Ultrahigh-pressure minerals and metamorphic terranes – The view from China

Diverse P–T paths of the northern Dabie complex in central China and its reworking in the early Cretaceous

“…Although evidence for convincing UHP coesite has not yet been reported from the NDC, the occurrence of UHP metamorphic evidence such as microdiamonds has been reported from the retroeclogites in the NDC (Xu et al, 2003 and zircon inclusions in retro-eclogite and banded gneiss in the NDC (Liu et al, 2007a,b), suggesting that the peak UHP conditions should at least have reached P4.0 GPa Liu et al, 2007a,b;Tong and Jahn, 2009). Furthermore, the Osm overgrowth ) and Spl-Crd-Qtz symplectite assemblage , together with the UHT metamorphic Pgt and Ab exsolution texture (Tong et al, 2007a;Liu and Jin, 2008;Tong and Jahn, 2009), indicate that the overprinted granulite facies metamorphism for the NDC could actually have attained UHT conditions (>900°C or 1000°C), as recently implied by Liou et al (2009). As mentioned in detail in the above section, a number of the Triassic ages (220-240 Ma) support the notion that the peak UHP metamorphic event in the NDC was closely associated with Triassic deep continental subduction, whereas the overprinting UHT granulite facies metamorphic event must be related to early Cretaceous magmatism and tectonism Xie et al, 2006;Zhao et al, 2007Zhao et al, , 2008Zheng, 2008;Tong and Jahn, 2009), and thus it is of an intracontinental nature.…”

“…1). Although oriented exsolution textures have been commonly considered as evidence for peak UHP metamorphism Zhang and Liou, 1999;Ye et al, 2000b;Chopin, 2003;Zhang et al, 2003), they have recently come under scrutiny as to their suitability as unambiguous marker for peak UHP conditions (Page et al, 2005;Hwang et al, 2007;Yang and Powell, 2008;Zheng, 2008;Liou et al, 2009;Zhang et al, 2009). However, the UHP metamorphic microdiamonds in retro-eclogite relics from Raobazhai, Huangweihe and Baizhangyan (Xu et al, 2003 and UHP microdiamond inclusions in zircon in gneiss from Ta'erhe and in the eclogite relic from Luotian (Liu et al, 2007a,b) (Fig.…”

“…As the largest ultrahigh-pressure (UHP) metamorphic belt recognized in the world, the Dabie-Sulu orogenic belt in east-central China is thought to have formed by continental subduction and collision between the North China and Yangtze blocks in the Triassic (240-220 Ma) (Li et al, , 1996Ames et al, 1996;Chavagnac and Jahn, 1996;Cong, 1996;Liou et al, 1996Liou et al, , 2004Liou et al, , 2009Hacker et al, 1998Hacker et al, , 2006Jahn, 1998;Jahn et al, 2003;Zheng et al, 2003;Liu et al, 2006;Zhang et al, 2009). The discovery of UHP metamorphic coesite and microdiamond in eclogite of the Dabie orogenic belt over 20 years ago (Okay et al, 1989;Wang et al, 1989;Xu et al, 1992), has led to extensive studies of the orogen.…”

Geochemistry of continental subduction-zone fluids

“…Continental subduction zones are generally marked by the occurrence of ultrahigh-pressure (UHP) eclogite-facies metamorphic rocks (e.g., Chopin 2003;Liou et al 2009;Zheng 2012;Hermann and Rubatto 2014). These rocks contain important records of physical and chemical changes that occur at the slab-mantle interface in deep subduction channel.…”

Drilling the solid earth: global geodynamic cycles and earth evolution

“…A notable past success for ICDP was the Chinese Continental Scientific Drilling Program, which investigated subduction and exhumation of the continental crust in the Dabie Shan-Sulu ultra-high-pressure terrane of China (Xu et al 2005(Xu et al , 2009Liou et al 2009). This area contains clear evidence that continental crustal material was subducted to depths of >150 km during Mesozoic collisional orogenesis.…”