Eocene migmatite formation and diachronous burial revealed by petrochronology in NW Himalaya, Zanskar

0531819 - GFÚ 2021 RIV GB eng J - Článek v odborném periodiku
Štípská, P. - Závada, Prokop - Collett, S. - Kylander-Clark, A. - Hacker, B. R. - Tabaud, A.-S. - Racek, M.
Eocene migmatite formation and diachronous burial revealed by petrochronology in NW Himalaya, Zanskar.
Journal of Metamorphic Geology. Roč. 38, č. 6 (2020), s. 655-691. ISSN 0263-4929. E-ISSN 1525-1314
Institucionální podpora: RVO:67985530
Klíčová slova: Eohimalayan metamorphism * monazite dating and REE * monazite growth and recrystallization * prograde and retrogradeP-T-tpath * Zanskar Himalaya
Obor OECD: Geology
Impakt faktor: 4.850, rok: 2020
Způsob publikování: Omezený přístup
https://onlinelibrary.wiley.com/doi/abs/10.1111/jmg.12534

In this contribution, we highlight the importance of in-situ monazite geochronology linked to P-Tmodelling for identification of timescales of metamorphic processes. Barrovian-type micaschists, migmatites and augengneiss from the Gumburanjun dome in the southeastern extremity of the Gianbul dome, NW Himalaya, have been studied in order to correlate the early stages of Himalayan metamorphism at different crustal levels and infer the timing of anatexis. P-T-tpaths are constrained through combined pseudosection modelling andin-situand in-mount monazite and xenotime laser ablation-split-stream inductively coupled plasma-mass spectrometry. Petrography and garnet zoning combined with pseudosection modelling show that garnet-staurolite schists record burial from similar to 530 to 560 degrees C and 5.5 kbar to similar to 630 to 660 degrees C and 7 kbar, staurolite-kyanite schists from similar to 530 to 560 degrees C and 5 kbar to similar to 670 to 680 degrees C and 7-9 kbar, and garnet-kyanite migmatites from 540-570 degrees C and 5 kbar to similar to 680 to 750 degrees C and 7-10 kbar, probably also to >750 degrees C and >9 kbar above the muscovite stability field. The decompression paths of garnet-staurolite schists indicate cooling on decompression, while garnet rim chemistry and local sillimanite growth point to a stage of re-equilibration at similar to 600 to 670 degrees C and 4-6 kbar in some of the staurolite-kyanite schists, and at similar to 670 to 700 degrees C and 6 kbar in garnet-kyanite migmatites. Some of the staurolite-kyanite schists and garnet-kyanite migmatites also contain andalusite or andalusite-cordierite. Monazite and xenotime were analysed in thin sections in garnet, staurolite and kyanite, and in the matrix, and in mounts. BSE images and compositional maps of monazite (xenotime was too small) show variable internal structures from homogeneous through patchy zoning with embayed to sharp boundaries.
Trvalý link: http://hdl.handle.net/11104/0310426