Ultrahigh-pressure metamorphism and multistage exhumation of eclogite of the Luotian dome, North Dabie Complex Zone (central China): Evidence from mineral inclusions and decompression textures

P-T evolution of elusive UHP eclogites from the Luotian dome (North Dabie Zone, China): How far can the thermodynamic modeling lead us?

“…145 Ernst et al, 2007;Jahn and Chen, 2007;Zhang et al, 2009), the Triassic 146 zircon U-Pb ages (220-240 Ma: Liu et al, 2000, 2011bWang 147 et al, 2012;Zhao et al, 2008) and Sm-Nd ages (Liu et al, 2005) of 148 these eclogites suggest that these rocks formed by the Triassic subduc-149 tion of the South China Block, similarly to those from the CDZ and 150 SDZ. The Triassic metamorphic ages (Liu et al, 2000(Liu et al, , 2007bXie et al, 151 2010) and the occurrence of micro-diamond inclusions in zircon and 152 garnet (Liu et al, 2007b) from the NDZ migmatitic orthogneisses tive data (spot size = μm) were acquired and processed using the two domains (Fig.…”

Muscovite Dehydration Melting in Silica-Undersaturated Systems: A Case Study from Corundum-Bearing Anatectic Rocks in the Dabie Orogen

“…The Triassic zircon U-Pb ages and Sm-Nd ages of the eclogites from the NDZ suggest that these rocks were formed by the Triassic subduction of the South China Block, similar to those from the CDZ and SDZ [45,56,64]. The Triassic metamorphic age and microdiamond inclusions in zircon and garnet from the NDZ banded gneisses suggest that the gneisses hosting the eclogites were also involved in the Triassic deep subduction of the South China Block, thus implying that the NDZ experienced UHP metamorphism as a coherent unit [57,58,63,64,68,69]. Differently from the CDZ and the SDZ, in which the UHP/HP eclogite-facies stage was followed by cooling and decompression under amphibolite-facies conditions, the NDZ experienced a pervasive granulite-facies overprinting accompanied by extensive partial melting and migmatization that partially or completely obliterated the evidence of the earlier metamorphic events at HP/UHP conditions [63,70].…”

“…The NDZ is characterized by the exposure of abundant high-T metamorphic rocks of lower crustal origin, mainly consisting of tonalitic to granitic orthogneisses with varying extents of migmatitization and post-collisional Cretaceous intrusions, with subordinate meta-peridotites, garnet-bearing amphibolites and eclogites [51,63,64]. The oriented mineral exsolutions in garnet and clinopyroxene, and the occurrence of micro-diamonds inclusions in zircon and garnet imply that the NDZ eclogites underwent UHP metamorphism at P > 3.5 GPa [49,50,57,58,64,68]. The Triassic zircon U-Pb ages and Sm-Nd ages of the eclogites from the NDZ suggest that these rocks were formed by the Triassic subduction of the South China Block, similar to those from the CDZ and SDZ [45,56,64].…”

“…The SDZ, CDZ and NDZ are three eclogite-bearing units of the Dabie orogen [46,49,51,[55][56][57][58]. The occurrence of diamond and coesite in the metamorphic rocks from the CDZ indicates that the UHP metamorphism occurred at 700-850 °C and >2.8 GPa [46][47][48]59,60], whereas the peak P-T conditions of the eclogites in the SDZ were estimated at 670 °C and 3.3 GPa [56].…”

Decoupling between Ti‐in‐zircon and Zr‐in‐rutile thermometry during ultrahigh temperature metamorphism of the Dabie Orogen, China

“…This terrane consists mainly of tonalitic and granitic orthogneisses and post‐collisional Cretaceous intrusions with subordinate metaperidotite, garnet pyroxenite, garnet‐bearing amphibolite, granulite, and eclogite (Figure ). After UHP and HP eclogite‐facies metamorphism, the NDT underwent a near‐isothermal decompression and long‐lived HT and UHT conditions during early exhumation (Y. C. Liu et al, ; Y. C. Liu, Gu, Li, Hou, & Song, ; Y. C. Liu, Gu, Rolfo, & Chen, ; Y. C. Liu, Li, Gu, Xu, & Chen, ; Y. C. Liu, Li, & Xu, ). Recently, Triassic UHT granulite‐facies metamorphism has been recognised in the NDT on the basis of TIZ thermometry, with P–T conditions of 11–12 kbar and 927°C (Lei et al, ).…”