Geophysical evidence of large-scale silica-rich fluid flow above the continental subduction interface  

作　　者：Yuantong MAO Liang ZHAO Marco G.MALUSA Stefano SOLARINO Silvia PONDRELLI Baolu SUN Coralie AUBERT Simone SALIMBENI Elena EVA Stéphane GUILLOT 

机构地区：[1]State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Earth and Environmental Sciences,University of Milano-Bicocca,Milan 20126,Italy [4]Istituto Nazionale di Geofisica e Vulcanologia,Osservatorio Nazionale Terremoti,Genova 16145,Italy [5]Istituto Nazionale di Geofisica e Vulcanologia,Sezione di Bologna,Bologna 40127,Italy [6]Université Grenoble Alpes,Université Savoie Mont Blanc,CNRS,IRD,UGE,ISTerre,Grenoble 38000,France

出　　处：《Science China Earth Sciences》2024年第9期2796-2809,共14页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.42488201)。

摘　　要：Fluids in subduction zones can have major effects on subduction dynamics.However,geophysical constraints on the scale and impact of fluid flow during continental subduction are still limited.Here we analyze the VP/VS ratios in the Western Alpine region,hosting one of the best-preserved fossil continental subduction zones worldwide,to investigate the impact of fluid flow during continental subduction.We found a belt of high VP/VS ratios>1.9 on the upper-plate side of the subduction zone,consistent with a partially serpentinized upper-plate mantle,and a belt of unusually low VP/VS ratios<1.7 on the lower-plate side,at depths shallower than 30 km.We propose that these low VP/VS ratios result from a widespread network of silica-rich veins,indicating past fluid flow along the continental subduction interface.Our results suggest that past fluid flow may have reduced the effective stress along the subduction interface thus favoring continental subduction.

关 键 词：Western Alps Crustal structure Receiver function Vp/Vs ratio Silica enrichment 

分 类 号：P631[天文地球—地质矿产勘探] P542[天文地球—地质学]