| Title | Tectonometamorphic evolution of the tip of the Himalayan metamorphic core in the Jajarkot klippe, west Nepal |
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| Author | Soucy La Roche, R ; Godin, L; Cottle, J M; Kellett, D A |
| Source | Journal of Metamorphic Geology vol. 37, issue 2, 2018 p. 239-269, https://doi.org/10.1111/jmg.12459  Open Access |
| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20180197 |
| Publisher | Wiley |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Himalayas; Nepal |
| Lat/Long WENS | 79.0000 95.0000 31.0000 26.5000 |
| Subjects | tectonics; geochemistry; geochronology; structural geology; mineralogy; crustal evolution; tectonic history; metamorphism; deformation; foliation; lineations; crustal thickness; accretion; bedrock
geology; structural features; klippen; faults, thrust; folds; anticlines; synclines; lithology; modelling; phase relations; equilibrium; pressure-temperature conditions; radiometric dating; argon argon dating; metamorphic facies; greenschist facies;
amphibolite facies; mineralogical analyses; Neogene; Miocene; Paleogene; Oligocene; Himalayan Metamorphic Core; Nepal Foreland; Jajarkot Klippe; Himalayan Orogeny; Main Central Thrust; South Tibetan Detachment; geological contacts; Phanerozoic;
Cenozoic; Tertiary |
| Illustrations | geoscientific sketch maps; cross-sections; tables; photomicrographs; profiles; phase diagrams; graphs; bar graphs |
| Program | GEM: Geo-mapping for Energy and Minerals GSC Science Laboratory Network |
| Released | 2018 10 24 |
| Abstract | New phase equilibrium modelling, combined with U-Th/Pb petrochronology on monazite and xenotime, and 40Ar/39Ar geochronology on white mica, reveal the style of deformation and metamorphism near the
southern tip of the extruded Himalayan metamorphic core (HMC). In the Jajarkot klippe, west Nepal foreland, greenschist to lower amphibolite facies metamorphism is entirely constrained to the Cenozoic Himalayan orogeny, in contrast with findings from
other foreland klippen in the central Himalaya. HMC rocks exposed in the Jajarkot klippe yield short-lived, hairpin pressure-temperature-time-deformation paths that peaked at 550-600°C and 750-1,200 MPa at 25 Ma. The Main Central thrust (MCT) and the
South Tibetan detachment (STD) bound the base and the top of the HMC, respectively, and were active simultaneously for at least part of their deformation history. The STD was active at c. 27-26 Ma and possibly as late as c. 19 Ma, while the MCT may
have been active as early as 27 Ma and was still active at c. 22 Ma. The tectonometamorphic conditions in the Jajarkot klippe are characteristic of crustal thickening and footwall accretion of new material at the tip of the extruding metamorphic
orogenic core. Our new results reveal that collisional processes active in the middle to late Miocene at the base of the HMC now exposed in the hinterland were also active earlier, during the Oligocene, at the tip of the southward-extruding middle
crust. |
| Summary | (Plain Language Summary, not published)
The Himalayan orogen is an important study case for understanding continent-continent collisions. In this study, the temperature, pressure and geological
timing of metamorphic in metamorphic rocks in the foreland of the mountain belt are investigated. The results show that in this region of the orogen, rocks do not preserve a pre-Himalayan (i.e. pre-Eocene) metamorphic history, although they were
metamorphosed earlier (Oligocene) than in the hinterland (Miocene). These results allow us to reconstruct the metamorphic evolution of the orogen from its Eocene beginning to the present day. |
| GEOSCAN ID | 311213 |
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