoic to Tertiary)
Gneissic rocks with complex histories, typically with well developed, light-colored granitoid layers and dark-colored biotite- and amphibole-rich layers. Protoliths are of Tertiary to Proterozoic age. This unit includes variably mylonitic gneisses in metamorphic core complexes that have been exhumed from middle crustal levels by large-displacement middle Tertiary normal faults, and gneiss exposed at scattered locations near the Colorado River in southwestern Arizona. These rocks are interpreted to record Proterozoic, Mesozoic, and Tertiary metamorphism and deformation. (15-1800 Ma)


Cenozoic (Tertiary) granitic rocks, unit 1 (Death Valley) (middle to late Miocene)
Cenozoic (Tertiary) granitic rocks--quartz monzonite, quartz latite, and minor monzonite, granodiorite, and granite; found in the Kingston, Panamint, Amargosa, and Greenwater Ranges in southeastern California.
Mesozoic granitic rocks, unit 1 (Salinian Block) (Early to Late Cretaceous)
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Mesozoic granitic rocks , unit 2 (Peninsular Ranges) (Middle Jurassic to Late Cretaceous)
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges) (Permian to Tertiary; most Mesozoic)
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Mesozoic granitic rocks, unit 4 (Klamath Mountains and Northern Sierra Nevada) (Devonian)
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Mesozoic granitic rocks, unit 5 (Klamath Mountains) (Jurassic to early Cretaceous)
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Paleozoic and Permo-Triassic granitic rocks, unit 1 (Eastern Klamath Mountains) (Permian)
Paleozoic and Permo-Triassic granitic rocks in the San Gabriel and Klamath Mountains
Paleozoic and Permo-Triassic granitic rocks unit 2 (San Gabriel Mountains) (Late Triassic)
Paleozoic and Permo-Triassic granitic rocks in the San Gabriel and Klamath Mountains
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


Granodiorite and muscovitic monzogranite; Oligocene Almo pluton; south-central Idaho, Albion Range metamorphic core complexIdaho (Oligocene)
Oligocene granodiorite to muscovite pegmatite, pegmatitic granite, and mylonitized granitic injection gneiss
Granodiorite, quartz monzonite, granite, alaskite, quartz monzodioirte, diorite; Tertiary to Cretaceous, intrusions, undivided; northern, west-central, and southwestern Idaho (Eocene to Cretaceous)
Eocene intrusions; Cretaceous plutons, intermediate, Cretaceous plutons, felsic; metamorphosed granitic intrusive rock
Intermediate intrusions; mostly Late Cretaceous dioritic to granodioritic plutons of the Idaho batholithic assemblage (Cretaceous)
Cretaceous plutons; intermediate; as granodiorite or diorite; probably includes unmapped older and younger crystalline bodies.
Intrusive rocks: mostly Late Cretaceous granodioritic to granitic plutons of the Idaho batholithic assemblage, but including some Eocene intrusions; northern Idaho and Atlanta batholith (Cretaceous to Eocene)
Cretaceous plutons; probably includes unmapped older and younger crystalline bodies.
Metamorphosed granodiorite, quartz monzonitek tonalite, quartz diorite; mostly Cretaceous orthogneiss and migmatite; northern and Atlanta batholith; margins of Bitterroot and Atlanta batholiths (Cretaceous)
Metamorphosed granitic intrusive rock; associated with pluton margins and stress areas.
Monzogranite, granodiorite, syenite, monzodiorite, monzonite, and diorite; Eocene phaneritic to porphyro-aphanitic intrusions (subunits are Teif and Teii); northern Idaho to central Idaho (Eocene)
Eocene intrusions including large granitic plutons and dike swarms of central Idaho
Peraluminous monzogranite, granodiorite, pegmatite, aplite, and migmatite; mostly Cretaceous intrusions of the Kaniksu batholithic assemblage, but with minor Eocene intrusions, undivided; northern Idaho (Cretaceous to Eocene)
Cretaceous plutons; felsic; as granite or quartz monzonite; probably includes unmapped older and younger crystalline bodies.
