题名 | 松潘-甘孜-甜水海造山带伟晶岩成因和锂矿化机制研究 |
其他题名 | RESEARCH ON THE GENESIS OF THE PEGMATITE IN THE SONGPAN-GANZE-TIANSHUIHAI OROGENIC BELT AND LI MINERALIZATION
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姓名 | |
姓名拼音 | ZHAO Hui
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学号 | 11849579
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学位类型 | 博士
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学位专业 | 083002 环境工程
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学科门类/专业学位类别 | 08 工学
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导师 | |
导师单位 | 地球与空间科学系
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论文答辩日期 | 2022-05-16
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论文提交日期 | 2022-06-25
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学位授予单位 | 哈尔滨工业大学
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学位授予地点 | 哈尔滨
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摘要 | 作为锂电池的重要原材料,锂被誉为“二十一世纪的绿色能源金属和白色石油”,对世界各国能源结构的调整和“双碳”战略规划的实现发挥着至关重要的作用。然而,我国的锂矿资源主要依靠进口,存在较高的供应风险,因此锂矿资源也是一种重要的战略资源。伟晶岩型锂矿床是锂矿资源的重要来源,勘探寻找新的伟晶岩型锂矿床已成为迫在眉睫的事情,但目前伟晶岩的成因与锂矿化机制还存在较大争议。松潘-甘孜-甜水海造山带中分布着大量的伟晶岩型锂矿床,为探讨这些科学问题提供了良好的条件。 甲基卡锂矿床位于青藏高原东缘的松潘-甘孜造山带,是中国最大的伟晶岩型锂矿床。在该矿区,大量的富锂伟晶岩(年龄为198 ~ 214 Ma)环绕晚三叠世马颈子二云母花岗岩分布。本文对马颈子二云母花岗岩、富锂伟晶岩脉和三叠纪西康群片岩进行了详细的矿物学、岩石学和地球化学研究。相比于毗邻的马颈子二云母花岗岩,甲基卡富锂伟晶岩具有较低的CaO、TFe2O3、MgO、Sr和Ba,以及较高的Li和Rb。甲基卡富锂伟晶岩的初始Sr同位素(ISr)为0.7212 ~ 0.7249(根据磷灰石获得),明显高于马颈子二云母花岗岩和西康群片岩(0.7128 ~ 0.7163)。全岩Li同位素分析表明,甲基卡富锂伟晶岩、马颈子二云母花岗岩和西康群片岩的δ7Li值分别为+0.3 ~ +1.9‰、-0.5 ~ -0.8‰和-3.2 ~ +2.4‰。微量元素模拟结果显示,甲基卡富锂伟晶岩不是马颈子二云母花岗岩分离结晶的产物,而是由一个以富锂黏土岩为主(含少量西康群片岩)的源区在高角闪岩相条件下通过低程度(5 ~ 20%)的白云母脱水熔融形成。进一步的Sr同位素模拟表明,甲基卡富锂伟晶岩的源区含有60 ~ 70%的富锂黏土岩。此外,锂同位素模拟结果显示,源区含有的富锂黏土岩越多,伟晶岩的锂同位素值越低。这很好地解释了在该矿区,富锂伟晶岩通常比贫锂伟晶岩富集轻锂同位素(6Li)的特征。据此,本文提出富锂黏土岩的存在是控制甲基卡伟晶岩锂矿化的关键因素。 大红柳滩锂成矿带位于甜水海地体中,蕴含大量的伟晶岩型稀有金属矿床。在该成矿带上,超过7000条伟晶岩脉围绕着大红柳滩花岗岩分布。本文对大红柳滩花岗岩、伟晶岩脉(道班贫锂伟晶岩、阿克沙依贫锂伟晶岩和阿克沙依富锂伟晶岩)和巴颜喀拉山群片岩进行了详细的年代学、矿物学、岩石学和地球化学研究。锆石和锡石的U-Pb定年结果表明,大红柳滩锂成矿带上伟晶岩的形成时代为195 ~ 216 Ma。相比于大红柳滩花岗岩,大红柳滩锂成矿带上的伟晶岩具有较高的SiO2和Al2O3,以及较低的TiO2、TFe2O3、MgO、和CaO。此外,贫锂伟晶岩的Rb、Cs和Li的含量与大红柳滩花岗岩相当,甚至略低于花岗岩。贫锂伟晶岩的εNd(t)值为-8.7 ~ -10.0,远低于大红柳滩花岗岩(-7.5 ~ -8.1),但均落入到围岩三叠纪片岩的范围。阿克沙依富锂伟晶岩的初始Sr同位素组成为0.7223 ~ 0.7227(根据磷灰石获得),远高于大红柳滩花岗岩(0.7108 ~ 0.7157)和三叠纪片岩(0.7107 ~ 0.7109)。大红柳滩花岗岩、伟晶岩和三叠纪片岩的全岩δ7Li值分别为+0.8 ~ +5.7‰、+0.8 ~ +14.4‰和-4.2 ~ +2.8‰。微量元素模拟以及Sr-Nd同位素一致表明,大红柳滩锂成矿带上的伟晶岩不是由大红柳滩花岗岩通过分离结晶形成,而是由变质深熔作用形成。贫锂伟晶岩主要由巴颜喀拉山群(可能含有黏土岩夹层)通过低程度的部分熔融形成,而富锂伟晶岩的源区是以富锂黏土岩为主的混合源区。此外,阿克沙依富锂伟晶岩具有较高的锂同位素值(+10.5 ~ +14.4‰),可能指示它的源区还含有大量的蒸发岩。锂同位模拟结果表明,富锂黏土岩和蒸发岩对大红柳滩锂成矿带伟晶岩的锂矿化发挥着重要的作用。同时,源区差异是造成贫锂伟晶岩和富锂伟晶岩锂同位素分馏的主要原因。通过对甲基卡伟晶岩与大红柳滩锂成矿带伟晶岩的对比研究,本文提出松潘-甘孜-甜水海造山带中的稀有金属伟晶岩具有相似的岩石成因和锂矿化机制。 |
