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Full-Text Articles in Physical Sciences and Mathematics
The Geochemistry And Setting Of The Demirci Paragneisses Of The Sünnice Massif, Nw Turkey, Erdi̇nç Yi̇ği̇tbaş, John A. Winchester, Christopher J. Ottley
The Geochemistry And Setting Of The Demirci Paragneisses Of The Sünnice Massif, Nw Turkey, Erdi̇nç Yi̇ği̇tbaş, John A. Winchester, Christopher J. Ottley
Turkish Journal of Earth Sciences
The Demirci migmatitic quartzofeldspathic gneisses of the Sünnice Massif, exposed in the İstanbul Zone north of Bolu, have compositions that show them to be paragneisses, associated with subordinate para-amphibolites. They consist principally of metamorphosed, rather calcareous greywackes, with sediment derived from a continental arc source. They occur in the para-autochthon below a nappe pile (Çele meta-ophiolite), deformed and subjected to amphibolite facies metamorphism before the emplacement of late Neoproterozoic metavolcanic rocks later subjected to greenschist-facies metamorphism (Yellice volcanics). As they are overlain in sequence by nappes comprising sections of the Çele meta-ophiolite with ocean floor basalt and island arc tholeiite …
Petrogenesis Of The Kösedağ Pluton, Suşehri-Ne Sivas, East-Central Pontides, Turkey, Durmuş Boztuğ
Petrogenesis Of The Kösedağ Pluton, Suşehri-Ne Sivas, East-Central Pontides, Turkey, Durmuş Boztuğ
Turkish Journal of Earth Sciences
The Kösedağ syenite crops out as a shallow-seated pluton within the Eocene volcano-sedimentary rocks and is unconformably overlain by Lower Miocene limestones in the Suşehri-NE Sivas region, east-central Pontides. It consists of syenites and quartz syenites with a phaneritic, porphyritic texture characterized by K-feldspar megacrysts set in a coarse- to medium-grained groundmass comprising K-feldspar, plagioclase, clinopyroxene, amphibole, biotite and quartz. Major element geochemistry data reveal a high-K, alkaline, metaluminous to slightly peraluminous character, with a low Aluminum Saturation Index (ASI) value. The main solidification process, which modified the composition of magma during crystallization, was fractional crystallization, in which syenites solidified …
Detailed Geochemistry And K-Ar Geochronology Of The Metamorphic Sole Rocks And Their Mafic Dykes From The Mersin Ophiolite, Southern Turkey, Ömer Faruk Çeli̇k
Detailed Geochemistry And K-Ar Geochronology Of The Metamorphic Sole Rocks And Their Mafic Dykes From The Mersin Ophiolite, Southern Turkey, Ömer Faruk Çeli̇k
Turkish Journal of Earth Sciences
The metamorphic sole rocks at the base of mantle peridotites from the Mersin ophiolite consist of amphibolites and metasedimentary lithologies. Mineral parageneses in the metamorphic sole rocks exhibit amphibolite and greenschist facies assemblages. Geothermobarometric studies based on mineral assemblages and chemical compositions of minerals indicate that average metamorphic temperature during the metamorphism was 522 ± 15 °C and the pressure was less than 5 kb. Amphibolites from the metamorphic sole rocks exhibit geochemical characteristics of a supra-subduction zone (SSZ) type ophiolite, based on their major, trace and rare earth element (REE) compositions. The Th/Nb ratios of the amphibolites are higher …