Timing of metamorphism in the Tauern Window, Eastern Alps; Rb-Sr ages and fabric formation

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Authors:Inger, S.; Cliff, R. A.
Author Affiliations:Primary:
University of Leeds, Department of Earth Sciences, Leeds, United Kingdom
Volume Title:Journal of Metamorphic Geology
Source:Journal of Metamorphic Geology, 12(5), p.695-707. Publisher: Blackwell, Oxford, United Kingdom. ISSN: 0263-4929
Publication Date:1994
Note:In English. 49 refs.; illus. incl. sects., 1 plate, 3 tables, geol. sketch maps
Summary:The peripheral Schieferhulle in this area represents post-Hercynian Penninic cover sequences and preserves a record of metamorphism in the Alpine orogeny without the inherited remnants of Hercynian events retained in basement rocks. The T-t-deformation history of rocks at the lower levels of these cover sequences have been studied by investigating units whose P-T evolution and structural setting are already well understood. The eclogite zone of the central Tauern formed from protoliths with Penninic cover affinities, and suffered early Alpine eclogite-facies metamorphism before tectonic imposition between basement and cover. It then experienced blue- and later greenschist facies conditions in the Alpine orogeny. The latter phase reset Sr isotopes in metasediments, recording deformation and peak metamorphism at 28-30 m.y. The peripheral Schieferhulle yields Rb-Sr white mica ages which can be tied to the structural evolution of the metamorphic pile. Early prograde fabrics predate 31 m.y., and were reworked at 28 m.y. Peak metamorphism post-dated this deformation, but did not produce widespread homogenization of the Sr isotopes. Localized deformation continued into the cooling path until at least 23 m.y., partially or wholly resetting Sr white mica ages in some samples. These isotopic ages may be integrated with structural data in regional tectonic models, and may constrain changes in the style of crustal deformation and plate interaction, though such interpretations must allow for the demonstrable variation in thermal histories over small distances. [R.E.S.]
Subjects:Absolute age; Alpine Orogeny; Cenozoic; Dates; Deformation; Eclogite facies; Fabric; Facies; Metamorphic rocks; Metamorphism; Mineral assemblages; Oligocene; Orogeny; P-T conditions; Paleogene; Petrography; Rb/Sr; Regional metamorphism; Tectonics; Tertiary; Veins; Alps; Austria; Central Alps; Central Europe; Eastern Alps; Europe; Pennine Alps; Tauern Window
Abstract Numbers:95M/2519
Record ID:1994054392
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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