Post-Variscan autochthonous cover in the eastern Sakarya Zone, Turkey: Evolution of the late Carboniferous back-arc ocean to the Triassic Karakaya Ocean

DOKUZ A., ALÇİÇEK M. C., Tuncdemir V., KANDEMİR R., AYDINÇAKIR E.

JOURNAL OF ASIAN EARTH SCIENCES, cilt.249, 2023 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 249
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1016/j.jseaes.2023.105621
  • Dergi Adı: JOURNAL OF ASIAN EARTH SCIENCES
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Artic & Antarctic Regions, Geobase, INSPEC
  • Anahtar Kelimeler: late Carboniferous, Autochthonous cover, eastern Sakarya Zone, Paleotethys, Back -arc basin migration, Geodynamics, ANATOLIDE-TAURIDE BLOCK, YUSUFELI-ARTVIN AREA, WEST-AFRICAN CRATON, NE TURKEY, SOUTHERN MARGIN, VOLCANIC-ROCKS, HF ISOTOPES, NW TURKEY, GEOCHRONOLOGICAL EVIDENCE, GEOCHEMICAL CONSTRAINTS
  • Recep Tayyip Erdoğan Üniversitesi Adresli: Evet

Özet

The processes that caused removal of the upper Carboniferous to Permian sediments in the eastern Sakarya Zone, Turkey, are modeled by using of geochemical data and LA-ICP-MS U-Pb ages from detrital zircons. A felsic provenance and passive margin setting during the deposition of the upper Carboniferous catalcesme sediments are inferred from the geochemistry of sandstones (SiO2 > 85 wt%). Chemical Index of Alteration (CIA) values (75 - 81) indicate warm and humid climatic conditions and tectonic tranquility during deposition. Fifty-three (58%) concordant zircon grains produce a youngest age population in the range of 308.7 +/- 4.4 to 342.1 +/- 6.9 Ma, typical for the Variscan events. The burgundy color and upward-fining in clast size and bed thickness are the most prominent features of the concordantly overlying Hardisi Formation. Geochemistry (SiO2 = 66-81 wt%) and CIA values (58-65) of the clastic rocks point to a subduction-related tectonic setting and increasing rate of erosion in the source area. We highlight that the catalcesme sediments were deposited in a back-arc basin opened to the south of a continental ribbon separated from Gondwana. Approaching of the Paleotethyan mid-ocean ridge to the subduction zone was resulted in flattening in subducting slab, which in turn caused the back-arc basin to migrate into the interior parts of Gondwana and the former back-arc basin to evolve into a lacustrine setting. Increase in the elevation of source areas was resulted in an increase in the rate of physical erosion and trans-portation of burgundy Hardisi clastic sediments into the lacustrine basin.