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Geochemistry of hydrothermal illitizations in Eocene Kösedağ magmatic rocks, Zara-Suşehri area, NE Sivas, East-Central Anatolia: Origin and age of alteration      
Yazarlar
Ömer Bozkaya
Pamukkale Üniversitesi, Türkiye
Doç. Dr. Zeynel BAŞIBÜYÜK Doç. Dr. Zeynel BAŞIBÜYÜK
Kırşehir Ahi Evran Üniversitesi, Türkiye
Hüseyin Yalçın
Türkiye
Gülcan Bozkaya
Pamukkale Üniversitesi, Türkiye
Deniz Hozatlıoğlu
Sivas Cumhuriyet Üniversitesi, Türkiye
Marek Szczerba
Özet
The study area located at the periphery of the collision zone between the Eurasian plate (i.e. Pontides) and Tauride-Anatolide platform, NE of Sivas in the east-central Turkey, which is part of the Tethyan Metallogenic Belt. Mixed-layer illite-smectite (I[sbnd]S) and illite minerals are derived within the hydrothermal alteration zones with a few km2 surface areas (up to 30 km2) in Eocene volcanic and plutonic rocks. The representative I[sbnd]S and illite samples taken from plutonic- and volcanic-hosted alteration zones are investigated by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), major and trace elements and O[sbnd]H isotope geochemistry and K[sbnd]Ar dating methods. Different types of hydrothermal alterations, such as propylitic and phyllic alteration in the plutonic rocks and argillic alteration in the volcanic rocks were developed as a result of intrusion of Kösedağ Pluton (syenite) into Karataş Volcanics (basaltic trachy-andesite and trachyte) with relations of hot-hot contact. The main phyllosilicate/clay minerals are characterized by kaolinite and I[sbnd]S in volcanic-hosted argillic alteration zones, whereas I[sbnd]S and illite in plutonic-hosted phyllic zones. The ordering types (Reichweite) of I[sbnd]S and illites are represented by R1 I[sbnd]S (I = 65--80 % in I[sbnd]S) + R3 I[sbnd]S (I = 90 % in I[sbnd]S) in the volcanic-hosted rocks, and R3 I[sbnd]S (I = 90 % in I[sbnd]S) and illite (S = 3--5 %). Dioctahedral (d060 ≤ 1.500 Å) R3 I[sbnd]S and illites have 1 Md + 1 M and 1 Md + 1 M + 2 M1 polytypes, respectively. The major and trace elements such as TiO2, Fe2O3, MgO, Na2O, P2O5, Sc, V, Cu, Ge, Sr, Hf, Zr and Y increase in the volcanic-hosted I[sbnd]S, whereas SiO2, Al2O3, K2O, Pb, W, Mo, As, Sb, Rb and U in the plutonic-hosted I[sbnd]S and illites. The chondrite-normalized distributions of I[sbnd]S and illites present a great similarity to those of host rocks. The chondrite-normalized rare earth element (REE) concentrations are more enriched in the volcanic-hosted I[sbnd]S in comparison with the plutonic-hosted I[sbnd]S and illites having distinctive Eu negative anomaly, which indicate deriving from volcanic matrix and K-feldspar, respectively. Oxygen and hydrogen isotope data of illitic clays indicate that the hydrothermal fluids are originated from magmatic water. According to stable isotopes and fluid inclusion data, I[sbnd]S and illites were formed at the temperature conditions ∼150 °C in volcanic-hosted argillic zone, whereas ∼250 °C in plutonic-hosted phyllic zones. K[sbnd]Ar dating of alunite, I[sbnd]S and illite minerals indicate that the hydrothermal alteration was started at 40.45 ± 1.28 Ma, almost 2 Ma after the Q-syenite intrusion, within the plutonic body as phyllic alteration stage, and continued up to 35.27 ± 2.81 Ma, with a duration of ∼5 Ma, and finalized before the exhumation of the Kösedağ Pluton (28--30 Ma). The geochemical characteristics of I[sbnd]S and illites were controlled by host-rock, condition, origin, and ages of alterations and they can be used as an important tool for magmatic-hydrothermal systems.
Anahtar Kelimeler
Clay minerals | Eocene magmatism | Hydrothermal alteration | K-Ar dating | Stable isotope geochemistry
Makale Türü Özgün Makale
Makale Alt Türü SSCI, AHCI, SCI, SCI-Exp dergilerinde yayımlanan tam makale
Dergi Adı Geochemistry
Dergi ISSN 0009-2819
Dergi Tarandığı Indeksler SCI-Exp, SCOPUS, Curation, Current Contents Physical Chemical & Earth Sciences, Essential Science Indicators, Pdf2xml, Pdf2xml, Reference Master, Sophia
Dergi Grubu Q2
Makale Dili Türkçe
Basım Tarihi 04-2024
Sayı 1
Doi Numarası 10.1016/j.chemer.2024.126121
Makale Linki http://dx.doi.org/10.1016/j.chemer.2024.126121