著者

李 讃熙 朴 喜寅

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.45, no.253, pp.323-329, 1995

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韓国,太白山鉱化帯北部に位置する屯田金鉱山には数種類のPb-Bi-Sb-S系鉱物(Sbコサライト,Sbヘイロフスキーアイト,Sbリリアナイト,Bi車骨鉱,(未詳Pb-Bi-Sb-S鉱物)が産出する.これらPb-Bi-Sb-S系鉱物は方鉛鉱,車骨鉱,四面銅鉱,黄鉄鉱,黄銅鉱,閃亜鉛鉱,エレクトラムなどからなる方鉛鉱に富む鉱石に比較的多量に産出する傾向がある.Sbコサライトの平均元素組成はPb;44.1,Bi;30.7,Sb;5.7,Ag;1.6,Cu;0.6,S;16.7重量%で,硫黄原子数5とした時の化学式はPb<SUB>2.08</SUB>(Bi<SUB>1.41</SUB>Sb<SUB>0.47</SUB>)<SUB>1.88</SUB>(Ag<SUB>0.15</SUB>Cu<SUB>0.15</SUB>)<SUB>0.27</SUB>S<SUB>5</SUB>で与えられる.Biブーランジェライトの平均元素組成はPb;55.5,Bi;6.5,Sb:19.3とS;18.2重量%で硫黄原子数11とした時の化学式はPb<SUB>5.18</SUB>(Bi<SUB>0.60</SUB>Sb<SUB>3.10</SUB>)<SUB>3.7</SUB>S<SUB>11</SUB>で与えられる.Sbリリアナイト,Sbヘイロフスキーアイト,未詳Pb-Bi-Sb-S鉱物の化学組成は,硫黄原子数を6,9,5とした場合,それぞれPb2.94(Ag<SUB>0.14</SUB>Cu<SUB>0.15</SUB>)<SUB>0.3</SUB>(Bi<SUB>1.54</SUB>Sb<SUB>0.40</SUB>)<SUB>1.94</SUB>S<SUB>6</SUB>, Pb<SUB>5.84</SUB>(Ag<SUB>0.15</SUB>Cu<SUB>0.15</SUB>)<SUB>0.3</SUB>(Bi<SUB>1.52</SUB>Sb<SUB>0.38</SUB>)<SUB>1.9</SUB>S<SUB>9</SUB> and Pb<SUB>2.12</SUB>(Ag<SUB>0.08</SUB>Cu<SUB>0.25</SUB>)<SUB>0.34</SUB>(Bi<SUB>0.76</SUB>Sb<SUB>0.93</SUB>)<SUB>1.69</SUB>Fe<SUB>0.23</SUB>S<SUB>5</SUB>である.Sbコサライト,未詳Pb-Bi-Sb-S鉱物およびBiブーランジェライトの化学組成はChang et al.(1980)によって合成されたSbコサライト(C相),Y<SUB>1</SUB>-Y<SUB>2</SUB>相,W相にそれぞれ相当する.アンテモンとビスマスは互いに相関することから,両元素は2PbS-Bi<SUB>2</SUB>S<SUB>3</SUB>-Sb<SUB>2</SUB>S<SUB>3</SUB>系において互いに置換しあっていることが明らかになった.最大Bi/(Bi+Sb)比はSbコサライトでは0.75,未詳Pb-Bi-Sb-S鉱物では0.45,Biブーランジェライトでは0.16であった.

著者

村上 浩康 佐藤 比奈子 石山 大三 石原 舜三

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.61, no.2, pp.129-137, 2011-05-25

参考文献数

23

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High-grade REE ores containing acid-resistant minerals, which are common in the Nolans Bore REE-P-U deposit, Northern Territory, Australia, were analyzed by ICP-MS after decomposition of two different preparation methods before the analyses; Li-borate-fusion in a commercial laboratory and multi-acid digestion in our organization. The result derived from multi-acid digestion method shows higher values on LREE relative to the other fusion method, yet Y and Zr showed us higher values on the fusion method. The high-grade REE ores are enriched in light-REE, especially Ce, La and Nd, with a maximum total REE value around 7 wt %. The quantitative analysis by multi-acid digestion seems highly reliable for a wide range of REE concentration when using suitable dilution ratio and digestion sequence with several types of acids which could totally dissolve acid-resistant minerals such as monazite. On the other hand, analysis by Li-borate-fusion at a commercial laboratory potentially gives lower values than that of multi-acid digestion; a given sample is extremely concentrated in light REE. It is necessary to examine the upper as well as the lower detection limits by a conventional analytical method in a commercial laboratory.

