内蒙古巴根黑格其尔铅锌矿花岗斑岩锆石U- Pb年代学、地球化学及Sr- Nd- Pb- Hf同位素研究
作者:
基金项目:

本文为国家重点研发计划(2017YFC0601303)及国家自然科学基金面上项目(41773030)联合资助成果。


Zircon U- Pb geochronology, geochemical characteristics, and Sr- Nd- Pb- Hf isotopic composition of granite porphyry in the Bagenheigeqier ore district, Inner Mongolia
Author:
  • 摘要
  • | |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • | |
  • 文章评论
    摘要:

    巴根黑格其尔矿床位于大兴安岭中段,该矿床为一中型矽卡岩型铅锌铁矿。本文对矿区内的花岗斑岩进行了锆石U- Pb年代学和岩石地球化学研究。花岗斑岩LA- ICP- MS锆石U- Pb年龄为151±2. 2Ma,是晚侏罗世岩浆活动的产物。花岗斑岩A/CNK在0. 83~1. 35之间,具有高硅(70. 21%~72. 85%)、富碱(6. 60%~8. 53%)、低P2O5(0. 09%~0. 11%)的特征;分异指数(DI)为85. 7~92. 8,固结指数(SI)为3. 52~5. 80,表明岩石经历了较强的分异演化作用;微量元素原始地幔标准化图解显示U、La、Hf、Yb、Lu、Rb、K相对富集,Sr、P、Ti、Ta、Nb和Ba出现不同程度的亏损;稀土元素配分曲线呈右倾的轻稀土元素富集型,且具有中等的Eu负异常,花岗斑岩属准铝质到过铝质的高分异I型花岗岩。花岗斑岩(87Sr/86Sr)i值为0. 70222~0. 70557,εNd(t)值为2. 3~2. 5,εHf(t值为6. 2~9. 2,二阶段Nd模式年龄为741~755Ma,二阶段Hf模式年龄为613~808Ma,经校正后的(206Pb/204Pb)t 值为18. 253~18. 396,(207Pb/204Pb)t 值为15. 521~15. 546,(208Pb/204Pb)t 值为37. 841~38. 066,具有混合成因Pb的特征,以上结果说明花岗斑岩岩浆起源于新元古代加入地壳的亏损地幔物质。巴根黑格其尔花岗斑岩岩浆与大兴安岭地区的晚侏罗世花岗岩岩浆基本同期侵位,其形成与晚侏罗世蒙古鄂霍茨克洋闭合的后碰撞过程有关,并可能叠加了古太平洋板块俯冲引发的弧后伸展的影响。巴根黑格其尔花岗斑岩对矿体起到破坏的作用,是在成矿以后形成的,后期的找矿勘查工作应重点围绕闪长岩展开。

    Abstract:

    The Bagenheigeqier ore deposit is located in the middle part of the Da Hinggan Mountains belt, which is a medium- sized Skarn- type Pb- Zn- Fe polymetallic deposit. The granite porphyry zircon U- Pb geochronology and geochemistry were studied in this paper. The granite porphyry’s zircon LA- ICP- MS U- Pb age is 150. 8±2. 2 Ma, which indicates that it is the product of magma movement during the Late Jurassic. The granite porphyry is characterized by high SiO2(70. 21%~72. 85%), is alkali- rich (6. 60%~8. 53%), has low P2O5 (0. 09~0. 11), with the A/CNK value of 0. 83~1. 35; the differentiation index (DI) is 85. 7~92. 8 and the solidification index (SI) is 3. 52~5. 80 which indicates that the granite porphyry’s crystallization differentiation is of higher degree. The geochemical features show the remarkable enrichment of some elements such as U, La, Hf, Yb, Lu, Rb, K and the depletion of elements such as Sr, P, Ti, Ta, Nb, Ba. The rare- earth element (ΣREE) is 127. 60×10-6~188. 33×10-6 (average is 159. 29×10-6) and the REE patterns show the “right type”, with moderately negative Eu anomalies (δEu =0. 57~0. 66), suggesting that it is quasi- aluminum to super- aluminum high- differentiation I- type granite. The (87Sr/86Sr)i value is 0. 70222~0. 70557, εNd(t) value is 2. 3~2. 5, εHf(t) value is 6. 2~9. 2, two stage Nd mode age is 741~755 Ma, two stage Hf mode age is 613~808 Ma, the corrected (206Pb/204Pb)t value is 18. 253~18. 396, (207Pb/204Pb)t value is 15. 521~15. 546, (208Pb/204Pb)t value is 37. 841~38. 066, and it has the characteristics of mixed source Pb, which indicates that magma originated by addition of the depleted mantle material to the crust in the Neoproterozoic. The granite porphyry magma and the Late Jurassic granite magma in the Da Hinggan area are basically contemporaneous emplacement, were perhaps formed after the closure of Mongol- Okhotsk Ocean related to the post- collision process, and influenced by the subduction of the Paleo- Pacific Plate caused tectonic back- arc extension. As the granite porphyry is unrelated to mineralization and ore body, future exploration work should be focussed on the diorite instead of the granite porphyry.

    参考文献
    相似文献
    引证文献
引用本文

郭向国,黄蒙辉,王兆强,李进文,张德会,王帅杰,王思耀,焦天龙.2020.内蒙古巴根黑格其尔铅锌矿花岗斑岩锆石U- Pb年代学、地球化学及Sr- Nd- Pb- Hf同位素研究[J].地质学报,94(2):527-552.
GUO Xiangguo, HUANG Menghui, WANG Zhaoqiang, LI Jinwen, ZHANG Dehui, WANG Shuaijie, WANG Siyao, JIAO Tianlong.2020. Zircon U- Pb geochronology, geochemical characteristics, and Sr- Nd- Pb- Hf isotopic composition of granite porphyry in the Bagenheigeqier ore district, Inner Mongolia[J]. Acta Geologica Sinica,94(2):527-552.

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:2018-09-11
  • 最后修改日期:2018-11-12
  • 录用日期:2019-03-18
  • 在线发布日期: 2019-03-18