| 刘繁奇,欧凯,高荣臻,张开,赵志颖.新疆乌拉根铅锌矿床下白垩统克孜勒苏群陆相红层“漂白”地质特征及其成因意义[J].矿产勘查,2026,17(3):491-502 |
| 新疆乌拉根铅锌矿床下白垩统克孜勒苏群陆相红层“漂白”地质特征及其成因意义 |
| Geological characteristics and genetic significance of "Bleaching" in the continental red beds of the Lower Cretaceous Kezilesu Group in the Uragen lead-zinc deposit, Xinjiang |
| 投稿时间：2025-09-18 |
| DOI：10.20008/j.kckc.202603006 |
| 中文关键词: 乌拉根铅锌矿床 下白垩统克孜勒苏群 陆相红层 成矿金属元素 赋存状态 |
| 英文关键词: Uragen Zn-Pb deposit Lower Cretaceous Kezilesu Group continental red beds ore metals occur-rence state |
| 基金项目:本文受国家自然科学基金项目(41902067)、辽宁省自然科学基金项目(2023-MSBA-116)与国家级大学生创新创业训练计划资助项目(S202310145004、X202510145134)联合资助。 |
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| 中文摘要: |
| 红层“漂白”是乌拉根铅锌矿床的重要找矿标志，多认为其与铁(Ⅲ)的氧化物与氢氧化物(IOH)溶解有关，但对其具体成因及成矿金属元素活动性认识不清。本文以矿区下白垩统克孜勒苏群同一纹层红色与“漂白”砂岩为研究对象，开展岩/矿相学观测、可见光-短波红外反射光谱测量、黑云母 EPMA主量元素和 LA-ICP-TOFMS微量元素扫面分析。发现砂岩显红色与碎屑颗粒表面 IOH有关，推测为成岩期黑云母等镁铁质矿物原地氧化水解形成；而“漂白”砂岩几乎不含 IOH，高岭石、蒙脱石等黏土矿物含量增多。红色砂岩 Cu-Pb-Zn-U等成矿金属元素与 IOH空间分布相耦合，在一定范围内与 Fe元素正相关，而与碎屑颗粒无关，指示其主要吸附于 IOH“漂白”砂岩中黑云母 FeOT、MnO等组分含量和 Fe3+/(Fe2++Fe3+)比值较红色砂岩降低，而 SiO2、Al2O3等组分含量则明显升高，指示漂白过程中黑云母有大量铁锰等金属元素迁出，与还原性流体活动有关。结合漂白砂砾岩孔隙中油斑或固态沥青和石英碎屑中次生含油气流体包裹体以及闪锌矿中液态和固态有机包裹物等油气显示，推测红层“漂白”可能与还原性油气流体有关。综上所述，红层因油气还原使得 IOH溶解而“漂白”，其所吸附的成矿金属元素也被淋滤萃取而参与成矿。 |
| 英文摘要: |
| The bleaching of red beds serves as a significant prospecting indicator for the Uragen lead-zinc de-posit. It is widely considered to be associated with the dissolution of iron (III) oxides and hydroxides (IOH), however,the specific genetic mechanism of bleaching and the mobility of ore metals remain poorly understood. This study fo-cuses on the red and bleached sandstones from the same sedimentary layer within the Lower Cretaceous KezilesuGroup in the mining area. Investigations including petrological and mineralogical observations, visible to short-wave infrared reflectance spectroscopy, EPMA major element analysis of biotite, and LA-ICP-TOFMS trace ele-ment mapping were carried out. The results indicate that the red color of the sandstone is related to IOH coatings ondetrital grain surfaces, which are inferred to have formed through in situ oxidative hydrolysis of mafic minerals suchas biotite during diagenesis. In contrast, the bleached sandstones contain almost no IOH but show increasedamounts of clay minerals such as kaolinite and montmorillonite. In the red sandstones, the distribution of ore metalssuch as Cu, Pb, Zn, and U correlate spatially with IOH, showing a positive relationship between ore metals and Fecontent within a certain range, while no correlation with detrital particles is observed. It suggests that these elementsare mainly adsorbed onto IOH. In the bleached sandstones, the contents of FeOT and MnO in biotite, as well as the Fe3+/(Fe2++Fe3+ ) ratio, are lower than those in red sandstones, whereas the contents of SiO2 and Al2O3 in biotite in-crease significantly. These changes indicate extensive leaching of iron, manganese, and other ore metals from biotiteduring the bleaching process, possibly associated with the activity of reducing fluids. Combined with hydrocarbonshowings such as oil stains or solid bitumen in the pores of bleached sandstones, hydrocarbon-bearing secondaryfluid inclusions in quartz fragments, and liquid and solid organic inclusions in sphalerite, it is inferred that thebleaching of red beds may be related to reducing fluids of oil and gas. In conclusion, the bleaching of red beds re-sults from hydrocarbon reduction-induced dissolution of IOH, and the adsorbed ore metals by IOH are leached andextracted, thereby contributing to ore-forming fluids and sandstone-hosted Pb-Zn mineralization. |
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