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Global compilations indicate that the geochemistry of arc mag-matism is sensitive to Moho depth. Magmatic products are prevalent throughout the history of Cordilleran orogenesis and can be employed to constrain the timing of changes in crustal thickness as well as the magnitude of those changes. We investigate temporal variations in crustal thickness in the(More)
Seismic data provide images of crust-mantle interactions during ongoing removal of the dense batholithic root beneath the southern Sierra Nevada mountains in California. The removal appears to have initiated between 10 and 3 Myr ago with a Rayleigh-Taylor-type instability, but with a pronounced asymmetric flow into a mantle downwelling (drip) beneath the(More)
The Upper Jurassic volcanic rocks of the Pre-Cordillera and High Andes of northern Chile (26 – 31°S) represent a back-arc magmatic chain that developed during the early Andean subduction stage. After the Callovian, the dominant marine environment of this back-arc basin became continental and restricted volume of basaltic to riolitic rocks erupted along two(More)
Continental magmatic arcs form above subduction zones where the upper plate is continental lithosphere and/or accreted transitional lithosphere. The best-studied examples are found along the western margin of the Americas. They are Earth's largest sites of intermediate magmatism. They are long lived (tens to hundreds of millions of years) and spatially(More)
Newly discovered xenoliths within Plio-cene and Quaternary intermediate volcanic rocks from southern Peru permit examination of lithospheric processes by which thick crust (60–70 km) and high average elevations (3–4 km) resulted within the Altiplano, the second most extensive orogenic plateau on Earth. The most common petrographic groups of xenoliths(More)
[1] Low-angle subduction of oceanic lithosphere may be an important process in modifying continental lithosphere. A classic example is the underthrusting of the Farallon plate beneath North America during the Laramide orogeny. To assess the relevance of this process to the evolution and composition of continental lithosphere, the mantle stratigraphy beneath(More)
[1] The Rand and Sierra de Salinas schists of southern California were underplated beneath the southern Sierra Nevada batholith and adjacent Mojave‐Salinia region along a shallow segment of the subducting Farallon plate in Late Cretaceous time. Various mechanisms, including return flow, isostatically driven uplift, upper plate normal faulting, erosion, or(More)