太行山北段赤瓦屋铜钼钨矿岩石地球化学、Sr-Nd-Pb同位素特征及地质意义

    The Chiwawu copper-molybdenum-tungsten deposit in northern Taihang Mountains: Petrogeochemistry, Sr-Nd-Pb isotopic characteristics and geological implication

    • 摘要: 赤瓦屋铜钼钨矿床是太行山北段南部典型斑岩矿床,铜钼钨矿赋存于赤瓦屋岩体中心相斑状花岗闪长岩中.赤瓦屋铜钼钨矿床的含矿岩体属于高钾钙碱性系列,随着σ减小,SiO2含量增加,CaO、MgO、Fe2O3、TiO2、P2O5等氧化物与SiO2含量呈负相关,表现为准铝质钙碱性Ⅰ型花岗岩的特征.Rb、Ba、Th、U、La、Nb出现相对亏损,具微弱的正Eu异常.赤瓦屋岩体87Sr/86Sr平均值为0.7068,岩浆初始比值εNd(t)为-20.9~-16.1,铅同位素比值206Pb/204Pb平均值为16.5,207Pb/204Pb平均值为15.2,208Pb/204Pb平均值为36.8,表明其岩浆以下地壳为主,混有少量地幔物质.结合区域地质背景,认为在华北克拉通受古太平洋板块俯冲影响下,下地壳和上地幔物质大规模重熔,沿太行山深断裂带上侵,最终形成了赤瓦屋铜钼钨矿床.赤瓦屋岩体及太行山北段岩浆岩带是今后找矿勘查的方向.

       

      Abstract: The Chiwawu Cu-Mo-W deposit, occurred in the central facies porphyritic granodiorite of Chiwawu rock mass, is a typical porphyry deposit in northern Taihang Mountains, belonging to the high-K calc-alkaline series. With the decrease of σ value, the content of SiO2 increases. The oxides such as CaO, MgO, Fe2O3, TiO2, and P2O5 are negatively correlated with the SiO2 content, showing the characteristics of quasi-aluminous calc-alkaline I-type granite. Elements of Rb, Ba, Th, U, La, and Nb are relatively depleted, with a slightly positive Eu anomaly. The 87Sr/86Sr ratio of Chiwawu rock mass is averagely 0.7068, with the initial ratio εNd(t) of -20.9 to -16.1, the 206Pb/204Pb ratio of 16.5, the 207Pb/204Pb ratio of 15.2 and the 208Pb/204Pb ratio of 36.8, indicating that the magma is primarily derived from the lower crust mixed with minor mantle materials. Combined with the regional geological background, it is concluded that under the influence of subduction of Paleo-Pacific Plate, the large-scale remelting of lower crust and upper mantle materials occur in North China Craton, leading to the upward invasion along the deep fault zone of Taihang Mountains, eventually forming the Chiwawu Cu-Mo-W deposit. The Chiwawu rock mass and magmatic rock belt in northern Taihang Mountains are promising targets for future mineral exploration.

       

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