Ar/Ar laser probe dating of detrital white micas from Cretaceous sedimentary rocks of the Eastern Alps: evidence for Variscan high-pressure metamorphism and implications for Alpine orogeny: comment and reply

Article Abstract:

The use of white phengitic micas with Si=3.3 p.f.u. to indicate Alpine high-pressure metamorphism is insufficient proof for the erosion of high-P metamorphic source rocks. Such a method is questionable because it does not provide buffer documentation and does not accurately establish the polytype of mica. That only locally preserved Variscan basement of the Alps does not contain blueschist relics does not connote that blueschist metamorphism during Variscan convergence did not occur.

Analysis, Rocks, Metamorphic, Metamorphic rocks, Metamorphism (Geology), Swiss Alps, Mica

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Late Jurassic blueschist facies pebbles from the Western Carpathian orogenic wedge and paleostructural implications for Western Tethys evolution

Article Abstract:

A study suggests a remarkable northward extension of the sublongitudinal Triassic Vardar (Meliata) Ocean and its subduction since the late Middle Jurassic, presumably balanced on the western end by coeval spreading in the Ligurian-Piedmont basin of the Apennine-Western Alpine Tethys. Some traces of the lost Tethys ocean have been found along the Pieniny Klippen Belt. Since the Callovian-Oxfordian boundary, a subduction-related blueschist facies metamorphism was generated.

Western Europe, Jurassic period, Tethys (Paleogeography), Carpathian Mountains

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Detrital blueschist-facies metamorphic mineral assemblages in early Cretaceous sediments of the foreland basin of the Brooks Range, Alaska, and implications for orogenic evolution

Article Abstract:

Blueschist-facies rocks on the Brooks Range's metamorphic core are the source of detrital minerals in the range's foreland basin. These rocks were exhumed between Late Jurassic and middle Albian periods and not in the late stage extensional collapse or postcontractional isostatic rebound. Contractional tectonic processes have uplifted and denuded the rocks. Thrust systems are used by metamorphic structures in the rocks to support their uplift.

Alaska, Facies (Geology), Geologic facies

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