Genesis and tectonic implications of podiform chromitite from the Renbu ophiolite in central Yarlung Zangbo suture zone, Tibet
Author:
Affiliation:

Clc Number:

Fund Project:

  • Article
  • |
  • Figures
  • |
  • Metrics
  • |
  • Reference
  • |
  • Related
  • |
  • Cited by
  • |
  • Materials
  • |
  • Comments
    Abstract:

    The Yarlung Zangbo suture zone (YZSZ) in southern Tibet is the suture zone with the most abundant chromite in China. This contribution reports the characteristics and genesis of the Renbu podiform chromitites within the central YZSZ and provides new constraints on the evolution and mineralization of the suture zone. The Renbu ophiolite cropping out as an E—W trending belt is mainly composed of ca. 30 mantle peridotite massifs with varying occurrences. Peridotites from these massifs are predominantly harzburgites with minor dunites that experienced varying amounts of serpentinization. Several irregular lenticular bodies of chromitite with ore textures ranging from massive to disseminated to sparsely disseminated have been found in serpentinized dunite and harzburgite. These orebodies with 0. 5~5 m in length and 0. 1~2 m width show dip directions and angles ranging from 143° to 245° and 14° to 70°, respectively. The spinel grains from these chromitites are similar in composition with Cr# (=100×Cr/(Cr+Al)) ranging from 79. 0 to 80. 1 and Mg# (=100×Mg/(Mg+Fe2+)) ranging from 48. 6 to 68. 6, indicating that the Renbu chromitites belong to the high- Cr type. The Renbu chromites exhibit higher Mn and Co but lower Ni and Ga content compared to those in mid- ocean ridge basalt (MORB) and their equilibrium melts show boninitic affinity, which implies a supra- subduction zone (SSZ) setting. Both spheroidal clinopyroxene grains and needle- shaped clinopyroxene lamellaes could be distinguished in the chromites, suggesting that the formation of the deposit probably involved deep and shallow processes. Since the field relationships and ore compositions of the podiform chromitites in the Renbu ophiolite are comparable with those from the Luobusa ophiolite in the eastern YZSZ, we propose that the Renbu ophiolite is likely to preserve the deep signatures of forearc extension at the southern margin of the Lhasa terrane and is a promising prospecting area for chromitite.

    Reference
    Related
    Cited by
Get Citation

Yang Shengbiao, Li Yuan, Yang Jingsui, Badengzhu, Badengzhu, Bo Rongzhong, Li Ruibao, Liu Chengjun, Xiong Fahui, Cao Chuqi.2022. Genesis and tectonic implications of podiform chromitite from the Renbu ophiolite in central Yarlung Zangbo suture zone, Tibet[J]. Acta Geologica Sinica,96(2):533-553

Copy
Share
Article Metrics
  • Abstract:
  • PDF:
  • HTML:
  • Cited by:
History
  • Received:November 17,2021
  • Revised:January 28,2022
  • Adopted:
  • Online: February 07,2022
  • Published: