2 0 0 0 OA 北海道大江鉱山産石筍状菱マンガン鉱について
- 著者
- 小島 晶二 苣木 浅彦
- 出版者
- Japan Association of Mineralogical Sciences
- 雑誌
- 岩石鉱物鉱床学会誌 (ISSN:00214825)
- 巻号頁・発行日
- vol.78, no.12, pp.491-496, 1983-12-05 (Released:2008-08-07)
- 参考文献数
- 13
From the Senzai vein of the Oe mine situated in southwestern Hokkaido, some kinds of rhodochrosite stalagmites are sometimes found out at the bottom of druse within the vein. The stalagmites show the shape of column, 2 to 30mm in diameter and 1 to 12cm in length. They consist of irregular fan-shaped crystals superficially and show the solution growth textures such as concentric bandings. These stalagmites have the chemical compositions of 53 to 89 mole % MnCO3, 2 to 20 mole % CaCO3. 7 to 26 mole % FeCO3 and 1 to 9 mole % MgCO3, which are mostly within the compositional region of drusy rhodochrosite of the vein. Chemical compositions of the rhodochrosite stalagmites change markedly with the concentric bands as shown in Fig. 7, which shows considerable increase of MnCO3 content from core to rim. This feature is considered as being due to chemical changes of the ore solution or ground water producing the rhodochrosite stalagmite.
1 0 0 0 OA 酸化鉄型銅金(IOCG)鉱床成因論に関する最近の進展,特にチリに分布する鉱床について
- 著者
- 小島 晶二
- 出版者
- 資源地質学会
- 雑誌
- 資源地質 (ISSN:09182454)
- 巻号頁・発行日
- vol.69, no.2, pp.97-109, 2019-12-16 (Released:2022-08-27)
- 参考文献数
- 78
- 被引用文献数
- 5
Recent progresses on the iron oxide-copper-gold (IOCG) deposits, especially on principal Chilean deposits, are summarized to clarify metallogenesis and exploration of the type of deposits in Mesozoic extensional subduction regime. The principal composite-mode deposits (Candelaria, Punta del Cobre, Mantoverde) are closely associated with Cretaceous Atacama fault system, and are characterized by the typical Na-Ca-K alteration with the early-stage magnetite (or hematite) and the following Mg alteration with copper-sulfide and gold mineralizations. Fluid inclusion and stable isotope studies suggest that the IOCG deposits were formed by high-temperature hypersaline magmatic-hydrothermal fluids. If the IOCG deposits are generated from FeCl2-bearing magmatic fluids, the spatial-temporal relation between the IOCG and iron oxide-apatite (IOA) deposits is well explained by the magmatic magnetite-bubble segregation model (Knipping et al., 2015b; Simon et al., 2018). Nevertheless, a few problems still remain unsolved in the genetic model including contribution of basinal brines.