Geochemistry and tectonic setting of metamorphic sole rocks and mafic dikes from the Pinarbasi (Kayseri) Ophiolite, central Anatolia (Turkey)

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Authors:Vergili, Ozden; Parlak, Osman
Author Affiliations:Primary:
Maden Tetkik ve Arama Genel Mudurlugu, Ankara, Turkey
Other:
Cukurova Universitesi, Turkey
Volume Title:Ofioliti
Source:Ofioliti, 30(1), p.37-52. Publisher: Pitagora Editrice, Bologna, Italy. ISSN: 0391-2612
Publication Date:2005
Note:In English. 76 refs.; illus., incl. geol. sketch maps, 4 tables, anals.
Summary:The Pinarbasi ophiolite is located in Central Anatolia and emplaced onto the Tauride platform in Late Cretaceous. It comprises remnants of lower part of oceanic lithosphere, namely mantle tectonites tectonically underlain by high-grade metamorphic sole rocks and ultramafic to mafic cumulates. Number of isolated microgabbro-diabase and pyroxenite dikes cut the mantle tectonites at different structural levels. The mantle tectonites are dominated by harzburgite and dunite, whereas the cumulates consist of wehrlite, clinopyroxenite, olivine gabbro, troctolite and gabbronorite. The metamorphic sole rocks in the Pinarbasi ophiolite crop out as thin slices beneath the sheared serpentinites and display inverted metamorphic gradient from amphibolite to greenschist facies. The rock types in the metamorphic sole are calcschists, epidote + plagioclase + amphibole schists, plagioclase + amphibole schists, amphibole schists, plagioclase amphibolites, amphibolites. The isolated microgabbro-diabase dikes are tholeiitic in character (Nb/Y = 0.03-0.07). The REE patterns, multi-element and tectono-magmatic discrimination diagrams suggest that the isolated dikes formed in a subduction-related environment. The metamorphic sole rocks exhibit two distinct geochemical features. The first group is alkaline (Nb/Y = 1.5-2.6), whereas the second group is tholeiitic (Nb/Y = 0.05-0.22) in nature. The REE patterns, multi-element and tectono-magmatic discrimination diagrams suggest that the protolith of the first group is similar to within-plate alkali basalts, whereas the second group is more akin to island arc tholeiitic basalts. All the evidences suggest that the Pinarbasi ophiolite and the isolated dikes formed in a supra-subduction zone tectonic setting. The alkaline amphibolites were formed as a result of metamorphism of the seamount type basaltic rocks in intraoceanic subduction zone whereas the tholeiitic amphibolites were formed as result of intraoceanic thrusting in a supra-subduction zone (SSZ) basin during the closure of the Inner Tauride Ocean in Late Cretaceous.
Sections:Geochemistry; Petrology
Subsections:Igneous petrology; Metamorphism: regional, dynamic
Subjects:Absolute age; Alkali basalts; Alkalic composition; Amphibole group; Amphibolites; Basalts; Calc-schist; Chain silicates; Chemical composition; Clinopyroxenite; Cretaceous; Cumulates; Dates; Diabase; Dikes; Dunite; Emission spectra; Epidote; Epidote group; Facies; Feldspar group; Framework silicates; Gabbros; Geochemistry; Greenschist facies; Harzburgite; ICP mass spectra; Igneous rocks; Intrusions; Island arcs; Isotope dilution; K/Ar; Lithosphere; Mafic composition; Major elements; Mantle; Mass spectra; Mesozoic; Metaigneous rocks; Metals; Metamorphic rocks; Metamorphism; Metasomatic rocks; Microgabbro; Neotethys; Norite; Ocean floors; Oceanic lithosphere; Olivine gabbro; Ophiolite; Orthosilicates; Outcrops; Peridotites; Petrography; Plagioclase; Plate tectonics; Plutonic rocks; Protoliths; Pyroxenite; Rare earths; Schists; Seamounts; Serpentinite; Silicates; Sorosilicates; Spectra; Subduction; Subduction zones; Tectonics; Tectonite; Tholeiite; Tholeiitic composition; Trace elements; Troctolite; Ultramafic composition; Ultramafics; Upper Cretaceous; Volcanic rocks; Wehrlite; Anatolia; Asia; Middle East; Turkey; Gabbronorite; Inner Tauride Ocean; Pinarbasi Ophiolite; Sole rocks
Coordinates:N383600 N383600 E0362000 E0362000
Abstract Numbers:05M/3294
Record ID:2006024445
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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