Depositional setting, provenance and tectonic-volcanic setting of Eocene-Recent deep-sea sediments of the oceanic Izu-Bonin forearc, NW Pacific (IODP Expedition 352)

New biostratigraphical, geochemical, and magnetic evidence is synthesized with IODP Expedition 352 shipboard results to understand the sedimentary and tectono-magmatic development of the Izu–Bonin outer forearc region. The oceanic basement of the Izu–Bonin forearc was created by supra-subduction zone seafloor spreading during early Eocene (c. 50–51 Ma). Seafloor spreading created an irregular seafloor topography on which talus locally accumulated. Oxide-rich sediments accumulated above the igneous basement by mixing of hydrothermal and pelagic sediment. Basaltic volcanism was followed by a hiatus of up to 15 million years as a result of topographic isolation or sediment bypassing. Variably tuffaceous deep-sea sediments were deposited during Oligocene to early Miocene and from mid-Miocene to Pleistocene. The sediments ponded into extensional fault-controlled basins, whereas condensed sediments accumulated on a local basement high. Oligocene nannofossil ooze accumulated together with felsic tuff that was mainly derived from the nearby Izu–Bonin arc. Accumulation of radiolarian-bearing mud, silty clay, and hydrogenous metal oxides beneath the carbonate compensation depth (CCD) characterized the early Miocene, followed by middle Miocene–Pleistocene increased carbonate preservation, deepened CCD and tephra input from both the oceanic Izu–Bonin arc and the continental margin Honshu arc. The Izu–Bonin forearc basement formed in a near-equatorial setting, with late Mesozoic arc remnants to the west. Subduction-initiation magmatism is likely to have taken place near a pre-existing continent–oceanic crust boundary. The Izu–Bonin arc migrated northward and clockwise to collide with Honshu by early Miocene, strongly influencing regional sedimentation

Evolution of the Lycian Allochthon, western Turkey, as a north-facing Late Palaeozoic to Mesozoic rift and passive continental margin

Special Issue: Advances in Turkish Geology, Part IRegional tectono-stratigraphic analysis allows widely distributed outcrops of mainly Mesozoic sedimentary rocks within the Lycian Allochthon, SW Turkey, to be correlated and placed within four regionally developed thrust sheets, the Karadag Thrust Sheet (lowest), the Teke Dere Thrust Sheet, the Koycegiz Thrust Sheet (highest), and the Yavuz Thrust Sheet. The Karadag Thrust Sheet records Late Carboniferous, Lower and Upper Permian continental shelf/ lagoonal deposition. The overlying Teke Dere Thrust Sheet includes a rift succession of Late Permian age that was subaerially exposed during much of the Triassic; a marine transgression followed in the Early Jurassic succeeded by subsidence that formed a continental slope from Middle Jurassic to Palaeocene times. The overlying Koycegiz Thrust Sheet records Upper Triassic oceanic crust (along a rifted margin), overlain by a Lower Jurassic carbonate platform; this then subsided to form a continental slope that survived until Late Cretaceous times. The Lycian Allochthon is restored as a north-facing Mesozoic rift and passive margin taking account of structural evidence indicating southward thrust emplacement and comparisons of sedimentary successions. Mainly deep-water sediments of Triassic to Late Cretaceous age, preserved as blocks within melange units above the Lycian Thrust Sheets (Layered Tectonic Melange and Ophiolitic Melange), are interpreted as deep-water sediments deposited on Mesozoic (Neotethyan) oceanic crust. Subduction of the ocean basin proceeded from north to south, beginning with accretion of oceanic-derived melange and disrupted thrust sheets. Debris was shed into a continentward-migrating flexural foredeep, initially located along the distal edge of the continental margin in Campanian-Maastrichtian times; this foredeep then propagated southwards in stages over more proximal continental crust (including an intra-platform basin). The first main stage of southeastward propagation was in Palaeocene and Eocene times followed by a second stage in Oligocene-Miocene times. The Lycian Allochthon was finally emplaced over the most proximal (southeasterly) foredeep (i.e. the Kas basin) in Late Miocene time.Alan S. Collins and Alastair H. F. Robertso

Tethyan tectonics of the Mediterranean region: Some recent advances

[No abstract available

Late Cretaceous–Cenozoic subduction–collision history of the Southern Neotethys: new evidence from the Çağlayancerit area, SE Turkey

Evidence of the subduction–collision history of the S Neotethys is well exposed in the frontal part of the SE Anatolian thrust belt and the adjacent Arabian continental margin. The foreland succession in the study area begins with Eocene shelf carbonates, ranging from shallow marine to deeper marine, without sedimentary input from the Tauride continent to the north. After a regional hiatus (Oligocene), sedimentation resumed during the Early Miocene with terrigenous gravity-flow deposition in the north (Lice Formation) and shallow-marine carbonates further south. Clastic detritus was derived from the Tauride continent and oceanic accretionary material. The base of the overriding Tauride allochthon comprises ophiolite-derived debris flows, ophiolite-related mélange and dismembered ophiolitic rocks. Above this, the regional-scale Bulgurkaya sedimentary mélange (an olistostrome) includes blocks and dismembered thrust sheets of metamorphic rocks, limestone and sandstone, which include Late Cretaceous and Eocene foraminifera. The matrix is mainly strongly deformed Eocene–Oligocene mudrocks, hemipelagic marl and sandstone turbidites. The thrust stack is topped by a regionally extensive thrust sheet (Malatya metamorphic unit), which includes greenschist facies marble, calcschist, schist and phyllite, representing Tauride continental crust. Beginning during the Late Mesozoic, the S Neotethys subducted northwards beneath a backstop represented by the Tauride microcontinent (Malatya metamorphic unit). Ophiolites formed within the S Neotethys and accreted to the Tauride active margin. Large-scale sedimentary mélange developed along the Tauride active margin during Eocene–Oligocene. On the Arabian margin, a sedimentary hiatus and tilting (Oligocene) is interpreted to record initial continental collision. The Early Miocene terrigenous gravity flows represent a collision-related flexural foreland basin. Southward overthrusting of the Tauride allochthon took place during Early-Middle Miocene. Associated regional uplift triggered large-scale alluvial deposition. The foreland folded and faulted in response to suture zone tightening (Late Miocene). Left-lateral strike slip characterised the Plio-Pleistocene. © 2015, Springer-Verlag Berlin Heidelberg

