Ion microprobe dating of zircons from active Dayingshan volcano, Tengchong, SE Tibetan Plateau: Time scales and nature of magma chamber storage

Abstract The rare occurrences of active volcanoes on the Tibetan Plateau provide a unique opportunity to investigate time scales of magma chamber processes for post-collisional potassic volcanism. This research utilizes high-spatial resolution U–Th disequilibrium dating methods to date zircons from the active Dayingshan volcano, Tengchong, SE Tibetan Plateau, which erupted last during the Holocene. Zircon crystal ages can be used to provide constraints on the magma chamber storage time. Measured zircon interiors yielded an isochron age of 87.5 ± 6.5 ka, while zircon outermost rims yielded an isochron age of 58 ± 13 ka. The calculated zircon crystal storage time for the most recent eruption is 48 ka. At least two separate late Pleistocene zircon crystallization events have occurred where the older age population represents antecrysts remobilized from an earlier magmatic episode, but protracted crystallization cannot be ruled out. Regardless, the similarity in zircon age populations between Dayingshan volcano and Maanshan volcano 13 km apart in the Tengchong volcanic field suggests a synchronous thermal history of the magma reservoir, possibly in an extensive interconnected magma chamber beneath the Tengchong volcanic field.