Stratigraphic features and geotectonic evolution of the south edge (narman-oltu-olur) of eastern Pontids (Northeast Turkey)
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Tarih
2008
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info:eu-repo/semantics/closedAccess
Özet
The southern edge of Eastern Pontids is covered by rock units belonging to two distinct continental crusts that reunited through a Late Upper Cretaceous-Eocene suture zone. In the north of the Suture zone (Olur), Paleozoic aged acid magmatits (Permo- Carboniferous) constitute the continental crust basement. On this basement, there is uninterrupted marine sediment which has disconformably developed between Upper- Lias Late Cretaceous. These sediments have deposited under the conditions of Lias- Lower Malm basic volcanic intercalated and fragmented shallow marine, carbonate Upper Malm-Neocomien (Valanjinien), Hotrivien-Kampanien flysh and Meastrihtien shallow marine carbonate facieses. Thus, the deposition period that was dominated by pyroclastics as a result of Kampanien volcanic activity has come into being. At the lowest level of suture zone (Oltu), Santonien-Meastrihtien aged external blocked (olistolithe) tectono-sedimenter mixture take place in the typical flysh facieces. In the south of Suture zone (Narman), ophiolite units take place in the position of tectonic segments that are generally inclined to the north and belonging oceanic crust in the shape of ophiolite mixture. In the north of continental crust where arc volcanism is situated, the fact that the ophiolite rocks, in the south, outcrops of north-inclined tectonic segments and oceanic crust is a proof of a northwards subduction. The volcanic activity that is seen in the pyroclastic type in this field has first started in Kampanien and then in dasitic Turonien type in the relatively north. This displays the fact that the northwards subduction has developed at the beginning of Upper-Cretaceous. These three rock units belonging distinct tectonic environments are generally covered with angular disconformity that are constituted by units of volcanic and Eocene aged shallow marine-continental fragments. Thus, opening in Lias, with the developed oceanic northwards subduction, has been closed before Eocene. At the end of Eocene, in the completely non-marine suture zone and intermountain molas basins, which were limited between the mountain ranges that are stuck between the overlapping postorogenic ophiolite, Oligocene aged continental fragments have been developed. These units have been covered by Post and Upper Miocene and generally horizontal or almost horizontally situated volcanic and continental sediments. This zone has been under the influence of the tectonic controls of both the Lias-Lower Cretaceous and the beginning of Upper-Cretaceous to recent compression. A control of mutual Upper Cretaceous-Upper Miocene compression and thickening, and another compression control influenced by Upper Miocene to recent compression and thickening activity have been dominant, because curved and overlapping structures of pre-upper Miocene have been covered by almost horizontally situated Late Miocene aged rock units in disconfirmity. In this respect, the beginning of the neotectonic period in this zone has to be in the Upper Miocene.
Açıklama
8th International Scientific Conference on Modern Management of Mine Producing, Geology and Environmental Protection, SGEM 2008 -- 16 June 2008 through 20 June 2008 -- Albena -- 101476
Anahtar Kelimeler
Eastern Pontids, Geotectonic evolution, Northeast Turkey, Stratigraphy, Suture zone
Kaynak
8th International Scientific Conference on Modern Management of Mine Producing, Geology and Environmental Protection, SGEM 2008
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N/A
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1
