Analytical and experimental studies on partitioning of elements and diffusion kinetics in some sulfide minerals in ore deposits

矿床中某些硫化物矿物的元素分配和扩散动力学的分析和实验研究

基本信息

批准号：
14340157
负责人：
MIZUTA Toshio
金额：
$ 10.94万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

High-performance ArF laser abration equipment for induced coupled plasma mass spectrometer (ICP-MS) were introduced in 1999 during this research period for analyses of covering various kinds of geological samples.1)First topics of this study is the mineralogy and textures of active Vienna Wood seafloor hydrothermal deposit, Manus Basin, Papua New Guinea. Three hydrothermal sites are distributed in the Manus Back-arc basin : Pacmanus, Desmos and Vienna Wood sites. The mineralogy and formation environments for the massive sulphide ores from the Vienna Wood hydrothermal site were examined in this study.The Vienna Wood hydrothermal site is hosted by MORB-type basalt in graben morphology. Three types of ore samples were collected from the Vienna Wood site : (1)top of 15m tall active chimneys (type IA), (2)small active chimneys 3 meters away from the big chimneys (type IB) and (3)dead chimneys sampled 20 meters away from the active chimney (type II). The type IA ores consist of massive anhyd … More rite with disseminated dendritic pyrite, sphalerite and chalcopyrite. Type IB ores consist of minor anhydrite, Fe-oxide, dendritic pyrite, subhedral pyrite, sphalerite and chalcopyrite. Type II ores are dominated by framboidal to idiomorphic pyrite, dendritic pyrite, subhedral pyrite, chalcopyrite and sphalerite with minor anhydrite and baryte.Bulk chemical composition of the Vienna Wood ores show high Zn (16.5-40.0 wt.%), Cu (1.0-2.0 wt.%) and Pb (0.01-1.7 wt.%) contents in type IB than type IA (Zn = 0.3-2 wt.%, Cu = <0.1 wt.%, Pb =< 0.01 wt.%) or type II (Zn = 10-17 wt.%, Cu = <1.0wt.%, Pb =<0.4 wt.%). The mineralogy and formation environment for the Vienna Wood site are quite different from actively forming pollymetallic sulphide deposits associated with felsic volcanic rocks in the Pacmanus and Desmos sites.2)Second target is the geochemical features of Cyprus-type ore deposits. The Ghuzayn Cu-Fe massive sulfide ore deposit is one of the typical Cyprus-type deposits hosted in Oman ophiolite which providing a uniqu opportunity to study geochemical conditions of paleo-oceanic crust. Vertical distribution of Cu, Zn, Co and Ni in sheeted-dike complex, altered pillow basalts and massive sulfide ores were examined to clarify the chemical mobility in oceanic crust because of hydrothermal circulation and precipitation of sulfide minerals.Cu and Co are deposited as chalcopyrite and trace element in pyrite from hydrothermal solution. Among some circulating elements, preferential fixation of Zn and N to chlorite in altered rocks is responsible to the reason that these metals are not precipitated into massive ores.3)Geochemical characteristics of sedimentary rocks of pre-and post-Kuroko mineralization, Akita, is the third topics. The Hokuroku Basin is the most famous Kuroko district for seafloor hydrothermal mineralization around 15 m.y.ago. To clarify the environmental changes of Middle Miocene age, trace elements in sedimentary rocks of pre-and post-Kuroko ages are analyzed by ICP-MS. Two Akita areas are chosen for the geochemical research on sedimentary rocks. First is the Wagaomono area located in the western flank of mountain range of NE Japanese Island-Arc. The Dainihon-Yoshino Kuroko deposit is distributed in the upper Nishikurosawa Formation of this region. Second is the Iwaki area located in "Akita Oil Field" of the coastal district of Japan Sea.(LA)-ICP-MS for 34 elements in the sedimentary rocks and O and C isotope spectrometry for carbonates are employed. Systematics of SiO2-Fe2O3 reveals that the Wagaomono mudstones are likely to be the sediments of the mixed sources between biogenic and acidic tuffs origin. Mn/U ratios from the Nishikurosawa to the Onnagawa stages decrease dramatically from 1,200 to 24. These compositional changes show that sedimentary environments change clearly from oxidation state to reducing condition. Chondrite-normalized REE patterns of sedimentary rocks from all analyzed specimens show clear Eu negative anomalies. These Eu anomalies of sedimentary rocks from the Nishikurosawa Stage are larger than those the Onnagawa Stage in Wagaomono area. Mn crusts of carbonate nodules in the Iwaki area show the distinctive negative anomalies of cerium. Those data could indicate that the sedimentary conditions and their diagenetic processes of the Onnagawa age are much reducing than those of the Nishikurosawa age, in spite of almost the same abundance of Fe and Mn concentration. It is obvious that geochemical information of minor elements in fine-grained sedimentary rocks by rapid LA-ICP-MS analysis is quite effective to discuss the sedimentary environments. Less

1999年在此研究期间引入了诱导的coupmasma质谱仪（ICP-MS）的高性能ARSER ABRATION（ICP-MS）。 S，Desmos和Vienna Wood的位置。）高15m高的活跃烟囱（IA型），（（IA型）2）距离大烟囱3米的小型烟囱（3）距离活跃烟囱20米的Dead Chimneys（II型IA型）。大量的Anhyd…具有散布的树突状葡萄矿，spherite和辣椒的仪式。。与Pacmanus和desmos站点中与英质火山岩相关的积极狂热的硫化物完全不同。2）第二个目标是塞浦路斯型矿石的地球化学特征，它沉积了Ghuzayn Cu-fe巨大的硫化物硫化物矿石矿石Ore Os托管的OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS OS研究古cu，Zn，Co和Ni的垂直分布的地球化学条件。 Cu作为铜硫酸石铜矿沉积，并从水热溶液中沉积在黄铁矿中。库鲁科矿化前的矿化，秋田是第三个主题，霍库鲁库盆地是海底水热矿化最著名的，大约15 m.y.ago。由ICP-MS分析。日本海沿海地区的Cota油田。采用了碳酸盐的同位素光谱法。Sio2-Fe2O3的系统学表明，Wagaomono泥石可能是生物源性和酸性毒tuff阶段的沉积物，而乌拉萨瓦的阶段则是Onagawa的阶段。从1,200到24。这些组成变化氧化状态减少了所有分析标本的沉积岩石模式。有些人在北那川时代的Diki Carbonatel ES中有些点头的碳质，这是nishikurosawa时代的重新质量，很明显，很明显-MS分析对于减少沉积环境非常有效