Tectonic and sedimentary evolution of the Cenozoic Hatay Graben, Southern Turkey: A two-phase model for graben formation

New structural and sedimentary studies form the basis of a new interpretation for the Neogene Hatay Graben. Fault analysis reveals three contemporaneous trends of fault orientation (000°-180°, 045°-225° and 150°-350°) suggesting that the graben is transtensional in nature. Sedimentary studies show that, following shallow-marine deposition from the Late Cretaceous to the Eocene, a hiatus ensued until Early Miocene fluvial sedimentation. After a Mid-Miocene marine transgression, water depths increased until the Messinian salinity crisis, followed by a regression from the Pliocene to the present day. The basin initially developed as the distal margin of a foreland basin of the Tauride allochthon to the north, developing a classic sedimentary sequence during Mid-Late Miocene. Stresses caused by loading of the crust created a flexural forebulge to the south that supplied sediment mainly northwards. During the Plio-Quaternary, transtensional graben development took place, primarily influenced by the westward tectonic escape of Anatolia along the East Anatolia Fault Zone and left-lateral offset along the northward extension of the Dead Sea Transform Fault. This area is, thus, an excellent example of a foreland basin reactivated in a strike-slip setting. Our new two-phase model: foreland basin, then transtensional basin for the Hatay Graben, is in contrast to previous models, in which it was generally assumed that the Plio-Quaternary Hatay Graben represents a direct extension of the Dead Sea Fault Zone or the East Anatolian Fault Zone. © The Geological Society of London 2006

Overview of the Palaeozoic-Neogene evolution of Neotethys in the Eastern Mediterranean region (Southern Turkey, Cyprus, Syria)

Valid palaeotectonic and palaeogeographical reconstructions of the easternmost Mediterranean and adjacent region involve a long-lived Tethys (Rheic, Palaeotethyan and Neotethyan oceans), northward subduction beneath Eurasia and rifting of continental fragments from Gondwana. Rifted microcontinents bordering Gondwana were separated (from south to north) by the Southern Neotethyan ocean, the Berit ocean (new name), the Inner Tauride ocean and the İzmir-Arkara-Erzincan ocean. Mid-Permian to Mid-Triassic pulsed rifting culminated in Late Triassic-Early Jurassic spreading of the Southern Neotethyan oceans (the main focus here). After Early-Mid-Jurassic passive subsidence, the Late Jurassic-Early Cretaceous was characterized by localized alkaline, within-plate magmatism related to plume activity or renewed rifting. Late Cretaceous ophiolites formed above subduction zones in several oceanic basins. Ophiolites were emplaced southwards onto the Tauride and Arabian platforms during the latest Cretaceous. The Southern Neotethys sutured with the Arabian margin during the Early-Middle Miocene, while oceanic crust remained in the Eastern Mediterranean further west. The leading edge of the North African continental margin, the Eratosthenes Seamount, collided with a subduction trench south of Cyprus during the Late Pliocene-Pleistocene, triggering rapid uplift. Coeval Plio-Quaternary uplift of the Taurides may relate to break-off or delamination of a remnant oceanic slab. © 2012 EAGE/Geological Society of London

Late palaeozoic-early cenozoic tectonic development of southern turkey and the easternmost mediterranean region: Evidence from the inter-relations of continental and oceanic units

Reconstructions of the Anatolian continent and adjacent areas assume the existence of one or more continental fragments during Mesozoic-Early Cenozoic time. These rifted from North Africa (Gondwana) during the Triassic, drifted across the Mesozoic Tethys and collided with Eurasia during latest Cretaceous-Paleocene time. Current reconstructions range from a regional-scale Tauride-Anatolide continent with oceanic basins to the north and south, to numerous rifted continental fragments separated by small oceanic basins. Field-based evidence for the inter-relations of the continental blocks and associated carbonate platforms is discussed and evaluated here, especially to distinguish between sutured oceans and intra-continental convergence zones. Several crustal units are restored as different parts of one large Tauride-Anatolide continent, whereas several smaller crustal units (e.g. Kirşehir massif; Bitlis/Pütürge and Alanya/ Kyrenia units) are interpreted as continental fragments bordered by oceanic crust. We infer a relatively wide I?zmir-Ankara-Erzincan ocean in the north and also a wide South Neotethyan ocean in the south. Several smaller oceanic strands (e.g. Inner Tauride ocean, Berit ocean and Alanya ocean) were separated by continental fragments. Our proposed reconstructions are shown on palaeotectonic maps for Late Permian to Mid-Miocene. The reconstructions have interesting implications for crustal processes, including ophiolite genesis and emplacement. © The Geological Society of London 2013

Permian–Recent palaeogeographical and tectonic development of Anatolia: some recent contributions

[No abstract available