The Carboniferous ophiolite in the middle of the Qiangtang terrane, Northern Tibet: SHRIMP U-Pb dating, geochemical and Sr-Nd-Hf isotopic characteristics

Qing Guo Zhai*, Bor Ming Jahn, Jun Wang, Li Su, Xuan Xue Mo, Kuo Lung Wang, Suo Han Tang, Hao Yang Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

159 Citations (Scopus)

Abstract

Ophiolite plays a key role in identifying paleo-ocean and paleo-plate and rebuilding the evolutionary history of ancient orogen. Mafic-ultramafic rocks are distributed in a broadly E-W direction in the middle of the Qiangtang terrane, northern Tibetan plateau. However, interpretation of these rocks as ophiolite and subsequent tectonic implications have been much disputed, and they were regarded by some to have an origin in a continental rift setting. A detailed zircon dating and geochemical and Sr-Nd-Hf isotopic study of this suite of rocks has been undertaken in order to clarify this important issue. The mafic-ultramafic suite was collected from the Gangma Co and Guoganjianian localities and is composed of cumulate and isotropic gabbro, basalt, actinolitite and plagiogranite. All basaltic rocks are tholeiitic and have low rare earth element (REE) abundances with variable REE patterns and slight negative Nb and Ti anomalies. These features are comparable with those of normal mid-ocean ridge basalts (N-MORB) and/or enriched mid-ocean ridge basalts (E-MORB). The positive whole-rock εNd(t) and zircon εHf(t) values indicate that these rocks were derived from a long-term depleted mantle source. Zircon U-Pb dating using a sensitive high-resolution ion microprobe (SHRIMP) on two cumulate gabbros and two plagiogranites samples yielded Carboniferous ages of 357±2.5Ma, 356.1±3.0Ma, 354.7±4.7Ma and 345.4±4.6Ma. The ophiolite marks a Paleo-Tethys Ocean basin in middle of the Qiangtang terrane, and it is interpreted as the western extension of the Changning-Menglian Paleo-Tethys ophiolite in the eastern margin of the Tibetan plateau.

Original languageEnglish
Pages (from-to)186-199
Number of pages14
JournalLithos
Volume168-169
DOIs
Publication statusPublished - May 2013
Externally publishedYes

Keywords

  • Geochemistry
  • Ophiolite
  • Paleo-Tethys Ocean
  • Qiangtang
  • SHRIMP dating
  • Tibet

Fingerprint Dive into the research topics of 'The Carboniferous ophiolite in the middle of the Qiangtang terrane, Northern Tibet: SHRIMP U-Pb dating, geochemical and Sr-Nd-Hf isotopic characteristics'. Together they form a unique fingerprint.

Cite this