Origin and significance of Early Miocene high‑potassium I-type granite plutonism in the East Anatolian plateau (the Taşlıçay intrusion)

Gültekin Topuz*, Osman Candan, Thomas Zack, Fukun Chen, Qiu Li Li

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The Early Miocene high-K I-type plutonic rocks constitute the early products of the Neogene to Quaternary magmatism, and the youngest exposed intrusions in the East Anatolian plateau. Here we deal with the petrogenesis of the Early Miocene Taşlıçay intrusion covering an area of ∼62 km2. The intrusion comprises leucogranite, and minor gabbro-monzodiorite and rhyolite porphyry. U-Pb dating of zircons from the leucogranite, monzodiorite and rhyolite porphyry yielded identical igneous crystallization ages of ∼19 Ma (Early Miocene). According to the modified alkali-lime index, the leucogranite and the rhyolite porphyry are alkali-calcic, while the gabbro-monzodiorite is transitional calcic to calc-alkalic. On variation diagrams, the gabbro-monzodiorite and the leucogranite as well as rhyolite porphyry form distinct bimodal groupings, whereby the leucogranite display well-defined linear differentiation trends, in contrast to the gabbro-monzodiorite. The leucogranite has relatively fractionated rate earth element (REE) patterns with concave-upward shapes and significant negative Eu anomalies; middle REEs are hardly fractionated with respect to heavy REEs. The gabbro-monzodiorite is characterized by high abundances of incompatible elements, slightly fractionated chondrite-normalized REE patterns with feebly negative Eu anomaly. The rhyolite porphyry is compositionally similar to the leucogranite. The geochemical features imply a fractionating mineral assemblage of hornblende, plagioclase and biotite for the leucogranite, and hornblende and ± plagioclase for the gabbro-monzodiorite. All the rock types display a narrow Sr and Nd isotopic variation (initial 87Sr/86Sr = 0.7053 to 0.7065; initial εNd = −0.5 to −3.8). The leucogranite and rhyolite porphyry exhibit gradually slightly higher initial 87Sr/86Sr and lower initial 143Nd/ 144Nd ratios relative to the gabbro-monzodiorite. Similarly, δ18O and initial εHf values of zircons suggest slightly increasing amount of crustal component from the leucogranite to the rhyolite porphyry. The gabbro-monzodiorite is probably related to partial melts from the slightly enriched lithospheric mantle. The magmas of the leucogranite and the rhyolite porphyry, on the other hand, probably resulted from the remelting of a middle- to high-K basic to intermediate rocks, compositionally similar to the gabbro-monzodiorite, and assimilated gradually slightly increasing amount of old high-silica crustal material. Several lines of evidence such as (i) presence of the well-developed dike swarm of rhyolite porphyry at the north eastern margin of the intrusion, (ii) exhumation of the intrusion at the earth's surface by Middle Miocene, (iii) widespread apatite fission tract ages between 22 and 16 Ma from literature, and (iv) the absence of the exposed intrusions younger than the Early Miocene suggest that the Early Miocene represents probably a time of continental extension and exhumation in Eastern Anatolia and NW Iran.

Original languageEnglish
Article number105210
JournalLithos
Volume348-349
DOIs
Publication statusPublished - 1 Dec 2019

Bibliographical note

Publisher Copyright:
© 2019 Elsevier B.V.

Funding

We are indebted to Bernard Bonin and one anonymous reviewer for their constructive comments, and Xian-Hua Li for editorial handling. This work was financially supported by the Scientific and Technological Research Council of Turkey ( #114Y226 ), and the Turkish Academy of Sciences Young Scientists Award Programme. The assistance of Mutlu Özkan, Lutfiye Akın and Evren Çubukçu during sample preparation and CL imaging are gratefully acknowledged. We have greatly benefitted from discussions with Aral. İ. Okay and A. M. Celâl Şengör. We are indebted to Bernard Bonin and one anonymous reviewer for their constructive comments, and Xian-Hua Li for editorial handling. This work was financially supported by the Scientific and Technological Research Council of Turkey (#114Y226), and the Turkish Academy of Sciences Young Scientists Award Programme. The assistance of Mutlu Özkan, Lutfiye Akın and Evren Çubukçu during sample preparation and CL imaging are gratefully acknowledged. We have greatly benefitted from discussions with Aral. İ. Okay and A. M. Celâl Şengör.

FundersFunder number
Bernard Bonin
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu114Y226
Türkiye Bilimler Akademisi

    Keywords

    • East Anatolian plateau
    • High-K granite
    • NW Iran
    • Sr-Nd-Pb isotopy
    • Turkey
    • Zircon O and Hf isotopy

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