Monazite geochronology and petrology of kyanite- and sillimanite-grade migmatites from the northwestern flank of the eastern Himalayan syntaxis

Palin, R; Searle, M; St-Onge, MR; Waters, D; Roberts, N; Horstwood, M; Parrish, R; Weller, O; Chen, S; Yang, J

Journal article

Monazite geochronology and petrology of kyanite- and sillimanite-grade migmatites from the northwestern flank of the eastern Himalayan syntaxis

Abstract:: A combined geochronological and petrological study of pelitic migmatites from the northwestern flank of the eastern Himalayan syntaxis has constrained the timing and P-T conditions of two high-grade metamorphic events that affected the south Lhasa block (Asian margin) and provides new insight into the tectonothermal evolution of the India-Asia collision. U(-Th)-Pb dating of in situ monazite shows that upper amphibolite-facies sillimanite-grade metamorphism and consequent partial melting occurred between c. 71 and 50 Ma at P-T conditions above 6.3 ± 1.2 kbar and 750 ± 30 °C. Further partial melting at upper amphibolite-facies kyanite-grade conditions occurred between c. 44 and 33 Ma at minimum P-T conditions of 10.4 ± 1.0 kbar and 698 ± 20 °C. These data are interpreted to record a south Lhasa block mid-crustal sillimanite-grade melting event in the Late Cretaceous to Early Eocene related to regional heat advection caused by coeval and prolonged emplacement of Gangdese batholith units. This was followed by a higher pressure and lower temperature kyanite-grade melting event during the Middle Eocene to Early Oligocene associated with deformation and crustal thickening in the south Lhasa block, coeval with kyanite-grade metamorphism along the Himalaya, as a result of the on-going India-Asia collision. These partially-melted crustal lithologies offer potential sources (or otherwise analogs for sources) for the Miocene emplacement of adakitic intrusions previously documented in the eastern Himalayan syntaxis region. © 2013 International Association for Gondwana Research.

Publication status:: Published

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APA Style

Palin, R., Searle, M., St-Onge, M. R., Waters, D., Roberts, N., Horstwood, M., Parrish, R., Weller, O., Chen, S., & Yang, J. (2014). Monazite geochronology and petrology of kyanite- and sillimanite-grade migmatites from the northwestern flank of the eastern Himalayan syntaxis. GONDWANA RESEARCH, 26(1), 323–347.

MLA Style

Palin, R, et al. “Monazite Geochronology and Petrology of Kyanite- and Sillimanite-Grade Migmatites from the Northwestern Flank of the Eastern Himalayan Syntaxis.” GONDWANA RESEARCH, vol. 26, no. 1, 2014, pp. 323–47.

Chicago Style

Palin, R, M Searle, MR St-Onge, et al. 2014. “Monazite Geochronology and Petrology of Kyanite- and Sillimanite-Grade Migmatites from the Northwestern Flank of the Eastern Himalayan Syntaxis.” GONDWANA RESEARCH 26 (1): 323–47.
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