BATI KARADENIZ (İSTANBUL), ORTA (GAZİPAŞA) VE DOĞU (TUFANBEYLİ-SAİMBEYLİ) TOROSLAR’DA ERKEN SİLÜRİYEN-ORTA DEVONİYEN İSTİFLERİNİN KONODONT TAKSONOMİSİ, BİYOSTRATİGRAFİSİ VE ÇÖKELME ORTAMLARI

Abstract

In this study, conodont taxonomy, biostratigraphy and depositional environments of the Early Silurian-Middle Devonian sequences have been studied in three different regions at the western Black Sea (İstanbul Region, İstanbul Unit), central Taurides (Gazipaşa region, Tahtalıdağ Nappe of the Antalya Nappes) and eastern Taurides (Tufanbeyli-Saimbeyli region, Geyikdağı parautochthonous) on seven stratigraphic sections. The conodont fauna and the standard conodont zones of each stratigraphic section have been determined. The Conodont Color Alteration Index (CAI) of each conodont taxa have been described and evaluated. The Çubuklu and Mihrabat Sections in the İstanbul Unit are performed from the Early Devonian Soğanlık Member of the Pelitli Formation. The conodont assemblage of the Çubuklu Section corresponds to the Lochkovian (Early Devonian) postwoschimidti and delta (omoalpha-trigonicus) zones. The CAI of the Çubuklu Section is equal to the 4.5-5.0 which indicates a temperature interval from 300-4800C. The microfacies properties of the carbonates in the Çubuklu Section indicate a deposition platform interior open-marine environments. The conodont fauna recovered from the Mihrabat Section corresponds to late Lochkovian (Early Devonian) delta (omoalpha-trigonicus) zone. The CAI of this assemblage is 5.0 and this is interpreted as to the temperature between 300 and 480oC. According to the microfacies analysis of the carbonates in this section, rock units deposited at platform interior open-marine environments. Two stratigraphic sections of the Tahtalıdağ Nappe of the Antalya Nappes were performed from the central Taurides as Silurian Kocaketir Section of the Sapandere Formation and the Early Devonian Yaylacık Section of the Güneyyaka Formation. Conodont faunas of the Kocaketir Stratigraphic Section corresponds to the Kockelella crassa and Ozarkodina excavata hamata zones and indicate late Ludlow (Late Silurian) age. The CAI value of the conodonts in this section is 4.0 and this indicate a 190-3000C temperature interval. The microfacies properties of the carbonates in the Kocaketir Section indicate a deposition slope environments. The Lochkovian conodont assemblage were retrieved from the Yaylacık Section and they corresponds to the woschimidti and postwoschmidti zones. The CAI value of the obtained association is equal to the 3.5 and indicating a temperature between 110 and 190oC. The microfacies of the carbonates in the Yaylacık Section are characteristics facies of the platform interior open-marine environments. Three stratigraphic sections from the Geyikdağı Paraaotochnous were performed respectively, the Pekmezli Section of the Silurian Yukarıyayla Formation, the Gökmenler Section from the Silurian Puşcutepe, Yukarıyayla and Sıradamlar Formations and the Bozgüney Section of Middle Devonian Şafaktepe Formation from the eastern Taurides. The Pterospathodus amorphognathoides amorphognathoides conodont zone has been recognised from basal part of the Pekmezli Section. The obtained conodont assemblage of the section indicates Llandovery-early Lochkovian (Silurian-Early Devonian) age. Based on the CAI value (4) of the conodonts in the section corresponds to 190-3000C temperature. Microfacies of the carbonates are comparable with the Toe-of-slope environments. Conodont biozones has not been recognised in the Gökmenler Section due to the long ranging (Ludlow-Pridoli, Late Silurian) conodont taxa. The conodont assemblage of the section corresponds to the 4 CAI value and indicates 190-300oC temperature. Depositional environment of the section defined as the Toe-of-slope environments based on microfacies descriptions from the carbonates. Age of the conodont taxa in Bozgüney Stratigraphic Section is assigned as Givetian (Middle Devonian). One conodont zone, Polygnathus ansatus have been recognized. The CAI value of the conodonts in the Bozgüney Section is 3.5-4.0 and they correspons to 110-300oC temperature. Based on the microfacies analysis of the carbonates in Bozgüney Section they correspons to the platform interior open-marine environments. A total of 41 species, subspecies and morphotypes belonging to 9 genus conodonts have been determined. Within these fauna one species (Ozarkodina dentatuslobis n. sp.) was determined as new. Seven conodont biozones are recognized based on the described conodont taxa in the studied sections.