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Geologic units containing syenite

Arkansas

Igneous rocks (Phanerozoic | Mesozoic | Cretaceous)

Includes undifferentiated altered sedimentary rocks of Paleozoic age at Granite Mountain, Pulaski County, and Mufreesboro, Pike County. Acid to intermediate - Nepheline syenite complexes at Magnet Cove and Potash Sulfur Springs, stocks at Granite Mtn., explosion breccias, and dikes and sills (principally trachyte,tinguaite, phonolite, some ranging from syenite to diabase.) Basic to ultrabasic - Lamproite pipes (Murfreesboro, Pike County) and dikes and sills (principally lamprophyres of fourchite, ouachitite, and monchiquite)

Arizona

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 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

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

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.

Precambrian rocks, undivided, unit 2 (Mojave Desert and Transverse Ranges) (Early Proterozoic to Miocene)

Conglomerate, shale, sandstone, limestone, dolomite, marble, gneiss, hornfels, and quartzite; may be Paleozoic in part

Connecticut

Syenite (Permian)

Syenite - Medium-gray, massive syenite, composed of microcline, amphibole (arfvedsonite), and biotite with accessory apatite and sphene.

Georgia

Syenite (Precambrian-Paleozoic)

Syenite

Idaho

Syenite, granite, quartz syenite, and gabbro; Ordovician to Cambrian plutons; east-central Idaho (Ordovician to Cambrian)

Intrusive rock of eastern Idaho; appears older than Cretaceous; possibly Precambrian

Syenite, monzonite, quartz syenite; Late to Early Cretaceous syenitic intrusions; northern Idaho (Cretaceous)

Cretaceous syenitic to monzonitic intrusions

Syenite, quartz syenite, monzodiorite, quartz diorite, gabbro, pyroxenite, and hornblendite; Late Proterozoic plutons; east-central Idaho (Late Proterozoic)

Younger or Intermediate Precambrian age intrusive rock undifferentiated.

Massachusetts

Cape Ann Complex (Lower Silurian or Upper Ordovician)

Cape Ann Complex - Beverly Syenite - Quartz-poor facies. Beverly Syenite is part of Cape Ann Complex. Forms subordinate elongate masses within main mass of Cape Ann; dikes of syenite also intrude gabbro at Salem Neck, as well as elsewhere in the Salem area, suggesting that Beverly is, at least in part, a differentiate. Described as cream colored, medium to coarse grained, and rich in alkali feldspar. Age is Late Ordovician and Early Silurian (Wones and Goldsmith, 1991).

Sharon Syenite (Proterozoic Z)

Sharon Syenite - Gray to dark-gray syenite containing microperthite, oligoclase and clinopyroxene, mixed with ferro-gabbro. Proterozoic Z Sharon Syenite forms long narrow mass along southeast side of Norfolk basin. Consists of gray to dark-gray syenite and minor ferrogabbro. Both rock types are intruded by Proterozoic Z Dedham Granite, but relationship to other Proterozoic Z gabbros is unknown. Near Sharon, unit is intruded by unnamed Proterozoic Z diorite (Wones and Goldsmith, 1991).

Maine

Carboniferous syenite (Carboniferous)

Carboniferous biotite syenite undivided

Devonian foid-bearing syenite (hornblende accessory mineral) (Devonian)

Devonian foid-bearing syenite (hornblende accessory mineral); hornblende-bitoite foid-bearing syenite

Devonian gabbro/diorite/ultramafic rocks - quartz diorite (Devonian)

Devonian gabbro/diorite/ultramafic rocks - quartz diorite - Devonian gabbro/diorite/ultramafic rocks to biotite quartz diorite - gabbro, diorite, ultramafic rocks, biotite monzodiorite, biotite syenite, and biotite quartz diorite.

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 - 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.

Devonian syenite (Devonian)

Devonian syenite - Devonian biotite syenite undivided

Devonian syenite, monzodiorite (porphyritic texture) (Devonian)

Devonian syenite, monzodiorite (porphyritic texture) - Devonian pyroxene-hornblende-biotite syenite and monzodiorite

Devonian syenite (pyroxene plus hornblende accessory mineral) (Devonian)

Devonian syenite (pyroxene plus hornblende accessory mineral) - Devonian pyroxene-hornblende-biotite syenite undivided

Mesozoic foid-bearing syenite (Mesozoic)

Mesozoic foid-bearing syenite - Mesozoic biotite foid-bearing syenite

Mesozoic syenite (Mesozoic)

Mesozoic syenite - Mesozoic biotite syenite undivided

Michigan

Granitic rocks (Early Proterozoic)

Granitic rocks - Gray to pinkish-gray, mottled, medium-grained syenite, granite, and granodiorite. Moderately strong propylitic alteration and weak cataclasis. Forms small bodies south of Crystal Falls, MI (James and others, 1968). A body near Tobin Location has a U-Pb concordia intercept age of 1840 +/-5 Ma (Z.E. Peterman, written communication, 1988). Includes porphyritic red granite that intrudes Lake Archean Dickinson Group - Red mylonitic gneissic granite (about 1970 Ma).

Minnesota

Multiphase intrusions of hornblende-pyroxene-bearing and biotite-bearing monzonite, monzodiorite, diorite, syenite, and granodiorite (Late Archean)

Multiphase intrusions of hornblende-pyroxene-bearing and biotite-bearing monzonite, monzodiorite, diorite, syenite, and granodiorite - Typically postdates regional metamorphism and deformation associated with the Algoman orogen.

