Abstract This 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.

中文翻译：

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来自 Guadix-Baza 盆地（Betic Cordillera，西班牙东南部）富含有机质的 Plio-Pleistocene 湖沉积物中的粘土盐成岩作用

摘要 本研究对富含有机质的高盐度湖泊环境对瓜迪克斯-巴扎盆地（Betic Cordillera）东部沉积物中矿物转化的影响进行了矿物学分析。带有有机质碎片的深色沉积物富含层状硅酸盐（K-白云母、伊利石-蒙脱石混合层、-I/S-少量的辉绿石、坡缕石、绿泥石和高岭石），并含有石英、长石和枝状黄铁矿。I / S（R0型，无序）的X射线衍射图显示纯蒙脱石和30％伊利石层的位置之间是连续的。I/S 混合层的化学成分表明 Si 被 AlIV、Fe + Mg > 1 个原子/分子式单元 (apfu) 显着取代，K 含量高达 0.42 apfu 这些数据表明在主要的蒙脱石层中存在少量和可变数量的伊利石层。湖泊的咸水和沉积物的还原环境有利于 Mg 和 Fe2+ 的吸收，产生八面体负电荷，与贝得利体取代一起为粘土层提供足够的负电荷，允许 K 掺入夹层，从而开始成岩作用低温照明。