High-Temperature Metamorphism, Anataxis and Tectonic Evolution of a Mafic Granulite from the Eastern Himalayan Orogen

Supplemental Material: Early onset and late acceleration of rapid exhumation in the Namche Barwa syntaxis, eastern Himalaya

“…Petrological data from the Namche Barwa massif (Palin et al, 2015;Zhang et al, 2018), the indubitable source of the young rutiles in our study, suggest formation of rutile during the prograde path and at or just below peak-metamorphic conditions (Fig. S8).…”

“…In fact, limited petrological data indicate that felsic and mafic gneisses, mafic granulites, and migmatites, likely sourced from Indian plate lower crust, dominate Namche-Barwa bulk-rock compositions (see compilation by Booth et al, 2008). Comparison of the rutile stability field for, and mineral assemblages in, a mafic granulite from the core of the syntaxis (Zhang et al, 2018) also precludes retrograde-path equilibration in the rutile stability field (Fig. S8B), likewise indicating that rutile U-Pb ages from syntaxial rocks should record cooling, as opposed to sub-closure-temperature crystal growth.…”

Timescales of Partial Melting and Melt Crystallization in the Eastern Himalayan Orogen: Insights From Zircon Petrochronology

“…Nonetheless, a high‐pressure metamorphic stage up to 12–13 kbar also has been estimated for mafic granulites occurring as blocks within pelitic and felsic granulites in the Sikkim area (Figure 12; Faak et al., 2012), as well as higher metamorphic pressures up to 14–20 kbar for granulitized eclogites in neighboring regions of Nepal and Bhutan (Corrie et al., 2010; Cottle, Jessup, et al., 2009; Groppo et al., 2007; Grujic et al., 2011; Kellett et al., 2014; Li et al., 2019; Lombardo & Rolfo, 2000; Wang et al., 2017; Warren et al., 2011). Recent studies have indicated that the GHS anatectic granulites in the eastern Himalaya commonly experienced high‐pressure granulite‐facies metamorphism with P‐T conditions of up to 12–16 kbar and clockwise P‐T paths (e.g., Ding et al., 2001; Groppo et al., 2012, 2010; Guilmette et al., 2011; Kali et al., 2010; Tian et al., 2016; Zhang et al., 2015, 2018; Z. M. Zhang et al., 2010). Thus, our inferred peak P‐T condition and P‐T path are consistent with numerous studies both nearby in Sikkim and more generally within the eastern sector of the Himalaya.…”

“… Metamorphic P‐T‐t path of the migmatitic pelitic granulite (this study) and published P‐T (‐t) paths for comparison. Published paths include pelitic and mafic granulites from the Sikkim region (Faak et al., 2012; Rubatto et al., 2013; Sorcar et al., 2014), felsic granulites from Nepal (Groppo et al., 2012; Iaccarino et al., 2015) and Namche Barwa (Guilmette et al., 2011), pelitic granulites from Nyalam (Wang et al., 2016) and Namche Barwa (Zhang et al., 2015), mafic granulite from Namche Barwa (Zhang et al., 2018), and channel flow model (Jamieson et al., 2004). All the numbers marked on P‐T path refer to metamorphic ages in Ma.…”

Petrofabrics and Seismic Properties of Himalayan Amphibolites: Implications for a Thick Anisotropic Deep Crust Beneath Southern Tibet

“…Solid lines are geotherms during thrusting at 10‐Myr intervals. The phase diagram is taken from Z. M. Zhang et al (2018). GS, greenschist facies; BS, blueschist facies; AM, amphibolite facies; GR, granulite facies; EC, eclogite facies.…”