New evidence of Middle Triassic (late Anisian to late Ladinian) radiolarians from blocks of pelagic volcanosedimentary successions in the Mersin Mélange, southern Turkey: Implications for the evolution of Neotethyan Izmir-Ankara-Ocean

2017-10-29
Tekin, Uğur Kağan
Bedi, Yavuz
Okuyucu, Cengiz
Göncüoğlu, Mehmet Cemal
Sayıt, Kaan
The Mersin Mélange (MM) as a part of the Mersin Ophiolitic Complex is a sedimentary complex including blocks and tectonic slices of oceanic litosphere and continental crust of various sizes. MM is mainly located to the north and northwest of city of Mersin in southern Turkey. Based on studies on four stratigraphic sections (the Cakalkayrak, the Aliclipinar-Southwest, the Sorgun-South and the Kocatepe-South) from either blocks or tectonic slices in MM reveals the presence of successions composing of thick basaltic pillow-and massive lava alternating with pelagic-clastic sediments and radiolarian cherts. Oldest radiolarian fauna corresponds to Spongosilicarmiger transitus zone of late Anisian age have been obtained from the Cakalkayrak section very close to contact with underlying basic volcanic. Higher in sequences of late Anisian age, radiolarian assemblages corresponding to Spongosilicarmiger italicus zone of late Anisian age have also been determined from alternation of chert and mudstone in the Cakalkayrak, the Aliclipinar-Southwest and the Sorgun-South sections. Considering the presence of sandstone layers over alternation of chert and mudstone in the Aliclipinar-Southwest section, it is suggested that latest Anisian was the beginning period of sandstone accumulation. Wide-spread sandstone sedimentation lasted at middle Early Ladinian taking into the consideration of sandstone layers at the base of the Kocatepe-South section. Lower and middle part of the Kocatepe-South section is represented by green chert-mudstone alternation corresponding to Muelleritortis firma Subzone of Muelleritortis cochleata Zone of late Early Ladinian and Pterospongus priscus and Spongoserrula rarauana subzones of Muelleritortis cochleata Zone of early-middle Late Ladinian age. The uppermost part of the section is represented by green-colored mudstones revealing that clastic sedimentation previaled up to the latest Ladinian time. Taking into the consideration of litho- and biostratigraphical data from Middle Triassic successions of several blocks in the MM, it is concluded that they correspond mainly to the blocks/slices of the Beysehir-Hoyran Nappes, which were originated from the southern margin of the Neo-Tethyan Izmir-Ankara Ocean. The late Anisian age found in the radiolarian cherts is the maximum age of a back-arc type basaltic volcanism in the Mersin Mélange. This is the first finding of representatives of the Middle Triassic oceanic basin formed above an intra-oceanic subduction zone in th Izmir-Ankara Ocean.
Citation Formats
U. K. Tekin, Y. Bedi, C. Okuyucu, M. C. Göncüoğlu, and K. Sayıt, “New evidence of Middle Triassic (late Anisian to late Ladinian) radiolarians from blocks of pelagic volcanosedimentary successions in the Mersin Mélange, southern Turkey: Implications for the evolution of Neotethyan Izmir-Ankara-Ocean,” presented at the Meeting of the International Association of Radiolarists, (20 - 29 Ekim 2017), Niigata, Japan, 2017, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/74895.