Geochemical Studies on Mg-bearing Carbonates in Ryukyu Islands and Okinawa Trough.

琉球群岛和冲绳海槽含镁碳酸盐的地球化学研究。

• 批准号: 01540488
• 负责人: OOMORI Tamotsu
• 金额: $ 0.77万
• 依托单位: University of the Ryukyus
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01540488/
• 关键词: Okinawa Trough; Coral reef; submarine hydrothermal activity; hydrothermal ore; heavy metal; radioactivity; carbonate; dolomite

Geochemical studies on carbonate sediments and related materials collected mainly from submarine hydrothermal sites of Taketomijima-Island and Okinawa Trough back arc basin have been carried out. The research results are summarized as follows.[A] Taketomijima submarine hydrothermal sites:(1) Samples of carbonate sediments, hot spring water and associated gas were collected from the bottom of coral reef of Taketomijima (ca. 22m in depth) by scuba divers.(2) The carbonate sediments are composed of foraminifera test, shell or fragments of coral skeleton. The dark colored secondary carbonates covered the cavity of pores of sediments. The proportion of dolomite and content of heavy metals such as Hg, As, Sb, Ba, Fe, Mn, Cd and U are abnormally high in the dark portion.(3) The chemistry and mineralogy of sediments of Taketomijime hydrothermal site is analogous to that of Kagosima-bay which is considered to be related to the volcanic activity of the adjacent area.(4) Frequent earthquake activ … More ity has been observed from January 23, 1991 until now at Iriomotejima Island, which is located ca. 30 Km west of Taketomijima hot spot. It will be important whether Taketomijima hot spring activity and Iriomote earthquake activity are related each other or not. The water temperature, chemical composition of water and associated gas should be monitored.[B] Okinawa Trough hydrothermal sites :(1) The carbonate sediments are collected from Iheya deep of Okinawa Trough by research submersible 'SINKAI2000' in 1989 and 1990.(2) X-ray diffraction and neutron activation analysis revealed that these carbonates are mainly composed of calcite, rhodechlosite (MnCO3) and kuthonite (CaMn (CO3) 2) and rich in Mn, As, Hg, and Ag.(3) On the other hand, sulphate and sulphide sediments are collectd from Izena deep in 1989. The gamma-ray spectroscopy showed that activity of Ra-226, Ra-228 and their daughter nucleides is extremly high in barium sulphate containing sediments. These sediments are deposited by hydrothermal activity in recent years.(4) Liquid CO2 and solid gas hydrate of CO2 were observed at Izena deep hydrothermal sites. Less

对主要采自竹富岛和冲绳海槽弧后盆地海底热液点的碳酸盐沉积物及相关物质进行了地球化学研究。研究结果总结如下。[A]竹富岛海底热液点：（1）从竹富岛珊瑚礁底部采集碳酸盐沉积物、温泉水和伴生气样品。22米深）的水肺潜水员。(2)碳酸盐沉积物由有孔虫化石、贝壳或珊瑚骨骼碎片组成。深色次生碳酸盐覆盖了沉积物的孔隙空腔。白云岩的比重和Hg、As、Sb、Ba、Fe、Mn、Cd、U等重金属的含量在暗部异常偏高。(3)竹富寺目热液区沉积物的化学和矿物学特征与鹿儿岛湾相似，被认为与邻近地区的火山活动有关。(4)地震频发 ...更多信息 从1991年1月23日至今，在西表岛（Iriomotejima Island）观测到了这一现象。竹富岛热点以西30公里。竹富岛温泉活动与西表地震活动之间是否存在相关关系将成为重要问题。应监测水温、水和伴生气的化学成分。[B]冲绳海槽热液区：（1）1989年和1990年，利用科考潜水器“SINKAI 2000”在冲绳海槽伊平谷深处采集了碳酸盐沉积物。(2)X射线衍射和中子活化分析表明，这些碳酸盐主要由方解石、菱锰矿（MnCO 3）和钾镁矾（CaMn（CO 3）2）组成，富含Mn、As、Hg和Ag。(3)另一方面，1989年在Izena深海采集了硫酸盐和硫化物沉积物。γ能谱表明，在含硫酸钡的沉积物中，Ra-226、Ra-228及其子核的活度极高。这些沉积物是近年来热液活动的产物。(4)在Izena深部热液站点观测到液态CO2和CO2的固态气体水合物。少

项目成果

大森保: "「しんかい2000」潜航調査で採集された沖縄トラフ海底熱水鉱床の化学組成と同位体組成" 地球(Chikyu Monthly). 12. (1990)

Tamotsu Omori：“新海 2000 年海底调查期间收集的冲绳海槽海底热液沉积物的化学和同位素组成”地球月刊 12。（1990 年）

木村政昭: "沖縄トラフの地質と熱水性鉱床" 鹿児島大学紀要. (1990)

Masaaki Kimura：“冲绳海槽的地质和热液沉积”鹿儿岛大学公报（1990）。

Sakai H. et al.: "Carbon dioxide fluid venting and hydrate formation at the JADE hydrothermal fields, in the mid-Okinawa Trough back arc basin." Science. Vol. 248. 1093-1096 (1990)

Sakai H. 等人：“冲绳海槽中部弧后盆地 JADE 热液田的二氧化碳流体排放和水合物形成。”

Sakai,H.: "Carbon dioxide-rich fluid venting and hydrate formation at the JADE hydrothermal field,in the mid-Okinawa Trough backarc basin." Science. (1990)

Sakai, H.：“冲绳海槽弧后盆地中部 JADE 热液田富含二氧化碳的流体喷发和水合物形成。”

酒井 均 大森 保ほか: "「しんかい2000」による伊是名海穴の熱水系の地球化学的研究:第413回および第424回潜航で採取した二酸化炭素液泡と包接化合物について" 第6回「しんかい2000」研究シンポジウム報告書. 69-86 (1990)

Hitoshi Sakai、Tamotsu Omori 等：“利用 Shinkai 2000 对伊是名海洞热液系统进行地球化学研究：关于第 413 次和 424 次潜水期间收集的二氧化碳气泡和包合物”第 6 次“Shinkai 2000”2000 年研究研讨会报告 69。 -86 (1990)