The origin and P-T conditions of the metamorphic sole rocks beneath the Late Cretaceous Pınarbaşı Ophiolite, Eastern-Central Anatolia

Metamorphic sole rocks of the Pınarbaşı Ophiolite are one of the best-preserved rock units observed along the Tauride Ophiolite Belt in Turkey. The metamorphic sole rocks observed as tectonic slices at the base of mantle tectonites as well as blocks in the mélange units consist mainly of garnet-clinopyroxene-amphibolite, garnet-amphibolite, amphibolite, epidote-amphibolite, quartz-amphiboleschist and metabasalt. The amphibolites display a wide range of geochemical signatures such as those of N-MORB, E-MORB, OIB and IAT. The metabasalts exhibit OIB geochemical characteristics. P-T estimates indicate that the garnet-clinopyroxene-amphibolites reached peak metamorphic conditions of 790-840 °C and 12-14 kbar. High-grade metamorphism is followed by a stage of decompression, which is indicated by the presence of symplectitic growth of amphibole and plagioclase over garnet in garnet-clinopyroxene-amphibolites. P-T estimates for garnet-clinopyroxene-amphibolites suggest that they were metamorphosed under granulite-facies conditions (ca. 35-40 km). High temperature estimated from granulite facies rocks should be ascribed to the occurrence of the sole rocks during the inception of the intra-oceanic subduction, beneath young or relatively hot oceanic lithosphere. On the other hand, mineral paragenesis of the metabasalts suggest greenschist facies metamorphic conditions. Protoliths of the metabasalts were probably metamorphosed during final stages of subduction where they were very close to sea floor as the subduction zone was probably clogged by a seamount. The greenschist- and granulite-facies sole rocks were metamorphosed probably beneath the hot oceanic lithosphere at different depths of the subduction zone. Considering all these data are important to better understanding intra-oceanic subduction and final obduction events of the Tethys Ocean

The origin of carbonatites from the eastern armutlu peninsula (Nw turkey)

Unusual carbonate dykes, which have a thickness of up to 4 m, cross-cut the amphibolites from the high-grade metamorphic rocks in the Armutlu Peninsula (NW Turkey). They are described as carbonatites on the basis of their petrographic, geochemical and isotope-geochemical characteristics. The carbonatites, which commonly show equigranular texture, are composed of calcite and clinopyroxene with other minor phases of plagioclase, mica, garnet, K-feldspar, quartz, epidote, titanite and opaque minerals. They contain abundant xenoliths of pyroxenite and amphibolite. The geochemical characteristics of the carbonatites are significantly different from those of mantle-derived carbonatites. They have remarkably low incompatible element (e.g. Ba, Th, Nb) and total REE (11–91 ppm) contents compared with mantle-derived carbonatites. The high87Sr/86Sr(i) (0.70797–0.70924) and low εNd(t) (−8.08 to −9.57) of the carbonatites confirm that they were derived from the continental crust rather than from a mantle source. Mica from carbonatite was dated by the40Ar/39 Ar method, yielding a Late Jurassic–Early Cretaceous age (148–137 Ma). This is significantly younger than the age of adjacent amphibolites (Upper Triassic). All data from field studies, as well as petrographic, geochemical and geochronological observations, suggest that these carbonatites were formed from anatectic melting of a carbonated source area in the continental crust

The Middle Jurassic and Early Cretaceous basalt-radiolarian chert association from the Tekelidağ Mélange, eastern İzmir-Ankara-Erzincan suture zone (northern Turkey)

Basaltic and deep-sea sedimentary rocks are widely exposed in the Tekelidağ Mélange, eastern part of the İzmir-Ankara-Erzincan (İAE) suture zone. In this study, we present petrogenetic features of the basaltic rocks and new micropalaeontological data from the radiolarian cherts. The basaltic rocks are divided into two different groups based on whole-rock geochemistry data. The first group of basaltic rocks displays MORB-like geochemical characteristics. The second group exhibits island-arc tholeiite (IAT) geochemical characteristics. The cherts, which coexist within the basaltic rocks, yielded Middle Jurassic to Early Cretaceous radiolarian assemblages. Late Bajocian (Middle Jurassic) to Tithonian (Late Jurassic) ages were obtained from the radiolarian cherts observed within the MORB-type basalts belonging to the first group. On the other hand, the supra-subduction zone (SSZ)-type basalts belonging to the second group are associated with upper Aalenian (Middle Jurassic) and lower Aptian (Lower Cretaceous) radiolarian cherts. The new Middle–Late Jurassic and Early Cretaceous radiolarian dates and MORB- and SSZ-type basaltic rocks are consistent with radio-isotopic ages previously obtained from ophiolites and ophiolitic mélanges along the İAE suture zone. The radiolarian ages associated with basaltic rock data indicate that the occurrence of the MORB- and SSZ-type magmatism were simultaneous. The coeval IAT and MORB-like basalt generation inferred to occur in the SSZ environment similar to the South Sandwich back-arc basin system from South Atlantic Ocean, the Mariana Trough (e.g., Fiji and Tonga basin) from the Western Pacific and Coast Range Ophiolite from California

New evidence for the presence of the Inner Tauride Ocean: Lithological, geochronological and P-T correlations with the Tavşanlı and Afyon zones of Central Anatolia (Türkiye)

The Tavs¸anlı and Afyon zones, which are well defined in western Türkiye, represent high pressure-low temperature (HP-LT) metamorphic rocks formed in a subduction zone. The Korumaz and Hınzır mountains (northeast of Kayseri) between the Central Anatolian Crystalline Complex and the Eastern Tauride Belt are represented by a HP-LT metamorphic sequence, which is thought to have formed between the Carboniferous and the Cretaceous. Here we present 40Ar/39Ar data from white micas within the Lower-Middle Triassic calc-phyllites from Korumaz Mountain, which yielded an age of 87 ± 2 Ma. Therefore, based on new mineralogical and geochronological data we suggest that this low-grade (HP-LT) metasedimentary sequence correlates with the Afyon Zone. Tectonically emplaced on-top of the HP-LT metasedimentary units of the Korumaz and Hınzır mountains is a meta-accretionary complex consisting of serpentinite, listvenite, marble, phyllite, calc-phyllite, metabasite, and meta-plagiogranite. Petrographic and mineral chemical studies show that the metaaccretionary complex was subjected to metamorphism under the HP-LT conditions that are similar to those of the Tavs¸anlı Zone in western Türkiye. Zircon Hf isotopic compositions from the meta-plagiogranite in the Korumaz and Hınzır mountains exhibit a depleted mantle signature with positive epsilon Hf(t) values of +5.6 to +13.1, and yielded a U-Pb crystallization age of 101.14 ± 0.84 Ma, which is the oldest age determined in oceanic crustal rocks of the ophiolites from the Tauride Belt. Geochemically, the metabasites and meta-plagiogranites from the meta-accretionary complex show subduction-related characteristics. White micas from phyllites and listvenite, which dominate the matrix of the meta-accretionary complex, yielded 40Ar/39Ar metamorphic ages ranging from 78 to 60 Ma. Our new geological and geochronological data suggest that metamorphic units of the Korumaz and Hınzır mountains are the eastern continuation of the Afyon and Tavs¸anlı zones. This indicates that the Inner Tauride Ocean, the existence of which has been controversial in the literature, was indeed present between the Central Anatolian Crystalline Complex and the Eastern Tauride Belt

Factors Predicting Patients that Will Not Benefit from Invasive Mechanical Ventilation

International Conference of the American-Thoracic-Society -- MAY 18-23, 2018 -- San Diego, CAWOS: 000449980301115Amer Thoracic So