青海茶卡北山伟晶岩中磷锰钠矿的发现及意义

doi:10.13745/j.esf.sf.2024.2.19

摘要/Abstract

摘要：

磷锰钠矿是一种罕见的磷酸盐矿物,国内目前尚无报道,特别是原生矿物,国内外均未发现。已有少量资料认为磷锰钠矿为磷锰锂矿经钠交代形成,为次生矿物。磷锰锂矿为伟晶岩中的常见矿物,普遍认为其为富磷伟晶岩中岩浆阶段的产物,为原生矿物。本文在茶卡北山稀有金属伟晶岩中发现有磷锰钠矿和发育在其上的磷锰锂矿,磷锰钠矿均表现为完整的矿物颗粒,不具交代残余的痕迹,并具有原生矿物特征的磷灰石蚀变;而磷锰锂矿为不规则状,发育在磷锰钠矿上,表现为典型的交代特征。同时电子探针数据显示磷锰钠矿的Mn/Fe值为1.692~1.875,磷锰锂矿的Mn/Fe值为2.519~2.548,这也指示了磷锰钠矿早于其上磷锰锂矿的形成,磷锰钠矿应为原生矿物,其上的磷锰锂矿为次生成因。而伟晶岩区成矿熔体成分更高的锰含量可能是磷锰钠矿出现的原因。磷锰钠矿上发育的磷锰锂矿和氟磷灰石蚀变特征反映了后期氧化作用和富Li、Mn、Ca、F流体的交代作用;同时结合区内锂辉石的蚀变,说明茶卡北山伟晶矿床内存在着锂的地球化学循环。

关键词: 茶卡北山, 伟晶岩, 磷锰钠矿, 磷锰锂矿, 发现及意义

Abstract:

Natrophilite is a rare phosphate mineral that has not been reported in China, especially its primary mineral, which has not been discovered both domestically and internationally. The literature with a few data suggests that natrophilite is formed by sodium replacement of lithiophilite as a secondary mineral. Lithiophilite is a common mineral in pegmatite, which is generally believed to be a product of the magmatic stage in phosphate rich pegmatites as a primary mineral. In this article, natrophilite and lithiophilite developed on natrophilite were found in the Chakabeishan rare-metal pegmatite. Natrophilite is characterized by euhedral mineral particles without any metasomatism, and has primary mineral features of apatite alteration. And the lithiophilite is irregular and develops on the natrophilite, showing typical metasomatic characteristics. Moreover, electron probe data showed that the Mn/Fe values of natrophilite were 1.692-1.875, and the Mn/Fe values of lithiophilite were 2.519-2.548. This also indicates that the formation of natrophilite occurred earlier than that of lithiophilite. Natrophilite should be the primary mineral, and the lithiophilite should be the secondary mineral. The higher manganese content of the parent magma in the pegmatite area may be a possible reason for the occurrence of natrophilite. The alteration of lithiophilite and fluoroapatite developed on the natrophilite reflect the later oxidation and metasomatism of Li, Mn, Ca, and F rich fluids. Meanwhile, combined with the alteration of spodumene in this area, it is indicated that there is a geochemical cycle of lithium in the Chakabeishan deposit.

Key words: Chakabeishan, pegmatite, natrophilite, lithiophilite, discovery and significance

中图分类号:

吕书俊, 董国臣, 赵志丹, 罗志波, 曲凯, 李小伟, 袁万明, 王艳娟, 孟佳. 青海茶卡北山伟晶岩中磷锰钠矿的发现及意义[J]. 地学前缘, 2025, 32(1): 380-387.

LÜ Shujun, DONG Guochen, ZHAO Zhidan, LUO Zhibo, QU Kai, LI Xiaowei, YUAN Wanming, WANG Yanjuan, MENG Jia. Discovery and significance of natrophilite in the pegmatite from Chakabeishan, Qinghai Province[J]. Earth Science Frontiers, 2025, 32(1): 380-387.

图/表 5

图1 青藏高原东北缘构造分区略图(a)、茶卡北山地区地质图(b)、茶卡北山伟晶岩分布图(c)和样品采集区地质图(d)(据文献[17-18]修改)

Fig.1 Structural zoning sketch map of the northeastern margin of the Qinghai-Tibet Plateau (a), Geological map of the Chakabeishan deposit (b), Distribution map of pegmatites in Chakabeishan (c), and Geological map of sample collection area (d). Modified after [17-18].

图2 磷锰钠矿显微照片 Ntp—磷锰钠矿;Col—铌钽铁矿;Ab—钠长石;Qz—石英;Brl—绿柱石。

Fig.2 Photomicrographs of natrophilite (Ntp—natrophilite; Col—coltan; Ab—albite; Qz—quartz; Brl—beryl)

图3 磷锰钠矿BSE图 Ntp—磷锰钠矿; Brl—绿柱石; Col—铌钽铁矿; Ap—磷灰石; Kfs—钾长石; Ab—钠长石; Ltp—磷锰锂矿。

Fig.3 BSE images of natrophilite (Ntp—natrophilite; Brl—beryl; Col—coltan; Ap—apatite; Kfs—K-feldspar; Ab—albite; Ltp—lithiophilite).

表1 茶卡北山磷锰钠矿和磷锰锂矿电子探针数据

Table 1 Electron probe data of natrophilite and lithiophilite in Chakabeishan

表2 茶卡北山磷锰钠矿和磷锰锂矿微量元素数据

Table 2 Trace Element Data of natrophilite and lithiophilite in Chakabeishan

参考文献 26

[1]	PAUL B M. Natrophilite, NaMn(PO₄), has ordered cations[J]. American Mineralogist, 1972, 57: 1333-1344.
[2]	BRUSH G J, DANA E S. On the mineral locality at Branchville, Connecticut: fifth paper[J]. American Mineralogist, 1890, 39: 201-216.
[3]	THOMAS R, WEBSTER J D. Strong tin enrichment in a pegmatite-formingmelt[J]. Mineralium Deposita, 2000, 35(6): 570-582.
[4]	PIECZKA A, WLODEK A, GOLEBIOWSKA B, et al. Phosphate-bearing pegmatites in the Góry Sowie Block and adjacent areas, Sudetes, SW Poland[C]. 7th International Symposium on Granitic Pegmatites, PEG 2015 Książ, Poland. 2015, 1: 77-78.
[5]	TWARDAK D, PIECZKA A. Phosphates in the Julianna pegmatitic system at Pilawa Gorna, Gory Sowie Block[C]// Joint 5th Central-European Mineralogical Conference and 7th Mineral Sciences in the Carpathians Conference. 2018, 1: 108.
[6]	FISHER D J. Pegmatite phosphates and theirproblems[J]. American Mineralogist, 1958, 43: 181-207.
[7]	FISHER D J. Natrophilite[J]. American Mineralogist, 1965, 50: 1096-1097.
[8]	LONDON D, BURT D M. Chemical models for lithium aluminosilicate stabilities in pegmatites and granites[J]. American Mineralogist, 1982, 67: 494-509.
[9]	张如柏. 阿尔泰伟晶岩中锰褐磷锂矿的发现[J]. 科学通报, 1981, 26(1): 40-42.
[10]	张如柏. 阿尔泰伟晶岩中的锌尖晶石和磷锰锂矿[J]. 地质论评, 1981, 27(1): 1-7.
[11]	杨岳清, 王文瑛, 倪云祥, 等. 南平花岗伟晶岩中的磷酸盐矿物及地球化学演化规律[J]. 福建地质, 1994, 13(4): 215-226.
[12]	凤永刚, 王艺茜, 张泽, 等. 新疆大红柳滩伟晶岩型锂矿床中磷铁锂矿地球化学特征及其对伟晶岩演化的指示意义[J]. 地质学报, 2019, 93(6): 1405-1421.
[13]	FRANSOLET A M, KELLER P, FONTAN F. The phoshate mineral associations of the Tsaobismund pegmatite, Namibia[J]. Contributions to Mineralogy and Petrology, 1986, 92(4): 502-517.
[14]	LONDON D. Pegmatites: the Canadian mineralogist special publication 10[M]. Quebec: Mineralogical Association of Canada, 2018: 347.
[15]	VIGNOLA P, DIELLA V, OPPIZZI P, et al. Phosphate assemblages from the brissago granitic pegmatite, western southern Alps, Switzerland[J]. The Canadian Mineralogist, 2008, 46(3): 635-650.
[16]	BAIJOT M, HATERT F, PHILIPPO S. Mineralogy and geochemistry of phosphates and silicates in the sapucaia pegmatite, Minas Gerais, Brazil: genetic implications[J]. The Canadian Mineralogist, 2012, 50(6): 1531-1554.
[17]	PAN T, DING Q F, ZHOU X, et al. Columbite-tantalite group mineral U-Pb geochronology of Chaqiabeishan Li-rich granitic pegmatites in the quanji massif, NW China: implications for the genesis and emplacement ages of pegmatites[J]. Frontiers in Earth Science, 2021, 8: 606951.
[18]	潘桂棠, 肖庆辉, 陆松年, 等. 中国大地构造单元划分[J]. 中国地质, 2009, 36(1): 1-16, 255, 17-28.
[19]	王秉璋, 韩杰, 谢祥镭, 等. 青藏高原东北缘茶卡北山印支期(含绿柱石)锂辉石伟晶岩脉群的发现及Li-Be成矿意义[J]. 大地构造与成矿学, 2020, 44(1): 69-79.
[20]	赵文涛, 刘少峰, 陈敏, 等. 宗务隆构造带西段三叠系隆务河组碎屑锆石特征及其构造意义[J]. 岩石矿物学杂志, 2022, 41(3): 569-591.
[21]	SUN W L, ZHAO Z D, MO X X, et al. Age and composition of columbite-tantalite group minerals in the spodumene pegmatite from the chakabeishan deposit, northern Tibetan Plateau and their implications[J]. Minerals, 2023, 13(2): 201.
[22]	吕书俊, 董国臣, 罗志波, 等. 茶卡北山锂辉石花岗伟晶岩锂矿化特征及成矿时限[J]. 岩石矿物学杂志, 2023, 42(3): 350-364.
[23]	FRANSOLET A M, HATERT F, FONTAN F. Petrographic evidence for primary hagendorfite in an unusual assemblage of phosphate minerals, kibingo granitic pegmatite, Rwanda[J]. The Canadian Mineralogist, 2004, 42(3): 697-704.
[24]	RODA E, FONTAN F, PESQUERA A, et al. The phosphate mineral association of the granitic pegmatites of the Fregeneda area (Salamanca, Spain)[J]. Mineralogical Magazine, 1996, 60(402): 767-778.
[25]	SCHMID-BEURMANN P, OTTOLINI L, HATERT F, et al. Topotactic formation of ferrisicklerite from natural triphylite under hydrothermal conditions[J]. Mineralogy and Petrology, 2013, 107(4): 501-515.
[26]	徐遥辰, 卢奂, 饶灿. 新疆阿尔泰协库斯特伟晶岩中锂的矿物学行为及其启示[J]. 高校地质学报, 2019, 25(3): 321-332.