Palaeozoic-Recent geological development and uplift of the Amanos Mountains (S Turkey) in the critically located northwesternmost corner of the Arabian continent

<p>We have carried out a several-year-long study of the Amanos Mountains, on the basis of which we present new sedimentary and structural evidence, which we combine with existing data, to produce the first comprehensive synthesis in the regional geological setting. The ca. N-S-trending Amanos Mountains are located at the northwesternmost edge of the Arabian plate, near the intersection of the African and Eurasian plates. Mixed siliciclastic-carbonate sediments accumulated on the north-Gondwana margin during the Palaeozoic. Triassic rift-related sedimentation was followed by platform carbonate deposition during Jurassic-Cretaceous. Late Cretaceous was characterised by platform collapse and southward emplacement of melanges and a supra-subduction zone ophiolite. Latest Cretaceous transgressive shallow-water carbonates gave way to deeper-water deposits during Palaeocene-Eocene. Eocene southward compression, reflecting initial collision, resulted in open folding, reverse faulting and duplexing. Fluvial, lagoonal and shallow-marine carbonates accumulated during Late Oligocene(?)-Early Miocene, associated with basaltic magmatism. Intensifying collision during Mid-Miocene initiated a foreland basin that then infilled with deep-water siliciclastic gravity flows. Late Miocene-Early Pliocene compression created mountain-sized folds and thrusts, verging E in the north but SE in the south. The resulting surface uplift triggered deposition of huge alluvial outwash fans in the west. Smaller alluvial fans formed along both mountain flanks during the Pleistocene after major surface uplift ended. Pliocene-Pleistocene alluvium was tilted towards the mountain front in the west. Strike-slip/transtension along the East Anatolian Transform Fault and localised sub-horizontal Quaternary basaltic volcanism in the region reflect regional transtension during Late Pliocene-Pleistocene (<4 Ma).</p

Stratigraphy and pre-Miocene tectonic evolution of the southwestern part of the Sivas Basin, Central Anatolia, Turkey

In central Anatolia there are several important basins developed mainly after closure of the northern branch of Neotethys. These are the Haymana, Tuzgolu, Ulukisla, Kizihrmak, Cankiri-Corum and Sivas basins. The Sivas Basin is located in the eastern part of central Anatolia between the Central Anatolian Crystalline Complex (CACC) in the north and Taurides in the south. The basement to the southeastern part of the basin consists of recrystallized limestone and clastics of the Permian-Lower Cretaceous Bunyan Metamorphics. These units are overlain by an Upper Cretaceous ophiolitic olistostrome that is overthrust by ophiolites and high pressure-low temperature metamorphic rocks. Lower Palaeocene cover units unconformably overlie this sequence. The basement to the northwestern part is constituted by CACC that includes a high temperature-low pressure polymetamorphic succession of Palaeozoic-Mesozoic age, overthrust by ophiolites and intruded by Upper Cretaceous post-collisional granitoids and syenitoids. The uppermost Maastrichtian-Palaeocene continental to shallow marine (lagoonal) unit unconformably overlies this unit. Upper Cretaceous-Palaeocene siltstone, shale, pelagic limestone, volcaniclastic rocks and basic volcanic rock intercalations of a within-continental-plate eruptive setting have also been developed on the basement unit. These sequences represent the products of an extensional episode during Late. Cretaceous-Palaeocene times in the region between the Taurides and CACC. The Middle Eocene is represented by a regional transgression which was followed by a compressional episode evidenced by thrust faults at the margins and continued regression in the central part of the basin. This compressional period continued up to the end of the Early Miocene. Units formed during this episode are overlain by Upper Miocene-Quaternary continental units intercalated with volcanic rocks formed in fault-controlled extensional basins. It is suggested that the palaeotectonic events were the result of terminal closure of the northern branch of Neotethys. However, the neotectonic events are the result of the collision of the Arabian Plate and Anatolides which causes a westward escape of the Anatolian Plate. Copyright (C) 1999 John Wiley & Sons, Ltd

Trace element and Sr-Nd isotope geochemistry of the alkali basalts observed along the Yumurtalik Fault (Adana) in southern Turkey

Young volcanics erupted since late Pliocene as a result of lithospheric extension within the transtensional zones along the NE-SW trending letf-lateral Yumurtalik fault zone that mark the boundary between the African and the Anatolian plates in southern Turkey. These volcanics are characterized by alkali olivine basalts. The REE patterns exhibit a strong fractionation characterized by (La/Yb)(N) ratio between 22 and 6. Primitive mantle normalized incompatible trace element patterns exhibit close similarity to OIB. Ratios of some selected incompatible trace elements (i.e., Ce/Y=1.4-3.8, Zr/Nb=3.9-6.5, La/Ba=0.05-0.1, La/Nb=0.6-0.8, Zr/Ba=0.4-0.8) are also well comparable to those of ocean island basalts. The 87Sr/86Sr ratios show low values (between 0.703081 to 0.703920), whereas the 143Nd/144Nd ratios show high values (ranging from 0.512601 to 0.512986), suggesting an OIB signature. All the evidence suggest that the intracontinental volcanics in this region were derived from an asthenospheric mantle following the fractures of the continental lithosphere that resulted from the left lateral strike-slip fault system bounding the African-Anatolian plates since Late Pliocene in southern Turkey

Intracontinental Plio-Quaternary volcanism along the African-Anatolian plate boundary, southern Turkey

