Mineral Chemistry and Geochemistry of Peridotites from the Zedang and Luobusa Ophiolites, Tibet： Implications for the Evolution of the Neo-Tethys

• Published in: Journal of earth science (Wuhan, China) China), 2015-12, Vol.26 (6), p.893-910
• Main Authors: Li, Qiang, Xia, Bin, Li, Jianfeng, Xia, Lianze, Huang, Qiangtai, Xia, Zhongyu
• Format: Article
• Language: English
• Subjects: Biogeosciences; Earth and Environmental Science; Earth science; Earth Sciences; Geochemistry; Geology; Geotechnical Engineering & Applied Earth Sciences; Mineral exploration; Paleoceanography; Platinum; Rocks; Trace elements; 二辉橄榄岩; 地球化学性质; 方辉橄榄岩; 特提斯演化; 矿物化学; 罗布莎蛇绿岩; 西藏; 铂族元素
• ISSN: 1674-487X; 1867-111X
• DOI: 10.1007/s12583-015-0544-9

We present a new dataset on platinum group elements（PGEs）, whole-rock major and trace elements, and mineral chemistry for the peridotites from the Zedang and Luobusa ophiolite suites, Tibet, in an attempt to better constrain the petrogenesis of the Zedang and Luobusa ophiolites and the tectonic evolution of the Neo-Tethys. Plots of chondrite-normalized PGE, PGE vs. Mg#, and PGE vs. Al_2O_3 suggest that the lherzolite and harzburgite from Zedang and Luobusa have similar PGE characteristics. The Zedang and Luobusa peridotites display U-shaped REE patterns and are enriched in some incompatible elements, indicative of melt-rock interaction. The PGE characteristics may be attributed to partial melting and heterogeneous melt-rock interaction. Mineral chemistry and whole rock major and trace elements data suggest that lherzolite and harzburgite from Zedang and Luobusa have similar geochemical properties. On the spinel Mg# vs. Cr# plot, the composition of the Zedang and Luobusa peridotites is consistent with both abyssal and subduction-zone peridotites. This study indicates that the Zedang and Luobusa peridotites have a similar origin and evolution path： they could have originated from a normal mid-ocean ridge environment and got refertilization in a supra-subduction zone setting.