Abstract

The Martinez Submarine Canyon, a fossil channel or gorge, is a subsurface feature present in Solano and Yolo Counties, California. This canyon was cut in late early to middle Paleocene and was filled in early late Paleocene time. Filling of the canyon occurred in a marine environment. The canyon has a west-to-east length of about 32 km, a north-to-south width of up to 12 km, and a maximum sediment thickness of about 400 m. Formations truncated by the Martinez Submarine Canyon are mostly arenaceous and Upper Cretaceous in age. The eastern part of the canyon fill is largely arenaceous; the fill in the western part is mostly shale.

A comparison of the Martinez Submarine Canyon and two associated younger fossil submarine canyons of different ages in the southern part of the Sacramento Valley indicates a cyclical sequence of tectonism, canyon-cutting, subsequent infill by marine sediments, followed by marine deposition.

In the Maine Prairie gas field, truncation of north-dipping Upper Cretaceous Mokelumne sands (i.e., Mokelumne formation) by the base of the Martinez Submarine Canyon shale resulted in the entrapment of commercial gas accumulations.