黔西上二叠统煤系关键金属富集层时空分布及地质控制因素
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本文为国家重点研发计划项目(编号2021YFC2902002)和国家自然科学基金项目(编号42172186)联合资助的成果


Spatiotemporal distribution and geological controlling factors of critical metal enrichment layers in the Upper Permian coal measures in western Guizhou
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    摘要:

    黔西晚二叠世煤系关键金属元素富集层在垂向上叠置分布,但其在地层中的时空分布规律尚不清楚。详细研究关键金属富集层的时空分布规律可以预测其分布特征及了解该时期富集成矿规律与地质事件的联系。本文分析了煤系关键金属富集层的地球化学特征及垂向分布规律,探讨了其形成的地质控制因素。结果表明煤系Ga- Zr- Nb- REY关键金属富集层为自然伽马高异常岩层,具有低Sr/Ba、较高的Rb/Sr和CIAcorr值,以及相对较高的V/Ni和V/(V+Ni),表明在气候相对炎热、海平面仍相对较低时期形成于水体相对较深的缺氧环境中。根据富集层垂向分布特征总结了6种Ga- Zr- Nb- REY富集层沉积序列及3种Li富集层沉积序列,其中Ga- Zr- Nb- REY富集层垂向分布特征表明富集层在沉积旋回内处于相对一致的层位。M2井长兴组的Li富集层在垂向上有显著的旋回性。Ga- Zr- Nb- REY关键金属富集层为含板内火山灰层,其垂向叠置规律及关键金属元素含量受板内火山活动规律及强度控制。古地理格局控制了沉积物在地表遭受淋滤作用的强度,经历较弱或未经历淋滤作用的含板内火山灰层具有关键金属元素富集的特征。弱水动力条件利于火山灰的保存,局限环境可能是形成Li富集层的重要原因。在热液流体的影响下形成了黔西地区偶现的Li、Ti富集层。这种富集成矿规律及分布模式可以有效地预测关键金属元素富集层位的时空分布规律。

    Abstract:

    The Late Permian coal measures of western Guizhou exhibit vertically superimposed critical metal element enrichment layers,yet their spatiotemporal distribution in the strata remains unclear. Understanding the spatial and temporal distribution of these critical metal- rich layers is crucial for predicting their distribution characteristics and elucidating the relationship between enrichment mineralization patterns and geological events during this period. This study analyzes the geochemical characteristics and vertical distribution of critical metal enrichment layers in these coal measures, aiming to identify the underlying geological controlling factors. The results show that the critical metal enrichment layers in the coal measures are characterized by a natural gamma- positive anomaly, low Sr/Ba ratios, elevated Rb/Sr and CIA corrvalues, and relatively high V/Ni and V/(V+Ni) ratios, indicating that they were formed in a relatively deep, anoxic environment during a period of relatively hot climate and low sea level. According to the observed vertical distribution patterns, we delineate six distinct depositional sequences for Ga- Zr- Nb- REY enrichment layers and three for Li enrichment layers. The vertical distribution consistently favors critical metal enrichment layers within coal seam roofs and floors, dirt bands, limestone interlayers, and mudstone interlayers. This consistent positioning in the sedimentary cycle suggests a shared depositional environment. The Ga- Zr- Nb- REY enrichment layers are mainly attributed to intraplate volcanic ash layers. Their vertical superposition pattern and critical metal element content are directly controlled by the pattern and intensity of intraplate volcanic activity. The paleogeographic setting influences the intensity of surface leaching, with intraplate volcanic ash layers experiencing weak or no leaching exhibiting enriched critical metal element characteristics. Weak hydrodynamic conditions are conducive to the preservation of volcanic ash, and the limited environment may be an important reason for the formation of Li- enriched layers. Hydrothermal fluidactivity is also implicated in the enrichment of Ti and Li in certain layers. The metallogenic regularity and distribution model can effectively predict the spatiotemporal distribution of critical metal element enrichment layers.

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杨天洋,沈玉林,金军,黄文,张云飞,曾丽君,姜帆,赵雅.2024.黔西上二叠统煤系关键金属富集层时空分布及地质控制因素[J].地质学报,98(8):2365-2378.
YANG Tianyang, SHEN Yulin, JIN Jun, HUANG Wen, ZHANG Yunfei, ZENG Lijun, JIANG Fan, ZHAO Ya.2024. Spatiotemporal distribution and geological controlling factors of critical metal enrichment layers in the Upper Permian coal measures in western Guizhou[J]. Acta Geologica Sinica,98(8):2365-2378.

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  • 收稿日期:2024-04-22
  • 最后修改日期:2024-05-20
  • 在线发布日期: 2024-08-20