著者

アルファロ フルートス

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.38, no.207, pp.15-25, 1988

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チリ南部の太平洋沿岸域(Coast Range)南部(南緯39°~42°)の古生層中に,ソレアイト玄武岩熔岩,チャート,堆積岩に伴って銅・亜鉛を主成分とする塊状硫化物鉱床が胚胎している.黄鉄鉱,磁硫鉄鉱と共生する閃亜鉛鉱中のFeS含有量は17.0~18.2mol%であり,変成作用の圧力は約2.5kbと推定される.黄鉄鉱のイオウ同位体比は+2.5%(+0.3~+5.4%)で,日本の別子型鉱床のそれ(+2.7‰)に近い,硫化鉱中のコバルトおよび金の含有量はそれぞれ0.1~0.6%,20~700ppbであった.<BR>微量元素およびREEの分析結果より母岩はoceanicbasaltであることが判るので,この塊状硫化物鉱床は日本の別子型鉱床ないしノルウェーのカレドニアのレッケン鉱床に似ていると結論される.

著者

中野 啓二 佐藤 憲隆 山田 亨

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.31, no.166, pp.81-97, 1981-06-05 (Released:2009-06-12)

参考文献数

7

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The Nebazawa deposits are epithermal, gold and silver-bearing quartz vein type deposits. They occur in E-W trending southward dipping steep fractures in the welded tuff member called Katashinagawa rhyoritic rocks of Paleogene age.The study of the geology and ore deposits of the mine has disclosed following facts and suggestions which could be useful guides for current and future exploration of the mine.1) Three stages of mineralization were identified, they are, from older to younger, base metalliferous mineralization (Stage I), auriferous mineralization (Stage II, Ag/Au≥10) and argentiferous mineralization (Stage III, Ag/Au≥100). The latter two mineralizations are important in economic sense.2) The assay contour is fully affected by low angle east dipping faults called No. 1, No. 2 and No. 3 fault which intersect the veins diagonally. High grade part of the vein is along the hangingwall side of the fault and barren part along the footwall side. This suggests possible important role of these faults as controlling factor of convection system of ground water at the time of ore deposition.3) Vein fractures are interpreted as high angle reverse type faults initiated by the differential block movement between relatively subsided northern block and southern relatively upheaved block. This block movement seems to be triggered by or related to the formation of N-S trending cauldron subsidence of Miocenc Kinugawa rhyolitic rocks to the east.

著者

草薙 忠明

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.5, no.16, pp.77-88, 1955-07-05 (Released:2009-06-12)

参考文献数

14

被引用文献数

1

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The funnel or basin shaped rhyolitic complex occupies almost the whole area of the Ashio mining district, and its surface distribution makes an imperfect ellipse-like outline, reaching about 3.3km in its minor axis and about 4.4 km in major axis, and the volcanic activities of these volcanic complex are supposed to have taken place in the late Tertiary period.The rhyolitic complex is composed of rhyolite massive flow and rhyolitic pyroclastics, such as volcanic breccia, tuff, tuff breccia, lapilli tuff and also welded tuff. They are accumulated alternately, forming nearly horizontal beds. The lower part of the complex consists mainly of rhyolitic lava, intercalating some rhyolitic volcanic breccia and tuff. In the upeer parts are found alternations of tuff breccia, lappili tuff and welded tuff, the last one being most conspicuous. Thus, the volcanic complex of the Ashio mining district seems to form a stratovolcano.The basal breccia, named by the writer, occurs along the contact surface between the rhyolitic complex and the Palaeozoic sediments or sometimes the late-Mesozoic granodiorite of basement complex, and is composed mainly of angular or subangular fragments of basal rocks, such as chert, clay slate, sandstone, siliceous slate, schalstein and granodiorite. Judging from the mode of occurence, it may be concluded that the basal breccia is not of explosion, but of talus origin, formed on the steep slope of the wall of the basin.The funnel or basin shaped hollow, filled up with rhyolitic rocks, may represent a caldera, formed by the depression preceding the volcanic explosion. The central vents of this rhyolitic volcano are supposed to be situated near the pyrophyllitized and brecciated zone of Tenguzawa, and the original crater, now indistinct by erosion, might be located also at the same place.Fissure veins are formed abundantly in rhyolite flow and welded tuff, but scantly in tuff and tuff breccia. Ore shoots of veins are mostly localized in favorable beds such as rhyolite or rhyolitic welded tuff, which lies nearly horizontally, and then the shoots may have a flat elongation. The localization of ore shoots may be attributed mainly to the deflection of each vein according to the different physical characters of each bed. Bonanzas of so-called "Kajika type" are formed sometimes in tuff and tuff breccia, only when the fissure veins swarm closely, though it is not the case where an isolated vein is present.

