Geochemistry of eclogites from the Dabie–Sulu terrane, eastern China: New insights into protoliths and trace element behaviour during UHP metamorphism

A perspective view on ultrahigh-pressure metamorphism and continental collision in the Dabie-Sulu orogenic belt

“…From geochemical analyses of high-T/UHP eclogite and granitic gneiss from core samples of CCSD-MH in the Sulu orogen, Zhao et al [83] found large variations in the abundance of such elements as SiO 2 , LREE and LILE at the contact between eclogite and granitic gneiss ( Figure 15), indicating their mobility between different slice components. However, Tang et al [86] only observed high mobility of LILE but immobility of REE and HFSE within eclogites, with approaching of trace element distribution equilibrium between garnet and clinopyroxene.…”

“…The mid-Neoproterozoic igneous rocks show somewhat double bimodal composition [81][82][83] , with bimodal lithochemistry and bimodal Hf-Nd isotope distribution. A small amount of metamafic protoliths was layered intrusions [84][85][86][87] . There are only very sporadic occurrences of Archean and Paleoproterozoic protoliths for UHP metamorphic rocks [54,80,88] .…”

Element mobility in mafic and felsic ultrahigh-pressure metamorphic rocks during continental collision

“…Furthermore, Xiao et al (2006a) observed that rutile from eclogite in the Sulu orogen show highly variable Nb/Ta ratios of 5.4-29.1 within single grains, and interpreted them as fluid-assisted fractionation during continental subduction. A geochemical study of the DabieSulu eclogites by Tang et al (2007a) demonstrates that LILE had high mobility but REE and HFSE were immobile during the UHP metamorphism.…”

Oxygen isotope and REE geochemistry of metamorphic veins within the Zhoutan Group, central Jiangxi Province

“…Due to more clay minerals in the protolith at immediate wall rocks of felsic veins, large amounts of fluids with higher CO 2 contents were produced during metamorphic dehydration. The HREEs in the protolith at immediate wall rocks of felsic veins are more easily mobilized into and transported by the metamorphic fluids, as suggested by Stable (1987), Bau (1991) and Hong-Feng Tang (2002, 2007. Therefore, REE behavior (including their mobility) during metamorphism is mainly controlled by the chemical composition of the metamorphic fluids, which, in turn, depends on the mineralogical composition of the protolith.…”