Development of strain fringes in sedimentary rocks: Evidence for deformation of Upper Ordovician glacial diamictites in the western Srednogorie Zone

Pages: 
pp. 51-62
Sofia University “St. Kliment Ohridski”, 15 Tsar Osvoboditel Blvd., 1504 Sofia
Abstract: 

The local formation of quartz strain fringes around authigenic pyrite crystals and chamosite strain fringes around detrital grains is described from Hirnantian glaciomarine diamictites (Sirman Formation) of the Palaeozoic Balkan Terrane, now cropping out in the Alpine western Srednogorie Zone. The fringes belong to the antitaxial type and are interpreted as products of synkinematic, low temperature growth in microdilatation sites as a result of diffusive mass-transfer processes. The relatively simple fringe geometry and fiber orientation reflect coaxial progressive deformation that can be broadly related to the Variscan orogeny. Performed XRD analysis of shales intercalated with the diamictites indicates that the Upper Ordovician glacial deposits underwent a high-grade diagenetic alteration. Therefore, this study reports a rare case of development of strain fringes in non-metamorphosed sedimentary rocks.

Keywords: 

quartz, pyrite, chamosite, strain fringes, diamictites, Hirnantian, Srednogorie Zone

VOLUME 43 (1-3)/December 2014

Sofia University “St. Kliment Ohridski”, 15 Tsar Osvoboditel Blvd., 1504 Sofia
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Sofia University “St. Kliment Ohridski”, 15 Tsar Osvoboditel Blvd., 1504 Sofia

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Bl. 24, 1113 Sofia; Bulgaria
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Historical Museum Etropole, 105, Ruski Boulevard, 2108 Etropole, p.o.b. 35, Bulgaria

FGU NPP "Geologorazvedka", Saint-Petersburg, Russia
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Geological Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria
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Saint-Petersburg State University, Saint Petersburg, Russia

National Institute of Marine Geology and Geoecology, 23-25 Dimitrie Onciul St., sector 2, Bucharest, Romania
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National Institute of Marine Geology and Geoecology, 23-25 Dimitrie Onciul St., sector 2, Bucharest, Romania

Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Laboratory of Nuclear Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece