The Ain Allega, Mjar Hannech and Sidi Driss Pb-Zn-Ba-Sr-As-(Hg) deposits in northern Tunisia are hosted in a post-nappe anticline with a core of a Triassic evaporite diapir affected by the NE–SW-trending Ghardimaou-Cap Serrat and E-W lineament. The ore minerals show different styles; particularly, impregnation in dolomite, cement of breccias, replacement ore and open space filling in the dissolution cavities and fractures. Ore minerals include sphalerite, galena, marcasite, pyrite and cinnabar. Principal gangue minerals are composed of barite, celestine, calcite, dolomite and quartz. The orebodies are hosted by Triassic carbonate rocks (Ain Allega ore deposits), Cretaceous carbonate rocks (Mjar Hannech ore deposits) and by the volcanoclastic layers (Sidi Driss ore deposits). These host rocks show hydrothermal alteration, dissolution and brecciation. Sphalerite in the carbonate-hosted Zn-Pb deposits in Tunisia occurs as nano-size microglobular blebs and peloids and forms finely-laminated bands with wavy and even ripped up features. Peloids are present in collapse breccias of karst cavities. Peloids (5–100 μm) and bacterial filaments (1 μm long) locally form the common micro-texture of the sulfide mineralization. The core and the shell of peloids are composed of different minerals; there are 1–3 shells and each shell is 1–1.5 μm thick, commonly with coarse crystals. These textures probably represent fossil microbial mats as in-situ sulfate-reducing bacteria products and are similar to nano-textures observed in bacterial biofilms. Electron microscopy, combined with major element changes (Zn, Pb, As, Fe, and Cd) and sulfur isotope values suggest that sphalerite nano-textures and nano-spheres are associated with fossilized bacterial-mat. The δ³⁴S values of sphalerite (−43.9 to +22.38‰) show that the microbial production of H₂S controlled sphalerite precipitation. The biogenic nano- to macro-textured sphalerite and sulfur isotope data suggest that microbes had an important role in the genesis of carbonate-hosted Zn-Pb deposits in Tunisia during the Miocene.

中文翻译：

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微生物对碳酸盐岩型突尼斯矿床中铅锌矿物沉积的控制

突尼斯北部的 Ain Allega、Mjar Hannech 和 Sidi Driss Pb-Zn-Ba-Sr-As-(Hg) 矿床位于推覆后背斜中，其核心是受 NE-SW 趋势影响的三叠纪蒸发岩底辟Ghardimaou-Cap Serrat 和 EW 线条。矿石矿物呈现出不同的风格；尤其是白云石的浸渍、角砾岩的胶结物、置换矿石以及溶蚀空穴和裂缝中的空地充填。矿石矿物包括闪锌矿、方铅矿、白铁矿、黄铁矿和朱砂。脉石矿物主要有重晶石、天青石、方解石、白云石和石英。矿体由三叠纪碳酸盐岩（Ain Allega 矿床）、白垩纪碳酸盐岩（Mjar Hannech 矿床）和火山碎屑层（Sidi Driss 矿床）组成。这些主岩显示出热液蚀变，溶解和角砾化。突尼斯以碳酸盐为主的 Zn-Pb 矿床中的闪锌矿以纳米级微球状气泡和球状体的形式出现，并形成具有波浪状甚至撕裂特征的精细层合带。岩溶洞的塌陷角砾岩中存在球状体。球状体（5-100 μm）和细菌细丝（1 μm 长）局部形成硫化物矿化的共同微观结构。球体的核和壳由不同的矿物质组成；有1-3个贝壳，每个贝壳厚1-1.5微米，通常有粗晶体。这些纹理可能代表化石微生物垫作为原位硫酸盐还原细菌产物，并且类似于在细菌生物膜中观察到的纳米纹理。电子显微镜，结合主要元素变化（Zn、Pb、As、Fe、和 Cd) 和硫同位素值表明闪锌矿纳米纹理和纳米球与化石细菌垫有关。δ^{闪锌矿的34} S 值（-43.9 至 +22.38‰）表明，微生物产生 H ₂ S 控制了闪锌矿的沉淀。生物成因的纳米到宏观纹理闪锌矿和硫同位素数据表明，微生物在中新世期间突尼斯以碳酸盐为主的 Zn-Pb 矿床的成因中具有重要作用。