Pre-Middle Jurassic volcanic rocks, undivided

Predominantly greenstone and spilitic volcanic rocks; includes some slate, argillite, and graywacke.
State Washington
Name Pre-Middle Jurassic volcanic rocks, undivided
Geologic age Early Cretaceous-Late Jurassic
Lithologic constituents
Metamorphic > Metaigneous > Greenstone (Greenschist)
Metamorphic > Metaigneous > Metavolcanic (Greenschist)Includes spilite, keratophyre, meta-basalt breccia and tuff, and metamorphosed andesite.
Metamorphic > Amphibolite (Greenschist)
Sedimentary > Clastic > Sandstone > Graywacke (Bed)
Igneous > Plutonic > Dioritic > Diorite (Dike or sill)
Metamorphic > Metasedimentary > Metaclastic > Slate
Metamorphic > Metasedimentary > Metaclastic > Argillite
Comments Spilitic volcanic rocks include meta-basalt flows, breccia, and tuff, as well as metamorphosed andesite and keratophyre (Tabor and others, 1982, Southwick, 1974). Outcrop in central Washington defined as part of Ingalls Tectonic Complex by Tabor and others, 1982. Huntting and others, 1961, lists "Hawkins" in the WApJph unit but I think it is more appropriately included in this unit (see maps and lithology descriptions of Tabor and others, 1982, and Southwick, 1974); all rocks in this formation are greenschist facies. Slate, argillite, and graywacke are part of the Peshastin formation.
Stratigraphic units Ingalls Tectonic Complex (Hawkins formation, Peshastin formation (in part))

Huntting, M.T., Bennett, W.A.G., Livingston, V.E.Jr., and Moen, W.S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.

Tabor, R.W., Waitt, R.B.,Jr., Frizzell, V.A.,Jr., Swanson, D.A., Byerly, G.R., Bentley, R.D., 1982, Geologic Map of the Wanatchee 1:100,000 Quadrangle, Central Washington: U. S. Geological Survey Miscellaneous Investigations Series Map I-1311, scale 1:100,000.

Southwick, D.L., 1974, Geology of the Alpine-type Ultramafic Complex and Mount Stuart, Washington: Geological Society of America Bulletin, v. 85, no. 3, p 391-402.

Dragovich, J.D., Logan, R.L., Schasse, H.W., Walsh, T.J., Lingley, W.S., Jr., Norman, D.K., Gerstel, W.J., Lapen, T.J., Schuster, J.E., Meyers, K.D., 2002, Geologic Map of Washington-Northwest Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, scale 1:250,000.

NGMDB product
Counties Chelan - Kittitas - Skagit