第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議室前フロ

Adachi Tatsuro

Baba Sotaro

Hokada Tomokazu

Nakano Nobuhiko

Osanai Yasuhito

Toyoshima Tsuyoshi

中野 伸彦

外田 智千

小山内 康人

豊島 剛志

足立 達朗

馬場 壮太郎

National Institute of Polar Research Repository

  セールロンダーネ山地中央部のユニット境界に関する新たな知見  外田智千 1、小山内康人 2、馬場壮太郎 3、中野伸彦 2、足立達朗 2、豊島剛志 4 1国立極地研究所 2九州大学 3琉球大学 4新潟大学  Newly obtained data for geologic unit boundaries at central part of Sør Rondane Mountains  Tomokazu Hokada1, Yasuhito Osanai2, Sotaro Baba3, Nobuhiko Nakano2, Tatsuro Adachi2 and Tsuyoshi Toyoshima4 1NIPR 2Kyushu University 3University of Ryukyus 4Niigata University  Recent geochronologic studies combined with metamorphic data indicated that granulite-facies metamorphic events at c.640 Ma are recorded in the Austkampane - Brattnipane areas, and that relatively lower-grade (greenschist-amphibolite-facies) metamorphism with its timing at c.550 Ma is predominant in southern and southwestern part of the Sør Rondane Mountains (Asami et al., 2005; Shiraishi et al., 2008; Osanai et al., 2008; Baba et al., 2008; Adachi 2010; Adachi et al., 2009; 2010, Hokada et al., 2009; Nakano et al., 2010).  It is also estimated two contrasting P-T evolutions for granulite-facies areas; CW P-T path for Austkampane and CCW P-T path for Brattnipene, respectively.   We have conducted U-Th-Pb monazite dating along with petrological study covering the area around Nipebreen (Austkampane – Menipa – Brattnipane), where is the boundary of juxtaposed three different geologic units (namely A, B and L-types of Adachi, 2010) in central part of Sør Rondane Mountains.  Accummulated U-Th-Pb dates suggest to constrain the timing of metamorphic events adound this area as follows.  From easternmost part of Brattnipere area, we have obtained ~550 Ma U-Th-Pb ages for monazites in biotite gneiss interpreted as timing of metamorphic event which is contrary to the previously interpreted c.640 Ma granulite-facies metamorphic record in the Brattnipene area.  From eastern part of Austkampane area, c. 800Ma~ monazites are relatively large proportion along with ~c.640 Ma monazites.  Based on these newly obtained data, we will discuss the nature of geologic unit boundaries at central part of Sør Rondane Mountains, and further on to the evolution of this part of Gondwana.  References Adachi, T., Metamorphic evolution and its implication for tectonic process in the central Sør Rondane Mountains, East Antarctica. Ph.D. thesis submitted to the Graduate University for Advanced Studies, 2010.  Adachi, T., Hokada, T., Osanai, Y., Toyoshima, T., Baba, S. and Nakano, N., Correspondence between P-T paths and U-Pb ages in the central Sør Rondane Mountains, East Antarctica, Abstract of 29th Symposium on Polar Geoscience, NIPR, 2009. Adachi, T., Hokada, T., Osanai, Y., Toyoshima, T., Baba, S. and Nakano, N., Titanium behavior in quartz during retrograde hydration: Occurrence of rutile exsolution and implications for metamorphic processes in the Sør Rondane Mountains, East Antarctica, Polar Science, 3, 222-234, 2010.  Asami, M., Suzuki, K. and Grew, E.S., Monazite and zircon dating by the chemical Th–U–total Pb isochron method (CHIME) from Alasheyev Bight to the Sør Rondane Mountains, East Antarctica: a reconnaissance study of the Mozambique suture in eastern Queen Maud Land, Journal of Geology, 113, 59-82, 2005.  Baba, S., Toyoshima, T., Osanai, Y., Nakano, N., Adachi, T. and Hokada, T., Metamorphism of the Brattnipene region, Sør Rondane Mountains, East Antarctica, Abstract of 115th Annual Meeting of the Geological Society of Japan, p134, 2008. Hokada, T., Adachi, T., Osanai, Y., Nakano, N., Toyoshima, T. and Baba, S., Staurolite, spinel and orthoamphibole in pelitic gneiss, and their implications for the metamorphic processes at Austkampane, Sør Rondane Mountains, Abstract of 29th Symposium on Polar Geoscience, NIPR, 2009. Nakano, N., Osanai, Y., Baba, S., Adachi, T., Hokada, T. and Toyoshima, T., Inferred ultrahigh-temperature metamorphism of amphibolitized olivine granulite from the Sør Rondane Mountains, East Antarctica, Polar Science, 5, 345-359, 2010.    Osanai, Y., Toyoshima, T., Baba, S., Hokada, T., Nakano, N. and Adachi, T., Metamorphic evolution of Ultramafic Complex from the Sør Rondane Mountains, Dronning Maud Land, East Antarctica, Abstract of 115th Annual Meeting of the Geological Society of Japan, p133, 2008. Owada, M., Sato, A., Osanai, Y., Toyoshima, T. and Shiraishi, K., Metamorphic processes of pelitic rocks at the deeper part of continental collision zone, Sør Rondane Mountains, East Antarctica, Abstract of Annual Meeting of the Japan Association of Mineralogical Sciences, p83, 2008. Shiraishi, K., Dunkley, D.J., Hokada, T., Fanning, C.M., Kagami, H. and Hamamoto, T., Geochronological constraints on the Late Proterozoic to Cambrian crustal evolution of eastern Dronning Maud Land, East Antarctica: a synthesis of SHRIMP U-Pb age and Nd model age data. In: Satish-Kumar, M., et al. (Eds.), Geodynamic Evolution of East Antarctica: A Key to the East-West Gondwana Connection. Geological Society, London, Special Publication 308, 21-67, 2008. 

Newly obtained data for geologic unit boundaries at central part of Sør Rondane Mountains

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Newly obtained data for geologic unit boundaries at central part of Sør Rondane Mountains

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