著者

草薙 忠明

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.13, no.58-59, pp.95-100, 1963-04-30 (Released:2009-06-12)

参考文献数

9

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The Ashio Mine is composed mainly of the rhyolitic comlex and the Palaeozoic formation. The ore deposits occur both in them as vein and "Kajika" deposits.Four hypogene mineral zones, a central Sn-W-Bi-Cu zone, an intermediate Cu-As-Zn zone, a marginal Zn-Pb-Cu-As zone and a barren zone are quite distinguished in the rhyolitic complex as Takeshi NAKAMURA (1961) clarified them.Hypogene mineralization in the Palaeozoic formation and in the southern part of the rhyolitic complex adjacent to the Palaeozoic formation is very similar to that in the rhyolitic complex, but large amounts of ealier pyrrhotite and marmatite occur in the Palaeozoic formation. In general, three mineral zones, a Fe-Zn-As zone, a Cu zone and a silicified and barren zone are distinguished remarkably from the foot-wall side to the hanging-wall side of the "Kajika" deposits in the Palaeozoics.The mineralizations both in the rhyolitic complex and the Palaeozoics are considered to be taken place at the same time after the rhyolitic complex extruded.The features of the high-temperature tin and tungsten minerals are associated with the low-temperature copper, lead, zinc and other minerals show the telescoped character of the Ashio deposits. The ore deposits at the Ashio Mine classified as the epithermal deposit are considered to be formed under the subvolcanic environment caused by the vocanism of the Ashio rhyolitic complex.

著者

田口 幸洋 広渡 文利 吉川 謙造

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.26, no.138, pp.263-271, 1976-10-30 (Released:2009-12-14)

参考文献数

15

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The Fuke mine, situated at about 10 km north of Okuchi city in Kagoshima Prefecture, is one of the gold-silver ore deposits of the epithermal vein type in the Green-tuff region. The ore deposit is considered to be an intermediate type between the gold-silver vein and the base metal vein.The high grade ore in the mine is named "Tozi-kin" in which can be visually recognized the part where fine-grained golds are concentrated. As for the electrum in this ore, mode of occurrence and chemical composition have been investigated by a microscope and EPMA. The results are as follows : 1. The Tozi-kin ore often shows a characteristic banded arrangement from the wall rock to the inner of the ore; Fe-Mg chlorite, drusy quartz with pyrite and hematite, fine-grained quartz with banded sulfides and electrum, and green clay mainly composed of chlorite-saponite mixed-layer.2. Paragenetic sequence of vein minerals may be divided into four stages; First stage: Drusy quartz accompanied by pyrite and hematite. Second stage: Fine-grained quartz characterized by sulfides and electrum. Third stage: Altered minerals. Fourth stage: Barren quartz associated with calcite. 3. Observed ore minerals are electrum, galena, sphalerite, chalcopyrite, pyrite, hematite, hessite, and an unkown Ag-Au telluride.4. Electrum precipitated after the precipitation of sulfides in the second stage.5. The electrum filling intergranular cavities of quartz is irregular and angular in shape, whereas that in sulfides varies from granular to cylindrical, and often amoebic.6. The grain size of electrum is generally less than 50 microns in diameter, but it attains 200 microns in some cases.7. The chemical composition of electrum from the Fuke-honpi vein shows a very little fluctuation among grains as well as in a grain, with an average chemical composition Ag 19.1 wt.%, Au 80.6 wt.%.Some of these properties of electrum such as the homogenity of composition and the relatively coarse grains, are considerably different from those of electrum in the Kuroko ore.

