南大西洋慢速洋中脊与地幔柱相互作用研究进展与展望  

Advance and perspective of study on the interaction between slow-spreading South Mid-Atlantic ridge and mantle plume

作　　者：张海桃 鄢全树 李传顺 关义立 石学法 ZHANG Haitao;YAN Quanshu;LI Chuanshun;GUAN Yili;SHI Xuefa(Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao,Shandong266061,China;Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology,Qingdao,Shandong266237,China;College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong266590,Chin)

机构地区：[1]自然资源部第一海洋研究所,海洋地质与成矿作用重点实验室,山东青岛266061 [2]青岛海洋科学与技术试点国家实验室,海洋地质过程与环境功能实验室,山东青岛266237 [3]山东科技大学地球科学与工程学院,山东青岛266590

出　　处：《地质学报》2022年第12期4167-4183,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41706060);中央级公益性科研院所基本科研业务费专项基金(编号GY0222Q04);中国大洋事务管理局项目(编号DY135-S2-2,DY135-S2-2-01)联合资助的成果。

摘　　要：揭示洋中脊与地幔柱(脊-柱)之间的可能联系为认识地球深部物质组成与深部地幔动力学过程提供了重要窗口,也是过去40多年以来固体地球科学研究领域的前沿与热点。在绵延八万多千米的全球洋中脊系统中,部分洋脊片段会受到地幔柱作用不同程度的影响。研究显示,大西洋的形成演化与地幔柱作用之间具有密切联系,尤其在南大西洋的裂解、打开演化过程中,南大西洋中脊系统始终与其周围地幔柱(如圣赫勒拿、阿森松、特里斯坦、高夫、发现等地幔柱)之间具有不同程度的相互作用关系,导致沿脊出露玄武岩在地球化学组成上呈现出明显的不均一性特征。本文在系统性总结脊-柱相互作用研究现状与南大西洋地区地质构造演化特征的基础上,详细阐述了南大西洋中脊13.2°S~24.2°S地区玄武岩的岩石地球化学特征;揭示了南大西洋中脊研究区的岩浆演化、地幔源区性质;指示出圣赫勒拿地幔柱物质向南大西洋中脊系统传播的主要方向;圈定了圣赫勒拿地幔柱对南大西洋中脊系统地幔源区性质在沿脊方向的影响范围(14.2°S~20.4°S);同时推测了南大西洋中脊系统与圣赫勒拿地幔柱之间受地幔柱影响的软流圈地幔物质在大洋岩石圈底部的空间展布。最后本文提出了关于南大西洋地区脊-柱相互作用领域现存的科学问题与未来的研究方向。Revealing the possible connection between mid-ocean ridge(MOR)and mantle plume would provide an important way with us to know the material components and dynamics of the Earth mantle,which has been the frontier and focus of solid earthscience research for more than forty years.The global MOR system is as long as more than eighty thousand kilometers,and a significant fraction of MOR segments has been influenced by their adjacent mantle plumes.Previous studies have shown that the formation and evolution of the Atlantic Ocean are closely associated with mantle plume.Especially,during the opening of the South Atlantic Ocean(SAO),the South Mid-Atlantic ridge(SMAR)system has been interacted with its nearby mantle plumes(e.g.,Saint Helena,Ascension,Tristan da Cunha,Gough,Discovery mantle plume)with different extents,which lead the mid-ocean ridge basalts(MORBs)along the SMAR system keep a significant compositional heterogeneity.In this paper,we systemically reviewed the characteristics of global ridge and plume(ridge-plume)interaction,and the tectonic evolution and mantle source nature of the SAO.Further,we summarized the geochemistry features of MORBs sampled from SMAR 13.2°S to 24.2°S segments,which have indicated that①the magma evolution and the nature of mantle source of the SMAR system;②the main direction of the Saint Helena plume materials propagating to the SMAR system;③the influence scope of Saint Helena plume on the SMAR system(14.2°S~20.4°S segments);④the spatial distribution of plume-affected asthenosphere mantle between the SMAR system and the Saint Helena plume.Finally,we raised several important scientific questions and proposed some future perspectives in this study field to scholars.

关 键 词：脊-柱相互作用 南大西洋中脊 洋中脊玄武岩 地幔柱 地幔动力学 

分 类 号：P736.1[天文地球—海洋地质]