Nepheline syenite

Medium- to dark-gray, medium- to coarse-grained, alkalic to alkalic-calcic nepheline syenite. Composed principally of nepheline, orthoclase, biotite, and clinopyroxene, and accessory minerals are magnetite, apatite, titanite, zircon, and pyrite. Restricted to two small bodies northwest of Beemerville. Intrudes the Martinsburg Formation, but appears to be unconformably overlain by the Shawangunk Formation. K-Ar and Rb-Sr ages of 435ñ20 Ma from biotite (Zartman and others, 1967) and a fission track date from titanite of 422ñ14 Ma (Eby and others, 1992) suggest emplacement in Late Ordovician to Early Silurian.
State New Jersey
Name Nepheline syenite
Geologic age Early Silurian? and Late Ordovician
Lithologic constituents
Major
Igneous > Plutonic > Foidal-syenitic > Nepheline-syeniteMedium- to dark-gray, medium- to coarse-grained, alkalic to alkalic-calcic nepheline syenite. Composed principally of nepheline, orthoclase, biotite, and clinopyroxene, and accessory minerals are magnetite, apatite, titanite, zircon, and pyrite.
Comments Beemerville Intrusive Suite (Early Silurian? and Late Ordovician) (Drake and Monteverde, 1992). Note that there is a unit SObl (Lamprophyre, ect...) that is described in the digital description and is used on the printed map; but it is NOT used on the digital map. Probably because it is a line feature and the digital geology is only polygons. Unit SObl has NOT been entered here.
References

Dalton, R.F., Herman, G.C., Monteverde, D.H., Pristas, R.S., Sugarman, P.J., and Volkert, R.A., 1999, New Jersey Department of Environmental Protection, Bedrock Geology and Topographic Base Maps of New Jersey: New Jersey Geological Survey CD Series CD 00-1; ARC/INFO (v. 7.1), scale 1:100,000.

Drake, Avery A. Jr.,Volkert, Richard, A., Monteverde, Donald H., Herman, Gregory C., Houghton,Hugh F., Parker, Ronald A., and Dalton, Richard F., 1996, Bedrock Geologic Map of Northern New Jersey: U.S. Geological Survey Miscellanenous Investigations Map I-2540-A, 4 cross sections, 2 sheets, size 56x40; 58x41, scale 1:100.000.

https://pubs.er.usgs.gov/publication/i2540A

Drake, A.A., Jr., and Monteverde, D.H., 1992a, Bedrock geologic map of the Branchville quadrangle, Sussex County, New Jersey: U.S. Geological Survey Geologic Quadrangle Map GQ1700, scale 1:24,000.

https://pubs.er.usgs.gov/publication/gq1700

Zartman, R.E., Brock, M.R., Heyl, A.V., and Thomas, H.H., 1967, K-Ar and Rb-Sr ages of some alkalic intrusive rocks from central and eastern United States: American Journal Science, v. 265, no. 10, p. 848-870.

Eby, G.N., Sclar, C.B., and Myers, P.B., 1992, A fission-track date on magmatic titanite from the Beemerville nepheline syenite, Sussex County, N.J.: Geological Society of America Abstracts with Programs, v. 24, no. 3, p. 18.

NGMDB product
Counties Sussex