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Quartz grains that appear to have been shock-metamorphosed occur within three closely spaced shale beds from the uppermost Triassic ("Rhaetian") Calcare a Rhaetavicula in the Northern Apennines of Italy. The upper shale coincides with the abrupt termination of the distinctive, uppermost Triassic Rhaetavicula fauna and is overlain by the Hettangian (Lower(More)
A B S T R A C T The Cordillera Huayhuash is a north-south-oriented range along the drainage divide of the northern Peruvian Andes. The range has high topography with peaks in excess of 5500 m and the second-highest peak in Peru, Nevados Yerupaja (6617 m). Bedrock is dominated by folded Mesozoic miogeoclinal rocks unconformably overlain by mid-Tertiary(More)
[1] As one of two well‐exposed intraoceanic arcs, the Talkeetna arc of Alaska affords an opportunity to understand processes deep within arcs. This study reports new Lu‐Hf and Sm‐Nd garnet ages, 40 Ar/ 39 Ar hornblende, mica and whole‐rock ages, and U‐Th/He zircon and apatite ages from the Chugach Mountains, Talkeetna Mountains, and Alaska Peninsula, which,(More)
[1] Wildfire heating of the outer few centimeters of exposed rock or soil generates short-duration, high-temperature thermal events that produce characteristic thermochronologic signatures in minerals. Contrasting activation energies of fission track annealing and He diffusion in apatite lead to a kinetic crossover whereby wildfire heating resets fission(More)
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