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 (Al^T) values in hornblende range from 1.17 to 1.97 p.f.u., X _Fe(=Fe/(Fe+Mg)) from 0.4 to 0.65, and corresponding pressure values from 256.8 to 676.2 MPa for Al^T 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.