Implications for Rodinia reconstructions for the initiation of Neoproterozoic subduction at ~860 Ma on the western margin of the Yangtze Block: Evidence from the Guandaoshan Pluton

article i nfo Neoproterozoic igneous rocks are widespread along the western margin of the Yangtze Block, but their petrogenesis and tectonic setting is debated. The Guandaoshan pluton is located at the southwestern margin of the Yangtze Block and is mainly composed of diorite and subordinate gabbro, with quartz diorite in its margin. Hornblende is an ubiquitous mineral in different phases of the pluton. SHRIMP zircon U-Pb dating of quartz diorite, gabbroic diorite, and gabbro from the pluton yielded 206 Pb/ 238 U ages of 857 ± 7 Ma, 856 ± 6 Ma, and 856 ± 8 Ma, respectively. Guandaoshan pluton samples show a large range of SiO2 (47.02-67.66%), MgO (1.12-7.5%), Fe2O3 T