近日，昆明理工大学Zhen Jia团队研究了青藏高原东南贡山地区黑马锌铝石矿床成因。这一研究成果于2025年9月16日发表在《地球化学学报》杂志上。

黑麻锌铝石矿床位于中国西南青藏高原东南部。NNW至NS走向的矿体赋存于高黎贡山变质带。

为了阐明黑马锌钠长石的成因，研究组对黑马伟晶岩进行了综合研究，结合了精确的地质年代学、同位素示踪和详细的矿物化学，以限制其形成年龄、岩石成因和矿化过程。他们采用岩浆锆石（56.93±0.53 Ma）和锡石（57.0±4.2 Ma）的稳健地质年代学框架，确定了晚古新世至早始新世的伟晶岩侵位，代表了锂矿化的最大年龄。 Hf同位素组成（εHf（t）=−14.3至−12.4）表明，黑马伟晶岩起源于古代沉积物的重熔，这使其有别于同时期始新世冈底斯-腾冲花岗岩（εHf(t) =  12.7 to +11.0）。

这种地壳特征与区域片麻状花岗岩（600-420 Ma）中Hf同位素的演化趋势一致，支持源自古代大陆地壳的深熔起源，而不是附近始新世花岗岩深成岩体的衍生物。对锂云母的详细地球化学分析揭示了两个不同的世代，形成机制截然不同。原生云母Ia（53.45±0.86 Ma，Rb-Sr年龄）表现出极端的不相容元素富集（Li、Be、Rb、Cs）和极低的K/Rb比值（3.98-4.37），这是高度分馏花岗岩熔体结晶的特征。相比之下，次生云母Ib和云母II（17.9-16.0 Ma，Rb-Sr年龄）显示出明显的Nb-Ta-W富集，反映了中新世变质热液事件中富F-P热液的沉淀。 

主成分分析（PCA）证实了这些云母世代之间的成分差异，后期归因于流体引起的蚀变和改造。区域对比确定了青藏高原东南部贡山地区两个不同的锂成矿事件。始新世（~55 Ma）以锌钠长石为主（如Heima、Puladi），与新特提斯闭合后的地壳熔融有关。中新世阶段（~17 Ma）以锂辉石为主（如丹竹、培里），与喜马拉雅结晶杂岩快速折返、剥蚀和减压部分熔融形成的喜马拉雅淡色花岗岩有关。 

附：英文原文

Title: Genesis of the Heima zinnwaldite deposit in the Gongshan region, Southeast Tibetan plateau

Author: Li, Shiping, Wang, Zechuan, Wang, Jing, Jia, Zhen, Cheng, Jialong, Chen, Fuchuan, Xiao, Shiyin, Dong, Chaofang, Luo, Yitian

Issue&Volume: 2025-09-16

Abstract: The middle-scale Heima zinnwaldite deposit is situated in the southeastern Tibetan Plateau, SW China. The NNW- to NS-trending orebodies are hosted in the Gaoligongshan metamorphic zone. To clarify the zinnwaldite genesis at Heima, this study presents an integrated investigation of the Heima pegmatites, combining precise geochronology, isotopic tracing, and detailed mineral chemistry to constrain its formation age, petrogenetic origin, and mineralization processes. Our robust geochronological framework, employing magmatic zircon (56.93 ± 0.53 Ma) and cassiterite (57.0 ± 4.2 Ma), establishes the pegmatite emplacement during the Late Paleocene to Early Eocene, representing the maximum age of lithium mineralization. Hf isotopic compositions (εHf(t) =  14.3 to 12.4) demonstrate that the Heima pegmatite originated from remelting of ancient sediments, distinguishing it from contemporaneous Eocene Gangdese–Tengchong granites (εHf(t) =  12.7 to +11.0) that show mantle contributions. This crustal signature aligns with the evolutionary trend of Hf isotopes in regional gneissic granites (600420 Ma), supporting an anatectic origin from ancient continental crust rather than being derivatives of nearby Eocene granitic plutons. Detailed geochemical analysis of Li-micas reveals two distinct generations with contrasting formation mechanisms. The primary mica-Ia (53.45 ± 0.86 Ma, Rb–Sr age) exhibits extreme incompatible element enrichment (Li, Be, Rb, Cs) and remarkably low K/Rb ratios (3.98–4.37), characteristic of crystallization from highly fractionated granitic melts. In contrast, secondary mica-Ib and mica-II (17.9–16.0 Ma, Rb–Sr age) show significant Nb–Ta–W enrichment, reflecting precipitation from F–P-rich hydrothermal fluids during Miocene metamorphic–hydrothermal events. Principal component analysis (PCA) confirms the compositional disparity between these mica generations, with the later phases attributed to fluid-induced alteration and reworking. Regional correlation identifies two distinct lithium mineralization episodes in the Gongshan area, southeast Tibetan Plateau. The Eocene phase (~ 55 Ma) is zinnwaldite-dominant (e.g., Heima, Puladi), associated with crustal melting following Neo-Tethyan closure. The Miocene phase (~ 17 Ma) is spodumene-dominant (e.g., Danzhu, Peili), linked to Himalayan leucogranites formed as the rapid exhumation, denudation, and decompression partial melting of Himalayan Crystalline Complex.

DOI: 10.1007/s11631-025-00822-6

Source: https://link.springer.com/article/10.1007/s11631-025-00822-6