In the Forez Basin of the French Massif Central, clay-rich alluvial deposits include a series of red- and green-colored sediments and carbonate cement that record evaporation and oxidizing/reducing conditions related to intra-continental climate during the Early to Middle Miocene. The mineralogy, chemistry and relative chronology of authigenic calcite-ankerite, ferroan dolomite, pyrite, and analcite-clinoptilolite in clay-rich sediment enabled reconstruction of a series of processes related to deposition, eogenesis, and mesogenesis. The low-Mg calcite, ankerite, and ferroan-dolomite cement, systematically associated with zeolites (analcite and clinoptilolite), represent eogenetic precipitation associated with oxic to post-oxic water with Ca–Fe–Mg carbonic, then Na–Al–Si(OH) 4 -rich water. Occurrence of framboidal and cubic pyrites with low-Mg calcite and analcite is related to post-oxic conditions associated with deposition, eogenesis and times of early mesogenesis. Changes in the morphology, size, and chemistry of framboidal and cubic pyrite grains were related to reducing-oxidizing cycles and to the growth of grains. Sulfur isotope measures on framboidal and cubic pyrite suggest that both morphologies are related to bacterial reduction of SO 4 2− to H 2 S and HS −1 . With the exception of some sample depths (0–40 m below surface), similar chemical contents (trace elements [TE], rare earth elements [REE] and platinoids) suggest a similar, constant reservoir of metal and metalloids associated with the clayey sediment and volcanic fragments. Moreover, the TE and REE chemistry of cubic pyrite, in contrast to carbonates, indicates growth of pyrite during eogenesis to mesogenesis stages. The mineralogical and chemical changes are interpreted as reflecting dissolution of iron oxyhydroxides, rather than ankerite and ferroan-dolomite. Chemical elements from dissolution of iron oxyhydroxides would have mixed with hydrogen monosulfide and contributed to the growth of cubic pyrite. The crystal size distributions of pyrite grains suggest a closed system with surface-controlled growth. Assuming those conditions, the growth time of framboidal to cubic pyrite, based on diffusion of HS −1 in the clay-rich sediments, was estimated to have been from several days to a few years, to as much as 500 years (mm-scale pyrite).

中文翻译：

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中新世古湖泊中与地球演化和中生发生相关的含氧和含氧后化学变化

在法国地块中部的 Forez 盆地，富含粘土的冲积矿床包括一系列红色和绿色沉积物和碳酸盐胶结物，它们记录了早中新世期间与大陆内气候相关的蒸发和氧化/还原条件。富含粘土沉积物中的自生方解石-铁白云石、铁质白云石、黄铁矿和方解石-斜发沸石的矿物学、化学和相对年代学能够重建与沉积、成因和介观相关的一系列过程。低镁方解石、铁白云石和铁白云石胶结物，系统地与沸石（方解石和斜发沸石）相关联，代表与含 Ca-Fe-Mg 碳酸，然后是 Na-Al-Si（ OH) 4 富水。含低镁方解石和方解石的方解石和方解石方解石和方解石的方解石和立方黄铁矿的出现与与沉积、成因和早期介晶时间相关的后含氧条件有关。菱形和立方黄铁矿晶粒的形态、尺寸和化学变化与还原-氧化循环和晶粒生长有关。硫铁矿和立方黄铁矿的硫同位素测量表明两种形态都与细菌将 SO 4 2- 还原为 H 2 S 和 HS -1 相关。除了某些样品深度（地表以下 0-40 m）外，相似的化学成分（微量元素 [TE]、稀土元素 [REE] 和铂类）表明，与粘土沉积物相关的金属和准金属具有相似的恒定储层和火山碎片。此外，立方黄铁矿的 TE 和 REE 化学与碳酸盐相比，表明黄铁矿在生发至介生阶段的生长。矿物学和化学变化被解释为反映铁羟基氧化物的溶解，而不是铁白云石和铁白云石的溶解。氢氧化铁溶解产生的化学元素会与一硫化氢混合并促进立方黄铁矿的生长。黄铁矿晶粒的晶体尺寸分布表明具有表面控制生长的封闭系统。假设这些条件，基于 HS -1 在富含粘土的沉积物中的扩散，方晶石到立方黄铁矿的生长时间估计为几天到几年，到多达 500 年（毫米尺度）黄铁矿）。而不是铁白云石和铁白云石。氢氧化铁溶解产生的化学元素会与一硫化氢混合并促进立方黄铁矿的生长。黄铁矿晶粒的晶体尺寸分布表明具有表面控制生长的封闭系统。假设这些条件，基于 HS -1 在富含粘土的沉积物中的扩散，方晶石到立方黄铁矿的生长时间估计为几天到几年，到多达 500 年（毫米尺度）黄铁矿）。而不是铁白云石和铁白云石。氢氧化铁溶解产生的化学元素会与一硫化氢混合并促进立方黄铁矿的生长。黄铁矿晶粒的晶体尺寸分布表明具有表面控制生长的封闭系统。假设这些条件，基于 HS -1 在富含粘土的沉积物中的扩散，方晶石到立方黄铁矿的生长时间估计为几天到几年，到多达 500 年（毫米尺度）黄铁矿）。