海底热液硫化物矿体内部流体混合过程的数值模拟:以大西洋TAG热液活动区为例
Numerical simulation for mixing process of fluid within seafloor sulfide deposit:taking example for the TAG field
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摘要: 大型海底热液硫化物矿体的形成机制是涉及多种控制因素的复杂地质过程,其中热液流体同海水的混合扮演着重要角色。大洋钻探计划(ODP)资料表明在大西洋TAG区热液硫化物矿体内部,热液流体同经过改造的海水之间发生着广泛的混合作用,这个过程在很大程度上控制着海底热液硫化物矿体的内部结构和化学组成。以TAG热液硫化物矿体为例,利用数值模拟方法模拟了热液流体与经过不同程度改造的海水的混合过程,试图探讨海水与热液流体混合在热液硫化物矿体形成中的作用。模拟计算结果表明:(1)来自矿体深部的热液流体与经围岩加热的下渗海水的混合是造成TAG热液活动区硬石膏大量沉淀的重要原因;(2)在热液流体与海水的混合过程中,混合流体的化学性质和矿物沉淀情况在330~310℃上下发生了较大变化,330~310℃是一个特殊的温度区域;(3)利用数值计算结果探讨了TAG热液活动区不同区块(TAG-1,TAG-2和TAG-5等)的流体混合作用和热液活动过程。Abstract: Formation mechanismof the sizable hydrothermal sulfide deposit is a complex geological process involving many types of controlling factors. Mixing between hy drothermal fluid and seawater plays a key role in this process. The previous results of Ocean Drilling Program(ODP)indicate that mixing of the evolveds eawater with the hydrothermal fluid is wildly developed within the TAG hydrothermal deposit, which governs the internal structure and chemical compositions of the deposit to great extent. Taking example for the TAG field,the mixing process of the hydrothermal fluid is calculated with the seawater that is heated to different extent,in order to discuss the impact of hydrothermal fluid/seawater mixing on the formation process of the sulfide deposit. The results indicate that:(1)mixing between the heated seawater and the hydrothermal fluid derived from the deep deposit should be largely responsible for the wild precipitation of anhydrite within the TAG hydrothermal deposit;(2)330~310 is a special temperature zone in the mixing process between the seawater and the hydrothermal fluid;(3)the mixing and hydrothermal processes in differentareas(TAG-1,TAG-2 and TAG-5,etc)of the TAG hydrothermal deposithave been discussed based on the calculated results.
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MILLS R A,DAMON A H,TIVEY M K.Fluid mixing and anhydrite precipitation within the TAG mound[J].Proc ODP,Sci Results,1998,158.-119-127. PETERSEN S,HERIZIG P M,HANNINGTON M D.Fluid inclusion studies as a guide to the temperature regime within the TAG hydrothermal mound,26N,Mid-Atlantic Ridge[J].Proe ODP,Sci Results,1998,158:163-178. TIVEY M K.Documenting textures and mineral abundance in minicores from the TAG active hydrothermal mound using X-ray computed tomography[J].Proc ODP,Sci Results,1998,158:5-26. HUMPHRIS S E.Rare earth element composition of anhydrite:implications for deposition and mobility within the active hydrothermal mound[J].Proc ODP,Sci Results,1998,158:143-159. HERIZIG P M,PETERSEN S,HANNINGTON M D.Geochemistry and sulfur-isotopic composition of the TAG hydrothermal mound,Mid-Atlantic Ridge,26 N[J].Proc ODP,Sci Results,1998,158:47-70. CHIBA H,UCHIYAMA N,TEAGLE D A H.Stable isotope study of anhydrite and sulfide minerals at the TAG hydrothermal mound,26N,Mid-Atlantic Ridge[J].Proc ODP,Sci Results,1998,158:85-90. GEMMELL J B,SHARPER.Detailed sulfur-isotope investigation of the TAG hydrothermal mound and stockwork zone,26N,Mid-Atlantic Ridge[J].Proc ODP,Sci Results,1998,158:71-90. TIVEY M K,MILLS R A,DAMON A H.Temperature and salinity of fluid inclusions in anhydrite as indicators of seawater entrainment and heating in the TAG active mound[J].Proe ODP,Sci Results,1998,158:179-190. HERZIG P M,PETERSEN S,HANNINGTON M D.Geochemistry and sulfur-isotopic composition of the TAG hydrothermal mound,Mid-Atlantic Ridge,26 N[J].Proc ODP,Sci Results,1998,158:47-70. GEMMELL J B,SHARPER.Detailed sulfur-isotope investigation of the TAG hydrothermal mound and stockwork zone,26N,MidAtlantic Ridge[J].Proc ODP,Sci Results,1998,158:71-84. CHIBA H,UCHIYAMA N,TEAGLE A H.Stable isotope study of anhydrite and sulfide minerals at the TAG hydrothermal mound,Mid-Atlantic Ridge,26 N[J].Proe ODP,Sci Results,1998,158:85-90. HUMPHIRSS E.Rare earth element composition of anhydrite:implications for deposition and mobility within the active TAG hydrothermal mound[J].Proc ODP,Sci Results,1998,158:143-159. RONA P A,DAVIS E E,LUDWING R J.Thermal properties of TAG hydrothermal precipitates,Mid-Atlantic Ridge,and comparison with Middle Valley,Juan de Fuca Ridge[J].Proe ODP,Sci Results,1998,158:329-335. LUDWING R J,ITURRIN O,RONA P A.Seismic velocity-porosity relationship of sulfide,sulfate,and basalt samples from the TAG hydrothermal mound[J].Proe ODP,Sci Results,1998,158:313-327. FOUQUET Y,HENRY K,KNOTT R,et al.Geochemical section of the TAG hydrothermal mound[J].Proc ODP,Sei Results,1998,158:363-387. 曾志刚,秦蕴珊,赵一阳,等.大西洋TAG热液活动区海底热液沉积物的硫同位素组成及其地质意义[J].海洋与湖沼,2000,31(5):518-529. 曾志刚,秦蕴珊,翟世奎.大西洋中脊TAG热液区硫化物中流体包裹体的He-Ne-Ar同位素组成[J].中国科学(D辑),2000,30(6);628-633. 曾志刚,秦蕴珊,翟世奎.大西洋洋中脊海底表层热液沉积物的铅同位素组成及其地质意St[J].青岛海洋大学学报,2001,31(1):103-109. 曾志刚,翟世奎,杜安道.大西洋洋中脊TAG热液区中块状硫化物的Os同位素研究[J].沉积学报,2002,20(3):394-398. 蒋少涌,杨涛,李亮,等.大西洋洋中脊TAG热液区硫化物铅和硫同位素研究[J].岩石学报,2006,22(10):2597-2602. TIVET M K,HUMPHRIS S E,THOMPSON G,et al.Deducing patterns of fluid flow and mixing within the TAG active hydrothermal mound using mineralogical and geochemical data[J].J Geophys Res,1995,100(B7):12527-12555. HOSHINO K,YAMAMOTO Y,GU X,et aL Preliminary examination of the ore-forming process by fluid mixing-a test of MIX99[J].Reso Geol,2000,50:185-190. HOSHINO K,ITAMI T,SHIOKAWA R,et aL A possible role of boiling in ore deposition:a numerical approach[J].Reso Geol,2006,56:49-54. JOHNSON J W,OELKERS E H,HELGESON H C.SUPCRT92-a software package for calculating the standard molal thermodynamic properties of minerals,gases,aqueous species,and reactions from l-bar to 5000-bar and 0 ℃ to 1000 ℃['J].Comput Geotech,1992,18:899-947. EDMOND J M,CAMPBEL L,GERMAN C R,et al.Time series studies of vent fluids from the TAG and MARK sites (1986,1990)Mid-Atlantic Ridge and a mechanism for Cu/Zn zonation in massive sulphide orebodies[M]//Hydrothermal Vents and Processes:Special Publication.London:Geological Society of London,1995:77-86. 李怀明,翟世奎,于增慧,等.大西洋TAG热液活动区流体演化模式[J].中国科学(D辑),2008,38(8):1-10. GALLANT R M,VON DAMN K L.Geochemical controls on hydrothermal fluids from the Kairei and Edmond vent fields,23°~25°S,Central Indian Ridge[J].Geoehem Geophys Geosyst,2006,7:1-24. DING K,SEYFIRED W E,ZHONG Z,et al.The in situ pH of hydrothermal fluids at mid-ocean ridges[J].Earth Planet Sci Lett,2005,237:167-174. 安伟.现代海底热液活动时空分布及其成矿作用特征研究[D].青岛:中国海洋大学,2005.69-84. KNOTT R,FOUQUET Y,HONNOREZ J,et aL Petrology of hydrothermal mineralization:a vertical section through the TAG mound[J].Proc ODP,Sci Results,1998,158; 5-26.
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