Contrasting P-T-t paths: thermochonologic evidence for a late peleozoic final assembly of the Avalon composite terrane in the New England Appalachians

Article Abstract:

Pressure-temperature-time paths for the Avalon composite terrane in eastern New England contrast with its overlying Putnam-Nashoba zone. Analysis suggests that the cover rocks were underthrust by the terrane sometime in the late Paleozoic. Models indicatethat the two belts were not in thermal equilibrium during the Permian metamorphism of the terrane, which had occured east of its present overlay. Major movement occured between the cover rocks and Avalon after Alleghanian metamorphism. Thermal equilibrium between instantaneously thrusted blocks is reached only after tens of millions of years.

Appalachian region, Metamorphism (Geology), Elasticity, Glacial landforms

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Pre-mid-Mesozoic tectonic evolution of the Yukon-Tanana terrane, Yukon and Alaska

Article Abstract:

Geochronological and isotopic analysis as well as field studies in the Yukon-Tanana Terrane (YTT) in Yukon and central Alaska were used to investigate the history of the formation before mid-Mesozoic. YTT evolved from intermittent magmatism along the continental arc with three principal pulses occurring from Late Devonian to Early Jurassic. The subhorizontal structural component of the terrane is reflective of a collision between land masses between mid-Permian to Late Triassic. The terrane was also compared with other formations in the area.

Yukon Territory, Geodynamics

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