During January–May in 2007,the Chinese research cruise DY115-19 discovered an active hydrothermal field at 49°39′E/37°47′S on the ultraslow spreading Southwest Indian Ridge (SWIR).This was also the first ...During January–May in 2007,the Chinese research cruise DY115-19 discovered an active hydrothermal field at 49°39′E/37°47′S on the ultraslow spreading Southwest Indian Ridge (SWIR).This was also the first active hydrothermal field found along an ultraslow-spreading ridge.We analyzed mineralogical,textural and geochemical compositions of the sulfide chimneys obtained from the 49°39′E field.Chimney samples show a concentric mineral zone around the fluid channel.The mineral assemblages of the interiors consist mainly of chalcopyrite,with pyrite and sphalerite as minor constitunets.In the intermediate portion,pyrite becomes the dominant mineral,with chalcopyrite and sphalerite as minor constitunets.For the outer wall,the majority of minerals are pyrite and sphalerite,with few chalcopyrite.Towards the outer margin of the chimney wall,the mineral grains become small and irregular in shape gradually,while minerals within interstices are abundant.These features are similar to those chimney edifices found on the East Pacific Rise and Mid-Atlantic Ridge.The average contents of Cu,Fe and Zn in our chimney samples were 2.83 wt%,45.6 wt% and 3.28 wt%,respectively.The average Au and Ag contents were up to 2.0 ppm and 70.2 ppm respectively,higher than the massive sulfides from most hydrothermal fields along mid-ocean ridge.The rare earth elements geochemistry of the sulfide chimneys show a pattern distinctive from the sulfides recovered from typical hydrothermal fields along sedimentstarved mid-ocean ridge,with the enrichment of light rare earth elements but the weak,mostly negative,Eu anomaly.This is attributed to the distinct mineralization environment or fluid compositions in this area.展开更多
新疆北部的喇嘛苏铜矿是一个较典型的夕卡岩型矿床 ,通过对该矿区内不同类型岩石的稀土元素地球化学研究 ,建立了各类岩石的 REE分布模式 ,探讨了矿区内中酸性浅成岩、碳酸盐岩、夕卡岩、基性岩脉等 4种主要岩石类型的稀土元素地球化学...新疆北部的喇嘛苏铜矿是一个较典型的夕卡岩型矿床 ,通过对该矿区内不同类型岩石的稀土元素地球化学研究 ,建立了各类岩石的 REE分布模式 ,探讨了矿区内中酸性浅成岩、碳酸盐岩、夕卡岩、基性岩脉等 4种主要岩石类型的稀土元素地球化学行为 ,认为该矿区内不同类型的岩石具有 REE分布型式相近、具清晰的 Eu负异常及弱 Ce负异常、w (L a) n/w (Sm ) n 值普遍高于w (Gd) n/w(Yb) n 值等共性 ,相比之下浅成岩具有较低的 w (L a) n/(w Yb) n 值与变化范围偏宽的δ(Eu)值 ,碳酸盐岩具有较高的 w (L a) n/w (Yb) n 值与变化范围偏窄的δ(Eu)值 ,夕卡岩的 w (L a) n/w (Yb) n 值与δ(Eu)值变化范围刚好居于这二者之间 ,中酸性浅成岩有随着 Si O2 质量分数增高而δ(Eu)展开更多
基金supported by the China Ocean Min-eral Resources Research and Development Association Program (DY115- 02-1-01)the State Oceanic Administration Youth Science Fund (2010318)
文摘During January–May in 2007,the Chinese research cruise DY115-19 discovered an active hydrothermal field at 49°39′E/37°47′S on the ultraslow spreading Southwest Indian Ridge (SWIR).This was also the first active hydrothermal field found along an ultraslow-spreading ridge.We analyzed mineralogical,textural and geochemical compositions of the sulfide chimneys obtained from the 49°39′E field.Chimney samples show a concentric mineral zone around the fluid channel.The mineral assemblages of the interiors consist mainly of chalcopyrite,with pyrite and sphalerite as minor constitunets.In the intermediate portion,pyrite becomes the dominant mineral,with chalcopyrite and sphalerite as minor constitunets.For the outer wall,the majority of minerals are pyrite and sphalerite,with few chalcopyrite.Towards the outer margin of the chimney wall,the mineral grains become small and irregular in shape gradually,while minerals within interstices are abundant.These features are similar to those chimney edifices found on the East Pacific Rise and Mid-Atlantic Ridge.The average contents of Cu,Fe and Zn in our chimney samples were 2.83 wt%,45.6 wt% and 3.28 wt%,respectively.The average Au and Ag contents were up to 2.0 ppm and 70.2 ppm respectively,higher than the massive sulfides from most hydrothermal fields along mid-ocean ridge.The rare earth elements geochemistry of the sulfide chimneys show a pattern distinctive from the sulfides recovered from typical hydrothermal fields along sedimentstarved mid-ocean ridge,with the enrichment of light rare earth elements but the weak,mostly negative,Eu anomaly.This is attributed to the distinct mineralization environment or fluid compositions in this area.
文摘新疆北部的喇嘛苏铜矿是一个较典型的夕卡岩型矿床 ,通过对该矿区内不同类型岩石的稀土元素地球化学研究 ,建立了各类岩石的 REE分布模式 ,探讨了矿区内中酸性浅成岩、碳酸盐岩、夕卡岩、基性岩脉等 4种主要岩石类型的稀土元素地球化学行为 ,认为该矿区内不同类型的岩石具有 REE分布型式相近、具清晰的 Eu负异常及弱 Ce负异常、w (L a) n/w (Sm ) n 值普遍高于w (Gd) n/w(Yb) n 值等共性 ,相比之下浅成岩具有较低的 w (L a) n/(w Yb) n 值与变化范围偏宽的δ(Eu)值 ,碳酸盐岩具有较高的 w (L a) n/w (Yb) n 值与变化范围偏窄的δ(Eu)值 ,夕卡岩的 w (L a) n/w (Yb) n 值与δ(Eu)值变化范围刚好居于这二者之间 ,中酸性浅成岩有随着 Si O2 质量分数增高而δ(Eu)
