Formation Mechanisms and Formation Environment of Seaflor Hydrothermal Ore Deposits

本科研项目的目的是解决火山成因块状硫化物矿床的构造环境和沉积机制。矿床的主要对象是中新世最具代表性的黑子矿床和现代海底热液矿床。矿石和有关火成岩的描述地质学和最新的地球化学调查是必不可少的，这两种研究方法的结合使得对矿石成因的地球科学解释成为可能。本研究首先考察了主要发育大型黑矿的秋田县北六地区的地质和金属资源意义。第二个目的是在黑矿火山成因背景下，对该区某些火山地层点的现状进行了研究，其中典型的黑矿之一的小坂内之台存款中的硅质丘正是在黑矿火山成因背景下的火山-地层点。 ...更多信息 调查事件的发生方式。本文研究了几个黑矿型和别志型火山成因块状硫化物矿床矿石的地球化学特征，并研究了矿石结构从原生成岩阶段到后续成岩阶段的变化。稳定同位素地质学研究表明，Kosaka-Uwamuki存款中的碳酸盐是由热液与生物成因的碳酸盐反应形成的，现代海底热液矿床研究表明，岩浆活动是西太平洋地区热液流体的重要来源。此外，还对冲绳海槽现代黑矿型矿床的海底沉积物进行了化学和矿物组成研究。在海底热液矿床中，矿石的结构、构造和矿物成分反映了矿床的形成环境，而中新世黑矿的结构、构造和矿物成分对研究矿床的原生特征、矿床的保存和成岩作用具有重要意义。少

The purposes of this Scientific Research Project are to solve the tectonic situation and depositional mechanism of colcanogenic massive sulfide ore deposits. The main objects of the ore deposits are one of the most representative Kuroko deposits of the Miocene age and the seafloor hydrothermal deposits of modern age. Descriptive geology on ores and related igneous rocks and up-to-date geochemical investigation are indispensable and the combination of both research procedures makes possible for the generalized earth scientific interpretation on ore genesis.In this study, the significance of geology and metal resources are examined first for the Hokuroku district in Akita Prefecture where the large scale Kuroko deposits were primarily developed. The second object is the presentatation for some volcano-stratigraphic points the area on the volcanogenic background of the Kuroko deposits.The siliceous mound in the Kosaka-Uchinotai deposit, one of the typical Kuroko deposits, are precisely in … More vestigated for the mode of occurrences. Geochemical characteristics are examined for ores from some Kuroko-and Besshi-type volcanogenic massive sulfide deposits, and the change of ore textures are studied from primary to successive diagenetic stages. The investigation of stable isotopic geology revelas that the carbonates from the Kosaka-Uwamuki deposit are formed by the reaction with hydrothermal fluid and carbonate in biogenic origin.Researches on seafloor hydrothermal deposits in modern age reveals that magmatic activities are important as the origin of hydrothermal fluids in the western Pacific region. Besides, seafloor sediments of the modern Kuroko-type deposits in the Okinawa Troughare investigated for the chemical and mineralogical compositions. In the seafloor hydrothermal deposits, the textures and structures of ores and the compositions of minirals are representing the generation circumstances, and those of Miocene Kuroko ores could be give some valuable hints for the consideration on primary features, preservation of ores and diagenetic processes. Less