Akademik Veri Yönetim Sistemi
European Geosciences Union General Assembly 2017, Vienna, Avusturya, 23 - 28 Nisan 2017, cilt.19, ss.11249
Two stratigraphical sections were measured along the Upper Jurassic – Lower Cretaceous carbonate successions
exposed in a tectonic klippe of the Sakarya Zone (Pontides), north of Sivrihisar. According to the biozonation and
microfacies types, two coeval but dissimiliar rock successions, separated by a thrust fault, have been detected.
These successions belong to different depositional belts of the Edremit-Bursa-Bilecik Carbonate Platform
(EBBCP), western Sakarya Zone. The lower succession displays a slope to basin facies and consists of the
Kimmeridgian – Berriasian Yosunlukbayırı Formation and the overlying Valanginian Sogukçam Limestone. ˘
Within these deposits the following biozones were defined: Globuligerina oxfordiana – Mohlerina basiliensis Zone
(Kimmeridgian), Saccocoma Zone (Lower Tithonian), Protopeneroplis ultragranulata Zone (Upper Tithonian),
Crassicollaria (massutiana subzone) Zone (uppermost Tithonian), Calpionella (alpina, Remaniella, elliptica
subzones) Zone (Lower Berriasian), Calpionellopsis (simplex, oblonga subzones) Zone (Upper Berriasian) and
Calpionellites (darderi subzone) Zone (Lower Valanginian). This succession is overthrusted from north to south
by another distinct succession characterized by the shallow marine carbonate facies of the Kimmeridgian Günören
Formation. Within this unit Labyrinthina mirabilis – Protopeneroplis striata (Kimmeridgian) Zone is recognized.
A facies model is proposed for the Sivrihisar transect of the EBBCP for Kimmeridgian – Valanginian interval,
based on the distribution of microfacies types. The toe-of-slope facies are characterized by peloidal-bioclastic
packstone, mudstone-wackestone and calpionellid/ radiolarian wackestone–packstone comprising pelagic taxa
(calpionellids, radiolaria, Globochaete sp., Pithonella sp., Saccocoma sp., calcareous dinocysts, aptychi, very
rare planktonic foraminifera and nannoconids) and rare fossil groups transported from the carbonate platform
(benthic foraminifera, microencrusters, worm tubes, bivalve, crinoid and echinoid fragments). These deposits
represent the background pelagic deposition on the slope. The slope facies are mainly composed of bioclasticpeloidal/ bioclastic-intraclastic packstone, rudstone-grainstone, bioclastic-lithoclastic floatstone-rudstone and
reflect generally the increase in the amount of platform derived material (benthic foraminifera, microencrusters,
worm tubes, corals, sponges, bryozoa). The matrix of these coarse grained deposits also contains pelagic taxa
(calpionellids, radiolaria, Saccocoma sp., Globochaete sp., Pithonella sp., aptyhci). The slope facies are sometimes
intercalataed with the toe-of-slope type facies indicating quiescence periods. The shallow marine carbonate
platform deposits are characterized by peloidal-intraclastic poorly washed grainstone with bioclasts, bioclastic
mudstone-wackestone, intraclastic packstone-rudstone and contain several shallow marine fossils (benthic
foraminifera, encrustres and rare echnoid, bivalve and coral fragments) without any pelagic taxa. These carbonates
are interpreted as back-reef platform deposits that should not be far away from the platform margin due to the
co-occurence of Protopeneroplis striata and Mohlerina basiliensis, abundant in the shelf edge and reefal areas with
the complex benthic foraminifera, Labyrinthina mirabilis common in lagoonal areas.
If the position of the studied sections with respect to the EBBCP is considered, the studied basin and slope
facies should represent the southern platform margin and slope environments of this carbonate platform that faced
an ocean to the south during the Jurassic-Cretaceous. The slope and basinal facies overthrusted by the shallow
marine deposits in a region situated to the south of the main ˙Izmir-Ankara-Erzincan (˙IAE) suture suggests an
important disruption and shortening of the EBBCP margin and slope deposits related to the closure of the ˙IAE
ocean.