Jiménez-Millán, JuanAbad, IsabelGarcía-Tortosa, Francisco JuanNieto, FernandoJiménez-Espinosa, Rosario2024-02-072024-02-072020-06-11Jiménez-Millán, J., Abad, I., García-Tortosa, F. J., Nieto, F., & Jiménez-Espinosa, R. (2020). Clay saline diagenesis in lake Plio-Pleistocene sediments rich in organic matter from the Guadix-Baza Basin (Betic Cordillera, SE Spain). Applied Clay Science, 195, 105739.0169-1317/1872-905310.1016/j.clay.2020.105739https://doi.org/10.1016/j.clay.2020.105739https://hdl.handle.net/10953/2131This study presents a mineralogical analysis of the effect of hypersaline lake environments rich in organic matter on the mineral transformations in sediments of the eastern part of the Guadix-Baza Basin (Betic Cordillera). Dark sediments with fragments of organic matter are rich in phyllosilicates (K-white mica, illite-smectite mixed layers, –I/S– minor amounts of paragonite, palygorskite, chlorite and kaolinite) and contain quartz, feldspars, and framboidal pyrite. X-ray diffraction patterns of I/S (R0 type, disordered) revealed a continuous between the positions of pure smectite and 30% of illite layers. Chemical composition of I/S mixed layers indicated a significant beidellitic substitution of Si by AlIV, Fe + Mg > 1 atoms per formula unit (a.p.f.u.) and K content up to 0.42 a.p.f.u. These data suggested the presence of a minor and variable amount of illitic layers among the major smectitic ones. Saline waters of the lake and the reducing environment of the sediment favored Mg and Fe2+ uptake, generating octahedral negative charge, which together with the beidellitic substitution would provide clay layer negative charge enough to admit K incorporation in the interlayer, hence the beginning of a diagenetic low temperature illitization.engAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/AuthigenicEnvironmental conditionsIllitizationIllite-smectite mixed-layersPalygorskite X-ray diffractioninfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess