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

在1999年，在本研究期间引入了用于诱导偶联血浆质谱仪（ICP-MS）的高性能ARF激光磨料设备，用于分析覆盖各种地质样品的分析。1）这项研究的第一个主题是该研究的第一个主题，是活跃的维也纳木质木质木质海洋水热沉积的矿物学和质地。三个水热位点分布在Manus后弧盆地：Pacmanus，Desmos和Vienna Wood遗址。在这项研究中检查了维也纳木木水热位点的大规模硫化物矿石的米拉学和地层环境。维也纳木木水热位点由Morb型玄武岩托管在graben形态中。从维也纳木材地点收集了三种类型的矿石样品：（1）高15m高的活性烟囱（IA型），（2）距离大烟囱（IB型）和（3）（3）距离活性烟囱（II型）的小烟囱（IB型）和（3）死亡烟囱的小型活性烟囱。 Ia型矿石由大规模的赤铁组成……更多的仪式，具有散布的树突状黄铁矿，闪烁石和辣椒岩。 IB型矿石由小赤绿石，氧化矿石，树突黄铁矿，吡咯酸盐，闪存岩和辣椒岩组成。 II型矿石由framboidal到特分形黄铁矿，树突状黄铁矿，吡咯酸盐，辣椒石和闪光石，带有次要赤铁矿和baryte.Bulk化学成分。维也纳矿石的化学成分（16.5-40.0 wt and pb and pb and pb and p wt and p.0％）。（0.01-1.7 wt。％）IB类型的含量（Zn = 0.3-2 wt。％，Cu = <0.1 wt。％，Pb = <0.01 wt。％）或II型（Zn = 10-17 wt。％，CU = <1.0wt。％，pb = <0.4 wt。％）。维也纳木地点的Mineraology和地层环境与积极形成与Pacmanus和Desmos位置中的兰氏火山岩相关的pollymetallic硫化物沉积物。2）第二个目标是塞浦路斯型矿石沉积物的地球化学特征。 Ghuzayn Cu-fe巨大的硫化物矿石沉积物是阿曼蛇绿岩中托管的典型塞浦路斯型沉积物之一，该沉积物提供了一个唯一的机会来研究古近海地壳的地球化学条件。检查了Cu，Zn，Co和Ni在薄片的复合物中的垂直分布，改变了枕头玄武岩和大量的硫化物矿石，以澄清海洋壳中的化学迁移率，因为硫化物矿物质的热液循环和沉淀物。CU和Co co co and Co co co co co co co co co co co co co co pyrite and trace元素及其从水面溶液中的痕量元素沉积。在某些循环元素中，在改变的岩石中，Zn和N对编年史的首选固定是原因是这些金属未沉淀成大量的矿石。3）库鲁科矿化前和后kuroko矿化的沉积岩石的地球化学特征，Akita是Akita，是第三个主题。 Hokuroku盆地是最著名的海底水热矿化区，约15 m.y.ago。为了阐明中新世中期的环境变化，ICP-MS分析了库鲁科年龄前后沉积岩石中的痕量元素。选择了两个秋田地区进行沉积岩石的地球化学研究。首先是位于日本岛 - 阿尔克山脉的西侧的Wagaomono地区。 Dainihon-Yoshino Kuroko矿床分布在该地区的Nishikurosawa上部。第二是日本海沿海地区“ Akita油田”的Iwaki地区。 SIO2-FE2O3的系统学表明，Wagaomono泥石可能是生物凝灰岩起源和酸性凝灰岩起源之间混合源的沉积物。 Nishikurosawa到Onnagawa阶段的MN/U比从1,200降低到24。这些复合变化表明，沉积环境从氧化状态明显变化为减少条件。来自所有分析标本的沉积岩的软骨范围标准化REE模式显示出明显的欧盟负异常。这些来自Nishikurosawa阶段的沉积岩的欧盟异常比Wagaomono地区的Onnagawa阶段大。伊瓦基地区碳酸盐结节的MN巡航显示出葡萄菌的独特负异常。这些数据可能表明，尽管Fe和Mn浓度的抽象几乎相同，但Onnagawa年龄的沉积条件及其成岩过程比Nishikurosawa年龄的年龄降低了很多。显然，通过快速LA-ICP-MS分析，细粒沉积岩中次要元素的地球化学信息对于讨论沉积环境非常有效。较少的