The geology and especially the magmatic rocks of Gökçeada, which is the biggest island of Turkey and located at 20 km's west of Biga Peninsula, constitute the subject of this study. Late Ediacaran/Early Paleozoic aged Çamlıca metamorphics which crop out with a tectonic uplift in a narrow area in northwest of Gökçeada are the oldest rocks of the island. Early Eocene aged Karaağaç Formation which is formed by submarine fan deposits unconformably overlies Çamlıca metamorphics. As for the Dağiçitepe volcanic member which is formed by rhyolitic lavas, tuff and tuffites emplaced into Karaağaç Formation cutting Çamlıca metamorphics is the oldest volcanic unit of the study area. On Karaağaç Formation, Koyunbaba Formation has unconformably been deposited which consists of Middle Eocene shallow marine sediments. Then it has conformably been overlain by Soğucak Formation which consists of SE-NW extending reefal limestone. Middle-Upper Eocene aged Ceylan Formation which conformably overlies the Soğucak Formation and the early Oligocene aged Mezardere Formation which conformably overlies Ceylan Formation have been deposited due to turbiditic currents in deep marine environment. Late Eocene(?) -Oligocene aged subvolcanics which cut Mesozoic and Eocene units and emplaced into Eocene aged sedimentary units in the form of crypto dome and dome form the recent rigid topography of the study area and are the second magmatic phase called the "Gökçeada Domes". Diorite-monzonites porphyry which crystallized in lower zones of subvolcanics on the other hand constitutes Mutludere intrusion. In eastern and southern parts of Gökçeada, Late Oligocene Gökçeada ignimbrites are located which are observed in the form of pumice flows on Mezardere Formation. These ignimbrites are then overlain by Early Miocene aged Kesmekaya volcanics which are formed by blocky ash flows. Middle Miocene aged Eşelek volcanics consisting of lava and pyroclastics with composition basaltic andesite and andesite are observed on a large area in east of Gökçeada. Upper Miocene aged Çanakkale Formation which is generally formed by the intercalation of poor consolidated conglomerate, sandstone, siltstone and marl crops out in narrow regions at east, southeast and south of Gökçeada. Quaternary alluvial deposits and debris composed of loose, unconsolidated sand, silt and other sediments unconformably overlie all previous units and complete the succession. Main tectonic structures of Gökçeada are formed by right lateral oblique faults which developed in Neo-tectonic period.
The geology and especially the magmatic rocks of Gökçeada, which is the biggest island of Turkey and located at 20 km's west of Biga Peninsula, constitute the subject of this study. Late Ediacaran/Early Paleozoic aged Çamlıca metamorphics which crop out with a tectonic uplift in a narrow area in northwest of Gökçeada are the oldest rocks of the island. Early Eocene aged Karaağaç Formation which is formed by submarine fan deposits unconformably overlies Çamlıca metamorphics. As for the Dağiçitepe volcanic member which is formed by rhyolitic lavas, tuff and tuffites emplaced into Karaağaç Formation cutting Çamlıca metamorphics is the oldest volcanic unit of the study area. On Karaağaç Formation, Koyunbaba Formation has unconformably been deposited which consists of Middle Eocene shallow marine sediments. Then it has conformably been overlain by Soğucak Formation which consists of SE-NW extending reefal limestone. Middle-Upper Eocene aged Ceylan Formation which conformably overlies the Soğucak Formation and the early Oligocene aged Mezardere Formation which conformably overlies Ceylan Formation have been deposited due to turbiditic currents in deep marine environment. Late Eocene(?)-Oligocene aged subvolcanics which cut Mesozoic and Eocene units and emplaced into Eocene aged sedimentary units in the form of crypto dome and dome form the recent rigid topography of the study area and are the second magmatic phase called the "Gökçeada Domes". Diorite-monzonites porphyry which crystallized in lower zones of subvolcanics on the other hand constitutes Mutludere intrusion. In eastern and southern parts of Gökçeada, Late Oligocene Gökçeada ignimbrites are located which are observed in the form of pumice flows on Mezardere Formation. These ignimbrites are then overlain by Early Miocene aged Kesmekaya volcanics which are formed by blocky ash flows. Middle Miocene aged Eşelek volcanics consisting of lava and pyroclastics with composition basaltic andesite and andesite are observed on a large area in east of Gökçeada. Upper Miocene aged Çanakkale Formation which is generally formed by the intercalation of poor consolidated conglomerate, sandstone, siltstone and marl crops out in narrow regions at east, southeast and south of Gökçeada. Quaternary alluvial deposits and debris composed of loose, unconsolidated sand, silt and other sediments unconformably overlie all previous units and complete the succession. Main tectonic structures of Gökçeada are formed by right lateral oblique faults which developed in Neo-tectonic period.
