西藏申扎县侧波积异地区超基性岩成因特征及找矿意义
DOI:
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:

国家重点基础研究发展计划(973计划)


Cause Features and Prospecting Significance of Ultrabasic Rocks in Cebojiyi Area,Xainza County,Tibet
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:

    侧波积异地区位于西藏申扎县城东北约40km处,区域构造上位于班公湖 怒江成矿带中段南侧。该区除在超基性岩及灰岩中均发现有镍的硫化物矿物外,在超基性岩中还产生铬、钴的矿化。因此,研究区内超基性岩的地球化学特征及成因等,对侧波积异,乃至整个班公湖 怒江成矿带的资源潜力评价和找矿勘查具有十分重要的理论指导意义。侧波积异赋镍岩石主要为方辉橄榄岩,普遍发生较强烈的蛇纹石化。镍矿物主要为镍铬铁合金、铁镍合金等合金矿物,针镍矿、铁针镍矿、六方硫镍矿等硫化物矿物,以及含镍橄榄石、含镍蛇纹石等硅酸盐矿物。方辉橄榄岩的Mg#为8703~8825,平均为8782,接近蛇绿岩中变质橄榄岩的Mg#(89~91)。m/f为671~751,平均为722,为镁质超基性岩。侧波积异方辉橄榄岩为碱性系列。总体上明显富集U、Th、Pb等大离子亲石元素和Ta、P等高场强元素,明显亏损Ba、K、Sr等大离子亲石元素和Nb、Ti等高场强元素,大体符合岛弧岩浆的特征。稀土元素总量很低,∑REE=039×10-6~137×10-6,平均值为094×10-6。LREE/HREE为507~604,(La/Yb)N为298~608,轻重稀土元素分异较明显。δEu=115~154,平均值为142,有较弱的Eu正异常。δCe=093~115,平均值为104,无明显Ce异常。206Pb/204Pb为18428~18554,平均值为18476;207Pb/ 204Pb为15498~15614,平均值为15575;208Pb/204Pb为37712~38730,平均值为38386。87Rb/86Sr比值为08686~38985,平均为21145,87Sr/86Sr比值为0709148~0711524,平均为0710257,147Sm/144Nd比值为01090~01237,平均为01178,143Nd/144Nd比值为0512028~0512112,平均为0512075。结果表明,侧波积异方辉橄榄岩产出的构造环境为岛弧环境,岩浆来源于下地壳与上地幔混合的俯冲带,岩浆源区为尖晶石角闪二辉橄榄岩富集型地幔源区。侧波积异方辉橄榄岩中的Ni含量平均为20173×10-6,蛇纹石化方辉橄榄岩中的Ni含量平均为24292×10-6,若为硫化物型,则均达到边界品位,侧波积异铁矿石中镍含量已达到边界品位,为63231×10-6。此外,侧波积异铁矿石中Co含量已达边界品位,为6326×10-6,达如错铁矿石中Cr含量已达边界品位,为526794×10-6。因此,应加强班公湖 怒江成矿带与蛇绿岩有关的超基性岩中,尤其是超基性岩铁矿石中镍、铬、钴的评价工作。

    Abstract:

    Cebojiyi area, belonging to southern middle Bangong Co Nujiang River metallogenic belt, is located at the northeast of Xainza county about 40km. There are produced with nickel sulfide minerals in the ultrabasic rocks of this deposit, also with chromium and cobalt mineralization been found. It plays an important role in resource potential evaluation and mineral exploration for Cebojiyi, even the whole Bangong Co Nujiang River metallogenic belt that researching the geochemical characteristics and origin of the ultrabasic rocks in this area. The rocks containing nickel are mainly ultrabasic rocks such as harzburgite, most of which were strongly serpentinized. Nickel minerals are mainly alloy minerals such as inconel alloy, iron nickel alloy, sulfide minerals such as millerite, iron millerite and heazlewoodite, silicate minerals such as nickel containing olivine, nickel containing serpentine and so on. The Mg# values of Cebojiyi harzburgite are in the range of 8703~8825, with an average of 8782, close to the Mg#(89~91) of metaperidotite in ophiolite. The m/f values are in the range of 671~751, with an average of 722, suggesting the harzburgite are magnesia. And the Cebojiyi harzburgite are alkaline series. In the rocks, large ion lithophile elements such as U, Th, Pb and high field strength elements such as Ta, P are enriched, while the elements such as Ba, K, Sr and Nb, Ti are poor, which roughly comply with the characteristics of island arc magmas. The total REE of the rocks are very low, and the ∑REE values are in the range of 039×10-6~137×10-6, with an average of 094×10-6. It is obvious of light and heavy REE fractionation, with LREE/HREE ranging from 507 to 604 and (La/Yb)N from 298 to 608. The rocks have a weak positive Eu anomaly(δEu=115~154, with an average of 142) and no obvious Ce anomaly(δCe=093~115, with an average of 104). The 206Pb/204Pb values are 18428~18554(average is 18476), 207Pb/204Pb are 15498~15614(average is 15575), and 208Pb/204Pb are 37712~38730(average is 38386). While the 87Rb/86Sr values are 08686~38985(average is 21145),87Sr/86Sr are 0709148~0711524(average is 0710257), 147Sm/144Nd are 01090~01237(average is 01178), and 143Nd/144Nd are 0512028~0512112(average is 0512075). The results show that the tectonic environment of Cebojiyi harzburgite are island arc environment, and the magma are from the subduction zone mixed with upper crust and mantle, simultaneously, the magma source are spinel amphibole lherzolite enriched mantle source region. The average nickel content of harzburgite in Cebojiyi deposit is 20173 × 10-6, while it is 24292 × 10-6 in Cebojiyi serpentinized harzburgite. If the nickel mineral were sulfide minerals, then the content have been reached the cut off grade both in Cebojiyi harzburgite and serpentinized harzburgite. At the same time, the nickel content of iron ore in Cebojiyi deposit has been reached the cut off grade, with an average of 63231×10-6. What’s more, the cobalt content of iron ore in Cebojiyi deposit has been reached the cut off grade, with an average of 6326×10-6. And the chromium content of iron ore in Darucuo deposit has been reached the cut off grade, with an average of 526794×10-6. So attention should be paid that the nickel, cobalt and chromium prospecting work in the ultrabasic rocks associated with ophiolite, especially the iron ore in ultrabasic rocks in Bangong Co Nujiang River metallogenic belt.

    参考文献
    相似文献
    引证文献
引用本文

李小赛,赵元艺,黄道袤,曲晓明,许虹.2014.西藏申扎县侧波积异地区超基性岩成因特征及找矿意义[J].地质学报,88(10):1843-1860.
Li Xiaosai, Zhao Yuanyi.2014. Cause Features and Prospecting Significance of Ultrabasic Rocks in Cebojiyi Area,Xainza County,Tibet[J]. Acta Geologica Sinica,88(10):1843-1860.

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:2013-12-20
  • 最后修改日期:2014-03-07
  • 录用日期:2014-11-03
  • 在线发布日期: 2014-11-17
  • 出版日期: