We have attempted to constrain the depth(s) at which the main differentiation processes in arc lavas occur, using two main approaches; REE characteristics. The REE patterns of volcanic rock suites produced by crystal-liquid differentiation processes are sensitive to garnet or amphibole fractionation at deep or intermediate levels, respectively. Not surprisingly La/Yb increases with differentiat...

Accurate assessment of the subsurface mechanical characteristics and how they correlate with dielectric properties is crucial to optimize future drilling and sampling investigations on planetary bodies. For 12 different types of basaltic rocks with different hardnesses, we use capacitive cells to measure the real part of the dielectric constant over the frequency range 100–1000 MHz, and a Schmi...

Whole-rock geochemical data on basaltic to rhyolitic samples from 12 volcanic centers are used to constrain the role of continental crust in the genesis of magmas formed beneath the anomalously wide subduction-related volcanic arc in Ecuador. Relatively homogeneous, mantle-like, isotopic compositions across the arc imply that the parental magmas in Ecuador were produced largely within the mantl...

•80 data have been obtained on 7 of the 17 intrusive centers of diorite and granodiorite (Miocene?) that lie along a N-S belt about 50 km west of the High Cascades. Whole-rock $ values (per mil relative to SMOW) in the intrusive stocks are: -[-2.3 to -t-4.9 (South Umpqua River), -0.7 to -t-3.8 (Bohemia mining district), -t-4.3 to -t-4.6 (Vida stock), -0.2 to -t-5.5 (Nimrod stock), --1.7 to -}-0...

Volcanic ash was recovered from lower Aptian to Albian deposits from DSDP Sites 463, 465, and 466; pelagic clay of the upper Pleistocene to Upper Cretaceous was recovered mainly from Site 464, with minor amounts at Sites 465 and 466 (Figs. 1 and 2). We present X-ray-mineralogy data on pelagic clay and altered volcanic ash recovered from the four Leg 62 sites (Table 1; Fig. 1). In addition, two ...