气候变化领域集成服务门户(CCPortal): Melt Segregation and Depletion During Ascent of Buoyant Diapirs in Subduction Zones

CCPortal

DOI	10.1029/2019JB018203
	Melt Segregation and Depletion During Ascent of Buoyant Diapirs in Subduction Zones
	Zhang N.; Behn M.D.; Parmentier E.M.; Kincaid C.
发表日期	2020
ISSN	21699313
卷号	125 期号:2
英文摘要	Cold, low-density diapirs arising from hydrated mantle and/or subducted sediments on the top of subducting slabs have been invoked to transport key chemical signatures to the source region of arc magmas. However, to date there have been few quantitative models to constrain melting in such diapirs. Here we use a two-phase Darcy-Stokes-energy model to investigate thermal evolution, melting, and depletion in a buoyant sediment diapir ascending through the mantle wedge. Using a simplified 2-D circular geometry, we investigate diapir evolution in three scenarios with increasing complexity. In the first two scenarios we consider instantaneous heating of a diapir by thermal diffusion with and without the effect of the latent heat of melting. Then, these simplified calculations are compared to numerical simulations that include melting, melt segregation, and the influence of depletion on the sediment solidus along pressure-temperature-time (P-T-t) paths appropriate for ascent through the mantle wedge. The high boundary temperature induces a rim of high porosity, into which new melts are focused and then migrate upward. The rim thus acts like an annulus melt channel, while the effect of depletion buffers additional melt production. Solid matrix flow combined with recrystallization of melt pooled near the top of the diapir can result in large gradients in depletion across the diapir. These large depletion gradients can either be preserved if the diapir leaks melt during ascent, or rehomogenized in a sealed diapir. Overall our numerical simulations predict less melt production than the simplified thermal diffusion calculations. Specifically, we show that diapirs whose ascent paths favor melting beneath the volcanic arc will undergo no more than ~40–50% total melting. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	melt migration; sedimentary diapirs; subduction wedge
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/188000
作者单位	Department of Geology and Geophysics, Woods Hole Oceanography Institution, Woods Hole, MA, United States; Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China; Earth Dynamics Research Group, Department of Applied Geology, Curtin University, Perth, WA, Australia; Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, United States; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, United States; School of Oceanography, University of Rhode Island, Narragansett, RI, United States
推荐引用方式 GB/T 7714	Zhang N.,Behn M.D.,Parmentier E.M.,et al. Melt Segregation and Depletion During Ascent of Buoyant Diapirs in Subduction Zones[J],2020,125(2).
APA	Zhang N.,Behn M.D.,Parmentier E.M.,&Kincaid C..(2020).Melt Segregation and Depletion During Ascent of Buoyant Diapirs in Subduction Zones.Journal of Geophysical Research: Solid Earth,125(2).
MLA	Zhang N.,et al."Melt Segregation and Depletion During Ascent of Buoyant Diapirs in Subduction Zones".Journal of Geophysical Research: Solid Earth 125.2(2020).