資源地質
Online ISSN : 2185-4033
Print ISSN : 0918-2454
ISSN-L : 0918-2454
51 巻, 1 号
選択された号の論文の7件中1~7を表示しています
  • 片山 弘行, 大岡 隆, 増田 信行
    2001 年 51 巻 1 号 p. 1-6
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
    The Metal Mining Agency of Japan has developed electromagnetic tomography system for mineral exploration since 1994. To evaluate the system whether it become effective for mineral exploration, test survey was conducted in Ghuzayn, South Batinah Coast area, Sultanate of Oman in 2000. The analyzed resistivity sections can delineate massive sulphide ore body clearly although drill hole which was used for survey does not intersect ore body.
  • 石川 信明, 久保田 博志, 荒井 英一, 細井 義孝
    2001 年 51 巻 1 号 p. 7-18
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
    The Okuzo prospect is located 20 km southeast of Odate city, Akita prefecture. The Metal Mining Agency of Japan (MMAJ) discovered Kuroko-style mineralisation accompanying lead, zinc, gold and silver during a regional geological survey of the area.
    The Okuzo prospect is located on the southeastern rim of the Hokuroku Kuroko Basin, which is closed along a line extending from the Gacchimaeda fault to the boundary of the southern rim of the Gattsu basin based on geological and gravity data. As a result of the geological survey by the MMAJ, a fragment of Kuroko ore with a diameter of 15cm was discovered in an outcrop of volcaniclastic rock; analysis returned 0.75g/t Au, 160g/t Ag, 0.2% Cu, 5.2% Pb, 23.0% Zn and 39.5% BaSO4.
    Based on induction polarization and drilling surveys, the characteristics or hanging-wall and foot-wall alteration associated with Kuroko mineralisation were identified as the presence plagioclase and chlorite-sericite, respectively. It is proposed that volcanic activity had been continuous at the middle Miocene after the Kuroko mineralisation and resulted in the formation of vent breccia.
  • 沢井 長雄, 景山 宗一郎, 岡田 利典, 板谷 徹丸
    2001 年 51 巻 1 号 p. 19-27
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
    A large number of epithermal vein-type gold deposits are distributed in the northern-central Kyushu. K-Ar ages were determined for sericite and K-feldspar separated from hydrothermally-altered rocks and quartz-K-feldspar veins, and for quartz-alunite altered rock, which were collected from gold deposits located outside the Beppu-Shimabara Graben, to examine their age of gold mineralization. The results are 2.61±0.06 and 2.74±0.13 Ma in Ogata, 2.48±0.06 and 2.75±0.06 Ma in Kinsei-Hoshino, 3.55±0.12 Ma in Tamarai, 3.59±0.09 and 3.53±0.10 Ma in Asahi, 2.87±0.23 Ma in Magane, 3.54±0.08 Ma in Usa, 3.92±0.09 Ma in Yamaura and 8.05±0.24 Ma in Bajo.
    Sericite age of Bajo deposit is 8.05 Ma, which is significantly older than those of other deposits. This is due to that relic muscovite of the host granitic rock mixed into the mineral separates to be dated. Newly and previously obtained K-Ar age data revealed that the gold deposits in outside of the Beppu-Shimabara Graben were formed in a period (1.5 million years) between 3.92 Ma and 2.48 Ma in Pliocene and that the gold mineralization occurred immediately after the end of major volcanic activity. The ages also show that the gold mineralization in Pliocene has close relationship with the volcanism.
  • 藤永 公一郎, 加藤 泰浩
    2001 年 51 巻 1 号 p. 29-40
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
    Major, trace and rare earth element concentrations of sedimentary rocks including umber, red shale and black shale from the Ryujin Formation (late Campanian-Maastrichtian) in the Shimanto belt were determined by X-ray fluorescence (XRF) and inductively-coupled plasma mass spectrometry (ICP-MS). These sedimentary rocks are closely associated with in-situ greenstones in the accretionary complex of the late Cretaceous age. Geochemical characteristics of sedimentary rocks are as follows; (1) the bulk-rock chemical compositions of black shale are generally similar to those of Post Archean Australian Shale (PAAS), (2) red shale is enriched in Fe, Co, Ni, Zn, Y, Mo and REEs compared to black shale, (3) umber exhibits a remarkable enrichment of Fe, Mn, P, V, Co, Cu, Ni, Zn, Y, Mo and REEs, (4) these enriched elements in umber and red shale show a good positive correlation with Fe, (5) these elements/iron ratios of umber are very similar to those of modern hydrothermal metallifer-ous sediments at mid-ocean ridge (MOR), (6) PAAS-normalized REE patterns of umber are characterized by a conspicuous negative Ce anomaly. These geochemical features suggest that a series of sedimentary rocks were deposited near the trench where temgenous materials from lands and hydrothermal Fe-rich suspended particulates from the MOR were supplied simultaneously. This conclusion supports that ridge-forearc collisions occurred near the late Campanian Japan.
  • 志賀 美英
    2001 年 51 巻 1 号 p. 41-53
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
    Advanced industrial countries including Japan have been dependent on the developing countries for a great deal of mineral resources. That is however risky for them since many developing countries tend to be unstable in political and economical situations. From a viewpoint of economic security, they have various strategies for ensuring a stable supply of mineral resources, e.g. promotion of mineral resources exploration both within and outside the country, furnishing financial and technical aids to the mineral resources-rich countries, storage of strategic materials, etc.
    The deep sea mining is considered to be one of the strategies, although the deep sea-bed and its resources are declared to be the common heritage of mankind and are supervised by the International Sea-Bed Authority established under the United Nations Convention on the Law of the Sea. Japan acquired the own mining claim in the high seas of the Pacific Ocean (southeast of Hawaii) in December 1987 and has conducted exploration and other activities in the area with the aim of com-mercial mining.
    The most serious problems in the world in the 60's to 70's, when the deep sea problem were dealt in the UN General Assembly and the third UN Conference on the Law of the Sea, were the North-South and West-East antagonisms. These antagonisms, which were barriers to the world trade of mineral resources, caused the above policy including deep sea development to the advanced countries. But the recent improvement in the North-South and West-East relationships from antagonism to interdependence promotes a smooth trade of mineral resources in the world. As a consequence of that, deep sea mining for ensuring a stable supply is toned down in its significance. It is expected that Japan, as an oceanic nation, continues deep sea activities long but on a limited scale.
  • 正路 徹也
    2001 年 51 巻 1 号 p. 55-68
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
  • 蓬田 清
    2001 年 51 巻 1 号 p. 69
    発行日: 2001/05/25
    公開日: 2009/06/12
    ジャーナル フリー
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