其他摘要 | As an important raw material of lithium battery, lithium is known as the “green energy metal and white oil of the 21st century”, and plays a crucial role in adjusting the energy structure and achieving the carbon peaking and carbon neutrality goals in the world. However, lithium resources in China mainly rely on imports and there is a high supply risk, so lithium resources are also an important strategic resource. Pegmatite-type lithium ore deposit is an important source of lithium. It is urgent to explore and search for new pegmatite-type lithium ore deposit, but the origin of pegmatites and associated Li-mineralization mechanism remain unclear. Abundant pegmatite-type lithium ore deposits are distributed in the Songpan-Ganze-Tianshuihai orogenic belt, which provides us a good opportunity to discuss this issue. As one of the largest lithium ore deposits in China, the Jiajika pegmatite field is located in the Songpan-Ganze orogenic belt of the eastern Tibetan plateau. The Jiajika Li-rich pegmatites with ages of 198 ~ 214 Ma are spatially associated with the late Triassic Majingzi two-mica granite. In this study, systematic mineralogical, petrological and geochemical investigations on the Majingzi two-mica granite, Li-rich pegmatites and Xikang Group metapelites are performed. The Jiajika Li-rich pegmatites show extremely low CaO, TFe2O3, MgO, Sr and Ba, and high Li and Rb when compared with the adjacent Majingzi two-mica granite, and their initial Sr isotopic ratios (0.7212 ~ 0.7249, obtained from apatite) are significantly higher than those of the granite and the surrounding Xikang Group metapelites (0.7128 ~ 0.7163). Whole rock Li isotopes analyses yield δ7Li values of +0.3 ~ +1.9‰ for the Jiajika Li-rich pegmatites, -0.5 ~ -0.8‰ for the Majingzi two-mica granite, and -3.2 ~ +2.4‰ for the Xikang Group metapelites, respectively. Modeling studies on trace elements demonstrate that the Jiajika Li-rich pegmatites are unlikely to have been originated from extreme differentiation of the Majingzi two-mica granite as traditionally thought. Instead, they could be directly generated by low degrees (5 ~ 20%) of muscovite-dehydration melting of a mixed source dominated by Li-rich claystones and subordinate Xikang Group metapelites under amphibolite facies conditions. The Sr isotopic modeling further suggests that about 60 ~ 70% Li-rich claystones are involved in the source of the Jiajika Li-rich pegmatites. The Li isotopic modeling suggests that involvement of more claystone results in lower d7Li values in pegmatites, which could explain the general observation that the Jiajika Li-rich pegmatites always show Li isotopic compositions lighter than the Li-poor counterparts. Accordingly, we proposed that the existence of Li-rich claystone is the key factor controlling whether Li mineralization happens or not. The Dahongliutan Li-mineralized belt is located in the Tianshuihai terrane and hosts a number of rare metal pegmatite deposits. More than 7000 pegmatite dykes are distributed around the Dahongliutan granite pluton. In this study, systematic geochronological, mineralogical, petrological and geochemical investigations on the Dahongliutan granite, pegmatites (Daoban Li-poor pegmatite, Akshay Li-poor pegmatite and Akshay Li-rich pegmatite) and associated