Paleogene extension in the Northern Aegean: Colluvial/debris flow deposits of the early-middle Eocene in the NW Thrace Basin, Turkey

The Thrace Basin consists of Paleogene-Neogene deposits that lie in the lowland south of the Strandja highlands in NW Turkey, where metagranitic and metasedimentary rocks occur. The Akalan Formation consisting of colluvial fan/debris flow deposits represents the base of the sequence in the northern Thrace basin where it is bounded by a right lateral strike-slip oblique fault called "The Western Strandja Fault Zone". This formation exhibits a coarse-grained, angular and grain-supported character close to the fault zone which has releasing-bends. Fine-grained. rounded, and matrix-supported sediments occur away from the contact. During this study, the Akalan Formation is described for the first time as having larger benthic foraminifera (LBF) of Coskinolina sp of Ypresian Lutetian, Nummulites obesus of early Lutetian, Diciyoconus egyptiensis of Lutetian, Orbitolites sp. of Ypresian-Bartonian, Afiliola sp of early-middle Eocene. ldalina grelaudae of early Lutetian-Priabonian, Ammobaculites agglutinans. Amphimorphina crassa, Dentalina sp., Nodosaria sp., Operculina sp., Lenticulina sp., Quinqueloculina sp. and Amphistegina sp. of Eocene. This unit passes upward with a conformity into reefal limestones of the middle/late Eocene-early Oligocene Sogucak Formation. At times, the limestone overlies the conformity, there is an indication of a prograding sedimentary sequence. The new stratigraphic, paleontological, sedimentological and structural findings related to the NW Thrace Basin suggest a strong transtensional/extensional tectonic control for the initial Paleogene sedimentary deposition during the Ypresian Lutetian period as shown by fossil content of the Akalan Formation. Right lateral-slip extensional tectonics appears to have had activity during the middle-late Eocene transgressive deposition of the Sogucak Formation when the basin became deepened and enlarged

Upper Cretaceous-middle Eocene aged olistrostromal pelagic units in the Biga Peninsula (NW Anatolia); Balikkaya formation

Balikkaya formation consists of olistostromal units with a burgundy coloured mudstone, siltstone and pelagic limestone matrix containing various sizes of UpperJurassic-Lower Cretaceous limestone (Bilecik Limestone) blocks and Triassic Karakaya Complex blocks, which crop out in the west, south and southwest of Biga Town in Biga Peninsula (NW Anatolia). The matrix of Balikkaya formation, of which age and sedimentary environment are controversial, contains Late Cretaceous (Maastrichtian) Abathomphalus mayaroensis (Bolli), Abathomphalus sp., Rosita fornicata (Plummer), Globotruncanidae, early Paleocene (Danian) Morozovella pseudobulloides (Plummer), late Paleocene (Thanetian) Morozovella velascoensis (Bolli), early Eocene Acarinina pentacamarata (Subbotina), middle Eocene Turborotalia frontosa (Subbotina), Turborotalia cerroazulensis (Cole), Orbulinoides beckmanni (Saito), Hantkenina sp. pelagic foraminifera and Radiolariafossils representing the deep marine environment. These paleontological, lithological and sedimentological data obtained from Balikkaya formation show that Balikkaya formation developed in a deep marine environment under tectonic control starting from Late Cretaceous and ending in early-middle Eocene. This pelagic unit indicates the presence of a extensional tectonic regime on the Biga Peninsula and the fault activity along the southeastern edge of the Thrace Basin in the Late Cretaceous-Middle Eocene time interval