Trakya havzasının kuzey ve doǧusundaki (kb türkiye) orta eosen-alt oligosen sıǧ-denizel birimlerinin stratigraf si ve i̇ri bentik foraminiferleri

Translated title of the contribution: Stratigraphy and larger foraminifera of the middle eocene to lower oligocene shallow-marine units in the northern and eastern parts of the trace basin, NW Turkey

György Less, Ercan Özcan, Aral I. Okay

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The shallow-marine Eocene Soǧucak Limestone and Oligocene Ceylan Formation were studied in the northern and eastern parts of the Thrace Basin with detailed biometric analysis of the full spectrum of larger benthic foraminifera (mainly nummulitids and orthophragmines). This allows us to establish a high-resolution biostratigraphy in the context of the shallow benthic zonation (with SBZ zones) of the Tethyan Palaeogene since larger foraminiferal assemblages show a very strong Western Tethyan af nity Only two species (Heterostegina armenica and Orbitoclypeus haynesi) are unknown so far to the west of the Thrace Basin. The age of particular larger foraminiferal sites is determined based on (i) the occurrence and developmental stage of different species of Heterostegina (H. armenica hacimasliensis n. ssp. is introduced here), (ii) the presence/absence of giant Nummulites, (iii) the presence/absence of Spiroclypeus, (iv) the developmental stage of reticulate Nummulites, (v) the occurrence and developmental stage of orthophragmines, (vi) the occurrence of particular Operculina and radiate Nummulites. Six larger foraminiferal horizons could be established. They correspond to (i) the vicinity of the early/late Bartonian boundary (SBZ 17/18), (ii) the middle late Bartonian (SBZ 18B), (iii) the latest Bartonian (SBZ 18C), (iv) the early Priabonian (SBZ 19), (v) the late Priabonian (SBZ 20) and (vi) the early Rupelian (SBZ 21). Three main shallow-water depositional environments could be recognized in both the late Bartonian and Priabonian: two of them took place in the middle shelf; one with low and another with high water-energy (back-bank and Nummulites-bank facies) whereas the third one refers to the outer shelf (fore-bank facies). Biostratigraphical and palaeoenvironmental observations allow us to reconstruct three subregions in the northern and eastern parts of the Thrace Basin with different depositional histories: (i) The eastern part of the territory, with an İstanbul Zone basement was fooded at the beginning of the middle late Bartonian (SBZ 18B), but the carbonate platform was drowned in the latest Bartonian (SBZ 18C). (ii) The Çatalca block, lying on the Istranca Massif, formed a palaeohigh in whose peripheries a similar depositional history to for the former sub-region can be reconstructed, although the central part was transgressed only in the late Priabonian and was not drowned at all. (iii) The northern margin of the recent Thrace Basin (also lying on the Istranca Massif) was fooded only in the latest Bartonian (SBZ 18C) or in the early Priabonian (SBZ 19) and the Priabonian carbonate platform had only partly and shallowly been drowned. This subregion very probably formed the real northern margin of the whole Thrace Basin in the Palaeogene.

Translated title of the contributionStratigraphy and larger foraminifera of the middle eocene to lower oligocene shallow-marine units in the northern and eastern parts of the trace basin, NW Turkey
Original languageTurkish
Pages (from-to)793-845
Number of pages53
JournalTurkish Journal of Earth Sciences
Volume20
Issue number6
DOIs
Publication statusPublished - Jan 1 2011

Keywords

  • Biometry
  • Biostratigraphy
  • Depositional history
  • Larger benthic foraminifera
  • Northern and eastern Thrace
  • Palaeogene
  • Taxonomy

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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