Quartz diorite, tonalite, granodiorite, orthogneiss, migmatite; Cretaceous to Jurassic quartz dioritic plutons; western Idaho, Blue Mountains island-arc complex (Early Cretaceous to Late Jurassic)
Lower Cretaceous to Upper Jurassic intrusions in west-central Idaho.
Quartz monzodiorite, monzogranite, granodiorite, monzonite, diorite; Eocene phaneritic to porphyro-aphanitic intrusions of the quartz monzodiorite suite; Challis magmatic belt (Eocene)
Eocene intrusions of intermediate (mafic to felsic) composition


Ayer Granite (Lower Silurian and Upper Ordovician?)
Ayer Granite - Devens-Long Pond facies. Equigranular to porphyritic gneissic biotite granite and granodiorite. Ayer Granite is divided into the Clinton facies and the Devens-Long Pond facies (Gore, 1976). In addition, there are some masses not assigned to either facies that intrude Berwick Formation west and northwest of Lawrence, and that intrude Paxton and Oakdale Formations south of Worcester and west of probable southern continuation of Wekepeke fault. Radiometric ages obtained for facies of Ayer pose problems in assigning ages to unfossiliferous sedimentary rocks they intrude. Clinton facies has a well-defined U-Pb zircon age of 433 +/-5 Ma (Zartman and Naylor, 1984) that authors cite as Early Silurian; Devens-Long Pond facies has a similar age. This age greatly compresses the time available for deposition, burial, deformation, and metamorphism of Berwick and Paxton if these units are truly Silurian. Some of the Ayer not assigned to a facies may have been more properly correlated with Early Devonian Chelmsford Granite and muscovite-biotite granite at Millstone Hill. Bodies south of Worcester may be more properly correlated with Canterbury Gneiss of CT, which lies on strike with Ayer and has Early Devonian age of 329 +/-9 Ma (Zartman and Naylor, 1984). Zartman and Naylor (1984) believe Ayer Granite has same age range as Newburyport Complex. It is quite possible, based on textural and mineralogical differences that the two facies should be separate units, representing different magmatic events (Wones and Goldsmith, 1991).
Dedham Granite (Proterozoic Z)
Dedham Granite - Gray granite to granodiorite more mafic than Zdgr north of Boston. Intrudes Zw, Zv. Extensive calc-alkaline plutons separated by Boston basin have long been mapped as Dedham. Those to the north of Boston and studied in this report, are referred to as Dedham North. Crystallization ages for the Dedham North suite (based on titanites and zircons) have been determined at 607+/-4 Ma, while ages for the Lynn are slightly younger at 596+/-3 Ma. Both are clearly part of the Late Proterozoic magmatic event. Dates on two samples from Sheffield Heights indicate that the diorite and granite are part of the Dedham North suite. The Dedham south and west of Boston has been dated at 630+/15 Ma (Zartman and Naylor, 1984). Dedham North Granite has a compositionally highly variable suite ranging from leucogranites to granodiorites, tonalites, and quartz diorite. The granites originated by partial melting of a sedimentary protolith, while the intermediate members show a mixing of granitic magma and mafic magma (Hepburn and others, 1993).
Diorite and gabbro (Proterozoic Z)
Diorite and gabbro - Complex of diorite and gabbro, subordinate metavolcanic rocks and intrusive granite and granodiorite.
Granodiorite (Precambrian to Paleozoic)
Granodiorite - Mostly nonfoliated.
Granodiorite (Devonian)
Granodiorite - Mostly nonfoliated, intrudes Dl.
Granodiorite of the Indian Head pluton (Precambrian to Paleozoic)
Granodiorite of the Indian Head pluton - Light-gray to pinkish-gray, fine- to medium-grained biotite granodiorite, and gray fine-grained hornblende-biotite tonalite. Intrudes OZm.
Grant Mills Granodiorite (Proterozoic Z)
Grant Mills Granodiorite - Medium- to coarse-grained porphyritic granodiorite. Gradational with Zegr.
