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Slab break-off and syncollisional origin of the Late Cretaceous magmatism in the central Anatolian crystalline complex, Turkey

Yusuf Kagan Kadioglu, Yildirim Dilek and Kenneth A. Foland
Slab break-off and syncollisional origin of the Late Cretaceous magmatism in the central Anatolian crystalline complex, Turkey (in Postcollisional tectonics and magmatism in the Mediterranean region and Asia, Yildirim Dilek (editor) and Spyros Pavlides (editor))
Special Paper - Geological Society of America (2006) 409: 381-415

Abstract

The Late Cretaceous calc-alkaline to alkaline plutons in the Central Anatolian crystalline complex are intrusive into metamorphic and ophiolitic rocks and mark a major magmatic pulse in the late Mesozoic evolution of the eastern Mediterranean region. We grouped the plutonic rocks with similar mineral and chemical compositions and inferred genetic relations into the granite, monzonite, and syenite supersuites. Granitic plutons mainly occur along the western edge of the Central Anatolian crystalline complex, whereas syenitic plutons form smaller bodies that crop out in the inner part. The granite supersuite is composed of granitic to granodioritic rocks, and the monzonite supersuite consists mainly of quartz monzonite and monzonitic rocks; both supersuites show enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE). The granitic-granodioritic rocks have compositions typical of high-K calc-alkaline and high-K shoshonitic series, whereas the monzonitic rocks display compositions characteristic of shoshonitic series. The syenite supersuite consists of quartz syenite, syenite, and nepheline-and pseudoleucite-bearing alkali rocks and shows more enrichment in LILE and a slight enrichment in HFSE compared to the other two supersuites. All three supersuite rocks have high (super 87) Sr/ (super 144) Nd ratios. These geochemical features suggest that the granite and monzonite supersuite magmas were derived from a subduction-modified and metasomatized mantle source and that the syenite supersuite magmas were derived from an enriched mantle source with considerable crustal contribution. New (super 40) Ar/ (super 39) Ar ages at 77.7+ or -0.3 Ma for the granite, 70.0+ or -1.0 Ma for the monzonite, and 69.8+ or -0.3 Ma for the syenite supersuite rocks indicate progressive evolution of the Central Anatolian crystalline complex magmatism from calc-alkaline to alkaline compositions with time. The latest Cretaceous emplacement of the complex's plutons and the chemical evolution of their magmas were syncollisional in nature, after the leading edge of the Tauride platform collided with a trench in the Inner Tauride ocean and became partially subducted. Subsequent slab break-off resulted in asthenospheric upwelling and perturbation of the subduction-metasomatized lithospheric mantle that collectively produced the primary melts for the Central Anatolian crystalline complex plutons. These melts evolved through combined assimilation-fractional crystallization and mixing-mingling processes during their ascent and were affected by the interactions between mantle-derived and crustal derived magmas. The late phases of this intracontinental magmatism were accompanied by tectonic extension of the thermally weakened orogenic crust in the Central Anatolian crystalline complex.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 409
Title: Slab break-off and syncollisional origin of the Late Cretaceous magmatism in the central Anatolian crystalline complex, Turkey
Title: Postcollisional tectonics and magmatism in the Mediterranean region and Asia
Author(s): Kadioglu, Yusuf KaganDilek, YildirimFoland, Kenneth A.
Author(s): Dilek, Yildirimeditor
Author(s): Pavlides, Spyroseditor
Affiliation: University of Ankara, Department of Geological Engineering, Ankara, Turkey
Affiliation: Miami University, Department of Geology, Oxford, OH, United States
Pages: 381-415
Published: 2006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2409-6
References: 93
Accession Number: 2007-022836
Categories: Igneous and metamorphic petrologyGeochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 6 tables, geol. sketch maps
N36°04'60" - N42°01'60", E26°10'00" - E44°49'60"
Secondary Affiliation: Aristotle University of Thessaloniki, GRC, GreeceMiami University, Oxford, OH, USA, United StatesOhio State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200713
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