Laser 40Ar/39 Ar ages of single detrital white mica grains related to the exhumation of Neoproterozoic and Late Devonian high pressure rocks in the Southern Urals; Russia

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doi: 10.1017/S0016756803008628
Authors:Willner, A. P.; Wartho, J. A.; Kramm, U.; Puchkov, V. N.
Author Affiliations:Primary:
Ruhr-Universität, Institut für Geologie, Mineralogie und Geophysik, Bochum, Federal Republic of Germany
Curtin University of Technology, Australia
RWTH, Federal Republic of Germany
Russian Academy of Sciences, Russian Federation
Volume Title:Geological Magazine
Source:Geological Magazine, 141(2), p.161-172. Publisher: Cambridge University Press, London, United Kingdom. ISSN: 0016-7568
Publication Date:2004
Note:In English. Includes appendices. 43 refs.; illus., incl. 2 tables, geol. sketch map
Summary:Single grains of detrital white mica from two different synorogenic sediments in the S Urals were analysed using the in situ UV laser ablation Ar-Ar dating technique to discriminate between age signatures associated with a high-P signal (phengites) from those related to muscovite only. Two disparately aged sandstone formations of Neoproterozoic (Upper Vendian) and Upper Devonian (Famennian) age were formed by the erosion of high-relief source areas with contemporaneously exhumed high-P rocks. A bimodal distribution of ages and chemical compositions can be detected in the two detrital populations. There is no age overlap between the two populations, reflecting completely different source areas containing high-P rocks of different ages. Within the Upper Vendian sandstones, detrital white mica from a 571-609 Ma age group is phengitic in composition (Si 3.3-3.41 per formula unit), while an older 645-732 Ma age group is comprised of muscovite composition grains only. [G.L.B.]
Sections:Age determination
Subjects:Absolute age; Accretionary wedges; Ar/Ar; Dates; Deformation; Detritus; Devonian; Electron probe data; Erosion; Exhumation; Faults; Geochemistry; Granites; High pressure; Igneous rocks; Island arcs; Laser ablation; Laser methods; Major elements; Metamorphic rocks; Mica group; Muscovite; Neoproterozoic; Nomenclature; Paleoenvironment; Paleozoic; Phengite; Plate collision; Plate tectonics; Plutonic rocks; Precambrian; Pressure; Proterozoic; Sedimentary rocks; Sheet silicates; Silicates; Suture zones; Terranes; Trace elements; Upper Devonian; Upper Precambrian; Vendian; Volcanic rocks; Asia; Chelyabinsk Russian Federation; Commonwealth of Independent States; Magnitogorsk Russian Federation; Russian Federation; Southern Urals; Urals; Beloretzk Terrane; Zigan Formation; Zilair Formation
Coordinates:N521500 N540000 E0600000 E0570000
Abstract Numbers:04M/2560
Record ID:2004066136
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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