Petrogenesis of the 130 Ma Taolin granitic intrusion: Implications for the tectonic setting and diversity of Early Cretaceous felsic rocks in the Sulu orogenic belt, eastern China

Early Cretaceous felsic intrusions are widely exposed in the Sulu omgenic belt (SOB), eastern China. The Taolin granitic intrusion is an example of these intrusions and mainly comprises monzogranite, syenogranite, and granite. Here we present new geochmnological and geochemical data for the intrusion. The similar to 130 Ma Taolin intrusion belongs to normal to fractioned I-type granite and is divided into two groups based on geochemical differences. Rocks in the Daxiezhuang and Malingzhan units belong to Group 1 and have relatively low SiO2 (61.35-69.44 wt%), high Sr/Y ratios (26.04-60.18), low epsilon Hf(t) values (-27.2 to -21.4), and old T-DM2 ages (2541-2903 Ma). They also display weak to no negative Eu anomalies (Eu/Eu*=0.65-1.29). Rocks from the Shibu and Tiqiushan units belong to Group 2 and have relatively high SiO2 (76.38-77.68 wt%), low Sr/Y ratios (0.61-12.38), high epsilon Hf(t) values (-24.3 to -17.2) and young T-DM2 ages (2271-2722 Ma). They have obviously negative Eu anomalies (Eu/Eu*=0.10-0.42). The partial melting of the Yangtze continental crust at different depths led to variable elemental and isotopic compositions of magma in Group 1 and Group 2. The SOB was in an extensional environment during the Early Cretaceous, which allowed the formation of felsic magmatic rocks with low Sr, Sr/Y, and Sr/CaO values. Early Cretaceous felsic magmatic rocks in the SOB were mainly sourced from the continental crust by crustal reworking. There are diverse rock types with variable geochemical features in the SOB, which is ascribed to the heterogeneity of the continental crust and the complex evolution of felsic magma.

Automated summary

The study of Early Cretaceous felsic intrusions in the Sulu omgenic belt reveals two distinct groups with different elemental and isotopic compositions, suggesting partial melting of the Yangtze continental crust led to the formation of varied magmas. These magmas were mainly sourced from crustal reworking, reflecting the heterogeneity of the continental crust and the complex evolution of felsic magma.