At southwest of Gölbafl› (Ankara) there are two different sequences in tectonic contact. The one at the bottom with low-degree metamorphism is represented by phyllite, metabasite, crystallized limestone, schist and quartz porphyry veins. Above them are early Carboniferous-late Permian neritic and pelagic carbonates which are unconformably overlain by late Permian clastics and carbonates. Samples collected from neritic carbonates yielded early Carboniferous (Visian-Serpuhovian) to middle Carboniferous (Bashkirian-Moskovian) ages. These carbonates of shallow facies character are overlain by radiolaritebearing pelagic deposits of middle Carboniferous-Permian age. Fossils from the upper most neritic carbonates gave Kubergandian-Murgabian age. This Permo-Carboniferous sequence is unconformably overlain by a sequence consisting of clastics and carbonates. Basal conglomerates and sandstones contain abundant quartz and fewer amounts of carbonated-cemented metamorphic rock fragments and they change to medium-thick bedded dolomitic limestone and limestones to the top. The age of these carbonates of shallow marine character is found Murgabian-Dorashamian. It is suggested that late Paleozoic carbonate basement was deposited in a neritic environment during early-middle Carboniferous, in a pelagic environment during middle Carboniferous-Permian and again in a neritic environment during Kubergandian-Murgabian. Following a deformation stage, it was accreted onto the Variscan basement at north and carbonate deposition took place as a result of late Permian transgression and finally some of exotic blocks within the upper Karakaya Complex were derived from this basement.
Orta Anadolu'da Kırşehir çevresinde Tersiyer öncesi temel birimlerini oluşturan Kırşehir Masifi'ne ait metamorfitler alttan üste doğru uyumlu ve geçişli Geç Devoniyen yaşlı Kalkanlıdağ, Karbonifer-Erken Permiyen yaşlı Kervansaray ve Geç Permiyen yaşlı Bozçaldağ formasyonları ile bunların üzerine uyumsuzlukla gelen Triyas yaşlı Demirtepe ve Jura-Kretase yaşlı Saytepe formasyonlarından oluşmaktadır. Demirtepe formasyonuna ait kuvarsitler içerisindeki kırıntı zirkonlardan U/Pb yöntemi ile 237 My çökelme yaşı, metabazitlerden ise toplam kayadan 40 Ar/ 39 Ar yöntemi ile 94.5 My ve 83.7±3.3 My metamorfizma yaşları elde edilmiştir. Bu birimler üzerine tektonik olarak yerleşen Neotetis'in kuzey koluna ait Çiçekdağı napı içerisinde Kasımağa ve Sırataşlar formasyonları ile Turoniyen-Santoniyen yaşlı ensimatik ada yayı magmatizması ürünü olan Kargınkızıközü formasyonu ayırtlanmıştır. Metamorfitler ile üzerlerindeki ofiyolitik kayaları kesen Orta Anadolu plütonik kayaları bileşim, köken ve yaşlarına göre ayırtlanmış olup U/Pb yöntemi ile Baranadağ plütonundan 71.9±1.7 My; Çayağzı plütonundan 84.0±1.9 My ve 71.9±7.2 My; Buzlukdağı plütonundan ise 69.1±1.2 My ve 40 Ar/ 39 Ar ile 65.3±1.1 My yaşlar elde edilmiştir. Granit, monzonit ve siyenit bileşimli plütonik kayaların yüzey-yarı derinlik kayaları olan Kötüdağ volkanitine ait trakiandezitlerden 40 Ar/ 39 Ar yöntemi ile toplam kayadan 79.1±1.2/68.2±1.2 My ve 74.5 My yaşlar elde edilmiştir. Tüm bu birimlerin üzerine Tersiyer örtü birimleri açısal uyumsuzlukla gelmektedir.
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