The Sierra Madre del Sur mountain range is an uplifted forearc associated with the subduction of the Cocos plate along the Acapulco trench beneath mainland southern Mexico. The shallow subduction angle, the truncation of geologic features along the modern Acapulco trench, and direct seismic and drill-hole observations in the trench through deep sea drilling data, suggest that subduction erosion is an important process during the evolution of this

Diffusion in minerals could induce or modify compositional zoning, and also reset mineral ages during the thermal evolution of rocks. These diffusion modified properties provide important records of the time scales of metamorphic processes. We critically summarize here the available diffusion data in garnet, which is the most commonly used mineral to recover these time scales from diffusion-kinetic modeling, along with new experimental data from

Salinia is an out-of-place granitic terrane in central coastal California, whose origin is critical to understanding the tectonic development of southwestern North America. Although Salinia most easily fits geologically and geochemically in the modern gap between the Sierra Nevada and Peninsular Ranges batholiths of the California arc, paleomagnetic and geologic arguments have been used to suggest Salinia may have originated much farther south, possibly

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The Xolapa complex of southern Mexico is composed of mid-crustal arc-related gneisses of poorly resolved ages, intruded by undeformed Cenozoic calc-alkaline plutons. Twelve undeformed and deformed tonalitic/granodioritic samples from three transects across the Sierra Madre del Sur (Acapulco, Puerto Escondido, and Puerto Angel) were chosen for U-Pb zircon analysis. The measurements were performed in-situ on single crystals of zircons, using a laser

We present new field, structural, petrographic and geochronologic data on a rare mid-crustal (~25 km) exposure of a Cordilleran arc, the Coast Ridge Belt, located in the Santa Lucia Mountains of central California. The study area is composed primarily of a deformed suite of upper amphibolite to granulite facies rocks (the ?Sur Series?), which is dominated by meta-igneous tonalites, diorites and gabbros with subordinate metasedimentary quartzite and

Ganguly and Tirone [1] recently presented a method of determining the cooling rates of rocks from the difference between the core- and bulk-ages of a crystal, as determined by a single decay system. Here we present the first application of the method using the core and bulk ages of garnet single crystals, according to the Sm-Nd decay system, in two rock samples with contrasting cooling rates, which can be constrained independently. The samples belong

Eclogites are commonly belived to be highly susceptible to delamination and sinking into the mantle from lower crustal metamorphic environments. We discuss the production of a specific class of eclogitic rocks that formed in conjunction with the production of the Sierra Nevada batholith; and further discuss the removal and sinking of these rocks into the mantle. These high-density eclogitic rocks, however, formed by crystal-liquid equilibria, and

The Pamir Mountains are an outstanding example of extreme crustal shortening during continental collision that may have been accommodated by formation of a thick crust?much thicker than is currently thought?and/or by continental subduction. We present new petrologic data and radiometric ages from xenoliths in Miocene volcanic rocks in the southeastern Pamir Mountains that suggest that Gondwanan igneous and sedimentary assemblages were underthrust