著者

石原 舜三 木村 幹 大田 浩二 佐藤 壮郎

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.35, no.192, pp.295-298, 1985-08-30 (Released:2009-12-14)

参考文献数

14

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Twenty-four granitoids from three magnetite-series granitic terranes and three ilmenite-series granitic terranes were analyzed for gold by the neutron activation method. The gold values of the magnetite-series granitoids range from 0.4 to 7.1 ppb and the average is 4.3 ppb, while those of the ilmenite-series granitoids vary from 0.4 to 4.8 ppb and the average is 2.5 ppb. The higher values of the magnetite-series granitoids than the ilmenite-series ones may be attributed to the presence of rock-forming magnetite in the former series. The gold values appear to increase with the in-creasing of silica contents within the range of 61-76%. Magnetite-series granitic terranes are considered to be more favarable basement than ilmenite-series ones for Neogene gold mineralization of the Green Tuff region.

著者

佐々木 昭 佐藤 和郎 George L. Cumming

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.32, no.176, pp.457-474, 1982-12-15 (Released:2009-06-12)

参考文献数

48

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The metallic mineralization in the Japanese islands can be divided into three groups in view of the ore lead isotope systematics.(1) The Paleozoic to Mesozoic stratiform (Besshi-type) mineralization is composed of cupriferous iron sulfide ores in which lead is usually a minor constituent (to the level of 10 1-10 2 ppm). The leads are isotopically variable, being consistently low in both 207Pb/ 204Pb and 208Pb/ 208Pb ratios as compared to the lead in the "major (conformable) lead orebodies" of similar ages.(2) The pre-Neogene mineralization excluding the Besshi-type deposits is mostly related to Cretaceous to Paleogene granitoids. Galena is fairly common and forms sizable orebodies in a few skarn-type deposits. Lead isotopic composition is more or less variable regionally, and even locally in some cases, all being, however, low in 206Pb/ 204Pb and high in 208Pb/ 204Pb ratio in comparison with the conformable ore leads.(3) The Neogene mineralization is represented by the kuroko-and related vein-type mineralization of middle Miocene age, carrying abundant lead as one of the major ore metals. The leads are isotopically rather uniform with consistently low 206Pb/ 204Pb and high 208Pb/ 204Pb ratio as compared to the major lead ore system; 43 samples from 30 localities give average 208Pb/ 204Pb 207Pb/ 204Pb and 208Pb/ 204Pb ratios of 18.471±. 108 (2σ), 15.609±.036, and 38.677±.220, respectively. A remarkably consistent isotopic composition close to this average is observed in the kuroko ores from an extensive area of northeast Japan.The Besshi-type ore leads except for those of the Mesozoic Taro deposit show an isotopic pattern similar to that of the ocean volcanic leads, strongly suggesting that the major evolutionary environment of these leads has been in the oceanic mantle. The Taro leads show isotopic features close to the major lead ore system and, in this respect, are unique among Japanese ore leads.The leads of the pre-Neogene and Neogene mineralizations may be identified as crustal lead with respect to their main evolutionary environments. The 207Pb/ 204Pb and 208Pb/ 204Pb ratios of the pre-Neogene leads exhibit a trend in which the relatively high values of these ratios occur in the area where the related granitoids have relatively high initial 87Sr/86Srr ratios; some Neogene leads seem to follow the same trend. The presence of a relatively old and thick continental crust in the source region of these leads can be deduced.The available isotopic data for the oceanic sediment lead occurring closer to the Japanese islands (samples near the Mariana volcanic arc and those from the Ryukyu Trench) apparently deviate from the major spectrum of the Pacific sediments data and plot closer to the data for the Japanese Neogene and pre-Neogene ore leads which may approximate the average of Japanese crustal leads. A relatively 208Pb-impoverished and 208Pb-enriched character indicates that the crustal lead around the Japanese islands has been strongly influenced by the lead evolved in the lower continental crust.

