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      https://www.ias.ac.in/article/fulltext/jess/126/05/0064

    • Keywords

       

      Mafic dikes; zircon U–Pb dating; tectonic setting; Bainaimiao Arc Belt; Central Asian Orogenic Belt.

    • Abstract

       

      The Taipusi area in the Bainaimiao Arc Belt is located in the northern margin of the North China Craton, at the southern margin of the middle Central Asian Orogenic Belt. It is characterized by large exposures of mafic dikes. In this contribution, we present first-hand whole-rock major and trace elements, zircon U–Pb geochronology and in situ trace element geochemistry data for these mafic rocks, which reveal their petrogenesis and tectonic evolution. These mafic dikes display varied compositions of SiO2 (49.42–54.29%), TiO2 (0.63–1.08%), Al2O3 (13.94–17.60%), MgO (4.66–10.51%), Fe2O3 (1.59–3.07%), FeO (4.60–6.90%), CaO (4.57–8.91%), Na2O (1.61–4.26%), K2O (0.92–2.54%) and P2O5 (0.11–0.29%). They are mainly of high-K calc-alkaline series with indistinct Eu anomalies, enriched in large ion lithophile elements (e.g., Rb, Ba, K and Sr) but depleted in high field strength elements (e.g., Nb, P and Ti). These suggest that the crystallizing magma was derived from enriched mantle altered by metasomatic fluids in a subduction setting with imprints of active continental margin features. The high concentrations of Hf, U, Th, Pb and Y, pronounced positive Ce but slightly negative Eu anomalies in zircons indicating that the magma underwent a fractional crystallization and crustal contamination process, with medium to high $f\hbox {O}_{2}$. Zircon LA–ICP–MS U–Pb dating yielded concordant ages of 437–442 Ma for these mafic dikes, which is consistent with the early Paleozoic volcanic arc magmatic activity in the Bainaimiao area. Hence, we conclude that the Bainaimiao Arc Belt is a continental arc formed by the southward subduction of the Paleo-Asian ocean during early Paleozoic.

    • Author Affiliations

       

      Jing-Hua Wu1 Huan Li1 Xiao-Shuang Xi2 Hua Kong2 Qian-Hong Wu2 Neng-Li Peng3 Xi-Ming Wu4 Jing-Ya Cao2 Jillian Aira S Gabo-Ratio5

      1. Department of Resources Science and Engineering, China University of Geosciences, No. 388 Lumo Road, Wuhan 430 074, People’s Republic of China.
      2. School of Geosciences and Info-Physics, Central South University, Changsha 410 083, People’s Republic of China.
      3. Hunan Institute of Geological Survey, Changsha 410 016, People’s Republic of China.
      4. Guangxi Land and Resources Planning Institute, Nanning 530 022, People’s Republic of China.
      5. National Institute of Geological Sciences, University of the Philippines, Diliman, 1101 Quezon City, Philippines.
    • Dates

       
  • Journal of Earth System Science | News

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