慢速-超慢速扩张洋中脊热液活动及其机理  

Hydrothermal activity and mechanism along slow-and ultraslow-spreading mid-ocean ridges

作　　者：宋珏琛 李江海[1,2,3] 冯博[1,2,3] SONG Juechen;LI Jianghai;FENG Bo(Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Institute of Oil and Gas,School of Earth and Space Sciences,Peking University,Beijing 100871,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]造山带与地壳演化教育部重点实验室,北京100871 [2]北京大学石油与天然气研究中心,北京100871 [3]北京大学地球与空间科学学院,北京100871

出　　处：《地质学报》2021年第8期2273-2283,共11页Acta Geologica Sinica

基　　金：中国大洋“十三五”课题(编号DY135-S2-1-01、DY135-S1-1-03)资助的成果。

摘　　要：海底热液系统是地球热量平衡的重要组成,也是地球化学循环和成矿作用发生的主要场所,与洋中脊系统在空间上具有很强的联系。慢速-超慢速扩张洋中脊中确认的活跃热液喷口数量约占全球总数量的三分之一,查明热液发育位置及发育岩性与岩浆-构造活动的耦合关系,对于研究海底热液活动演化过程和海底找矿具有很好的指示意义。本文将全球慢速-超慢速扩张洋中脊中已确认的活跃热液活动进行统计分类,其中受岩浆活动控制的热液活动有29处,而受构造活动控制的热液活动有15处,相对于快速-中速扩张洋中脊显示出较强的构造相关性。研究发现,岩浆作用控制下的热液活动集中在洋中脊轴部中央裂谷内,而构造主控型热液活动常发育在非转换不连续间断和拆离断层系统内。随着大洋核杂岩成熟,热液活动位置向着离轴方向迁移,并且热液类型由高温"黑烟囱"型向低温弥散流型转变。Seafloor hydrothermal system is an important component of the earth’s heat balance,and is also the main site of geochemical cycling and mineralization,which has strong spatial relationship with the mid-ocean ridge system.The hydrothermal deposits developed in the slow-and ultraslow-spreading mid-ocean ridges have the characteristics of high distribution density and large mineral resource,among which the number of active hydrothermal vents confirmed accounts for about one third of the total number of the world.The development of hydrothermal massive sulfide deposits is controlled by magmatism and tectonic background,in which the tectonic setting includes non-transform discontinuities and detachment fault system,and the hydrothermal deposits controlled by tectonic setting have higher metal grade and larger deposit area.The study found that the grow of detachment fault has strong connection with the heat source and metallogenic location of hydrothermal activity in space and time.As the oceanic core complex matures,the heat source moves from the ridge axis to the footwall,and the hydrothermal metallogenic position changes from the central valley to the termination and then transfers to the crest of the oceanic core complex.At the same time,the lithologic differences of host rocks also have certain constraints on the types and concentrations of hydrothermal massive sulfide metals.To find out the coupling relationship between hydrothermal mineralization location and lithology and tectonic activity is of great significance for studying the evolution process of hydrothermal activity and prospecting.

关 键 词：热液活动 岩浆作用 拆离断层 蛇纹石化作用 洋中脊 

分 类 号：P736[天文地球—海洋地质]