Edward A du Bray (Former Employee)

Present-day High Cascades arc magmatism was preceded by ∼40 m.y. of nearly cospatial magmatism represented by the ancestral Cascades arc in Washington, Oregon, and northernmost California (United States). Time-space-composition relations for the ancestral Cascades arc have been synthesized from a recent compilation of more than 4000 geochemical analyses and associated age data. Neither...

The Miocene Tatoosh intrusive suite south of Mount Rainier is composed of three broadly granodioritic plutons that are manifestations of ancestral Cascades arc magmatism. Tatoosh intrusive suite plutons have individually diagnostic characteristics, including texture, mineralogy, and geochemistry, and apparently lack internal contacts. New ion-microprobe U-Pb zircon ages indicate...

No abstract available.

This report presents all petrographic, major oxide, and trace element data for a set of 109 samples collected during an investigation of Jurassic igneous rocks in the Bald Mountain mining district, Nevada. Igneous rocks in the district include the Bald Mountain stock, quartz-feldspar porphyry dikes, basaltic andesite dikes, aplite sills, and rare lamprophyre dikes. These rocks, although...

Geochemical data presented in this report pertain to Cretaceous igneous intrusions of the Boulder batholith and its satellitic plutons in southwest Montana. The geographic area addressed in this compilation is approximately bounded by lats 45.6 deg and 46.7 deg N. and longs 112.75 deg and 111.5 deg W. These data were compiled in order to establish the geologic framework for world-class...

Volcanic rocks that form the southern segment of the Cascades magmatic arc are an important manifestation of Cenozoic subduction and associated magmatism in western North America. Until recently, these rocks had been little studied and no systematic compilation of existing composition data had been assembled. This report is a compilation of all available chemical data for igneous rocks...