North Carolina

Syenite of Concord Plutonic Suite (Devonian/Silurian)

Syenite of Concord Plutonic Suite (404 my) - includes the Concord ring dike.

New Hampshire

Hornblende-biotite quartz syenite to syenite (Late Ordovician)

Hornblende-biotite quartz syenite to syenite.

Hornblende (or alkalic amphibole) syenite (Jurassic)

Hornblende (or alkalic amphibole) syenite.

Nepheline-sodalite-hastingsite syenite (Jurassic)

Nepheline-sodalite-hastingsite syenite - Found at Red Hill in Mt. Chocorua quadrangle (see index accompanying "Sources of Map Data").

Porphyritic syenite (Jurassic)

Porphyritic syenite - Hastingsite or hornblende and (or) hedenbergite are present.

New Jersey

Hornblende Granite (Middle Proterozoic)

Hornblende Granite - Pinkish-gray- to medium-buff-weathering, pinkish-white or light-pinkish-gray, medium- to coarse-grained, gneissoid to indistinctly foliated granite and sparse granite gneiss composed principally of microcline microperthite, quartz, oligoclase, and hornblende. Some phases are quartz syenite or quartz monzonite. Includes small bodies of pegmatite and amphibolite not shown on map. U-Pb age approximately 1,090 Ma (Drake and others, 1991b).

Hornblende Syenite (Middle Proterozoic)

Hornblende Syenite - Tan- to buff-weathering, pinkish-gray or greenish-gray, medium- to coarse-grained, gneissoid syenite and lesser amounts of quartz syenite containing microcline microperthite, oligoclase, quartz, and hornblende. Some phases are monzonite or monzodiorite.

Lamprophyre, tinguaite (phonolite with acicular acmite crystals), phonolite, bostonite (trachyte), and malignite (mafic nepheline syenite), undifferentiated (Silurian - Ordovician)

Lamprophyre, tinguaite (phonolite with acicular acmite crystals), phonolite, bostonite (trachyte), and malignite (mafic nepheline syenite), undifferentiated - Light-medium- to medium-dark-gray, aphanitic to fine-grained, alkalic to calcic-alkalic dikes and sills. Unit intrudes rocks from the Middle Proterozoic to the High Point Member of the Martinsburg Formation, but does not intrude the Shawangunk Formation. K-Ar data of 422 +/- 14 Ma from biotite phenocrysts in a minette (lamprophyre with biotite phenocrysts) dike (Charles Milton, written communication, 1972) suggests an Early Silurian age for some of these rocks.

Ouachitite breccia (Early Silurian? and Late Ordovician)

Ouachitite breccia - Medium-dark-gray, fine-grained ouachitite (olivine-free biotite lamprophyre) containing pebble- to cobble-size xenoliths of Middle Proterozoic rock, dolomite of the Kittatinny Supergroup(?), the Martinsburg Formation, and autoliths of potassic syenite, lamprophyre, and carbonatite. Found in numerous diatremes in the Beemerville area; largest of at Rutan Hill.

Pyroxene Syenite (Middle Proterozoic)

Pyroxene Syenite - Gray- to buff- or tan-weathering, greenish-gray, medium- to coarse-grained, massive, indistinctly foliated syenite composed of mesoperthite to microantiperthite, oligoclase and clinopyroxene. Contains sparse amounts of quartz, titanite, magnetite, and trace amounts of pyrite.

South Carolina

Syenite- Buffalo pluton (Devonian to Silurian)

Syenite- Buffalo pluton

Syenite- Mount Carmel pluton (Devonian to Silurian)

Syenite- Mount Carmel pluton

Utah

Tertiary intrusive rocks in southeastern Utah (Oligocene)

Virginia

Striped Rock Granite (Proterozoic Z)

Striped Rock Granite - Biotite granite and syenite.

Valley and Ridge Igneous Intrusions; Peridotite (Jurassic-Tertiary)

Valley and Ridge Igneous Intrusions; p: Peridotite - Dikes in Augusta and Rockingham Counties: nepheline syenite, teschenite-syenite, and teschenite-picrite. Igneous bodies in Highland County: andesite and basalt.

Vermont

Syenite (Permian-Triassic)

Syenite - Hornblende, biotite, quartz and augite syenites.

Washington

Mesozoic alkali intrusive rocks (Jurassic-Cretaceous)

Syenite in Nighthawk and Buckhorn Mountain areas of Okanogan County; malignite on Kruger Mountain near Nighthawk.

Mesozoic granitic rocks, undivided (Mostly Cretaceous-Jurassic)

Granite, quartz monzonite, quartz diorite, granodiorite, and trondhjemite. Includes diorite in southeastern Washington; diorite and gabbro near Concunully in Okanogan County; gneiss, schist, and migmatites in areas of Chelan, Colville, and Okanogan batholiths. Includes high-grade metamorphic rocks of Precambrian age in Spokane area.

Wisconsin

Stettin pluton (about 1520 Ma) (Middle Proterozoic)

Stettin pluton (about 1520 Ma) - Pyroxene syenite, amphibole syenite, tabular syenite, and nepheline syenite. Age approximately 1520 Ma (Sood and others, 1980).

Wausau Pluton; Quartz syenite (Middle Proterozoic)

Wausau Pluton; Quartz syenite- Contains flow-oriented xenoliths of biotite schist and sillimanite-bearing quartzite