The genesis of ca. 1.78 Ga granitoids in the Xiong’er large igneous province: Implications for continental crust generation

The genesis of intermediate-felsic rocks and the implications for crustal growth are highly controversial. These issues particularly relevant to large igneous provinces, which one most effective methods generation. Mafic magmas, even those with continental marks, have been considered as contribution from mantle crust, whereas series in provinces has uncertain due uncertainty about their modes In this paper, we focus on granitoids, i.e., Gushicun diorites granites, Xiong’er province (ca. 1780‒1750 Ma) through detailed study petrology, chronology, geochemistry. Our new data show that both granites same emplacement age ca. 1780 Ma were synchronized province. granitoids characterized by enrichment light rare earth elements (LREEs) ion lithophile (LILEs; e.g., Li, Ba, Rb) but depletion high field strength (HFSEs; Nb, Ta, Ti). They almost ΣREE (rare element) contents TTi-Zircon (∼850 °C), whole-rock Nd (εNd(t) −8.24 −5.76), zircon Hf (εHf(t) isotope ratios −14 −8 ratios), O-isotope compositions (average δ18O = 5.3‰). fine-grained low Sr/Nd (<10) Eu/Sm (<0.3) Si/Al (>3.2) similar basaltic andesites province, suggests crystallization melts differentiated along liquid line descent. Rayleigh fractionation model based REE shows formed 40%‒50% fractional melts. characteristics K2O (3.8‒4.7 wt%) Yb (4.0‒6.5 ppm), Sr/Y (1.4‒3.3), metaluminous values (A/CNK 0.8‒1.1) mantle-like rule out melting (<0.5 amphibolite trondhjemite−tonalite−granodiorites (TTGs) surrounding Taihua Complex. a geochemical affinity alphaMELTs simulation major argues against partial TTGs supports intermediate water (<1 wt%). findings shed formation felsic remelted previous mafic-intermediate via underplating magmas. Despite having enriched Nd- Hf-isotope features, represent juvenile while reworking crust instead ancient crust. This paper also radiogenic isotopic cannot be reliably used assess types