Subduction, peak and multi-stage exhumation metamorphism: Traces from one coesite-bearing eclogite, Tso Morari, western Himalaya

High-pressure Tethyan Himalaya rocks along the India-Asia suture zone in southern Tibet

“…GPa at 560-760 ºC (Wilke et al, 2015). Mafic enclaves in the Tso Morari orthogneiss are the likely protolith of Tso Morari coesite-bearing eclogite (de Sigoyer, 1998).…”

“…Coesite-bearing eclogite lenses in granitic orthogneiss record peak-P conditions of 4.4-4.8 GPa at 560-760 ºC (Wilke et al, 2015) whereas metasedimentary rocks record much lower peak-P conditions of ~2.0 GPa at ~550 ºC (Guillot et al, 1997). Retrogression under blueschist-amphibolite facies conditions was accompanied by the development of S2 foliation defined by phengite, chlorite and staurolite (de Sigoyer, 1998).…”

Tso Morari coesite eclogite: pseudosection predictions v. the preserved record and implications for tectonometamorphic models

“…With NW India now joining the select few locations with UHP, coesite-bearing eclogites, there followed a proliferation of petrological studies of these rocks; in many cases aided by an excursion to this remote and travel-restricted region of Ladakh as part of the Himalaya-Karakoram-Tibet (HKT) Workshop in August 2008. Despite the existence of numerous mapped bodies of eclogite (Steck et al 1998;Epard & Steck 2008: Fig. 3) an extraordinary number of studies have concentrated on just one ( (Mukherjee et al 2003;Wilke et al 2015). The cold subduction paths appear to be influenced by the modelled paths for slab surfaces worldwide (Syracuse et al 2010: shaded region of Fig.…”

Subduction undone

“…This inference was challenged in dramatic fashion by the discovery of 'ultrahigh-pressure' (UHP) mineral assemblages in exposed continental rocks in the western Alps 1 and the Scandinavian Caledonides 2 . Since then, UHP assemblages have been documented in many mountain systems 3 -some of the best examples are found in the Tso Morari region of the northwest Indian Himalaya [4][5][6] (Fig. 1).…”

“…But how can the same protein be activated in response to both cell stretching and cellular overcrowding, which probably have opposite effects on physical tension in tissues and their constituent cells? Piezo1 is a large transmembrane protein that might respond to changes in membrane curvature that occur because of alterations in cell shape 6 . It is possible that, rather than responding directly to an increase in membrane tension, Piezo1 responds to alterations in cell shape and membrane curvature that occur as a consequence of changes in tissue tension.…”