Triassic Baryanharshan Group metapelites are performed. The U-Pb dating of zircon and cassiterite yields that the emplacement of pegmatites in the Dahongliutan Li-mineralized belt occurred at ca. 195 ~ 216 Ma. The pegmatites in the Dahongliutan Li-mineralized belt are characterized by higher SiO2 and Al2O3 contents, and lower TiO2, TFe2O3, MgO and CaO contents compared to the Dahongliutan granite. The Li-poor pegmatites have comparable or lower Rb, Cs and Li contents relative to the Dahongliutan granite. The εNd(t) values (-8.7 ~ -10.0) of the Li-poor pegmatite are much lower than those (-7.5 ~ -8.1) of the Dahongliutan granite, but they fall into the field of the surrounding Triassic metapelite. The Akshay Li-rich pegmatite has significantly higher ISr values (0.7223 ~ 0.7227, obtained from apatite) than the granite (0.7108 ~ 0.7157) and metapelite (0.7107 ~ 0.7109). The whole-rock δ7Li values of the Dahongliutan granite, pegmatite and metapelite are +0.8 ~ +5.7‰, +0.8 ~ +14.4‰ and -4.2 ~ +2.8‰, respectively. The trace elements modeling combined with Sr-Nd isotopes suggests that the pegmatites in the Dahongliutan Li-mineralized belt did not originate from fractional crystallization of the granite. Instead, they formed by direct anatexis. The Li-poor pegmatites mainly derived from the Baryanharshan metapelite (probably with claystone interlayers), whereas the source of the Li-rich pegmatite is dominated by Li-rich claystone. In addition, the extremely heavy Li isotopic composition (+10.5 ~ +14.4‰) of the Akshay Li-rich pegmatite indicates that large amounts of evaporites are likely to be involved in the source of the Li-rich pegmatite. The Li isotopic modeling implies that Li-rich claystone and evaporate in the source are crucial to pegmatitic spodumene mineralization. Meanwhile, the source character is the main factor resulting in the Li isotopic fractionation between the Li-poor pegmatite and the Li-rich pegmatite. Overall, the rare metal pegmatites in the Songpan-Ganze-Tianshuihai Orogenic belt share similar petrogenesis and metallogenesis based on the comparison between the Jiajika Li-rich pegmatite and the pegmatite in the Dahognliutan Li-mineralized belt. |
关键词 | |
其他关键词 | |
语种 | 中文
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培养类别 | 联合培养
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入学年份 | 2018
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学位授予年份 | 2022-07
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参考文献列表 | [1] 徐康宁. 垂直流人工湿地污水处理甲烷减排研究[D]. 重庆. 重庆大学,2016. |
所在学位评定分委会 | 地球与空间科学系
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国内图书分类号 | P618.71
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来源库 | 人工提交
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成果类型 | 学位论文 |
条目标识符 | http://sustech.caswiz.com/handle/2SGJ60CL/342786 |
专题 | 理学院_地球与空间科学系 |
推荐引用方式 GB/T 7714 |
赵慧. 松潘-甘孜-甜水海造山带伟晶岩成因和锂矿化机制研究[D]. 哈尔滨. 哈尔滨工业大学,2022.
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