著者

苣木 淺彦 長谷川 修三

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.2, no.6, pp.185-196, 1952-12-25 (Released:2009-06-12)

参考文献数

49

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The Hayama Mine is situated on the Abiikuma Plateau about 15 kilometers to the southeast of Fukushima City. The district is composed mostly of hornblende biotite granodiorite. However, some hornfels and ultra-basic rocks, such as dunite and diallagite, are present in the form of a roof-pendant. The nickel-bearing minerals, such as niccolite, gersdorffite, pentlandite and nickeliferous pyrrhotite etc., occur as fine grains in the forsterite aggregates, which form a vein-like body in dunite. The forsterite rock is also cut by remarkable black veinlets, composed of the acicular or fibrous crystals of ludwigite. Ludwigite is known to be produced by the chemical reaction of boron- and iron-bearing emanations from granitic magma on some magnesium-bearing rocks such as dolomite and magnesite. Under the microscope, the nickel minerals generally appear in pure crystals, filling up the interstices between the forsterite grains. The niccolite, is rarely rimmed with gersdorffite. Ludwigite is always accompanied by magnetite and chromite which are thought to have been derived from the ultra-basic rock.The paragenesis of nickel minerals-forsterite-ludwigite-chromite is very critical in the interpretation of the ore genesis. This deposit must be studied from two viewpoints, one from magmatic differentation and the other from contact metasomatism.

著者

丸茂 克美 江橋 俊臣 氏家 亨

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.53, no.2, pp.125-146, 2003-12-04 (Released:2009-06-12)

参考文献数

20

被引用文献数

8

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Soil Contamination Countermeasures Law (referred to hereafter as the Law) was made on 29 May 2002, for preventing health damage which toxic substances as Pb, As, Cr(VI) and Cd in soils could cause by oral ingestion.In order to carry out the Law, we must judge whether soils have high toxic metal concentrations or high leachabilities caused by anthropogenic or natural processes. If high toxic metal concentrations or high leachabilities are caused by natural processes, the administration of the Law should not oblige landowners, managers and occupiers of contaminated sites to remedy them.Therefore, it is essential to determine natural levels of Pb, As, Cr(VI) and Cd concentrations and their leachabilities of Japanese soils which have a wide range of chemical and mineralogical composiotion. It is also very important to develop chemical and mineralogical analytical methods to judge whether soils have high toxic metal concentrations or high leachabilities caused by anthropogenic or natural processes.We obtained Pb, As, Cr(VI) and Cd concentrations and leachabilities of stream and marine sediments, as well as soils formed by weathering of volcanic ashes and granite and granitoid, using XRF and conventional wet chemical analytical methods. We also obtained mineralogical data of these sediments and soils, using XRD, TG-DTA and analytical TEM. Furthermore, we obtained lead isotope ratios of these sediments and soils, using ICP-Mass.

著者

麻木 孝郎 末岡 慎也 深澤 秀明 伊東 靖彦 古野 正憲 長 久

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.54, no.1, pp.27-36, 2004-05-20 (Released:2009-06-12)

参考文献数

5

被引用文献数

1

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Since 2001, Nittetsu Mining has been carrying out copper exploration activities in twenty-two promising areas in Northern Chile, which were extracted using ASTER image analysis. In these areas, Furano area in Region I has been selected as the most important target considering its high mineral potential inferred from the ASTER image analysis and its easy access.Furano area, covering 282km2, locates some 15km northwest of Cerro Colorado copper mine. Geology of the basement rocks mainly consists of lower Cretaceous andesite and Paleogene intrusive rocks. They are widely covered by ignimbrite and alluvium sediment of Tertiary to Quaternary age. The RC drilling program of 13 holes, totaling 3, 704m, was carried out on the prospective locations in the western part of the project area, which were selected by geological and geochemical surveys. Dominant copper and gold mineralizations were observed in some holes. Above all, a tourmaline breccia zone in silicified andesite showed average copper grade of 0.9% over the depth from 110m to 190m in one hole. The ore body shows 40m in width, dipping 55 degrees towards north, and is expected to be 400m continuation from the distribution of surface mineral occurrences. About 20 million tons of ore reserve was estimated above the depth of 300m. In another hole, drilled in ignimbrite-covered area, oxidized and corroded tourmaline breccia and underlying chalcopyrite-disseminated granite porphyry were observed. A secondary precipitation of chalcocite was also recognized in the lower part of the tourmaline breccia. These evidences suggest that the adjoining area covered by ignimbrite still has high potential for porphyry copper deposition. Additional drilling exploration is required around those holes.

