Early Cretaceous uplift history of the Dabie orogenic belt: Evidence from pluton emplacement depths

The North Dabie complex unit (NDC) is a widely exposed petro-tectonic unit. To understand post-orogenic uplift history and mechanism of the Dabie orogenic belt, many samples of granite, granodiorite, diorite, and alkali feldspar granite with precise zircon U-Pb ages were collected for electron microprobe analysis of hornblende. Emplacement pressure values were then calculated by using an Al-in-hornblende geobarometer. The result shows that total Al (AlT) values in hornblende range from 1.17 to 1.97 p.f.u., XFe(=Fe/(Fe+Mg)) from 0.4 to 0.65, and corresponding pressure values from 256.8 to 676.2 MPa for AlT greater than 1.17. It is suggested that although the main mechanism for the uplift is tectonic extension, inhomogeneous uplift related to the pluton emplacement is also important during post-orogenic evolution of the Dabie orogenic belt. Emplacement depth distribution of the plutons shows that uplift in the NDC is affected by horst-graben structures since 120 Ma.