Plio-Quatemary volcanics crop out along the African-Anatolian plate boundary in southern Turkey. NE-SW trending sinistral strike-slip fault systems controlling this volcanism have resulted from the of continuous compressional tectonic regime at the K. Maras triple junction (southern Turkey), where the collision of the African-Arabian and Anatolian plates occurs. As a result, intracontinental basaltic volcanic have erupted within the transtensional zones oriented along the strike of the main fault. Massive basaltic lava flows displaying columnar jointing are often intercalated with agglomerates and tuffs. Volcanic rocks are represented by olivine alkali basalts (Na2O+K2O=4-7%). These basaltic rocks exhibit high TiO2 (2-3%) and low SiO2 (43-48%) values. The clinopyroxene compositions (high TiO2, CaO and Al2O3) also confirm their alkaline affinity. Tectonomagmatic discrimination diagrams based on major and trace element geochemistry suggest that these volcanic rocks belong to the within-plate basalt environment. REE geochemistry shows LREE enrichment indicating typical intracontinental alkaline basaltic volcanism

Oceanic crust generation in an island arc tectonic setting, SE Anatolian orogenic belt (Turkey)

A number of Late Cretaceous ophiolitic bodies are located between the metamorphic massifs of the southeast Anatolian orogenic system. One of them, the Göksun ophiolite (northern Kahramanmaraş), which crops out in a tectonic window bounded by the Malatya metamorphic units on both the north and south, is located in the EW-trending nappe zone of the southeast Anatolian orogenic belt between Göksun and Afş in (northern Kahramanmaraş). It consists of ultramafic-mafic cumulates, isotropic gabbro, a sheeted dyke complex, plagiogranite, volcanic rocks and associated volcanosedimentary units. The ophiolitic rocks and the tectonically overlying Malatya-Keban metamorphic units were intruded by syn-collisional granitoids ( ~ 85 Ma). The volcanic units are characterized by a wide spectrum of rocks ranging in composition from basalt to rhyolite. The sheeted dykes consist of diabase and microdiorite, whereas the isotropic gabbros consist of gabbro, diorite and quartzdiorite. The magmatic rocks in the Göksun ophiolite are part of a co-magmatic differentiated series of subalkaline tholeiites. Selective enrichment of some LIL elements (Rb, Ba, K, Sr and Th) and depletion of the HFS elements (Nb, Ta, Ti, Zr) relative to N-MORB are the main features of the upper crustal rocks. The presence of negative anomalies for Ta, Nb, Ti, the ratios of selected trace elements (Nb/Th, Th/Yb, Ta/Yb) and normalized REE patterns all are indicative of a subduction-related environment. All the geochemical evidence both from the volcanic rocks and the deeper levels (sheeted dykes and isotropic gabbro) show that the Göksun ophiolite formed during the mature stage of a suprasubduction zone (SSZ) tectonic setting in the southern branch of the Neotethyan ocean between the Malatya-Keban platform to the north and the Arabian platform to the south during Late Cretaceous times. Geological, geochronological and petrological data on the Göksun ophiolite and the Baskil magmatic arc suggest that there were two subduction zones, the first one dipping beneath the Malatya-Keban platform, generating the Baskil magmatic arc and the second one further south within the ocean basin, generating the Göksun ophiolite in a suprasubduction zone environment. © 2004 Cambridge University Press

Paleozoic stratigraphy of the Geyik Dagi unit in the Eastern Taurides (Turkey): New age data and implications for Gondwanan evolution

The stratigraphy of the Geyik Dagi Unit of the Eastern Taurides has been revised on the basis, of new field observations from this critical tectono-stratigraphic unit. The Emirgazi Formation. of Precambrian age. is shown to occur throughout the whole Tauride Belt. The Cal Tepe Formation probably reaches the Upper Cambrian. The Carnbrian -Ordovician boundary is close to the base of the Seydisehir Formation: the latter includes mixed carbonate-siliciclastic tempestites. Its upper part may be of late Middle Ordovician age. The stratigraphic gap between the Seydisehir and Sort Tepe Formations is the result of a thermal event, as recorded in man), other places in the peri-Gondwanan terranes of Europe. The graptolite-bearing black shales of the Puscu Tepe Shale Formation of early Silurian age, overlying the, glacier-related sediments of the Halit Yaylasi Formation is a typical unit in most of the peri-Gondwanan terranes in S Europe and N Africa. The "Orthoceras Limestones" of the overlying Yukan Yayla Formation are of latest Llandovery to earliest Wenlock and post-middle. Ludlow age. The Lower Devonian basal quartzites of the Ayi Tepesi Formation are interpreted as overlying an unconformity, which may coincide with the stepwise, detachment of-some small microcontinenis from Gondwana accompanying the opening of Palcotethys. The conformably overlying Safak Tepe Formation yielded Eifelian-Givetian conodonts and is overlain by the Gumusali Formation of Frasnian-Famennian age. The Devonian-Carboniferous boundary is located within the black shales of the Ziyarettepe Formation. The deposition of these black shales seems to be related to an anoxic event. Although the available geological data in the Taurides are still too fragmentary to provide a comprehensive picture, the new findings may facilitate the con-elation of the Eastern Tauride stratigraphic units with corresponding strata in the Central and Western Taurides and improve the understanding of Early to middle Paleozoic events in NE peri-Gondwana

A comparative study on the histological structure of the spleen in the ostrich (Struthio camelus), the kestrel (Falco tinnunculus) and the osprey (Pandion haliaetus)

The spleen structurally and functionally belongs to the hematopoietic organs and is also an important component of the reticuloendothelial system, which is known to play a major role in host defense. The histological structure of the spleen was investigated in the ostrich, a non-flying bird, the kestrel, a raptor, and the osprey, a fish-eating bird of prey (fish eagle). For this purpose, Mallory’s modified triple stain, methyl green-pyronin and silver stain were used. Germinal centers were not present in the spleen of the osprey. In the spleen of the kestrel, penicillar arterioles and the surrounding lymphoid tissue were markedly dense. Compared to the other two birds, the red and white pulps were clearly distinguishable in the spleen of the ostrich