Milford granite (Proterozoic Z)
Milford Granite - Mafic phase. Gray, seriate to sub-porphyritic granite to granodiorite, mafic minerals tend to be in clots; locally gneissic. Intrudes Zb. Occupies an area of about 100 sq km. Central mass near Milford is elliptical and is divided into and mapped as a light-colored phase and a dark-colored phase; dark-colored phase defines an irregular border for largest of light-colored plutons. Intrudes Blackstone Group rocks and Ponaganset Gneiss, but was deformed with them at some later unknown time. Isotopic age of 630 +/-15 Ma was determined using U-Pb methods on zircon by Zartman and Naylor (1984). Characterized by salmon-pink color, bluish quartz on weathered surfaces, and lineations defined by lenticular mosaics of quartz and oriented patches of biotite; texture contrast strongly with that of Dedham Granite (Wones and Goldsmith, 1991).
Newburyport Complex (Silurian or Ordovician)
Newburyport Complex - Gray, medium-grained tonalite and granodiorite. Newburyport Complex was divided into two facies, tonalitic granodiorite and granite, by Shride (1971). Tonalitic facies was originally termed Newburyport Quartz Diorite and included dioritic rocks north of Clinton-Newbury fault zone that are now called Sharpners Pond Diorite in Nashoba zone, and Topsfield Granodiorite in Milford-Dedham zone. These correlations are no longer tenable due to differences in age and composition. Therefore, Newburyport Complex is restricted to the two facies present in Newburyport area. Rocks formerly mapped as Newburyport Quartz Diorite and Salem Gabbro-Diorite, except for gabbros at Salem Neck, MA, are included in undifferentiated diorite and gabbro unit (Zdigb) on MA State Geologic Map (Zen and others, 1983), largely because they could not be mapped separately at 1:250,000 scale. Unit Zdigb also includes mafic dikes and sills that are probably younger or contemporaneous. Most of the dioritic rocks northeast of Boston previously assigned to Newburyport Quartz Diorite are now assigned to an undifferentiated diorite unit (Zdi) on MA State Geologic Map. Newburyport Complex forms a large mass near Newburyport and a small one to its west, both truncated by Clinton-Newbury fault. Tonalite and granodiorite facies occupies core of Newburyport Complex at Newburyport and is intruded to the north by granite facies; described as medium to dark gray in fresh rock, weathering to both green and red, fine to medium grained, and highly variable in mineralogy. A U-Pb zircon age of 455 +/-15 Ma was determined by Zartman and Naylor (1984) for the tonalite. Granite facies intrudes both the Kittery Formation and the tonalite and granodiorite facies and covers an area of about 45 sq km. Described as light gray to dark gray, buff weathering, and porphyritic. No radiometric ages available for granite facies, but it is conceivable that the two facies are different in age. [Papers presented as chapters in U.S. Geological Survey Professional Paper 1366 are intended as explanations and (or) revisions to MA State bedrock geologic map of Zen and others (1983) at scale of 1:250,000.] (Wones and Goldsmith, 1991).
Orange-pink, rusty-weathering, medium- to coarse-grained biotite granite to granodiorite (Silurian)
Orange-pink, rusty-weathering, medium- to coarse-grained biotite granite to granodiorite - Locally porphyritic. Intrudes Ssqd.
Topsfield Granodiorite (Proterozoic Z)
Topsfield Granodiorite - Gray to gray-green, porphyritic granodiorite containing blue quartz; usually cataclastically foliated and altered. Intrudes Zrdi, Zv. Topsfield Granite occupies area of 80 sq km between Middleton and Newbury, eastern MA. Occurs as part of Dedham batholith. Composition ranges from granite to tonalite. Intrudes unnamed diorite and gabbro unit, and unnamed mafic and felsic metavolcanic rocks. Bounded on northwest by faults bordering Newbury and Middleton basins and by northwest extensions of Bloody Bluff (and Mystic?) faults, and on southeast by a splay(?) of Bloody Bluff fault. Probably overlain by Silurian and Devonian Newbury Volcanic Complex (Dennen, 1975), but contact is now a fault. Although not radiometrically dated, considered to be Proterozoic Z in age because it is similar in mineralogy to Dedham Granite and it intrudes Proterozoic Z mafic complex (Wones and Goldsmith, 1991).
White to gray and black-spotted muscovite-biotite granite and granodiorite (Ordovician)
White to gray and black-spotted muscovite-biotite granite and granodiorite - Intruded near or along thrust faults. Intrudes CAZh and Proterozoic Y gneisses.
