Magmatic signature of the closure of the northern branch of the Neo-Tethys: Upper Paleocene-Middle Eocene magmatism at the boundary of the Tavsanli-Sakarya Zone (Turkey)

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Güllü B., Kadioglu Y. K.

GEOLOGICAL QUARTERLY, cilt.66, sa.2, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 66 Sayı: 2
  • Basım Tarihi: 2022
  • Doi Numarası: 10.7306/gq.1645
  • Dergi Adı: GEOLOGICAL QUARTERLY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Geobase
  • Anahtar Kelimeler: cooling age, sub-volcanic phase, shoshonites, enclave, petrological modelling, SLAB BREAK-OFF, WESTERN ANATOLIA, NORTHWEST TURKEY, PETROGENETIC EVOLUTION, ISOTOPE GEOCHEMISTRY, SIVRIHISAR MASSIF, VOLCANIC-ROCKS, NW TURKEY, GENESIS, ND
  • Ankara Üniversitesi Adresli: Evet

Özet

Numerous plutons composed of granite, granodiorite, diorite-porphyry, monzonite, granodiorite-porphyry and diorite/microdiorite-porphyry occur at the boundary of the TaveanlI-Sakarya Zone, in the eastern part of the northwestern Anatolian magmatic belt, Turkey. These rocks belong to two differ ent types: a medium-K calc-alkaline granodiorite series (with associated dykes and sub-volcanic rocks) and a shoshonitic series of granites. The rocks of the shoshonitic series have SiO2 from 67.5 to 75.6 wt.% with Mg# from 35.1 to 59.5, whereas the medium-K calc-alkaline series rocks have SiO2 between 54.6 and 67.7 wt.% with Mg# from 43.5 to 60.8. There is a clear enrichment of LILE with respect to the HFSE in all magmatic units of the region. These magmatic rocks reflect prop erties of collision-related arc magmatism in the var ious geochemical discrimination di agrams. The initial Sr-87/Sr-86 and Nd-143/Nd-144 istopic ratios of the magmatic units range from 0.705506 to 0.710902 and 0.512178 to 0.512594, respectively. Collision-related granitoids yielded a Ar-40/Ar-39 cooling age age of 59.13 +/- 1.87 Ma, and arc-re lated granitoids and associated sub-volcanic units 44.3 +/- 0.47 and 44.11 +/- 0.89 Ma. The data obtained re vealed that conti nent-conti nent collision in the Paleocene together with the initia tion of the closure of the Neo-Tethys took place between the Anatolide-Tauride Platform and Sakarya Plate from the end of the Cre taceous. The shoshonotic granite may cooled in the Mid dle Paleocene, as regards the subduction-accretion zone in which subduction impacts have been observed. The medium-K calc-al kaline magmatic products in the region were formed by partial melting of the continental lithospheric mantle caused by the upwelling of asthenospheric mantle after the subducted slab was delaminated.