ABSTRACT: Petrology and Provenance of the Great Valley Group. Southern Klamath Mountains and Northern Sacramento Valley

Paul F. Short, Raymond V. Ingersoll

Lower Cretaceous sandstone and conglomerate of the Great Valley Group rest depositionally on the southern Klamath Mountains at the north end of the Sacramento Valley. Exposures include nonmarine, shallow marine, and deep marine sediments, which are part of the Platina Formation (petrofacies).

Approximately 150 sandstone point counts (500 points per section using Gazzi-Dickinson method) and 32 conglomerate clast counts indicate a Klamath provenance of mixed magmatic-arc and recycled orogenic character. Standard triangular plots and multivariate analyses (combined with paleocurrent and paleogeographic data) suggest discrete source areas within the Klamath terrane. However, the general homogeneity of both sandstone and conglomerate petrology is consistent with all of the units being included within the Platina petrofacies.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990