著者

宮下 敦

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.45, no.253, pp.313-321, 1995-10-31 (Released:2009-06-12)

参考文献数

36

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Based on a compilation of geological and geophysical data, a new hypothesis is proposed for the formation of epithermal Au-Ag deposits in the Hokusatsu region, Kyushu, Japan. Several Plio-Pleistocene stratovolcanos in a graben with anortheasterly trend would have the following feature of gravity data:a regional low anomaly (-10mgal) corresponds to the graben being filled with low density sediments, and areal high anomalies (+30mgal) in the reagional low gravity correspond to the center of andesitic stratovolcanoes.In the Hokusatsu region, all stratovolcanic bodies are accompanied with one or more epithermal Au-Ag ore deposits. Veins of these deposits have a northeast orientation approximately perpendicular to the regional tensional stress orientation related to the opening of the Okinawa Trough.

著者

宮沢 俊彌

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.4, no.13, pp.139-146, 1954-10-10 (Released:2009-06-12)

参考文献数

16

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There are two known modes of occurrence of hematite and magnetite at the Chichibu Mine, Saitama Prefecture.One type of hematite occurs as the earliest ore mineral. This type of hematite has been largely transformed into magnetite, especially at the time of formation of earlier pyrite. The other type of hematite is only found within the zone of oxidation product of granular magnetite.As for magnetite, one type occurs as granular aggregates or well-shaped crystals. Most of them may be of primary origin and may have crystallized out as magnetite during the earliest stage of metallization, but some of them are closely related with the formation of platy magnetite. The other type shows a platy form and may largely be the reduction (hypogene secondary) product of primary hematite.

著者

荻原 成騎

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.42, no.234, pp.249-257, 1992-08-30 (Released:2009-06-12)

参考文献数

23

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Phosphorite nodules were newly found in laminated lacustrine diatomaceous sediments of the Middle Pleistocene Nogami Member in Kusu Formation northern Kyusyu (Japan) which deposited in palaeo-Kusu lake. The phosphorous content of these nodules is about 25% in P2O5. These nodules resemble marine phosphorite nodules in composition, consisting primarily of carbonate-fluorapatite.Phosphorite nodules were formed from phosphate originally contained in diatom during early diagenesis. These nodules show compositional zoning and color banding due to dissolution by meteoric or hydrothermal water. The fixation of phosphorous is likely to have been controlled by concentration of Ca.

著者

沢井 長雄 景山 宗一郎 岡田 利典 板谷 徹丸

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.51, no.1, pp.19-27, 2001-05-25 (Released:2009-06-12)

参考文献数

27

被引用文献数

1

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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.

著者

バクヒット F.S.

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.37, no.201, pp.29-43, 1987-03-31 (Released:2009-06-12)

参考文献数

33

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鉱脈型あるいは割目充填型ウラン鉱化作用の母岩として最も適している花崗岩の決定法を調べた.対象としたのは,エジプトの東砂漠に分布する赤色花崗岩である.ウラン鉱化作用に最も適した赤色花崗岩は,珪酸分が高く,ナトリウムとカリウムに富んでおり,鉄,マグネシウム,カルシウムが少いことが明らかとなった.また,ウラン鉱化作用に適した地質構造は,主要断層に平行な,あるいは隆起帯の下盤に沿う副次的な断層ないし割目である.花崗岩体の縁からはるかに離れたところには,ウラン鉱床は存在しない.

著者

石原 舜三

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.27, no.145, pp.293-305, 1977-10-30 (Released:2010-03-04)

