| Fluid components in accessory minerals of Pan-African granitoids in the Sor Rondane Mountains, East Antarctica |
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| 作者姓名： | LI Zi-long CHEN Han-lin YANG Shu-feng TAINOSHO Yoshiaki SHIRAISHI Kazuyuki OWADA Masaaki |
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| 作者单位： | [1]Department of Earth Science, College of Science, Zhejiang University, Hangzhou 310027, China [2]Faculty of Human Development, Kobe University, Nada, Kobe 657-8507, Japan [3]National Institute of Polar Research, Kaga 1-chome, ltabashi-ku, Tokyo 173-8515, Japan [4]Department of Earth Sciences, University of Yamaguchi, Yamaguchi 753-8512, Japan [5]Department of Earth and Planetary Science, Harvard University, Cambridge, MA 02138, USA |
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| 基金项目： | Project （Nos. 40472040 and 40472120） supported by the National Natural Science Foundation of China |
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| 摘 要： | Fluids (fluorine, chlorine, and OH) in accessory minerals (apatite, titanite and allanite) of Pan-African granitoids(Group-Ⅰ granitoids, Group-Ⅱ granitoids and Mefjell Plutonic Complex) from the Sor Rondane Mountains, East Antarctica were precisely measured by an electronic microprobe analyzer in this study. Apatites in the granites have commonly high fluorine contents. However, fluorine contents from the Group-Ⅰ, Group-Ⅱ granitoids and Mefjell Plutonic Complex (MPC) are of important variation, which F contents (3.21～7.20 wt%) in apatite from the Group-Ⅱ granitoids are much higher than those from the Group-Ⅰ granitoids (1.22～3.60 wt%) and the MPC (3.21～4.11 wt%). Titanite in the MPC has a low fluorine content (0.23～0.50 wt%), being less than those in the Group-Ⅰ granitoids (2.28 wt%) and Group-Ⅱ granitoids (1.85～2.78 wt%). Fluorine in allanite in the Group-Ⅱ granitoids seems to have much lower contents than those from the Group-Ⅰ granitoids and the MPC. Higher fluorine contents in the titanite from the Group-Ⅱ granitoids may be mainly controlled by late-magmatic fluid-rock interaction processes associated with melt, but may not be indicative of original magma contents based on its petrographic feature. Due to very lower chlorine contents from all of accessory minerals, the authors suggest that titanite and apatite with higher fluorine contents in the Group-Ⅱ granitoids have much lower H2O (OH) contents compared with those in the Group-Ⅰ granitoids according to the partition among (F, Cl, OH).Fluorine contents in whole-rock samples show a variation from the higher in the Group-Ⅰ granitoids to the lower in the Group-Ⅱ granitoids and the MPC, which are consistent with the changes of those from the biotite and hornblende as well as fluorite occurred in the Group-Ⅰ granitoids reported previously. Based on the above study of fluorine in accessory minerals and combined with the previous fluorine contents from biotites and hornblendes, the authors suggest that apatites and titanites with higher F contents in the Group-Ⅱ granitoids and the MPC may not be an indicator of higher fluorine contents in whole-rock, which reflect fluorine contents in magma sources and/or late-thermal activity. Higher fluorine contents in apatite, titanite and allanite may be an additional evidence of A-type affinity.
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| 关 键 词： | 氟元素 矿物质 非洲 花岗石 |
| 收稿时间： | 2 April 2007 |
| 修稿时间： | 2007-04-022007-05-14 |
Fluid components in accessory minerals of Pan-African granitoids in the Sør Rondane Mountains,East Antarctica |
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| LI Zi-long CHEN Han-lin YANG Shu-feng TAINOSHO Yoshiaki SHIRAISHI Kazuyuki OWADA Masaaki.Fluid components in accessory minerals of Pan-African granitoids in the Sor Rondane Mountains, East Antarctica[J].Journal of Zhejiang University Science,2007,8(7):1004-1010. |
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| Authors: | Li Zi-long Chen Han-lin Yang Shu-feng Tainosho Yoshiaki Shiraishi Kazuyuki Owada Masaaki |
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| Institution: | (1) Department of Earth Science, College of Science, Zhejiang University, Hangzhou, 310027, China;(2) Faculty of Human Development, Kobe University, Nada, Kobe 657-8507, Japan;(3) National Institute of Polar Research, Kaga 1-chome, Itabashi-ku, Tokyo 173-8515, Japan;(4) Department of Earth Sciences, University of Yamaguchi, Yamaguchi 753-8512, Japan;(5) Department of Earth and Planetary Science, Harvard University, Cambridge, MA 02138, USA |
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| Abstract: | Fluids (fluorine, chlorine, and OH) in accessory minerals (apatite, titanite and allanite) of Pan-African granitoids (Group-I granitoids, Group-II granitoids and Mefjell Plutonic Complex) from the Sør Rondane Mountains, East Antarctica were precisely measured by an electronic microprobe analyzer in this study. Apatites in the granites have commonly high fluorine contents. However, fluorine contents from the Group-I, Group-II granitoids and Mefjell Plutonic Complex (MPC) are of important variation, which F contents (3.21～7.20 wt%) in apatite from the Group-II granitoids are much higher than those from the Group-I granitoids (1.22～3.60 wt%) and the MPC (3.21～4.11 wt%). Titanite in the MPC has a low fluorine content (0.23～0.50 wt%), being less than those in the Group-I granitoids (2.28 wt%) and Group-II granitoids (1.85～2.78 wt%). Fluorine in allanite in the Group-II granitoids seems to have much lower contents than those from the Group-I granitoids and the MPC. Higher fluorine contents in the titanite from the Group-II granitoids may be mainly controlled by late-magmatic fluid-rock interaction processes associated with melt, but may not be indicative of original magma contents based on its petrographic feature. Due to very lower chlorine contents from all of accessory minerals, the authors suggest that titanite and apatite with higher fluorine contents in the Group-II granitoids have much lower H2O (OH) contents compared with those in the Group-I granitoids according to the partition among (F, Cl, OH). Fluorine contents in whole-rock samples show a variation from the higher in the Group-I granitoids to the lower in the Group-II granitoids and the MPC, which are consistent with the changes of those from the biotite and hornblende as well as fluorite occurred in the Group-I granitoids reported previously. Based on the above study of fluorine in accessory minerals and combined with the previous fluorine contents from biotites and hornblendes, the authors suggest that apatites and titanites with higher F contents in the Group-II granitoids and the MPC may not be an indicator of higher fluorine contents in whole-rock, which reflect fluorine contents in magma sources and/or late-thermal activity. Higher fluorine contents in apatite, titanite and allanite may be an additional evidence of A-type affinity. |
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| Keywords: | Fluorine contents Accessory minerals Pan-African granitoids Sor Rondane Mountains Antarctica |
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