Permian subduction of the Paleo-Pacific (Panthalassic) oceanic lithosphere beneath the Jiamusi Block: Geochronological and geochemical evidence from the Luobei mafic intrusions in Northeast China

Abstract The late Paleozoic tectonic evolution of eastern northeast China and, in particular, the Jiamusi Block and its relationship with the Paleo-Pacific (Panthalassic) Ocean are controversial. Here we present petrological, zircon U-Pb age, whole-rock major and trace elements, and zircon Hf isotopic data for Permian (273–260 Ma) subduction-related mafic intrusions from the Luobei region along the western margin of the Jiamusi Block. These intrusions have mineral assemblages of pyroxene, Ca-rich plagioclase, and hornblende, indicating their crystallization from a water-saturated parental magma. The Luobei mafic rocks are calc-alkaline, enriched in large-ion lithophile and light rare earth elements, depleted in high-field-strength elements, and have variable zircon e Hf (t) values (−7.7 to +5.0). These geochemical features suggest that their parental magma was probably derived by