Metamorphic evolution of high-pressure and ultrahigh-temperature granulites from the Highland Complex, Sri Lanka

Yasuhito Osanai, Krishnan Sajeev, Masaaki Owada, K. V.Wilbert Kehelpannala, W. K.Bernard Prame, Nobuhiko Nakano, Sarath Jayatileke

研究成果: ジャーナルへの寄稿記事

46 引用 (Scopus)

抄録

Sapphirine+quartz-bearing pelitic granulites, garnet-clinopyroxene-quartz-bearing mafic granulites and quartzo-feldspathic granulites with corundum-garnet-quartz constitute rare but important members of the Highland Complex in Sri Lanka. Peak metamorphic conditions from the Highland Complex generally have been considered to be up to ∼850-900 °C and ∼8 10 kbar. However, this study on the above mentioned rocks indicates that ultrahigh-temperature and high-pressure conditions (>1100 °C and ∼12 kbar) were attained during peak conditions. A metamorphic evolution of the ultrahigh-temperature metamorphic rocks was determined from careful analyses of shifts in divariant assemblages and reaction textures. This shows a clockwise P-T path from more high-pressure conditions (∼1000 °C and ∼17 kbar; stage 0 as part of the prograde metamorphic path) to lower-pressure and -temperature conditions (∼950 °C and ∼9 kbar; stage 4 as part of the retrograde path) through the peak metamorphic conditions (stage 1). Widespread lower pressure and temperature granulite-facies metamorphic rocks surround the ultrahigh-temperature granulites and are interpreted to have formed by the strong effect of the retrograde metamorphism and deformation. The widely reported Pan-African metamorphic ages derived from similar granulite-facies metamorphic rocks in the Gondwana fragments (Highland Complex in Sri Lanka, Lützow-Holm Complex in east Antarctica, etc.) may also be the result of retrograde metamorphism of ultrahigh-temperature metamorphic rocks. There remains a possibility that this early ultrahigh-temperature/high-pressure granulite-facies metamorphism in the Highland Complex, as well as that in the Lützow-Holm Complex, might pre-date Pan-African metamorphism.

元の言語英語
ページ(範囲)20-37
ページ数18
ジャーナルJournal of Asian Earth Sciences
28
発行部数1
DOI
出版物ステータス出版済み - 10 15 2006
外部発表Yes

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metamorphic rock
granulite facies
retrograde metamorphism
temperature
quartz
low pressure
garnet
metamorphism
sapphirine
corundum
Gondwana
clinopyroxene
texture
rock

All Science Journal Classification (ASJC) codes

  • Geology
  • Earth-Surface Processes

これを引用

Metamorphic evolution of high-pressure and ultrahigh-temperature granulites from the Highland Complex, Sri Lanka. / Osanai, Yasuhito; Sajeev, Krishnan; Owada, Masaaki; Kehelpannala, K. V.Wilbert; Prame, W. K.Bernard; Nakano, Nobuhiko; Jayatileke, Sarath.

:: Journal of Asian Earth Sciences, 巻 28, 番号 1, 15.10.2006, p. 20-37.

研究成果: ジャーナルへの寄稿記事

Osanai, Yasuhito ; Sajeev, Krishnan ; Owada, Masaaki ; Kehelpannala, K. V.Wilbert ; Prame, W. K.Bernard ; Nakano, Nobuhiko ; Jayatileke, Sarath. / Metamorphic evolution of high-pressure and ultrahigh-temperature granulites from the Highland Complex, Sri Lanka. :: Journal of Asian Earth Sciences. 2006 ; 巻 28, 番号 1. pp. 20-37.
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abstract = "Sapphirine+quartz-bearing pelitic granulites, garnet-clinopyroxene-quartz-bearing mafic granulites and quartzo-feldspathic granulites with corundum-garnet-quartz constitute rare but important members of the Highland Complex in Sri Lanka. Peak metamorphic conditions from the Highland Complex generally have been considered to be up to ∼850-900 °C and ∼8 10 kbar. However, this study on the above mentioned rocks indicates that ultrahigh-temperature and high-pressure conditions (>1100 °C and ∼12 kbar) were attained during peak conditions. A metamorphic evolution of the ultrahigh-temperature metamorphic rocks was determined from careful analyses of shifts in divariant assemblages and reaction textures. This shows a clockwise P-T path from more high-pressure conditions (∼1000 °C and ∼17 kbar; stage 0 as part of the prograde metamorphic path) to lower-pressure and -temperature conditions (∼950 °C and ∼9 kbar; stage 4 as part of the retrograde path) through the peak metamorphic conditions (stage 1). Widespread lower pressure and temperature granulite-facies metamorphic rocks surround the ultrahigh-temperature granulites and are interpreted to have formed by the strong effect of the retrograde metamorphism and deformation. The widely reported Pan-African metamorphic ages derived from similar granulite-facies metamorphic rocks in the Gondwana fragments (Highland Complex in Sri Lanka, L{\"u}tzow-Holm Complex in east Antarctica, etc.) may also be the result of retrograde metamorphism of ultrahigh-temperature metamorphic rocks. There remains a possibility that this early ultrahigh-temperature/high-pressure granulite-facies metamorphism in the Highland Complex, as well as that in the L{\"u}tzow-Holm Complex, might pre-date Pan-African metamorphism.",
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AU - Osanai, Yasuhito

AU - Sajeev, Krishnan

AU - Owada, Masaaki

AU - Kehelpannala, K. V.Wilbert

AU - Prame, W. K.Bernard

AU - Nakano, Nobuhiko

AU - Jayatileke, Sarath

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