Role of mantle and lower continental crust in the genesis of Eocene post-collisional granitoids: Insights from the Topuk pluton (NW Turkey)


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Güraslan I. N. , Altunkaynak Ş.

JOURNAL OF ASIAN EARTH SCIENCES, cilt.179, ss.365-384, 2019 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 179
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1016/j.jseaes.2019.05.012
  • Dergi Adı: JOURNAL OF ASIAN EARTH SCIENCES
  • Sayfa Sayıları: ss.365-384

Özet

We present here new mineral chemistry and major trace element and Sr-Nd-Pb-O isotope data as well as detailed field and petrographic studies of the Topuk Pluton (TP; ca. 48 Ma) and its hypabyssal counterparts. We aim to constrain the granitic magma genesis and emplacement and magmatic processes within the framework of post-collisional evolution of NW Anatolia. The TP is a shallow level intrusion (1.5-2.1 kbar, 680-760 degrees C, and 4.5-6.3 km depth) which is characterized by a dominant granodiorite composition and presents holocrystalline porphyritic texture. The pluton includes mafic microgranular enclaves (MMEs) of diorite/quartz diorite composition. During its emplacement, the pluton developed radial and ring fractures around itself, and aplite, porphyry dykes, and stocks were emplaced coeval with the pluton along these ring and radial fractures. The TP shows metaluminous and calc-alkaline I-type characteristics. Normal-mid ocean ridge basalt-normalized trace element patterns show that the samples are enriched in large-ion lithophile elements and light rare earth elements but depleted in Nb, Ti, and Ta elements. Granodiorite, MMEs, and hypabyssal rocks present similar initial Sr-87/Sr-86 and Nd-143/Nd-144 isotopic values, which lie in the ranges 0.705860-0.706247 and 0.512455-0.512584, respectively. The (206)pb/(204)pb, (207)pb/(204)pb, (208)pb/Pb-206, and Pb-207/(20)6Pb ratios are 18.831-19.046, 15.673-15.748, 2.0621-2.0725, and 0.82816-0.83321 values, respectively, while the delta O-18 isotope values range from 9.6 to 10.7.