The mine drainage of the Ibbenbüren anthracite coal mine is characterized by exceptionally high concentrations of dissolved iron and sulfate. The elevated position of the coal field with respect to the surrounding area makes the neighboring sediments an unlikely source of these elements. Accordingly, it has been hypothesized that interaction between infiltrating rainwater and the fractured overburden is a key process governing the mine drainage chemistry. To test this hypothesis, two full-diameter core samples drilled above the discharging adit of the coal mine were investigated. The methodology combined several analytical techniques to identify and characterize traces of water–rock interaction related to both diagenesis and relatively recent weathering processes along open fractures. The coupled appearance of kaolinite-dickite-illite minerals in weathered and unweathered rock sections was clearly connected to the burial history of the Carboniferous sequence. In contrast, the formation of iron (oxide-) hydroxides together with the presence of oxidized pyrite in weathering profiles along both sides of the fractures was positively related to the geochemical footprint of the coal mine drainage. Thus, open fractures, possibly originated from mining activities, may play a significant role in the drainage chemistry, especially considering the rather poor hydraulic conditions of the overburden.

中文翻译：

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Ibbenbüren矿石炭纪层序的岩相学调查：追踪煤矿排水的起源

Ibbenbüren无烟煤煤矿的矿井排水特点是溶解铁和硫酸盐的浓度非常高。煤田相对于周围地区的位置较高，使得邻近的沉积物不太可能成为这些元素的来源。因此，已经假设渗透的雨水和裂缝覆盖层之间的相互作用是控制矿井排水化学的关键过程。为了验证该假设，研究了在煤矿排料口上方钻出的两个全直径岩心样品。该方法学结合了多种分析技术，以识别和表征与成岩作用和沿开放裂缝的相对较新的风化过程有关的水岩相互作用的痕迹。在风化和未风化的岩石剖面中，高岭石-迪克石-伊利石矿物的结合出现显然与石炭纪层序的埋葬历史有关。相反，沿裂缝两侧的风化剖面中铁（氢氧化物）氢氧化物的形成以及氧化黄铁矿的存在与煤矿排水的地球化学足迹成正相关。因此，可能源自采矿活动的露天裂缝可能在排水化学中起重要作用，特别是考虑到上覆岩层的水力条件较差时。沿裂缝两侧的风化剖面中铁（氢氧化物）氢氧化物的形成以及氧化黄铁矿的存在与煤矿排水的地球化学足迹呈正相关。因此，可能源自采矿活动的露天裂缝可能在排水化学中起重要作用，特别是考虑到上覆岩层的水力条件较差时。沿裂缝两侧的风化剖面中铁（氢氧化物）氢氧化物的形成以及氧化黄铁矿的存在与煤矿排水的地球化学足迹呈正相关。因此，可能源自采矿活动的露天裂缝可能在排水化学中起重要作用，特别是考虑到上覆岩层的水力条件较差时。