Abstract

Upper Jurassic Galice Formation of interbedded argillite, mudstone, graywacke and fine conglomerate, deposited in Fraser Belt eugeosyncline, was folded and metamorphosed to schists of Colebrooke Formation (greenschist facies) during Nevadan orogeny; the Pearse Peak Diorite implaced; and the ancestral Klamath Mountains and Sierra Nevada became an important source area. Eugeosynclinal conditions persisted into latest Jurassic when Otter Point Formation of interbedded volcanics, cherts, sandstones, and mudstones was deposited. The eugeosyncline was terminated by Diablan orogeny, which imposed northwest-striking wrench faults and folds on northeast-striking Nevadan structures; diorites, gabbros and ultramafics were implaced. The Lower Cretaceous Humbug Mountain conglomerate and later Rocky Point Formation were deposited in transgressing sea followed by several orogenies until early Miocene when marine clastics deposited followed by regional uplift and faulting.

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