Decades of experimental work has illustrated the high degree to which the partitioning of most elements is dependent on phase composition, temperature and pressure. In order to quantitatively describe clinopyroxene partitioning it is required to derive expressions using theoretical constraints calibrated with experimental data.
The experimental database available for such...
The archaeological record of the First Americans is known almost exclusively from interior sites located away from coastal margins. While archaeologists hypothesize that early peoples initially migrated into the Americas along the Pacific coast, environmental changes associated with postglacial sea level rise may have destroyed or obscured such early sites....
In an attempt to understand the phase equilibria and petrogenesis of MORB anorthitic plagioclase, Cr-spinel commonly hosted within anorthitic plagioclase has been investigated petrographically and compositionally. Based on spinel-anorthite relationships from three samples of plagioclase ultra-phyric basalt (PUB; Southeast Indian Ridge, Axial Seamount and West Valley Segment, Juan de Fuca...
The detection of subtle variations in mineral chemistry in zoned hydrothermal
alteration associated with the formation of porphyry copper deposits by short-wave
infrared spectroscopy and rock chemistry are potentially valuable vectoring tools for
mineral exploration. In order to correctly interpret the data collected by these methods,
results must be calibrated...
The climatic and tectonic framework of the St. Elias orogen makes it an excellent place to study the interactions between tectonic processes such as deformation and erosive processes, in particular glacial erosion. One type of link between these processes, proposed by numerical models of orogenic development, is an effect of...
Magmatic sulfides from Yerington, Nevada, and Yanacocha, Peru, were analyzed by laser ablation-inductively coupled mass spectrometry (LA-ICPMS) and electron microprobe to determine copper, gold, and silver concentrations and ratios in order to examine the relationship to the metal content of related magmatic-hydrothermal ores. The magmatic sulfides occur in plutonic rocks...
The Cretaceous Merín aborted-rift basin of eastern Uruguay is composed of sub-alkaline Paraná-Etendeka province basaltic flows and shallow intrusives (~133 to 131 Ma), rhyolitic ignimbrites (~130 to 128 Ma) and associated mildly alkaline to alkaline intrusions and volcanic rocks (~128 to 127 Ma). Four intrusive complexes from 20 to >30...
Oblique subduction of the Juan de Fuca plate beneath the North American plate characterizes the tectonic setting of the Pacific Northwest. North American plate deformation at the latitude of central Oregon consists of the clockwise-rotation of the Siletzia block in the forearc and the extensional Basin and Range province in...
Coastal stream basins are of great importance to efforts aimed at refining our understanding of the earliest populations that inhabited the ancient Oregon coast. However, geomorphic responses to post-glacial sea level rise in these settings has produced depositional environments that destroy or deeply bury late Pleistocene and early Holocene-age archaeological...
The ~5 km3, 4.54 to 4.09 Ma Caspana Ignimbrite of the Altiplano-Puna Volcanic Complex (APVC) of the Central Andes records the eruption of an andesite and two distinct rhyolitic magmas. It provides a unique opportunity to investigate the production of silicic magmas in a continental arc flare-up, where small volumes...