Cr - spinel and clinopyroxene compositions from metagabbro of Nui Ngoc complex in Tam Ky area: evidence of island - arc magma

  • Affiliations:

    1 Hanoi University of Mining and Geology, Hanoi, Vietnam
    2 National Central University, Taoyuan, Taiwan
    3 Vietnam Institute of Geosciences and Mineral Resources, Hanoi, Vietnam

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  • Received: 18th-June-2021
  • Revised: 19th-Sept-2021
  • Accepted: 5th-Oct-2021
  • Online: 31st-Oct-2021
Pages: 1 - 11
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The hornblende and biotite - bearing metagabbro of the Nui Ngoc complex were exposed into a few small blocks in the southwest Tam Ky city and were viewed as parts of the Tam Ky - Phuoc Son ophiolitic complex (TPO). These rocks were undergone mylonitic deformation and metamorphism. The rocks consist mainly of orthopyroxene, clinopyroxene, plagioclase, olivine, hornblende, biotite and very few microscopic Cr - spinel. The clinopyroxene and Cr - spinel minerals were analyzed for their composition by EPMA, the results showed that: (1) The clinopyroxenes have low Al2O3 (3,2÷3,5 wt %), TiO2 (0,70÷0,82 wt %) contents and (2) the Cr - spinels have low TiO2 (0,23÷0,58 wt %) content and Mg#100* (Mg/ (Mg+Fe2+)) (32÷42) but has medium Cr# (Cr/ (Cr+Al)) (45÷52).These features are similar to those of rocks formed in anoceanic - oceanicsubduction zone that was reported for the plagiogranite of Dieng Bong complex nearby. This study results combined with previous research results in the Tam Ky - Phuoc Son suture zone show the existence of island arc, continental arc, and MOR - magmatic types.

How to Cite
Ngo, T.Xuan, Nguyen, D.Khac, ., D.Anh Vu, Pham, C.Thi, Nguyen, H.Hong Thi and Pham, D.Ngoc 2021. Cr - spinel and clinopyroxene compositions from metagabbro of Nui Ngoc complex in Tam Ky area: evidence of island - arc magma (in Vietnamese). Journal of Mining and Earth Sciences. 62, 5 (Oct, 2021), 1-11. DOI:

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