As a critical element, Li is currently in high demand due to rapid technological development. Anomalous Li enrichment in Pennsylvanian coals, such as those in Shanxi Province, has been discovered in China. Previous studies have shown that Li enrichment in coal and coal-bearing strata in Shanxi Province is generally evident in clay minerals and is related to mineral matter originating from nearby granite or bauxite and, in some cases, it is associated with hydrothermal fluid. Determining the exact sources of Li responsible for the Li enrichment in these coals is essential. This study investigated the spatiotemporal provenance of mineral matter evolution and source-to-sink system of No. 9 coal seam in the Anjialing Mine, Ningwu Coalfield, northeastern Shanxi Province, China. In total, 17 coal samples, six parting samples, one roof sample, and one floor sample from No. 9 coal seam were collected. Geochemical, mineralogical, and geochronological analyses were conducted using X-ray powder diffraction (XRD) and Raman spectroscopy for minerals, inductively coupled plasma–optical emission spectroscopy (ICP–OES) for major-element oxides, inductively coupled plasma–mass spectrometry (ICP–MS) for trace elements, and laser ablation–ICP–MS (LA–ICP–MS) for geochronology. The mineral matter in the coal samples consists mainly of kaolinite, boehmite, quartz, with varying proportions of calcite, pyrite, nacrite, anatase and goyazite, whereas in non-coal samples, the mineral matter is dominated by kaolinite, quartz, with minor amounts of anatase and pyrite. There are two heavy mineral assemblages: titanite–biotite–zircon–apatite and titanite–biotite–anatase–apatite. Relative to the elemental composition of the World hard coal, the coal benches are enriched in Li and Sr and slightly enriched in Ga, Zr, Hf, and Th. Relative to the elemental composition of the World clays, the parting samples in No. 9 coal seam are enriched in Li and slightly enriched in Mo, the roof sample is slightly enriched in Hf, and the floor sample is slightly enriched in Li and Hf. Detrital zircon ages in the roof and floor samples can be divided into two main ages: 2500–1700 and 326–293 Ma. The youngest UPb ages of zircon grain in the roof and floor samples are 292.7 ± 7.1 and 295.5 ± 9.7 Ma, respectively, indicating a well-constrained Early Asselian–Sakmarian stage. Detrital zircons, with ages of 326–293 Ma, in No. 9 coal seam are mainly derived from granitic intrusions and volcanic rocks in the Inner Mongolia Paleo-uplift (IMPU) rather than bauxite deposits. Based on mineralogical, geochemical, and geochronological evidence, the high Li enrichment in the studied samples is mainly caused by detrital material input. The dominant detrital materials in the coal and non-coal samples originate from felsic-intermediate igneous rocks in the IMPU.

中文翻译：

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控制山西宁武9号煤田关键元素锂富集的碎屑物质：重矿物和碎屑锆石的限制


作为一种关键元素，由于技术的快速发展，Li 目前的需求量很大。宾夕法尼亚州的煤炭（例如山西省的煤炭）中发现了异常的锂富集。以前的研究表明，山西省煤炭和含煤地层中的锂富集在粘土矿物中通常很明显，并且与来自附近花岗岩或铝土矿的矿物物质有关，在某些情况下，它与热液流体有关。确定导致这些煤中锂富集的锂的确切来源至关重要。本研究调查了山西省东北宁武煤田安嘉岭煤田 9 号煤层矿物物质演化的时空来源和源汇系统。共收集了 9 号煤层的 17 个煤样、6 个分型样、1 个屋顶样和 1 个楼板样。使用 X 射线粉末衍射 （XRD） 和拉曼光谱对矿物进行地球化学、矿物学和地质年代学分析，使用电感耦合等离子体-光学发射光谱 （ICP-OES） 对主要元素氧化物进行分析，使用电感耦合等离子体-质谱法 （ICP-MS） 对痕量元素进行分析，使用激光烧蚀-ICP-MS （LA-ICP-MS） 进行地质年代学分析。煤样品中的矿物物质主要由高岭石、勃姆石、石英组成，还有不同比例的方解石、黄铁矿、钠铁矿、锐钛矿和戈雅铜矿，而在非煤样品中，矿物物质以高岭石、石英为主，还有少量的锐钛矿和黄铁矿。有两种重矿物组合：钛矿-黑云母-锆石-磷灰石和钛铁矿-黑云母-锐钛矿-磷灰石。 相对于世界硬煤的元素组成，煤台阶富含 Li 和 Sr，略微富含 Ga、Zr、Hf 和 Th。相对于世界粘土的元素组成，9 号煤层的分离样品富含 Li，略微富含 Mo，屋顶样品略微富含 Hf， 屋顶和地板样品中的碎屑锆石年龄可分为两个主要年龄：2500-1700 和 326-293 马。屋顶和地板样品中锆石晶粒最年轻的 UPb 年龄分别为 292.7 ± 7.1 和 295.5 ± 9.7 马，表明早期 Asselian-Sakmarian 阶段受到良好约束。9 号煤层的碎屑锆石年龄为 326-293 马，主要来自内蒙古古隆起 （IMPU） 的花岗岩侵入体和火山岩，而不是铝土矿床。根据矿物学、地球化学和地质年代学证据，研究样品中的高锂富集主要是由碎屑物质输入引起的。煤和非煤样品中的主要碎屑物质来源于 IMPU 中的长英质-中间火成岩。