Qusongite (WC): A new mineral

Petrogenesis of the Kangjinla peridotite in the Luobusa ophiolite, Southern Tibet

“…Diamonds and serpentine pseudomorphs after octahedral olivine were discovered many years ago in podiform chromitite of the Luobusa ophiolite (IGCAGS, 1981;Yang et al, 1981) and have been confirmed by subsequent workers (Hu, 1999;Bai et al, 2000a;Robinson et al, 2004;Yang et al, 2007Yang et al, , 2008Yang et al, , 2009. Similar UHP and highly reduced minerals have also been found recently in both the chromitites and peridotites of Luobusa, including coesite (possibly pseudomorphing stishovite) (Yang et al, 2007), kyanite, a diamond inclusion in Os-Ir alloy (Yang et al, 2007), diamond in peridotite , inclusions of silicon spinel in Os-Ir alloy (Bai et al, 2005), and reduced phases such as moissanite, wüstite, native elements and base-metal alloys (Hu, 1999;Bai et al, 2000bBai et al, , 2006Robinson et al, 2004;Fang et al, 2009;Shi et al, 2009;Xu et al, 2009). Diamond and moissanite have now been confirmed as insitu phases in the chromitites .…”

“…These include moissanite (SiC), wüstite (FeO) and many native elements such as Si, Ti, Fe, Al, W, Cr, and Ni, along with a range of base-metal and PGE alloys (Bai et al, 2000a(Bai et al, , 2001(Bai et al, , 2005(Bai et al, , 2006Robinson et al, 2004;Yang et al, 2003Yang et al, , 2007Xu et al, 2008Xu et al, , 2009Fang et al, 2009;Shi et al, 2009). There is no evidence, either in the ophiolite or surrounding rocks, of a meteorite impact, so we conclude that the UHP minerals must have came from minimum depths of 120-280 km, and possibly deeper.…”

Carbon Mineralogy and Crystal Chemistry

“…(2) within the Mengyin kimberlite field, Linyi Prefecture; (3) within the Yangliuping N-Cu-PGE Deposit, Sichuan Province; and (4) at Liu Village, Henan Province. These deposits incorporate minor amounts of three carbides that are unknown from any other region: qusongite (WC; Fang et al 2009;Shi et al 2009), yarlongite [(Fe 4 Cr 4 Ni)C 4 ; Nicheng et al 2005Nicheng et al , 2008, and tongbaite (Cr 3 C 2 ; Tian et al 1983;Dai et al 2004). The association of these carbides with moissanite, cohenite, and khamrabaevite [(Ti,V,Fe)C], as well as other dense, high-temperature phases such as diamond, coesite (a high-pressure form of SiO 2 ), and varied native metals, including Fe, Ni, W, Cr, Pb, and W, points to a high-temperature, high-pressure origin in a reduced mantle environment (Robinson et al 2001;Shi et al 2009).…”

Mid-ocean ridge (MOR) and suprasubduction zone (SSZ) geological events in the Yarlung Zangbo suture zone: Evidence from the mineral record of mantle peridotites

“…A great deal of work has been done on the mantle minerals in the ophiolites of the eastern and middle Yarlung-Zangbo suture zone (Mercier and Li, 1980;Girardeau et al, 1985;Zhou et al, 1996), especially in the easternmost Luobusa massif. This body is of particular interest because of the discovery of many ultrahigh pressures (UHP) and highly reduced minerals in the chromitites and peridotites (Bai et al, 1999(Bai et al, , 2001(Bai et al, , 2007Robinson et al, 2004;Yang et al, 2007;Shi et al, 2009;Fang et al, 2009;Yamamoto et al, 2009). Wang et al (2005) carried out a detailed geochemical study of more than 500 Cr-spinels in ophiolites of the eastern and middle Yarlung-Zangbo suture zone, which showed that they have a wide range of composition, characteristic of both MOR and SSZ settings.…”