首页|希夏邦马峰地区含绿柱石花岗伟晶岩的地球化学及年代学研究

希夏邦马峰地区含绿柱石花岗伟晶岩的地球化学及年代学研究

扫码查看
喜马拉雅淡色花岗岩是印度和欧亚板块碰撞造山过程中的重要产物,在造山带演化和高原隆升的相关研究中受到高度关注.近年来的研究发现其经历过高度结晶分异且与超大型锂-铍-铷-铯等稀有金属矿床紧密相关.本文报道了与希夏邦马峰淡色花岗岩相关的含绿柱石伟晶岩的矿物学、地球化学和年代学资料.这些伟晶岩中的绿柱石普遍呈自形,多数被包裹在长石和石英等主要造岩矿物中,显示出岩浆结晶的特点.矿物化学显示绿柱石的元素变化以通道-八面体替代和通道-四面体替代为主.希夏邦马伟晶岩中绿柱石地球化学组成与铍成矿伟晶岩中绿柱石相当,相对喜马拉雅锂成矿伟晶岩中的绿柱石具有更低的Li2O、Cs2O和Na/Li比,显示出寄主岩石以铍矿化为主.这与全岩地球化学显示的伟晶岩高铍低锂的特点相一致.除此之外,伟晶岩中铷、铯、锡等稀有金属元素也发生了明显的富集.伟晶岩中稀有金属元素与Rb/Sr比之间的强正相关性表明它们的富集主要受控于分离结晶作用.独居石U-Th-Pb年代学分析表明这些伟晶岩主要形成于ca.18~17Ma,与希夏邦马淡色花岗岩岩体的年龄相一致.同时,伟晶岩中的独居石还记录了ca.25~23Ma和ca.21 Ma两期年龄,代表了区域上其他两期淡色花岗岩岩浆事件.在喜马拉雅中部地区,普遍发育这三个阶段的淡色花岗岩岩浆事件以及稀有金属成矿作用,进一步表明了淡色花岗岩的形成与分异演化对伟晶岩成矿的贡献.
Geochemical and geochronological study of beryl-bearing granitic pegmatite in the Mount Shisha Pangma Himalaya region
The Himalayan leucogranite,an essential product of the collisional orogenesis between the Indian and Eurasian plates,has drawn significant attention in studies related to orogenic evolution and plateau uplift.Recent research has revealed its highly fractionated nature and close association with large rare metal(e.g.,Li,Be,Rb,Cs)deposits.This study presents mineralogical,geochemical and geochronological data related to the beryl-bearing pegmatites associated with the Shisha Pangma leucogranite in the central Himalayas.The beryl in these pegmatites typically exhibits euhedral texture,mostly enclosed within major rock-forming minerals like feldspar and quartz,indicating characteristics of magmatic crystallization.Mineral chemistry reveals that the trace elemental changes in beryl are dominated by channel-octahedral and channel-tetrahedral substitution.It has a similar geochemical composition to that of beryl in Be-mineralized pegmatite,and a lower Li2O,Cs2O and Na/Li ratio than beryl in Himalayan Li-mineralized pegmatite,highlighting the attributes of Be mineralization in the host rock.It is consistent with the whole rock geochemical characteristic of high beryllium and low lithium in pegmatite.Additionally,rubidium,cesium and tin in pegmatite were also enriched.The strong positive correlation between rare metal elements and the Rb/Sr ratio in the pegmatite indicates that their enrichment is mainly controlled by fractional crystallization.U-(Th)-Pb dating of monazite indicates that these pegmatites primarily formed at ca.18~17Ma,consistent with the age of the Shisha Pangma leucogranite.Monazite in the beryl-bearing pegmatites also records ages of ca.25~23Ma and ca.21 Ma,representing two other regional magmatic events.In the central Himalayan region,the widespread occurrence of these three stages of leucogranitic magmatic events,along with rare metal mineralization,further emphasize the contribution of the generation and differentiation of leucogranite to the mineralization of pegmatite in the Himalayas.

HimalayaShisha PangmaLeucograniteBerylFractional crystallizationRare metal mineralization

杨雷、贺一凡、王佳敏、侯康师、田雨露

展开 >

成都理工大学地球科学学院行星科学国际研究中心,成都 610059

南京大学内生金属矿床成矿机制研究国家重点实验室,南京 210023

中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京 100029

喜马拉雅 希夏邦马 淡色花岗岩 绿柱石 分离结晶 稀有金属成矿

青藏高原综合科学考察研究项目(第二次)青藏高原综合科学考察研究项目(第二次)国家自然科学基金南京大学内生金属矿床成矿机制研究国家重点实验室开放基金

2022QZKK02032019QZKK0802422020622023-LAMD-K13

2024

岩石学报
中国矿物岩石地球化学学会,中国科学院地质地球物理研究所

岩石学报

CSTPCD北大核心
影响因子:2.74
ISSN:1000-0569
年,卷(期):2024.40(5)
  • 87