Mineralogy, geochemistry and genesis of newly discovered Sinandede kaolin deposit (Balıkesir, NW Türkiye): Potential applications

This paper presents first X-ray diffraction (XRD), scanning electron microscopy (SEM), bulk-rock geochemical analyses, isotopic (O-H-C) and differential thermal analysis-thermogravimetric (DTA-TG), physical and thermal tests of Sinandede kaolin deposit (SKD) formed by hydrothermal alteration of Lower Miocene dacitic-rhyodacitic tuffs. The mineralogical analyses revealed that the SKD comprises mainly kaolinite with dickite, illite, smectite-chlorite, Ca-montmorillonite, alunite, halloysite, feldspar, quartz, opal CT, hematite and anhydrite. Geochemically, Al₂O₃, H₂O, Sr, S and Zr contents were markedly enriched, while Rb, Cs, U, Y and Ba were depleted compared with the parent rocks. The chondrite-normalized rare earth element (REE) patterns show identical trends characterized by light rare earth element (LREE) enrichment (La/Sm)_CN = 1.96–10.96 and (La/Yb)_CN = 20.51–37.08), heavy rare earth element (HREE) depletion (Gd/Yb)_CN = 1.37–5.62), slightly Eu anomaly (Eu/Eu* <1), and positive Gd anomaly (Gd/Gd* = av.1.06). The δ¹⁸O values of the samples vary between +0.48 ‰ and, −4.96 ‰; δD values vary between −81.05 ‰ and − 89.97 ‰. On the other hand; δ¹³C (VPDB) values ranging between −25.70 ‰ and − 28.83 ‰ (VPDB) in kaolin samples are compatible with the δ¹³C (VPDB) values of hydrothermal waters mixed with meteoric water fed by C3 plants, indicating the contribution of meteoric water in SDK. Small positive Ce and Gd anomalies, which indicates the presence of a hypogene-supergene mix, further support the contribution of meteoric water. The SDK was formed as a result of post-magmatic hydrothermal activities at temperatures above 100 °C and influenced by both hypojene and supergene conditions. Technological tests suggest that the SDK can be used for wall and floor tiles in ceramic industry.