Sedimentologic to metamorphic processes recorded in the high-pressure/low-temperature Mesozoic Rosetta Marble of Anatolia


Scheffler F., Oberhaensli R., Pourteau A., Immenhauser A., CANDAN O.

INTERNATIONAL JOURNAL OF EARTH SCIENCES, vol.105, no.1, pp.225-246, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 105 Issue: 1
  • Publication Date: 2016
  • Doi Number: 10.1007/s00531-015-1214-y
  • Journal Name: INTERNATIONAL JOURNAL OF EARTH SCIENCES
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.225-246
  • Keywords: Gypsum, High-pressure metamorphism, Neotethys, Anatolia, WESTERN TURKEY, LYCIAN NAPPES, EVOLUTION, CARBONATE, TRANSFORMATION, EVAPORITES, BLUESCHIST, CALCITE, SIVRIHISAR, MECHANISM
  • Dokuz Eylül University Affiliated: Yes

Abstract

Anatolia's high-pressure metamorphic belts are characterized in part by a Neotethyan stratigraphic succession that includes a mid-Cretaceous hemi-pelagic marble sequence. This unit contains, towards its stratigraphic top, dm-to-m-long radiating calcitic rods forming rosette-like textures. Here, we refer to these features as "Rosetta Marble". The remarkable textural similarity of non-metamorphic selenite crystals and radiating calcite rods in the Rosetta Marble strongly suggests that these textures represent pseudomorphs after selenites. Metamorphosed hemi-pelagic limestones, dominated by Rosetta selenite pseudomorphs, are alternating with siliceous meta-sediments containing relictic radiolaria tests. This stratigraphic pattern is indicative of transient phases characterized by evaporites precipitated from basinal brines alternating with non-evaporative hemi-pelagic deposition from normal-marine seawater. The regional distribution of Rosetta Marble exposures over 600 km is indicative of basin-scale evaporitic intervals. High-pressure, low-temperature metamorphism of these rocks is witnessed by Sr-rich (up to 3500 ppm), fibrous calcite pseudomorphs after aragonite and isolated aragonite inclusions in quartz. Peak metamorphic conditions of 1.2 GPa and 300-350 A degrees C are attested by high-Si white mica thermobarometry. The Rosetta Marble case example examines the potential to unravel the complete history from deposition to diagenesis and metamorphism of meta-sedimentary rocks.