Tertiary-Cretaceous basic intrusive rocks

Diorite and gabbro in western Snohomish County.
State Washington
Name Tertiary-Cretaceous basic intrusive rocks
Geologic age Cretaceous-Jurassic
Lithologic constituents
Igneous > Plutonic > Gabbroic > GabbroIncludes metagabbro.
Igneous > Plutonic > Dioritic > DioritePrimarily metadiorite. Possibly major in rank.
Metamorphic > Metaigneous > GreenstonePossibly major in rank.
Sedimentary > Clastic > Sandstone (Bed)
Igneous > Plutonic > Granitic > Tonalite
Metamorphic > Metasedimentary > Metaclastic > Argillite
Metamorphic > Gneiss
Igneous > Plutonic > Ultramafic > Hornblendite
Metamorphic > Amphibolite
Comments Tabor and others, 1993, maps this as greenstone and metadiabase with metagabbro, argillite, and sandstone, and may include metatonalite, gabbro, flasar gneiss, amphibolite and hornblendite. Similarly mapped as such by Dragovich and others, 2002. Because greenstone is mentioned first in the above descriptions, I am assuming that it is more prevalent than metadiabase with the caution that the referenced literature does not explicitly say this is the case. This unit is considered part of the Western melange belt.

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., Frizzell, V.A.,Jr., Booth, D.B., Waitt, R.B., Whetten, J.T., Zartman, R.E., 1993, Geologic Map of the Skykomish River 30- by 60-Minute Quadrangle, Washington: U. S. Geological Survey Miscellaneous Investigations Series Map I-1963, scale 1:100,000.

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 Snohomish