The geological and petrological properties of volcanic rocks in Çanakkale-Çan area in the northwest Anatolia and investigation of evolution of volcanism

Kuzey batı Anadolu'da Çanakkale-Çan yöresi volkanik kayaçlarının jeolojik ve petrolojik özellikleri ve evriminin araştırılması

Abstract

The study area between Çanakkale and Çan is located in Northwest Anatolia where metamorphic, igneous and sedimentary rocks all together crop out. The Çamlıca Metamorphics, form the basement.In the study area, magmatic activity began during late Eocene-Early Oligocene period and produced andesitic lavas and pyroclastic rocks (Dededağ volcanic). It was followed by andesitic and basaltic andesitic during the Early Miocene period (Kirazlı volcanic). Partly contemporaneously with the developments of these volcanic associations granitic intrusive rocks were emplaced to the subvolcanic depths (Çamyayla Plüton). A contact metamorphic aureole formed around the pluton displaying actino-lite-hornfels mineral assemblage. During the late Miocene the tectonic regime charged; a N-S extension began. The present E-W trending grabens began to developed. Basaltic lavas were erupted (Caf-erler Basalt) along the graben-bounding faults. The early phases of volcanic products were generated. In the upper mantle and geochemically enriched by the crustal components during its ascent. These volcanic rocks are similar to the subduction-induced lavas. In upper Miocene the Caferler trahy-basalts developed and located along the fracture zone. Magmatism, calc-alkaline characteristics, developed from upper-mantle and contaminated by crust is originated from subduction zone.The study area, its location in Biga peninsula, located in the North of Sakarya continent and Ezine zone which are Turkey's tectonic units. Sakarya continent along E-W, covered by Intra-Pontid zone in the North and Izmir-Ankara ofiyolit zone formed as a result of collision of Sakarya continent and Torid-Anatolid platform after Neo-Tethys ocean closed. There have been numerous studies related to geological events during Cretase-Oligocene in the NW Anatolia. As a result of these studies, it is known that Neo-Tethys ocean start to subducted towards North and closed, in the Cretase. N-S collision developed in the region continued between Upper Cretase and Miocene and continental crust shortened and thickened. In the study area Dededağ formation, investi- gated as lower volcanic unit, continued Upper Eo-cene-Oligocene. After Upper Eocene the region became terrestrial environment. Granitic intrusions associated with thickened and shortened continental crust located. In the study area Çamyayla pluton which formed with upper part of Dededağ volcanic as one inside the other, intruse into the Akpinar metamorphic rocks and cause contact metamorphism. Dededağ volcanic rocks resemble geochemical characteristics with Çamyayla pluton, showed calc-alkalen metaluminus features. However, two fresh ryholite samples, plotted into the peraluminus region, suggest that Lower Eocene-Upper Oligocene age volcanism's later stage may have been contaminated by the continental crust. The data obtained from major and trace elements diagrams showed volcanic arc and consumed continental border.Kirazlı formation lied uncomfortable on the Dededağ formation form middle volcanic units. Lower-Middle Miocene age Kirazlı formation represents middle-basic characteristics. In the Dededağ volcanic Ta/Th-Ta diagram, it is seen that AFC could be important where as in the Kirazlı volcanic assimilation with volcanic crystallization could be important. Volcanism developed until late Eocene after Paleotectonics units collision and became unit (Late Cretase-Middle Eocene) in the Aegean subduction zone. During subduction, it moved to south and volcanic side also moved along with it. The study area, represent the subduction zone associated magmatism aged between late Oligocene-Early Miocene.In the study area upper volcanic units outcropped during Late Miocene. The unit made of ryholite lava andpyroclastics developed one inside the other with Çan formation. During upper Miocene the volcanism changed its characteristics due to N-S extension regime causing thinning the continental litospher and alkaline volcanism developed. Starting with late Miocene West Anatolia-Aegean continental crust which are shortened-thickened started to collapse and graben formed. During this time, volcanism originated in the subduction zone left their place to volcanism originated in the north-south extension system. This volcanism is alkalen in character and basalt is widespread. Caferler basalt is different from the other basaltic rocks in the study area and contains large and group olivine. Caferler basalts represent basaltic-traciandesitic, tracibasalt characteristics.

Özet

nceleme alanı KB Anadolu 'da, Çanakkale-Çan arasında KB Anadolu 'nun metamorfık temel kayaç-ları, magmatik ve çökel kayaçların bir arada bulunduğu bir bölge konumundadır. Bölgedeki istifin temelini Üst Kretase-Alt Paleosen yaşlı Çamlıca metamorfıkleri oluşturmaktadır. înceleme alanında Üst Eosen-Alt Oligosenden itibaren kalkalkalen karakterli yaygın bir magmatik faaliyet Dededağ volkaniklerinin andezitik ve riyolitik karakterli lav ve bunların piroklastikleri ile başlayıp andezit, riyolit lav akıntılarıyla devam etmektedir. Dededağ formasyonu kalkalkalen ve metaluminus özellik göstermekte ve volkanik yay bileşeni ve tüketilen levha sınırı alanında yer almaktadır. Alt-Orta Miyosen, andezitik ve bazaltik kayaçlardan oluşan Kirazlı volkanikleri ve Çamyayla plütonu ile temsil edilir. Kirazlı formasyonun da yay bileşeni ve tüketilen levha sınırı volkanik kayaçları alanında yer aldığı görülür. Çamyayla plütonu sığ sokulumlu olup granit, granodiyorit, kuvars diyorit bileşimlidir. Çamyayla Plütonu çevresinde aktinolit hornfels ve kuvars-alkali feldspat hornfels fasiyesin de kontak metamorfızma zonu gelişmiştir. Plütonik kayaçlar kalkalkalen nitelikte olup, metaluminus özelliği göstermektedir. Ana ve iz elementlerin kullanıldığı diyagramların değerlendirilmesi sonucunda Çamyayla plütonunun yitim zonu bileşeni içerdiği belirlenmiştir. Üst Miyosen'de Caferler trakibazaltı gelişmiştir. Bu birim kırık zonları boyunca yerleşmiştir. Üst Miyosen dönemine kadarki süreçte gelişmiş olan magmatizma, Ege bölgesinin magmatizmasıyla uyumlu ve onun bir parçasını temsil ettiği kalkalkalen nitelikli, üst mantodan gelişen, kabukta kirlenen bu magmatizmadır. Dalma-batma kökenli olduğu ortaya konulmuştur. Bölgede Geç Miyosen 'den itibaren başlayan yeni tektonik rejim altında ise yeni bir magmatizmanın oluştuğu ve o dönemde de rift tipi bazaltların geliştiği belirlenmiştir.