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Author Imayama, Takeshi
Source SpringerLink
Content type Text
Publisher Springer Basel
File Format PDF
Copyright Year ©2014
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Earth sciences
Subject Keyword Nepal Himalaya ♦ P–T evolution ♦ Metabasites ♦ Tectonic block ♦ Geology
Abstract Metabasites exposed in far-eastern Nepal provide an important insight into the metamorphic evolution of the Himalayan orogen independent from data obtained on metapelites. The P–T conditions and formation process of mafic granulite intercalated within Early Oligocene migmatites and two amphibolites surrounded by Early Miocene metapelites were inferred from pseudosection modeling and conventional geothermobarometry combined with the occurrences of field and microstructures. A mafic granulite in the Higher Himalaya Crystalline Sequence (HHCS) yields P–T conditions of 6.5–8 kbar, 730–750 °C. The similar peak P–T condition and retrograde path with low P/T gradient of mafic granulite and surrounding migmatite indicate that both rocks were simultaneously metamorphosed and exhumed together along the tectonic discontinuities in the HHCS. In contrast, the P–T conditions (2–5 kbar, 500–600 °C) of highly-deformed amphibolite block above the Main Central Thrust (MCT) records significantly lower pressure than garnet-mica gneisses in the country rock, suggesting that the amphibolite block derived from upper unit of the MCT zone and became tectonically mixed with the gneisses of hanging wall near the surface. An amphibolite lense below the MCT preserves the prograde P–T conditions (6–7.5 kbar, 550–590 °C) of Early Miocene syn-tectonic metamorphism that occurred in the MCT zone. This study indicates the top-to-the south movement of the MCT zone results in the tectonic assembly of rocks with different P–T–t conditions near the MCT.
ISSN 16618726
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2014-05-22
Publisher Place Basel
e-ISSN 16618734
Journal Swiss Journal of Geosciences
Volume Number 107
Issue Number 1
Page Count 19
Starting Page 81
Ending Page 99


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Source: SpringerLink