Zircon U–Pb age, Hf and O isotope constraints on protolith origin of ultrahigh-pressure eclogite and gneiss in the Dabie orogen

Petrogenesis of the early Cretaceous volcanic rocks in the North Huaiyang tectono-magmatic unit of the Dabie Orogen, eastern China: Implications for crust–mantle interaction

“…The end member of the YZC crustal materials is comprised by 60% YZC upper/middle crust (SiO 2 = 76 wt.%) and 40% YZC lower crust (SiO 2 = 59 wt.%) . Wu et al, 2005a), and in (b) are zircon Hf model ages for UHP metaigneous rocks in the Dabe orogenic belt (data after (Zheng et al, 2005(Zheng et al, , 2006bChen et al, 2007;Zhao et al, 2008)). …”

“…Nd isotopes reveal that crustal growth in the NCC occurred in three episodes (3.6-3.3 Ga, 2.8-2.6 Ga and 2.2-2.0 Ga), dominantly during the Archean (Wu et al, 2005a;Lu et al, 2006;Geng et al, 2012), whereas the YZC primarily exhibits 2.4-1.0 Ga of crustal growth (Chen and Jahn, 1998;Zhang et al, 2006;Zheng et al, 2006a). Ziron Hf isotope studies of igneous and metamorphic rocks also reveal two episodes of crustal growth in the YZC, late Mesoproterozoic to early Neoproterozoic and middle Paleoproterozoic (Zheng et al, 2006b;Chen et al, 2007;Zhao et al, 2008), whereas the NCC primarily exhibits Archean ages of crustal growth (Wu et al, 2005a;Geng et al, 2012). These features have been successfully used to constrain source of the Mesozoic intermediate-mafic igneous rocks along the Dabie-Sulu Orogen (Yang et al, 2012c;Zhao et al, 2012).…”

Detrital zircon of 4.1 Ga in South China

“…During the analysis, the standard zircons gave 0.282303±8 (n = 15, 1σ) for 91500 with the recommended Hf value of 0.022 for the average lower continental crust [23]. The model ages (T DM ) were taken for positive ε Hf (t) values, and two-stage Hf model ages (T DM2 ) were taken for negative ε Hf (t) values [24].…”

Tracing carbonate–silicate interaction during subduction using magnesium and oxygen isotopes

“…Eclogites are widespread as pods, discontinuous layers or blocks in gneisses, ultramafic massifs and marbles. Previous studies suggest that these eclogites were formed by UHP metamorphism of Neoproterozoic basaltic rocks during the Triassic subduction of the South China Block [21][22][23][24] . Diamond and coesite inclusions present in eclogites and their country rocks indicate that they were in situ subducted and exhumed with peak metamorphic temperatures of 700-880°C and pressures up to 5.5 GPa (refs [25][26][27].…”