The influence of Ryukyu subduction on magma genesis in the Northern Taiwan Volcanic Zone and Middle Okinawa Trough - Evidence from boron isotopes

摘要

Boron (B) is an excellent geochemical tracer for investigating crustal recycling processes at convergent margins, due to its high fluid mobility under high P-T conditions, distinct elemental abundances and isotopic compositions in the mantle wedge and subducting slabs. The Northern Taiwan Volcanic Zone (NTVZ), wherein the nature of magma genesis has long been a topic of debate, is located at the rear side of the Okinawa Trough (OT), an atypical back-arc rift in the Ryukyu subduction system. In this study, B and B isotopes (delta B-11) were measured in 19 volcanic rocks collected from the NTVZ and the middle Okinawa Trough (MOT) to assess the influence of the Ryukyu subduction system on magma genesis.