Timing of granulite-facies metamorphism in the eastern Himalayan syntaxis and its tectonic implications

Abstract

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Rapid Eocene erosion, sedimentation and burial in the eastern Himalayan syntaxis and its geodynamic significance

“…The protracted time of the Indian continental subduction recorded in both the hanging wall and footwall of the subduction zone in the EHS is markedly later than that in the western Himalaya, where the deep subduction rocks had exhumed to the upper crust depth before~40 Ma (de Sigoyer et al, 2000;Leech et al, 2005;Parrish et al, 2006). This observation might reflect real diachroneity in the timing of subduction of the Indian continent along the length of the Himalayan orogen (Guillot et al, 2008;Zhang et al, 2010b), although the metamorphic history of the eastern and western parts of the Himalayan belt appear to become broadly synchronous after~24 Ma (Xu et al, 2010;Su et al, 2012).…”

“…The Zhibai Formation comprises garnet-bearing gneisses containing sporadic boudins of HP granulite, with peak metamorphic temperature-pressure conditions estimated at~850°C and 14-18 kbar (Zhong and Ding, 1996;Liu and Zhong, 1997;Ding and Zhong, 1999;Geng et al, 2006;Booth et al, 2009). The age of peak metamorphism for the HP granulites has been variably estimated from~40 Ma to~24 Ma (Ding et al, 2001;Liu et al, 2007b;Xu et al, 2010;Zhang et al, 2010b;Su et al, 2012). The Duoxiongla Complex comprises migmatitic gneisses and orthogneisses with protolith ages ranging from 1.6 Ga to 1.8 Ga, as determined by U-Pb zircon dating (Guo et al, 2008;Zhang et al, 2012).…”

“…Geochronological study of the granulite-facies metamorphic rocks has yielded contentious results, with peak metamorphic age ranging from~40 Ma to~24 Ma (Ding et al, 2001;Liu et al, 2007b;Xu et al, 2010;Zhang et al, 2010b;Su et al, 2012). As a result, the subduction process in the eastern part of the orogen is poorly constrained.…”

“…To better understand the Indian continental subduction, investigations that were carried out over recent decades have focused largely on the Himalayan metamorphic and magmatic rocks of the Indian plate that form the footwall of the subduction zone (Tonarini et al, 1993;Guillot et al, 1997;de Sigoyer et al, 2000;Ding et al, 2001;O'Brien et al, 2001;Kaneko et al, 2003;Mukherjee et al, 2003;Leech et al, 2005;Parrish et al, 2006;Liu et al, 2007b;Guillot et al, 2008;Booth et al, 2009;Cottle et al, 2009;Xu et al, 2010). The hanging wall of the subduction zone, known as the southern Lhasa terrane, is dominated by Jurassic-Paleocene magmatic rocks related to the tectono-thermal evolution of an Andean-type arc (Mo et al, 2003;Chu et al, 2006;Mo et al, 2007;Mo et al, 2008;Wen et al, 2008;Chiu et al, 2009;Ji et al, 2009;Chu et al, 2011;Xia et al, 2011;Zhu et al, 2011bZhu et al, , 2012Guan et al, 2012).…”

Arc and Slab-Failure Magmatism in Cordilleran Batholiths II – The Cretaceous Peninsular Ranges Batholith of Southern and Baja California

“…The effects of slab failure are important, diverse, and may be responsible for features such as rapid uplift (Chatelain et al 1992), syncollisional magmatism (Davies and von Blanckenburg 1995;Keskin 2003;Macera et al 2008), tomographic gaps in the descending slab (Wortel and Spakman 1992), thick-skinned foreland deformation (Cloos et al 2005), seismic discontinuities (Wortel and Spakman 1992), crustal recycling (Hildebrand and Bowring 1999), transitory pulses of mafic magmatism (Ferrari 2004) doubly vergent orogens (Regard et al 2008), plateau uplift (Rodgers et al 2002), ultra-high pressure exhumation Babist et al 2006;Xu et al 2010), changes in plate motion (Austerman et al 2011); subhorizontal swarms of deep earthquakes (Chen and Brudzinski 2011), lateral shifts in foredeep sedimentation (van der Meulen et al 1998), opening of small ocean basins (Carminati et al 1998), switchover from foredeep flysch to orogenic molasse (Sinclair 1997;Wilmsen et al 2009), and porphyry copper and other mineralization (Solomon 1990;de Boorder et al 1998;Cloos et al 2005;Hildebrand 2009). …”