GÖKÇEADA’NIN (ÇANAKKALE) JEOLOJİSİ

Abstract

The geology and especially the magmatic rocks of Gokceada, 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 Camlica metamorphics which crop out with a tectonic uplift in a narrow area in northwest of Gokceada are the oldest rocks of the island. Early Eocene aged Karaagac Formation which is formed by submarine fan deposits unconformably overlies Camlica metamorphics. As for the Dagicitepe volcanic member which is formed by rhyolitic lavas, tuff and tuffites emplaced into Karaagac Formation cutting Camlica metamorphics is the oldest volcanic unit of the study area. On Karaagac Formation, Koyunbaba Formation has unconformably been deposited which consists of Middle Eocene shallow marine sediments. Then it has conformably been overlain by Sogucak Formation which consists of SE-NW extending reefal limestone. Middle-Upper Eocene aged Ceylan Formation which conformably overlies the Sogucak 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 “Gokceada Domes”. Diorite-monzonites porphyry which crystallized in lower zones of subvolcanics on the other hand constitutes Mutludere intrusion. In eastern and southern parts of Gokceada, Late Oligocene Gokceada 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 Eselek volcanics consisting of lava and pyroclastics with composition basaltic andesite and andesite are observed on a large area in east of Gokceada. Upper Miocene aged Canakkale 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 Gokceada. 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 Gokceada are formed by right lateral oblique faults which developed in Neo-tectonic period