摘要
玻安岩(Boninite)是一种特殊的镁铁质火山岩,主要形成于与板块俯冲相关的特殊地质环境,是俯冲起始的直接地质记录.其斑晶矿物组合以橄榄石和辉石为主,不含斜长石,具有高Mg和Si含量、低Ti含量,富集大离子亲石元素和轻稀土元素,亏损高场强元素和中稀土元素.典型的玻安岩呈特殊的“U”型稀土元素配分模式.玻安岩的特殊化学成分反映了其地幔熔融的特殊条件,如高温、低压和相对富水的环境.初始岩浆形成涉及地幔的二次熔融过程,发生在地幔经历初次熔融并亏损之后.这种特殊的熔融过程为揭示地幔源区组成、熔融程度及流体在地幔熔融和俯冲起始过程中的作用提供了重要信息.本文回顾了俯冲带玻安岩的矿物学、地球化学特征及岩石成因机制,总结了其深部动力学和岩浆演化过程,并探讨其对地球动力学领域的重要意义.最后,还探讨了当前研究中的问题及未来可能的研究方向.
Boninite is a special type of magnesium-iron volcanic rock,primarily formed in unique geological environments associated with plate subduction.It serves as a direct geological record of the subduction initiation.The phenocryst are mainly olivine and pyroxene,with no plagioclase.Boninite is characterized by high Mg and Si,but lower Ti content.They are also and enriched in large ion lithophile elements(LILEs)and light rare earth elements(LREEs),but depleted in high field strength elements(HFSEs)and medium rare earth elements(MREEs).Typicalboninite exhibits a distinctive"U"-shaped rare earth element(REE)distribution pattern.The unique chemical composition of boninite reflects its uniquemantle melting conditions,such as high temperature,low pressure,and relatively high water content.Primarymagma was generated throughre-melting processes in the mantle source,which has already undergone partial melting before.This unique melting process provides crucial insights into mantle source composition,degree of melting,and the role of fluids in mantle melting and the initiation of subduction.In this review,we discuss the mineralogy,geochemical characteristics,and petrogenetic mechanisms of subduction-related boninite,emphasizing its significance in geodynamics and magma evolution processes.Finally,we also summarized the current research issuesand potential future directions in boninite studies.
作者
林若澜
吴涛
田丽艳
鲁江姑
Lin Ruolan;Wu Tao;Tian Liyan;Lu Jianggu(Ocean College,Zhejiang University,Zhoushan 316022,China;Hainan Institute of Zhejiang University,Sanya 572025,China;Institute of Deep-Sea Science and Engineering,Chinese Academy of Sciences,Sanya 572000,China;Key Laboratory of Submarine Geosciences,Ministry of Natural Resources,Hangzhou 310012,China)
出处
《地球科学》
北大核心
2025年第8期2956-2976,共21页
Earth Science
基金
国家自然科学基金面上项目(No.42072069)。
关键词
玻安岩
地球化学
岩石成因
地幔熔融
俯冲起始
俯冲带
boninite
geochemistry
petrogenesis
mantle melting
subduction initiation
subduction zone
