各位老師和同學(xué)：
美國萊斯大學(xué)Julia Ribeiro博士近期訪(fǎng)問(wèn)我所，并將于本周四上午做“同位素室學(xué)術(shù)報告”2018年第21次報告。Julia Ribeiro博士主要從事俯沖帶物質(zhì)和水循環(huán)研究，取得了很多重要的進(jìn)展，目前已在EPSL、JP和G-Cubed等國際著(zhù)名刊物發(fā)表不少相關(guān)的文章。歡迎大家參加并積極參與討論！

報告題目：The Deep Water Cycle at Subduction Zones
報 告 人：Dr. Julia Ribeiro (Rice University, USA)
報告時(shí)間：6月7日（周四）上午10:00
報告地點(diǎn)：綜合樓702會(huì )議室

Abstract：
The depth of slab dehydration is thought to be controlled by the thermal state of the downgoing slab: cold slabs are thought to mostly dehydrate beneath the arc front while warmer slabs should mostly dehydrate beneath the fore-arc. Cold subduction zone lavas are thus predicted to have interacted with greater extent of water-rich fluids released from the downgoing slab, and should thus display higher water content and be elevated in slab-fluid proxies (i.e., high Ba/Th, H2O/Ce, Rb/Th, etc.) compared to hot subduction zone lavas. Arc lavas, however, display similar slab-fluid signatures regardless of the thermal state of the slab, suggesting more complexity to volatile cycling in subduction zones. Here, we explore whether the serpentinized fore-arc mantle may be an important fluid reservoir in subduction zones and whether it can contribute to arc magma generation by being dragged down with the slab. Using simple mass balance and fluid dynamics calculations, we show that the dragged-down fore-arc mantle could provide enough water (～7–78% of the total water injected at the trenches) to account for the water outfluxes released beneath the volcanic arc. Hence, we propose that the water captured by arc magmas may not all derive directly from the slab, but a significant component may be indirectly slab-derived via dehydration of dragged-down fore-arc serpentinites. Fore-arc serpentinite dehydration, if universal, could be a process that explains the similar geochemical fingerprint (i.e., in slab fluid proxies) of arc magmas.