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Timing and origin of multi-stage magmatism and related W–Mo–Pb–Zn–Fe–Cu mineralization in the Huangshaping deposit, South China: An integrated zircon study
Chemical Geology ( IF 3.9 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.chemgeo.2020.119782
Wei-Cheng Jiang , Huan Li , Simon Turner , Da-Peng Zhu , Chong Wang

Abstract The Huangshaping deposit (South China) is closely related to hypabyssal granites (e.g., quartz porphyry, granophyre, and granite porphyry), developing massive skarn-type W–Mo–Fe polymetallic mineralization, skarn-type Pb–Zn–Cu mineralization, and vein-type Pb Zn ( Cu) mineralization. To better constrain the geochronology, fluid composition, magma source, metallogenic affinity, and source of ore-forming materials in the Huangshaping deposit, morphological, textural, in situ geochronological, compositional, and Lu Hf isotopic studies on zircons hosted in granitoids, skarns (ores), and wall rocks have been carried out. Overall, five types of zircons are identified: low-U magmatic (abbreviated as LUMZ), high-U magmatic (HUMZ), hydrothermally-altered metamict (HAZ), inherited, and detrital types. Round-shaped inherited and detrital zircons with low trace element compositions are rarely captured in the granite porphyry and largely hosted in sulfide skarn ores and wall rocks. The HUMZ are mainly observed in the granophyre and are easily distinguished from LUMZ by their much higher U, Th, and Y contents, black CL images, and stronger Eu anomalies. In addition, the crystallization time of HUMZ was later than that of LUMZ. The HAZ uniquely exists in granite porphyry and genetic-related skarns with cracked and porous textures and strong enrichment of many trace elements. These zircons were originally HUMZ that have undergone rapid partial metamictization and subsequent fluid-zircon interaction. This study demonstrates that the granophyre is a two-stage intrusion with ages of 179 ± 0.3 Ma and 163 ± 0.7 Ma, whereas the granite porphyry yields younger ages of 157 ± 0.5 Ma. The discovery of Triassic inherited zircons in the latter leads us to propose the presence of a concealed Triassic pluton (~220 Ma). The zircon populations of W−Mo−Fe mineralized garnet skarns are mainly composed of ~160 and 180 Ma magmatic zircons, whereas magnetite skarn ores contain both magmatic zircons (~50%) and inherited zircons (~50%). In contrast, inherited zircons are the dominant zircon population of the skarn Pb−Zn ores. This may indicate that the granite porphyry (the foremost one) and granophyre mostly contributed to the skarn-type W−Mo−Fe mineralization, whereas the Carboniferous and Devonian carbonate strata significantly contributed to the skarn-type Pb−Zn ( Cu) mineralization. Fluids separated from the granite porphyry that modified the zircons are likely the principal ore-forming fluids, which are enriched in F, U, Th, Y, REE, Nb, Ta, Hf, Fe, Ca, P, Ti, Pb W, Mo, and Fe. Zircon Hf isotopes suggest that these magmas, at least the granophyre and granite porphyry, were generated by reworking of Mesoproterozoic crustal rocks without significant input of mantle materials. This study highlights the use of different types and generations of zircons from variable rock types to reveal fluid compositions and mineralization potentials in complex metallogenic systems.

中文翻译:

华南黄沙坪矿床多期岩浆作用及相关W-Mo-Pb-Zn-Fe-Cu成矿时间和成因:综合锆石研究

摘要 黄沙坪矿床(华南)与浅海花岗岩(如石英斑岩、花岗斑岩、花岗斑岩)密切相关,发育块状矽卡岩型 W-Mo-Fe 多金属矿化、矽卡岩型 Pb-Zn-Cu 矿化,和脉型铅锌(铜)矿化。为了更好地限制黄沙坪矿床的年代学、流体成分、岩浆来源、成矿亲和力和成矿物质来源,对花岗岩、矽卡岩中的锆石进行了形态、结构、原位年代学、成分和 Lu Hf 同位素研究(矿石)和围岩已进行。总的来说,确定了五种类型的锆石:低 U 岩浆(缩写为 LUMZ)、高 U 岩浆(HUMZ)、热液变质变质岩(HAZ)、继承和碎屑类型。具有低微量元素组成的圆形继承和碎屑锆石很少在花岗岩斑岩中捕获,主要存在于硫化矽卡岩矿石和围岩中。HUMZ 主要在花斑中观察到,并且通过它们更高的 U、Th 和 Y 含量、黑色 CL 图像和更强的 Eu 异常很容易与 LUMZ 区分开来。此外,HUMZ 的结晶时间比 LUMZ 晚。热影响区独特地存在于花岗岩斑岩和与成因相关的矽卡岩中,具有裂隙和多孔的纹理,并且富含多种微量元素。这些锆石最初是 HUMZ,经历了快速的部分变质化和随后的流体-锆石相互作用。这项研究表明,花斑岩是一个两阶段的侵入体,年龄分别为 179±0.3 Ma 和 163±0.7 Ma,而花岗岩斑岩产生的年龄更小,为 157 ± 0.5 Ma。后者中三叠​​纪继承锆石的发现使我们提出存在隐蔽的三叠纪岩体(~220 Ma)。W−Mo−Fe 矿化石榴石矽卡岩的锆石种群主要由~160 和 180 Ma 岩浆锆石组成,而磁铁矿矽卡岩矿石同时包含岩浆锆石(~50%)和继承锆石(~50%)。相比之下,继承锆石是矽卡岩 Pb-Zn 矿石的主要锆石种群。这可能表明花岗岩斑岩(最前面的一个)和花斑岩主要促成了矽卡岩型 W-Mo-Fe 矿化,而石炭系和泥盆纪碳酸盐岩地层对矽卡岩型 Pb-Zn (Cu) 矿化有显着贡献。从改变锆石的花岗岩斑岩中分离出的流体可能是主要的成矿流体,富含 F、U、Th、Y、REE、Nb、Ta、Hf、Fe、Ca、P、Ti、Pb W、钼和铁。锆石 Hf 同位素表明,这些岩浆,至少是花岗斑岩和花岗岩斑岩,是通过中元古代地壳岩石再加工而产生的,而没有大量的地幔物质输入。这项研究强调了使用来自不同岩石类型的不同类型和世代的锆石来揭示复杂成矿系统中的流体成分和成矿潜力。是通过中元古代地壳岩石的再加工而产生的,而没有大量的地幔物质输入。这项研究强调了使用来自不同岩石类型的不同类型和世代的锆石来揭示复杂成矿系统中的流体成分和成矿潜力。是通过中元古代地壳岩石的再加工而产生的,而没有大量的地幔物质输入。这项研究强调了使用来自不同岩石类型的不同类型和世代的锆石来揭示复杂成矿系统中的流体成分和成矿潜力。
更新日期:2020-10-01
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