Mersin Melanjı (Kb Mersin) Geç Triyas - Erken Jura Yaşlı Pelajik İstiflerinin Radyolarya Biyostratigrafisi, Taksonomisi Ve Ortamsal Yorumlamaları

Abstract

The subject of this study is to set up the Radiolarian biostratigraphy, taxonomy and environmental interpretations of the Late Triassic - Early Jurassic pelagic sequences of the Mersin Melange which is widely dipersed at the north west of Mersin city. In this study, three measured stratigraphic sections as Tavusçayırı, Çağılpınar and Sahançanak of Mersin Melange have been studied. The aim of the study is to achieve data about the generataion and origin of Mersin Melange. Mersin Melange is composed of tectonic slices and blocks of pelagic limestones, platform limestones, ophiolite components and volcanics ranging from meters to kilometres, characteristics and different ages. The matrix is composed of units such as mudstone and conglomerate. The Mersin Melange is in sedimentary melange type showing block in matrix feature. The occurence of the Mersin Melange is Late Cretaceous and the depositional environment of the melange is in an active continental margin. The blocks and the tectonic slices within the matrix are settled down in the melange by big landslides. A total of 77 samples have been collected from the sections measured in Mersin Melange. 59 of samples are from the sedimentary rocks while 18 are from the volcanic rocks. 20 of sedimentary rock samples yielded Radiolarian faunas. A total of 311 taxa belonging to 109 genus of Radiolarians are determined. Within these fauna one genus (Mersinosaturnalis) and 8 species (Cantalum magna, Sarla okuyucui, Nazarovella trifurcata, Mersinosaturnalis simplex, Mersinosaturnalis spinosa, Quadrisaturnalis deceum, Quadrisaturnalis undecium, Annulopoulpus robustus) are determined for the first time. Detailed work have been carried out about the Radiolarian faunas and their correlation has been done with the studies carried out around the world. As a result the age of the sections are identified as Late Triassic to Early Jurassic. Besides, microfacies properties of thin sections of the sedimentary rocks have been utilised. As a result, it is defined as the examined rocks have been precipitated at deep sea, toe-of-slope and slope facies in the basin environment. In Tavusçayırı Section there Early - Middle Carnian shallow marine limestones overlain by late Middle Carnian - Late Carnian Huğlu Sequence and Early Norian - Sinemurian pelagic limestones at the top. Highly diversed radiolarian fauna recovered from the limestones of Tavusçayırı Measured Section corresponds to Tetraporobrachia haeckeli Zone [1], Elbistanium gracile Zone [2], Spongotortilispinus moixi Zone [3], Capnodoce ruesti Zone [1] and Trexus dodgensis Zone [4]. The deposition interval of Tavusçayırı Section is Early Carnian - Sinemurian. Çağılpınar Section is composed of Middle Carnian shallow marine limestones overlain by Late Carnian pillow lavas and alternation of tuffites and thin-bedded limestones. Highly diverse radiolarian fauna recovered from the limestones corresponds to Spongotortilispinus moixi Zone [3] in Çağılpınar Measured Section. The deposition interval of Çağılpınar Section is Middle - Late Carnian. Sahançanak Section is composed of Late Carnian tuffites and thin-bedded limestone alternation. The radiolarian fauna recovered from the Sahançanak Measured Section corresponds to Spongotortilispinus moixi Zone [3]. The deposition interval of Sahançanak Section is Late Carnian. . Huğlu Sequence of Beyşehir - Hoyran Nappe is composed of Middle - Late Carnian tuff and basic volcanics with intercalations of limestones and shales overlain by Late Triassic - Cretaceous pelagic limestones with chert nodules and clastics. Tavusçayırı, Çağılpınar and Sahançanak Measured Sections of Mersin Melange has great similarities with the characteristics of Huğlu Sequence of Beyşehir - Hoyran Nappe according to their litological characteristics, age intervals and biostratigraphic features.