Mafic intrusions

Sheets, sills, and dikes of massive granophyric ferrogabbro; some bodies strongly differentiated and include pegmatitic gabbro, ferrogranophyre, and granophyre (MacLeod, 1981). Plagioclase and amphibole from unit have yielded K-Ar ages of about 30 Ma (Snavely and others, 1976a)
State Oregon
Name Mafic intrusions
Geologic age Oligocene
Lithologic constituents
Igneous > Plutonic > Gabbroic > Gabbro (Dike or sill)
Igneous > Plutonic > Granitic (Dike or sill)
NGMDB product
Counties Benton - Clatsop - Douglas - Lane - Lincoln - Marion - Polk - Tillamook - Washington - Yamhill