In situ characterization of forearc serpentinized peridotite from the Sulu ultrahigh-pressure terrane: Behavior of fluid-mobile elements in continental subduction zone  

作　　者：Zhipeng Xie Keiko Hattori Youpu Dong Jian Wang 

机构地区：[1]Department of Earth Sciences,Kunming University of Science and Technology,Kunming 650093,PR China [2]Department of Earth and Environmental Sciences,University of Ottawa,Ottawa K1N 6N5,Canada [3]College of Earth Sciences,Jilin University,Changchun,Jilin 130061,PR China

出　　处：《Geoscience Frontiers》2021年第4期110-121,共12页地学前缘（英文版）

基　　金：by the National Natural Science Foundation of China(Grant Nos.41603032,41472051,41802215 and 4176201);Applied Basic Research Foundation of Yunnan Province(Grant No.2017FB075)to ZPX,JW and YPD.

摘　　要：Serpentinized peridotites in the Yangkou(YK),Suoluoshu(SLS) and Hujialin(HJL) areas in the Sulu ultrahighpressure terrane represent the relic of ancient subcontinental lithospheric mantle below the North China Craton.Their protoliths,harzburgite and dunite,were variably hydrated by aqueous fluids released from subducting Yangtze continent.The rocks are enriched in fluid-mobile elements(FME) including Sb(42–333 times the depleted mantle value) and Pb(30–476 times).The degrees of the FME enrichment are comparable to that of the Himalayan forearc serpentinites,and greater than forearc mantle serpentinites from Marianas,suggesting that the degrees of FME enrichment in the forearc serpentinites are greater in continental subduction zones than those in the oceanic subduction zones.Lizardite after olivine in the SLS serpentinite shows higher degrees of enrichment in Sb and As than those for antigorite after both olivine and orthopyroxene in the YK area.The antigorite has highly enriched in Pb,U,Cs,and LREE,but not for the lizardite.The abundance of FME in two different species of serpentine reflects the different temperature of hydration.At temperature lower than 300 ℃,formed lizardite at shallow depths of the mantle wedge incorporates elements that are fluid mobile at low temperatures,such as Sb and As.When the temperature greater than 300 ℃,formed antigorite at a relatively deep mantle wedge incorporate more FME from the subducting continental slab(or fragments),including Pb,U,Cs,LREE as well as Sb and As.The eventual breakdown of antigorite(600–700 ℃) in prograde metamorphism would discharge water as well as FME into the subducting channel and/or the overlying mantle.

关 键 词：Continental subduction channel Subcontinental lithospheric mantle Fluid-mobile element SERPENTINITE ANTIGORITE LIZARDITE 

分 类 号：P542[天文地球—构造地质学] P588.125[天文地球—地质学]