Mineralogy and Geochemistry of Turquoise from Tianhu East, Xinjiang, China
-
摘要:
中国是世界绿松石的主要产地之一,拥有丰富的绿松石资源,主要分布于湖北、安徽、陕西、河南和新疆等地。根据赋矿类型可分为沉积变质岩和岩浆岩[1]。其中,鄂豫陕和新疆矿区绿松石均属于沉积变质岩类型[1],安徽的马鞍山和铜陵矿区绿松石属于岩浆岩类型[2]。天湖东绿松石矿床位于中国新疆维吾尔自治区哈密市东南180 km处。该矿床最早被开采的时间可以追溯到公元前1279-379年,属于古代采矿遗址[3]。2015年左右,天湖东绿松石矿被重新开采,产出的绿松石在中国市场上短暂销售过一段时间。出于对该古矿遗址保护的考虑,这里的开采活动后来被禁止了。长期以来,沉积变质岩类型的绿松石一直是我国绿松石市场上的主要来源,如产自湖北竹山、郧西、郧县、以及陕西白河等地的绿松石均属于此种类型,其成因与黑色岩系密切相关[4-6]。关于该类型绿松石的成矿机制,一直有不同的观点[6-8]。本研究以新疆哈密天湖东绿松石为例,结合野外地质特征和地质资料,对其进行了系统性的宝石学、矿物学和地球化学研究,重点研究了该地区绿松石的产地特征,并阐明其成矿过程。天湖东绿松石常呈蓝色和蓝绿色细脉出现在寒武纪坡城山组石英岩的裂隙和剪切带中。该矿点绿松石的地球化学特征以高Li、V、Cr、Sr、Ga以及低Ba为显著特征。通过拉曼光谱和电子探针显微分析,发现该矿点绿松石中典型的杂质矿物有石英、磷灰石、硫磷铝锶石、针铁矿、赤铁矿、黄钾铁钒、三水胆矾、白云母、石膏等。同时本研究首次在中国绿松石中发现了氯铜矿,该矿物可作为该产地的标志性矿物,可与中国其他产地绿松石区分,具有重要的产地鉴别意义。根据岩石学、矿物学和地球化学特征,以及伴生矿物的结晶顺序,本文提出天湖东绿松石矿属于表生风化淋滤成因。黑色岩系是绿松石成矿的主要物质来源,为绿松石的形成提供了所需的Al、P和Cu元素,而石英岩为其沉积成矿提供了空间。
Abstract:China is one of the main producing areas of turquoise in the world, boasting significant deposits mainly located in regions such as Hubei Province, Anhui Province, Shaanxi Province, Henan Province, and Xinjiang. Turquoise deposits in China can be categorized into two types: sedimentary metamorphic rock and magmatic rock[1]. The turquoises from Hubei Province, Henan Province, and Xinjiang are of the sedimentary metamorphic rock variety, whereas the specimens from Maanshan and Tongling in Anhui Province are extracted from magmatic rock[1]. The turquoise deposit from Tianhu East is located 180 km southeast of Hami (also known as Kumul) in Xinjiang, China. This deposit had been mined since as early as 1 279-379 BCE[3]. The turquoise mine from Tianhu East was re-exploited around 2015, and some of the production emerged briefly on the Chinese market. The mining was subsequently prohibited because of the location's protected status as an archaeological site. For a long time, turquoise sourced from sedimentary metamorphic rocks has dominated the Chinese market. Regions such as Zhushan, Yunxi, Yunxian in Hubei, and Baihe in Shaanxi are known for producing this type of turquoise, which is closely associated with black rock series[4-6]. The metallogenic mechanism of this variety of turquoise has been subject to various interpretations[6-8]. The geology of turquoise deposit from Tianhu East as well as updated reports and field exploration systematically summarized in this study. The turquoises usually occur as blue and bluish green veins in the fissures and shear zones of quartzite in the Cambrian Pochengshan Formation. It is characterized by high lithium, vanadium, chromium, strontium, and gallium concentrations and low barium contents. Multiple associated minerals (e.g., quartz, apatite, goethite, hematite, jarosite, bonattite, muscovite, atacamite, svanbergite, and gypsum) were identified using Raman spectroscopy and electron probe microanalysis. This study contains the first report of atacamite in Chinese turquoise, a mineral that could serve as a distinctive marker for this specific origin. Petrography, mineralogy, and geochemistry of the bedrock as well as the crystallization sequences of the associated minerals are highlighted. Based on the results, the authors propose a supergene weathering origin and elemental derivation for turquoise from Tianhu East. Black shale is likely the main original source of the aluminum, phosphorus, and copper necessary for formation, while quartzite provides enough space for precipitation.
-
Keywords:
- turquoise /
- associated mineral /
- supergene weathering origin /
- Tianhu East, Xinjiang
-
-
[1] 刘玲. 中国出土绿松石产地溯源关键技术及其应用[D]. 武汉: 中国地质大学, 2023. Liu L. Key techniques and their applications for tracing the provenance of turquoise unearthed in China[D]. Wuhan: China University of Geosciences, 2023. (in Chinese)
[2] 沈崇辉. 宁芜盆地马鞍山绿松石矿带典型矿床成因研究[D]. 北京: 中国地质大学, 2020. Shen C H. Study on the genesis of typical deposits in Maanshan turquoise metallogenic belt of Ningwu basin[D]. Beijing: China University of Geosciences, 2020. (in Chinese)
[3] 李延祥, 谭宇辰, 贾淇, 等. 新疆哈密两处古绿松石矿遗址初步考察[J]. 考古与文物, 2019(6): 22-27. Li Y X, Tan Y C, Jia Q, et al. Preliminary investigation on two ancient turquoise mining sites in Kumul, Xinjiang[J]. Archaeology and Cultural Relics, 2019(6): 22-27. (in Chinese)
[4] 姜泽春, 陈大梅, 王辅亚, 等. 湖北、陕西一带绿松石的热性能及其共生矿物[J]. 矿物学报, 1983(3): 198-206, 247. Jiang Z C, Chen D M, Wang F Y, et al. Thermal properties of turquoise and its intergrowing minerals in a certain district of China[J]. Acta Mineralogica Sinica, 1983(3): 198-206, 247. (in Chinese)
[5] 涂怀奎. 陕鄂相邻地区绿松石矿地质特征[J]. 陕西地质, 1996(2): 59-64. Tu H K. Geological characteristics of turquoise ore in the areas adjacent to Shaanxi and Hubei Province[J]. Geology of Shaanxi, 1996(2): 59-64. (in Chinese)
[6] 谢家涛, 韩岭, 徐鹏, 等. 湖北省竹山县观山寺绿松石矿床成因及控矿因素[J]. 矿产勘查, 2022, 13(11): 1 656-1 666. Xie J T, Han L, Xu P, et al. Ore genesis and ore-controlling factors of the Guanshansi turquoise deposit in Zhushan county, Hubei Province[J]. Mineral Exploration, 2022, 13(11): 1 656-1 666. (in Chinese)
[7] Li W T, Jiang S Y, Zhang H, et al. Origin of gem-quality turquoise associated with quartz-barite veins in western Hubei Province, China: Constraints from mineralogical, fluid inclusion, and C-O-H isotopic data[J]. American Mineralogist, 2024, 109(1): 103-121. doi: 10.2138/am-2022-8643
[8] 涂怀奎. 秦岭东段绿松石成矿特征[J]. 建材地质, 1997(3): 24-25. Tu H K. Metallogenic characteristics of turquoise in the eastern Qinling mountains[J]. Nonmetallic Geology, 1997(3): 24-25. (in Chinese)