极地研究

极地研究 ›› 1998, Vol. 9 ›› Issue (2-English): 79-91.

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The 40Ar-39Ar ages of hornblendes in Grt-Pl-bearing amphibolite from the Larsemann Hils, East Antarctica and their geological implication

 Tong Laixi1, Liu Xiaohan1, Zhang Liansheng1, Chen Haihong1, Chen Fukun2, Wang Yanbin3 and Ren Liudong3   

  1. 1Laboratory of Lithosphere Tectonic Evolution, Institute of  Geology, Chinese Academy of Sciences, Beijing 100029, China 2Institut für Petrologie and Geochemie, Universität Tübingen, 72074 Tübingen, Germany 3Institute of Geology, Chinese Academy of Sciences, Beijing 100037, China
  • 出版日期:1948-06-30 发布日期:1948-06-30
  • 通讯作者: Tong Laixi

The 40Ar-39Ar ages of hornblendes in Grt-Pl-bearing amphibolite from the Larsemann Hils, East Antarctica and their geological implication

 Tong Laixi1, Liu Xiaohan1, Zhang Liansheng1, Chen Haihong1, Chen Fukun2, Wang Yanbin3 and Ren Liudong3   

  1. 1Laboratory of Lithosphere Tectonic Evolution, Institute of  Geology, Chinese Academy of Sciences, Beijing 100029, China 2Institut für Petrologie and Geochemie, Universität Tübingen, 72074 Tübingen, Germany 3Institute of Geology, Chinese Academy of Sciences, Beijing 100037, China
  • Online:1948-06-30 Published:1948-06-30
  • Contact: Tong Laixi

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摘要：

In this paper we reported the 40Ar-39Ar dating results of hornblendes in Grt-P1-bearing amphibolite from the Larsemann Hills, East Antarctica. Their apparent ages respectively are 1586 Ma, 1011-1080 Ma, 761 Ma, 529-582 Ma. Their plateau ages of 1036 Ma and 554 Ma as well as an Ar-Ar isochron age of 1010 Ma have also been obtained respectively. These isotopic dating results for the first time by the Ar-Ar method for hornblendes completely record almost all the structural metamorphic thermal events that this region experienced, and provide an answer to the controversial question on the structural metamorphic thermal events of this region in recent several years, namely, which one is more important, the late Proterozoic 1000 Ma event (Grenvillian) or the early Palaeozoic 500 Ma event ( Pan African), as well as whether the former exists or not. The 40Ar-39Ar dating results of hornblendes show that the Larsemann Hills experienced a complicated poly metamorphic evolutionary history, and their protoliths were probably formed in early to mid Proterozoic. The late Proterozoic 1000 Ma event (Grenvillian) has been confirmed to be a predominant tectonothermal event whilst the early Palaeozoic 500 Ma event (Pan-African) has been confirmed just to be the last strong tectonothermal event in this region.

关键词: East Antarctica, Grt-P1-bearing amphibolite, hornblendes, 40Ar-39Ar ages, tectonothermal events

Abstract:

In this paper we reported the 40Ar-39Ar dating results of hornblendes in Grt-P1-bearing amphibolite from the Larsemann Hills, East Antarctica. Their apparent ages respectively are 1586 Ma, 1011-1080 Ma, 761 Ma, 529-582 Ma. Their plateau ages of 1036 Ma and 554 Ma as well as an Ar-Ar isochron age of 1010 Ma have also been obtained respectively. These isotopic dating results for the first time by the Ar-Ar method for hornblendes completely record almost all the structural metamorphic thermal events that this region experienced, and provide an answer to the controversial question on the structural metamorphic thermal events of this region in recent several years, namely, which one is more important, the late Proterozoic 1000 Ma event (Grenvillian) or the early Palaeozoic 500 Ma event ( Pan African), as well as whether the former exists or not. The 40Ar-39Ar dating results of hornblendes show that the Larsemann Hills experienced a complicated poly metamorphic evolutionary history, and their protoliths were probably formed in early to mid Proterozoic. The late Proterozoic 1000 Ma event (Grenvillian) has been confirmed to be a predominant tectonothermal event whilst the early Palaeozoic 500 Ma event (Pan-African) has been confirmed just to be the last strong tectonothermal event in this region.

Key words: East Antarctica, Grt-P1-bearing amphibolite, hornblendes, 40Ar-39Ar ages, tectonothermal events