参考文献数

47

被引用文献数

30

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表題の2組の花崗岩類について,主として鏡下観察結果から構成鉱物の特徴が記載され,分類の基準・両者の分布・成因・鉱化作用との関連性などがのべられた.2組の花崗岩類は一般の鏡下観察(100×)で磁鉄鉱が認められるか否かの点で分類され,磁鉄鉱系花崗岩類は0.1―2容量%の磁鉄鉱とごく少量のチタン鉄鉱を有し,チタン鉄鉱系花崗岩類は0.1容量%以下のチタン鉄鉱を伴うにすぎない.すなわち,両者は苦鉄質珪酸塩鉱物とFe-Ti酸化鉱物の量比において著しく異なり,チタン鉄鉱系花崗岩類はFe-Ti酸化鉱物に欠ける系列とみなしてよい.このFe-Ti酸化鉱物に欠ける事実から,チタン鉄鉱系花崗岩類が磁鉄鉱系花崗岩類より低い酸素フュガシテイの条件下で生成されたものと推論された.このように考えると,2組の花崗岩類にそれぞれ特徴的に認められる他の苦鉄鉱物や硫化鉱物の組合せが説明し易い.両者の酸素フュガシティを定量的に推定する共通の鉱物組合せは得られていないが,黒雲母のFe+3/Fe+3+Fe+2比から両者の境界はほぼNi-NiOバッファー付近と考えられた.花崗岩類の生成時の酸素フュガシティを規制する要因としては花崗岩質マグマの発生から固結に至る過程における炭質物によるバッファーが重視され,H2Oの解離とH2の逸散は磁鉄鉱系花崗岩類の一部について考慮された.磁鉄鉱系花崗岩類は炭質物が存在しない深所起源であり,チタン鉄鉱系花崗岩類は炭質物を伴う大陸地殻起源であろうと考えられた.花崗岩類中かその近傍に産出する鉱床においては花崗岩類にみられる性質が継続して認められ,たとえばポーフィリーカッパー鉱床では磁鉄鉱系花崗岩類と共通の鉱物組合せが産出する.2組の花崗岩類の性質はマグマ期末期から後マグマ期の一部に及んでおり,花崗岩類に密接な鉱床探査では両者を識別することが重要である.スズ-鉄マンガン重石鉱床がチタン鉄鉱系花崗岩類と密接な経験則から,環太平洋地域の西側では磁鉄鉱系花崗岩類に乏しいことが予想され,このことが沿海州―中国大陸南東部―マレ―半島に至る中生代花崗岩類にポーフィリーカッパー鉱床が発見されない一因と考えられた.

著者

地質調査所 原子燃料公社

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.14, no.63, pp.1-10, 1964-02-29 (Released:2009-06-12)

参考文献数

12

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The prospecting for nuclear raw material resources in our country was undertaken in 1954 by the Geological Survey of Japan. Based upon the geological consideration, the prospecting operations were carried out in the so-called "massif" region consisting mainly of granites. The first discovery of uranium mineralization in sedimentary rocks was made by a car-borne team towards the end of the year at Ningyô-tôgé in the Chugoku massif, Southwest Japan. It was confirmed by the geological research that the uranium minerals occur in conglomerates and sandstones of the Neogene Tertiary unconformably overlying the granites.The task of detailed survey for economic development was handed over to the Atomic Fuel Corporation which was established in 1956. The Corporation proceeded to trenching, geophysical and geochemical prospecting, drilling and tunnelling. As the result of these operations, three million tons of the ore reserves containing two thousands tons of uranium metal have been recognized.The uranium ores of Ningyô-tôgé are soft and porous, and the uranium minerals occurring as finegrained crystals in the matrix are easily soluble in acid. Such characteristice of the ore enable 1) to raise their grade several times as high by washing and screening, 2) to exploit by the hydraulic method and 3) to extract the uranium under the mild condition. Furthermore, it must be noted that there are almost no minerals containing elements which interfere with the refining process or possess high cross-section for neutron absorption.

著者

一国 雅巳

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.16, no.75, pp.12-15, 1966-02-28 (Released:2010-03-04)

参考文献数

22

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There are many field evidences suggesting that the limonite deposits of the Akita iron mine were formed by sedimentation of hydrous ferric oxides separated from iron-containing spring waters. The ferruginous precipitates adsorbed various substances from the spring waters, being amorphous when formed. We have, however, no information on the environmental conditions of the precipitation and the mode of crystallization of the precipitates. It is of particular importance from a geochemical point of view to define the temperature and the pH of the solution from which the precipitates formed, and to elucidate the processes of crystallization after the sedimentation of the precipitates.The mineralogical and chemical features of the limonite ores are much suggestive of the genesis of the deposits. The ores, composed mainly of goethite and jarosite, have low crystallinity, which may provide an evidence that they were formed at ordinary temperatures. The chemical compositions of the ores are shown in Table 1. Considering the results of investigations on aging of hydrous ferric oxides and on coprecipitation of anions with insoluble hydrous oxides, the present author concludes that the precipitation and crystallization of hydrous ferric oxides took place at ordinary temperatures and at low pH, presumably at pH 2 to 3.In consequence, we may summarize the formation of the limonite deposits as follows : acidic spring waters, containing ferrous iron, phosphates and sulfates, precipitated hydrous ferric oxides during their flow on the ground surface. A certain microbiological process accelerated the oxidation of ferrous iron. The accumulation and the subsequent crystallization of the precipitates containing phosphates and sulfates have formed finally the limonite deposits composed of goethite, jarosite and some iron phosphate minerals.