Comparison of Epithermal Kaolin Deposits from the Etili Area (Çanakkale, Turkey): Mineralogical, Geochemical, and Isotopic Characteristics

Hatice Ünal Ercan*, Işık Ece, Emin Çiftçi, Ayça Aydın

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Hydrothermal solutions related to magmatic intrusions that occurred during the Oligo-Miocene resulted in advanced multi-stage alterations and, to varying degrees, kaolinization over a wide area of the Biga Peninsula. The most important formations in these kaolin deposits occurred along the NE–SW-trending Çan-Etili-Bayramiç fault zone. The Bahadırlı, Duman, and Çaltıkara quarries are well preserved kaolin deposits throughout these fault zones located within the Çan Volcanics. Mineralogical, geochemical, and isotopic analyses were performed to identify the environments of formation of kaolins and the origin of the hydrothermal solution that led to the formation of these deposits. The mineralogical assemblages of each of the quarries differ from each other. The Bahadırlı kaolin quarry comprises kaolinite + alunite ± quartz ± smectite ± plagioclase ± K-feldspar. The Çaltıkara kaolin deposits consist of kaolinite + quartz + alunite ± iron-oxide and ore minerals. The Duman kaolin quarry was considered in two different slopes as a hanging wall block and a footwall block, and the blocks contain kaolinite + quartz + plagioclase ± smectite and kaolinite ± alunite ± smectite ± quartz ± plagioclase ± K-Feldspar ± gypsum, respectively. During petrographic investigations, it was observed that kaolinization occurred generally in K-feldspar and plagioclase phenocrysts and partially in the matrix. Mineralogical and micromorphological investigations revealed that the kaolin group includes the dioctahedral minerals kaolinite and halloysite. According to the trace element contents of the kaolinites, the Çaltıkara and Bahadırlı deposits had a hypogene origin, while the Duman deposit had a supergene origin. δ18O isotopic values of kaolinites ranged from +10.3 to +18.3‰. δ34S isotopic values ranged from –17.2 to +20.2‰ of alunite, galena, and pyrite minerals, which indicate different formation environments for the kaolin quarries. 40Ar/39Ar dating of alunite revealed that the timing of acid-sulfate alteration was compatible with the magmatic intrusions. All these data revealed the mineralogical, chemical, and isotopic differences caused by the effect of different hydrothermal processes in three kaolin deposits located on the same fault zone, close to each other and similar in age.

Original languageEnglish
Pages (from-to)753-779
Number of pages27
JournalClays and Clay Minerals
Volume70
Issue number5
DOIs
Publication statusPublished - Oct 2022

Bibliographical note

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to The Clay Minerals Society.

Funding

This research was supported by TUBITAK Project No: 112Y369 (Project coordinator: Prof. Dr. Ömer Işık Ece). The authors are grateful to ITU-JAL labs for providing analytical support during geochemical analysis in ITU, Turkey. They also thank the Kalemaden Mining Corp. for logistical support and accommodation during the fieldwork.

FundersFunder number
Kalemaden Mining Corp.
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu112Y369

    Keywords

    • Alunite
    • Hydrothermal alteration
    • Kaolinite
    • Silica sinter
    • Stable isotopes

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