Introduction: The source and duration of the heating event responsible for eucrite metamorphism is not well constrained. Three hypotheses have been proposed for the source of heat: Impact, conduction from the mantle, and rapid production of successive flows [1]. Textural and chemical relationships of noncumulate eucrites are investigated to constrain the thermal and temporal conditions responsi...

Large earthquakes occur in rocks undergoing high-pressure/low-temperature metamorphism during subduction. Rhythmic major-element zoning in garnet is a common product of such metamorphism, and one that must record a fundamental subduction process. We argue that rhythmic major-element zoning in subduction zone garnets from the Franciscan Complex, California, developed in response to growth-dissol...

Four metasedimentary zircon populations from different tectonometamorphic units of the Central and the Northern Schwarzwald (Variscan belt, SWGermany) were investigated using SEM, cathodoluminescence and SHRIMP dating. Despite partially strong modifications of primary internal morphologies during Variscan metamorphism at amphibolite (750 C, 0.4– 0.6 GPa) and granulite-facies conditions (950–1,0...

The Dalradian Supergroup of Britain and Ireland is mineralised by gold-tellurium vein deposits. The host succession includes carbonaceous, pyritic shales (pelites) which were a source of trace elements, including gold and tellurium. LA-ICP-MS mapping of pyrite crystals shows that late stages are enriched in gold, tellurium and lead, representing concentration of these elements during metamorphi...

The Himalayan range exposes a spectacular assemblage of metamorphic rocks from the midand deep crust that have fostered numerous models of how the crust responds to continental collisions. Recent petrogenetically based petrologic and geochronologic studies elucidate processes with unprecedented resolution and critically test models that range from continuum processes to one-time events. The pro...

Akermanite (Akg0) coexists with monticellite (Mo92) and wollastonite (Wo99) in an unusual calc-silicate xenolith in anorthosite at Cascade Slide in the Adirondack Mountains, New York. Experimental results bearing on the stability of akermanite have been evaluated through calculations based on thermochemical data and by chemical analysis of experimental products (Yoder 1975). A temperature of 75...

Ion microprobe analysis with a sub-micrometer diameter spot reveals a sharp, 2 μm gradient in oxygen isotope ratio proving that oxygen diffusion in zircon is slow even under prolonged high-grade metamorphism. The data are consistent with an oxygen diffusion coefÞ cient of 10–23.5±1 cm2/s. Furthermore, this gradient is found in a zircon that contains clear textural evidence of recrystallization ...

Shock metamorphism in chondritic parent bodies produces typical textures, visible under the microscope, which are a consequence of structural deformation of the crystals. Such deformations can be studied with Raman spectroscopy. The vibrational characteristics of olivines and pyroxenes, structurally deformed by weak-to-moderate shock metamorphism, have been determined on four Spanish ordinary c...