Alpine metamorphism of organic matter in metasedimentary rocks from Mt. Medvednica (Croatia)

Katalin Judik, Gerd Rantitsch, Thomas M. Rainer, Péter Árkai, Bruno Tomljenović

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The diagenetic to low-temperature metamorphic alteration of Mt. Medvednica (Internal Dinarides, Croatia) has been studied by vitrinite reflectance, ordering data of organic matter determined by X-ray powder diffraction and Raman spectroscopy of extracted carbonaceous material. In metapelites of the Medvednica Metamorphic Complex (MMC), maximum vitrinite reflectance varies between 6.9 and 9.8%. By X-ray powder diffraction, the finely dispersed carbonaceous material is classified as d1-graphite. Based on the "Raman Spectroscopy of Carbonaceous Material Thermometer", peak metamorphic temperatures of ca. 410 °C are estimated. The degree of organic maturation and the estimated peak temperature correlate fairly well with the Cretaceous (120-80 Ma) high-temperature anchizonal to epizonal metamorphism of the unit, determined by illite Kübler index, chlorite " crystallinity" and K-white mica - chlorite thermobarometry. In the tectonically higher Jurassic Ophiolitic Mélange and in the unconformably overlying Cretaceous-Paleocene Sequence, random vitrinite reflectance between ca. 0.7 and 2.2% suggest a stratigraphical trend of the data and therefore a common burial history. In the Jurassic Ophiolitic Mélange and the Cretaceous-Paleocene Sequence, the synmetamorphic carbonaceous material is classified as d3-graphite. In both units, organic thermometers provide peak temperatures of 100-240 °C. These estimates are in accordance with phyllosilicate reaction progress indicators, showing no systematic variation in the stratigraphic succession.

Original languageEnglish
Pages (from-to)605-616
Number of pages12
JournalSwiss Journal of Geosciences
Volume101
Issue number3
DOIs
Publication statusPublished - Dec 1 2008

Keywords

  • Croatia
  • Internal Dinarides
  • Metamorphism
  • Mt. Medvednica
  • Organic matter
  • Raman spectroscopy
  • Structural ordering
  • Vitrinite reflectance

ASJC Scopus subject areas

  • Geology

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