Williamsburg Granodiorite (Devonian)
Williamsburg Granodiorite - Equigranular biotite-muscovite granodiorite. Overprinting used in area where sufficient metasedimentary outcrop allows continuity in stratigraphic mapped. Intrudes Dg, Dw, Dgm, Dl, and De.


Devonian granite-granodiorite (hornblende accessory mineral) (Devonian)
Devonian granite-granodiorite (hornblende accessory mineral)
Devonian granite-quartz diorite (Devonian)
Devonian granite-quartz diorite: biotite granite, biotite granodiorite, biotite tonalite, biotite quartz syenite, biotite quartz monzodiorite, and biotite quartz diorite.
Devonian granite-quartz monzonite (hornblende accessory mineral) (Devonian)
Devonian granite-quartz monzonite (hornblende accessory mineral) Devonian hornblende-biotite granite to quartz monzonite- hornblende-biotite granite, hornblende-biotite granodiorite, hornblende-biotite tonalite, hornblende-biotite alkali feldspar quartz syenite, hornblende-biotite quartz syenite, and hornblende-biotite quartz monzonite.
Devonian granodiorite (Devonian)
Devonian granodiorite - biotite granodiorite
Devonian granodiorite (hornblende accessory mineral) (Devonian)
Devonian granodiorite (hornblende accessory mineral) - hornblende-biotite granodiorite
Devonian granodiorite (hornblende accessory mineral, porphyritic texture) (Devonian)
Devonian granodiorite (hornblende accessory mineral, porphyritic texture) - porphyritic hornblende-biotite granodiorite
Devonian granodiorite (muscovite accessory mineral) (Devonian)
Devonian granodiorite (muscovite accessory mineral) - muscovite-biotite granodiorite
Devonian granodiorite - quartz diorite (Devonian)
Devonian granodiorite - quartz diorite - Devonian biotite granodiorite to biotite quartz diorite - biotite granodiorite, biotite tonalite, biotite quartz syenite, biotite quartz monzodiorite, and biotite quartz diorite.
Devonian granodiorite - quartz monzodiorite (hornblende accessory mineral) (Devonian)
Devonian granodiorite - quartz monzodiorite (hornblende accessory mineral) - Devonian hornblende-biotite granodiorite to quartz monzodiorite - hornblende-biotite granodiorite, hornblende-biotite tonalite, hornblende-biotite quartz syenite, and hornblende-biotite quartz monzodiorite.
Devonian granodiorite - quartz syenite (porphyritic texture) (Devonian)
Devonian granodiorite - quartz syenite (porphyritic texture) - Devonian porphyritic biotite granodiorite to quartz syenite - porphyritic biotite granodiorite, porphyritic biotite tonalite, porphyritic alkali feldspar-biotite quartz syenite, and porphyritic biotite quartz syenite.
Ordovician granite, granodiorite ()
Ordovician biotite granite and granodiorite
Ordovician granodiorite (Ordovician)
Ordovician granodiorite - Ordovician biotite granodiorite

New Hampshire

Ayer Granodiorite (Early Silurian)
Ayer Granodiorite - Gneissic granite to tonalite, locally coarsely porphyritic and muscovitic, southeastern New Hampshire.
Bethlehem Granodiorite (Early Devonian)
Bethlehem Granodiorite (Bethlehem Gneiss of Billings, 1955) - Gray, strongly foliated biotite-muscovite granodiorite and associated tonalite and granite.
Biotite granodiorite (Late Ordovician)
Biotite granodiorite.
Biotite-hornblende granodiorite (Cretaceous)
Biotite-hornblende granodiorite.
Exeter Diorite (Early Devonian)
Exeter Diorite - Includes associated intrusive rocks of southeastern New Hampshire; pyroxene and pyroxene-hornblende diorite and gabbro, along with minor granodiorite and granite.
Granite, granodiorite, and tonalite (Late Ordovician)
Granite, granodiorite, and tonalite.
Granite, granodiorite, and trondhjemite (Late Ordovician)
Granite, granodiorite, and trondhjemite.
Granodiorite to tonalite (Late Ordovician)
Granodiorite to tonalite.
Hornblende granite to granodiorite (Late Ordovician)
Hornblende granite to granodiorite - Part of Lost Nation pluton of northwestern New Hampshire.
Hornblende granodiorite (Late Ordovician)
Hornblende granodiorite.
Hornblende granodiorite of Highlandcroft pluton (Late Ordovician)
Hornblende granodiorite of Highlandcroft pluton - Contains minor tonalite and diorite.
Kinsman Granodiorite (Early Devonian )
Kinsman Granodiorite - (Kinsman Quartz Monzonite of Billings, 1955) - Foliated granite, granodiorite, tonalite, and minor quartz diorite; large megacrysts of potassium feldspar characteristic; garnet locally abundant.
Newburyport Complex (early Late Silurian)
Newburyport Complex - Gray, medium-grained tonalite and granodiorite.
Porphyritic biotite granodiorite (Early - Late Devonian)
Porphyritic biotite granodiorite - Found in Mt. Cube quadrangle.
Porphyritic biotite granodiorite in northern Jefferson dome in Milan quadrangle (Late Ordovician )
Porphyritic biotite granodiorite in northern Jefferson dome in Milan quadrangle.
Spaulding Tonalite (Early Devonian)
Spaulding Tonalite (Spaulding Quartz Diorite of Fowler-Billings, 1949) - Weakly foliated to nonfoliated, spotted biotite quartz diorite, tonalite, granodiorite, and granite; garnet and muscovite may or may not be present.
Tonalite, diorite, granodiorite, and granite (Late Ordovician )
Tonalite, diorite, granodiorite, and granite - More mafic rocks have hornblende; part of Lost Nation pluton.
Winnipesaukee Tonalite (Early Devonian)
Winnipesaukee Tonalite (Winnipesaukee Quartz Diorite of Billings, 1955) - Gray, massive to foliated tonalite and minor quartz diorite, granodiorite, and granite. Probably coeval with Spaulding Tonalite.


Granite and diorite (Jurassic and Triassic) (Triassic and Jurassic)
Felsic to intermediate, granitoid intrusive rocks. Includes Jurassic muscovite granodiorite, hornblende gabbro, tonalite, and quartz diorite of southwest Oregon (Smith and others, 1982)
Hypabyssal intrusive rocks (Miocene and Miocene?) (Miocene)
Hypabyssal, medium-grained, hornblende diorite and quartz diorite in small stocks and large dikes; includes intrusions of medium- to fine-grained gabbro and plugs and small stocks of medium-grained, holocrystalline, olivine andesite. Also includes medium-grained, commonly porphyritic biotite quartz monzonite and leucocratic granodiorite. Many of these intrusive bodies are moderately to intensely propylitized, as are wallrocks they intrude; locally, along shears, the rocks also are sericitized. Potassium-argon ages on several of these shallow intrusions range from about 8 Ma to about 22 Ma (Wise, 1969; Bikerman, 1970; Sutter, 1978; Power and others, 1981a, b; Fiebelkorn and others, 1983)
Intrusive rocks (Cretaceous and Jurassic) (Jurassic to Cretaceous)
Hornblende and biotite quartz diorite (tonalite), trondhjemite, granodiorite, and small amounts of norite, in batholithic masses and large dikelike bodies. Includes Bald Mountain Tonalite and Anthony Lake Granodiorite of Taubeneck (1957), tonalite and trondhjemite of Wallowa batholith and Cornucopia stock (Taubeneck, 1964; Nolf, 1966), quartz diorite intrusion in the Snake River area (Morrison, 1963), quartz diorite and minor other intrusive rocks in the Caviness quadrangle (Wolff, 1965), quartz diorite northeast of John Day and southeast of Ironside Mountain (Thayer and Brown, 1964), quartz diorite in the Sparta and Durkee quadrangles (Prostka, 1962; 1967), and granodiorite and related rocks of the Pueblo Mountains (Roback and others, 1987). Rubidium-strontium and potassium-argon ages indicate an age range from about 94 to 160 Ma (Taubeneck, 1963; Thayer and Brown, 1964; Armstrong and others, 1976)

Rhode Island

Esmond Igneous Suite - granodiorite (Late Proterozoic)
Esmond Igneous Suite - granodiorite - Gray, tan, greenish, or pale-pink, medium- to coarse-grained, mainly porphyritic rock (phenocrysts of microcline). Contains microcline, perthite, plagioclase, quartz, and accessory biotite, epidote, zircon, allanite, monazite, apatite, sphene, and opaque minerals; secondary muscovite, chlorite, and calcite. Mainly massive. Includes rock mapped formerly as Grant Mills Granodiorite.
