赞比亚东北部卡布韦卢马组碎屑锆石U- Pb年代学和Hf同位素特征
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:

本文为商务部技术援外项目(\[2015\]352和\[2012\]558)及中国地质调查局项目(编号DD20201150和1212011220910)资助的成果。


Detrital zircon U- Pb dating and Hf isotope analyses of the Kabwelumu Formation, northeastern Zambia
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    卡布韦卢马组广泛出露于赞比亚东北部姆波罗科索盆地中心部位,作为覆盖在变质基底之上的稳定盖层姆波罗科索群的一部分,其沉积环境、沉积时代和蚀源区的研究对了解班韦乌卢地块的演化具有重要意义。本文在详细的野外调查基础上,通过对卡布韦卢马组的实测地质剖面、LA- (MC)ICP- MS 碎屑锆石微区U- Pb 定年和Hf 同位素分析,笔者认为卡布韦卢马组主体岩性为一套在稳定的水动力条件下缓慢沉降的远滨沉积序列,其下部主要表现为辫状河、曲流河或湖口三角洲相沉积特征,中上部则逐渐过渡为远滨深水湖相沉积;本次得到的碎屑锆石谐和年龄范围2228±20~1712±22Ma,最年轻的碎屑锆石和已经公开报道的卡萨马群碎屑锆石年龄共同限定了卡布韦卢马组沉积时限可能介于1712±22Ma~1434±14Ma,属于中- 古元古代;卡布韦卢马组的碎屑锆石表现出明显的近源特征且大部分为岩浆成因,表明其蚀源区为近端的岩浆岩;卡布韦卢马组及整个沉积盖层的碎屑锆石普遍存在两个年龄峰值区:2100~1960Ma、1900~1740Ma,分别和区域上乌本迪构造带乌萨加兰期和乌本迪期构造热事件相吻合,其主要物源区可能为班韦乌卢地块及其周边的古元古代岩浆岩、花岗质片麻岩和火山岩;获得的碎屑锆石Hf同位素 ε Hf ( t )为-8. 9~+5. 1,二阶段年龄集中在2. 3~3. 0Ga,揭示了班韦乌卢地块基底杂岩大部分来源于古老陆壳(~2. 7Ga)的重熔和再循环,同时也存在2. 4Ga的新地壳生长事件,并且其地壳生长时间晚于附近的坦桑尼亚克拉通。

    Abstract:

    As a stable sedimentary sequence coveringthe crystalline basement in northeastern Zambia,the Kabwelumu Formation is widely exposed in the center of Mporokoso basin. Therefore,its depositional age,provenance and sedimentary environment can provide important information for understanding of the crustal evolution. Based on our new detailed field geological mapping results, this paper reports geological profile characteristics, detrital zircons LA- ICP- MS U- Pb ages, and Hf isotope analysis of the Kabwelumu Formation. We show that theKabwelumu Formation is a set of sedimentary sequences that settled slowly under stable hydrodynamic conditions. The lower part is mainly characterized by braided river, meanderstream, river, or lacustrine delta facies, while the upper was gradually transformed into far shore deep- water lacustrine facies. The obtained detrital zircons range in age from 2228±20 to 1712±22Ma. The youngest detrital zircons and previously reported detrital zircons from the Kasama Group together define the sedimentary time limit of the Kabwelumu Formation, which may be between 1712±22Ma to 1434±14Ma, belonging to the Meso- Proterozoic. The detrital zircons of the Kabwelumu Formation show obvious proximal features and are mostly magmatic in origin, indicating that the provenance area is the proximal magmatic rock. The detrital zircon age of the Kabwelumu Formation and the sedimentary cover display two peaks at 2100 ~ 1960 Ma, 1900 ~ 1740 Ma, which is in agreement with the Usagaran stage and the Ubendian stage tectonic thermal events in the Ubendian regional tectonicbelt. The main provenance may be paleoproterozoic magmatic rocks, granitic gneiss and volcanic rock of Bangweulu Block. ε Hf( t ) values are -8. 9~+5. 1 with corresponding T DM2 ages of 2. 3~3. 0 Ma, indicating that the basement complex of the Bangweulu block is mostly derived from re- melting and recycling of the ancient continental crust (~ 2. 7Ga), and an accretion occurred at 2. 4Ga, which is later than the Tanzania Craton.

    参考文献
    相似文献
    引证文献
引用本文

邢仕,纪山青,王杰,任军平,刘子江,古阿雷,孙宏伟,张金达,刘川,张殿领.2021.赞比亚东北部卡布韦卢马组碎屑锆石U- Pb年代学和Hf同位素特征[J].地质学报,95(4):1191-1211.
Xing Shi, Ji Shanqing, Wang Jie, Ren Junping, Liu Zijiang, Gu Alei, Sun Hongwei, Zhang Jinda, Liu Chuan, Zhang Dianling.2021. Detrital zircon U- Pb dating and Hf isotope analyses of the Kabwelumu Formation, northeastern Zambia[J]. Acta Geologica Sinica,95(4):1191-1211.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2020-07-13
  • 最后修改日期:2020-08-27
  • 录用日期:2020-11-09
  • 在线发布日期: 2020-11-18
  • 出版日期: