The 7,900-foot-thick Cenozoic section in Monterey and Salinas Quadrangles, northern Santa Lucia Mountains, lies on Mesozoic granite and Paleozoic (?) Sur Series schist. Age of the 1,100-foot-thick Carmelo Formation is confirmed by new micro- and megafossil material. Eocene and Oligocene rocks are missing from the section. An 850-foot-thick middle Miocene sandstone-conglomerate formation of two members, containing a typical Temblor fauna, is assigned new member and formation names. Conformably above it is the Monterey Formation consisting of three mappable members: a lowermost Luisian sandstone, up to 200 feet thick; a Luisian through Mohnian siliceous shale, 2,000 feet thick; and an uppermost Delmontian diatomite, up to 800 feet thick. A 60-foot-thick olivine basalt lies etween the Monterey and underlying Temblor-age formations, dating this volcanism as middle Miocene. Conformably overlying the Monterey Formation is the Santa Margarita Formation, up to 1,600 feet thick.

Choice of the Monterey vicinity as the type locality of the Monterey Formation was unfortunate because the section there is not typical of the Monterey Formation in well-known localities elsewhere in California, either in age, thickness, or completeness. A few miles east of the type section, the shale and diatomite members of the Monterey Formation begin to interfinger with the Santa Margarita Formation and the entire Miocene section grades into sandstone against the Sierra de Salinas.

Overlapping the Miocene and basement units is the Plio-Pleistocene Paso Robles Formation, up to 500 feet thick, and several thin younger Quaternary units.

The structural pattern is essentially a series of northwest-trending open folds punctuated by the development of three horsts. Several Miocene units are warped over the noses of these horsts. The sense of movement on the northwest-trending faults is normal and strike-slip; thrusting was not identified.

The best possibilities for oil are possible fault-stratigraphic traps along the western side of the Salinas Valley, northeast of the projection of the King City fault.

End_of_Article - Last_Page 1081------------