Narragansett Pier Plutonic Suite - granite (Permian)
Narragansett Pier Plutonic Suite - granite - Dark-pink to pale-gray, medium-grained equigranular granite, with lesser granodiorite and quartz monzonite. Composed of microcline, oligoclase, quartz, and accessory biotite, magnetite, ilmenite, apatite, sphene, zircon, monazite, apatite, and allanite; muscovite and garnet locally present; secondary chlorite and calcite. Mainly massive, but locally exhibits faint flow foliation. Cut locally by abundant pegmatite, aplite, and composite aplite-pegmatite of mineralogy similar to the host granite. Unit is a 5 km by 40 km batholith that underlies the southern coast of RI. Intrusion during the latter part of Alleghanian deformation of the Narragansett Basin is indicated by its Permian age, rapid cooling, and field relations. The age of the Narragansett Pier is well constrained by several factors. Brown and others (1978) report a Pennsylvanian fossil contained in an inclusion in the pluton. Radiometric ages of 276 Ma by Kocis and others (1978), 272+/-4 Ma by Hermes and others (1981), and 273+/-2 Ma by Zartman and Hermes (1987) are consistently Early Permian. Structural studies by Mosher (1983) and Reck and Mosther (1988) indicate that intrusion began during the third period of deformation in the Narragansett Basin. Argon release patterns (Dallmeyer, 1982) indicate that the granite and intruded sediments had cooled below argon retention temperatures of hornblende by the Late Permian and of biotite by the Early Triassic. Intruded by the Westerly Granite, which has been radiometrically dated at 276+/-7 Ma. The two granites are probably genetically related based on similarities in age, mineralogy, and geochemistry (Hozik, 1992).
Scituate Igneous Suite - granodiorite (Devonian)
Scituate Igneous Suite - granodiorite - Dark-gray to black, fine- to medium-grained, massive to faintly foliated rock, containing plagioclase, microcline, quartz, and accessory hornblende, biotite, sphene, apatite, and opaque minerals. Includes some rock previously mapped as Cowesett Granite.


Athelstane Quartz Monzonite (Early Proterozoic)
Athelstane Quartz Monzonite - Pink, coarse-grained granite to granodiorite containing nearly equal amounts of microcline microperthite, plagioclase, and quartz and 5-10 percent biotite and (or) hornblende. Mafic minerals are interstitial and give a clotty appearance. (1836 +/- 15 Ma)
Foliated tonalite (Early Proterozoic)
Foliated tonalite - Medium-gray, mottled, medium-grained, equigranular tonalite and granodiorite. Intrudes rocks of the Milladore Volcanic Complex.
Granitic rocks of 1760-Ma age group (Early Proterozoic)
Granitic rocks of 1760-Ma age group - In northern Wisconsin, granite to granodiorite of varied texture. In southern Wisconsin (not mapped separately), red to pink alkali-feldspar granophyric granite associated with rhyolites of both peraluminous and metaluminous affinities (unit Xr of Marshfield terrane).
Granodiorite-tonalite (Early Proterozoic)
Granodiorite-tonalite - Gray, medium-grained intrusive rocks, including intrusion breccias. Exposed in central Wisconsin. Zircon ages range from 1837 to 1847 Ma
Puritan Quartz Monzonite (Late Archean) (Late Archean)
Puritan Quartz Monzonite (Late Archean) - Pink to pinkish-gray, medium- to coarse-grained, equigranular to inequigranular granite to granodiorite in Puritan batholith south of Gogebic Range. Age 2710 +/- 140 Ma (Sims and others, 1977)
Wolf River batholith (1470 Ma); High Falls Granite (Middle Proterozoic)
Wolf River batholith (1470 Ma); High Falls Granite - Gray to pink, equigranular to porphyritic granite to granodiorite containing microcline microperthite, concentrically zoned plagioclase, quartz, biotite, and hornblende