Eocene to Miocene metamorphic evolution and tectonic implication of the Ilam Nappe in Nepal Himalaya: Constraints from P–T conditions and monazite petrochronology

Constraining the evolution of shear zones in the Himalayan mid crust in Central–Western Nepal: implications for the tectonic evolution of the Himalayan metamorphic core

“…These processes are, however, complicated, particularly since ductile contractional shear zones within the GHS were found in several transects across the belt (Carosi et al . 2010; Martin et al 2010, 2015; Corrie & Kohn, 2011; Imayama et al 2012, 2022; Montomoli et al 2013, 2015; Ambrose et al . 2015; Cottle et al .…”

“…The occurrence of the STDS at the top of the GHS and of the MCTz at its bottom, as two coeval northdipping shear zones with opposite kinematics, played a key role in shaping the Himalayas and exhuming the GHS. These processes are, however, complicated, particularly since ductile contractional shear zones within the GHS were found in several transects across the belt (Carosi et al 2010;Martin et al 2010Martin et al , 2015Corrie & Kohn, 2011;Imayama et al 2012Imayama et al , 2022Montomoli et al 2013Montomoli et al , 2015Ambrose et al 2015;Cottle et al 2015;He et al 2015;Khanal et al 2015;Larson et al 2015;Wang et al 2015Wang et al , 2016Zeiger et al 2015;Agustsson et al 2016;Iaccarino et al 2017a;Walters & Kohn, 2017;Goscombe et al 2018;Chakraborty et al 2019;Waters, 2019; showing the trace of the Jagat Shear Zone (JSZ) and sample locations. On the right-hand side: stereoplot (Wulff net, lower hemisphere) of the mylonitic foliation and grain/object lineation (red dots) of the JSZ.…”

“…It is not trivial to link the obtained dates to the different generation of structures. Nevertheless, the complexity in age and mineral chemistry of geochronometers is the key to unravel the history of deformation and metamorphism (Engi, 2017;Schulz, 2021;Dumond et al 2022;Imayama et al 2022). Approaches combining in situ U-Th-Pb data, with textural position and geochemical composition of minerals, are useful to date geologic events (e.g., Williams et al 1999Williams et al , 2007Gibson et al 2004;Pyle, 2006;Rubatto et al 2013;Kohn et al 2017).…”

“…2022; Imayama et al . 2022). Approaches combining in situ U-Th-Pb data, with textural position and geochemical composition of minerals, are useful to date geologic events (e.g., Williams et al 1999, 2007; Gibson et al .…”