西藏中冈底斯成矿带中段铍矿化体的发现与意义
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摘要
经过初步工作,在西藏中冈底斯成矿带发现极具潜力的铍矿找矿线索。新发现的铍矿化体赋存在侵位于古生代地层的粗粒状和伟晶状二云母花岗岩中,岩体和岩脉即为矿化体,并与围岩具有截然的界线。围岩发育热液蚀变和热变质,包括角岩化、硅化、电气石化、石榴子石化、红柱石化、堇青石化等,但分带不甚明显,矿化体和围岩间还发育有"云母线"。矿化体罕见黑钨矿和锂辉石,萤石较少,主要为铌钽矿物和含铍矿物。这一新发现丰富了中冈底斯成矿带新矿种和新的矿床类型,对更加深入地认识冈底斯成矿带构造-岩浆演化与成矿作用、丰富和完善青藏高原南部碰撞造山与成矿理论有重要意义。
The potential clues for beryllium mineralization are newly found in the middle part of the central Gangdise metallogenic zone,Xizang. The beryllium-mineralized bodies herein are hosted in the coarsely granular and pegmatoid two-mica granites emplaced in the metamorphic Palaeozoic strata,occur as rock bodies and rock veins,and are well-defined with the wall rocks. There occur in the wall rocks both hydrothermal alteration and thermal metamorphism,including hornfeldsization,silicification,tourmalinization,garnetization,andalusitization and cordieritization. The "mica line"is also observed between the beryllium-mineralized bodies and wall rocks.The minerals wolframite and spodumene are scarce in the beryllium-mineralized bodies,with additional a small amount of fluorite. The economic minerals include niobium-tantalum minerals and beryllium-bearing minerals. The discovery in this study has revealed that there is a great prospecting potentiality not only for lead,zinc,iron,molybdenum and gold deposits, but also for beryllium deposits in the central Gangdise metallogenic zone.Furthermore,this discovery also has an important geological significance to the better understanding of the tectonicmagmatic evolution and mineralization,collision and mountain building and metallogenesis in the southern part of the Qinghai-Xizang Plateau.
The potential clues for beryllium mineralization are newly found in the middle part of the central Gangdise metallogenic zone,Xizang. The beryllium-mineralized bodies herein are hosted in the coarsely granular and pegmatoid two-mica granites emplaced in the metamorphic Palaeozoic strata,occur as rock bodies and rock veins,and are well-defined with the wall rocks. There occur in the wall rocks both hydrothermal alteration and thermal metamorphism,including hornfeldsization,silicification,tourmalinization,garnetization,andalusitization and cordieritization. The "mica line"is also observed between the beryllium-mineralized bodies and wall rocks.The minerals wolframite and spodumene are scarce in the beryllium-mineralized bodies,with additional a small amount of fluorite. The economic minerals include niobium-tantalum minerals and beryllium-bearing minerals. The discovery in this study has revealed that there is a great prospecting potentiality not only for lead,zinc,iron,molybdenum and gold deposits, but also for beryllium deposits in the central Gangdise metallogenic zone.Furthermore,this discovery also has an important geological significance to the better understanding of the tectonicmagmatic evolution and mineralization,collision and mountain building and metallogenesis in the southern part of the Qinghai-Xizang Plateau.
引文
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[4] Zhu D C,Zhao Z D,Niu Y L,et al. The Lhasa terrane:record of a microcontinent and its histories of drift and growth[J]. Earth and Planetary Science Letters,2011,301(1):241-255.
[5]张立雪,王青,朱弟成,等.拉萨地体锆石Hf同位素填图:对地壳性质和成矿潜力的约束[J].岩石学报,2013,29(11):3681-3688.
[6]侯增谦,莫宣学,杨志明,等.青藏高原碰撞造山带成矿作用:构造背景、时空分布和主要类型[J].中国地质,2006,33(2):340-351.
[7]唐菊兴,张志,李志军,等.西藏尕尔穷-嘎拉勒铜金矿集区成矿规律、矿床模型与找矿方向[J].地球学报,2013,34(4):385-394.
[8]李光明,刘波,董随亮,等.冈底斯成矿带中段铜铁铅锌矿集区的叠合成矿作用及意义——以斯弄多铅锌矿床为例[J].矿床地质,2010,29(S1):217-218.
[9]黄瀚霄,李光明,曾庆高,等.西藏查个勒铅锌矿床成矿时代研究及地质意义[J].中国地质,2012,39(3),750-759.
[10]雍永源.锡和钨:西藏冈底斯带潜在的优势矿种[J].沉积与特提斯地质,2007,27(1):1-8.
[11]段志明,李光明,李应栩,等.中冈底斯成矿带龙根铅锌矿床含矿斑岩年代学与地球化学特征[J].矿床地质,2014,33(3):625-638.
[12]李光明,张林奎,焦彦杰,等.西藏喜马拉雅成矿带错那洞超大型铍锡钨多金属矿床的发现及意义[J].矿床地质,2017,36(4):1003-1008.
[13]李建康,邹天人,王登红,丁欣.中国铍矿成矿规律[J].矿床地质,2017,36(4):951-978.
[14]谢学锦.中国地球化学图集[M].北京:地质出版社,2012.1-135.
[15]王登红,刘丽君,侯江龙,等.初论甲基卡式稀有金属矿床“五层楼+地下室“”勘查模型[J].地学前缘,2017,(5):1-7.