著者

寺島 進世意 鎌田 治郎 土屋 徹

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.30, no.162, pp.211-227, 1980

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Metal Mining Agency of Japan (MMAJ) had carried out a systematic exploration program for regional mineral resources in the Bantan district, western Japan, using geologic, gravimetric, aeromagnetic and drilling methods, during a period of about seven years from 1971. The district embraces one of the major metallogenic provinces in this country, where famous polymetallic vein deposits of Ikuno and Akenobe are known.<BR>Although there are many exposures of magnetic body and high density body which are expected to cause magnetic and gravimetric anomalies in the district, the solutions derived from the conventional analysis of the data could not disclose the proper geologic boundaries because many anomalies of different wave-length and amplitude interfere each other to form composite anomalies.<BR>The authors reexamined the gravimetric data with the manual bandpass filtering process (TERASHIMA and TsucHIYA, 1976a, b; TERASHIMA and YOSHIZAWA, 1976; TERASHIMA et al., 1979) and clarified the subterranean geologic structure that is quite consistent with the surface geology. A remarkable conclusion of the new analysis is the existence of a relatively shallow, mostly hidden emplacement of granitic batholith in the central district, along the periphery of which major Sn- and W-bearing polymetallic mineralizations such as Akenobe-Ohmidani, Kawakami and Ikuno seem to occur.<BR>The aeromagnetic data were also reexamined with special attention to the distribution pattern of pair (positive and negative) anomalies of the second vertical derivatives and of pair (high and low) anomalies of the total magnetic field. The detailed magnetic structure thus obtained succeeded to delineate the distribution of granodioritic intrusives which have genetic relation to Mo-bearing mineralization in the district.

著者

青木 義和 肥田 昇

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.24, no.125, pp.201-211, 1974-06-30 (Released:2009-06-12)

参考文献数

23

被引用文献数

4

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Mihara mine, Hiroshima Prefecture, had been exploited for dissemination fluorite deposits in skarn and monzonite. Rocks of this area consist of Paleozoic limestone, chert and diabasic rocks intruded by Cretaceous biotite granite. The Paleozoic formation is thermally metamorphosed and metasomatised by the granite which is partly monzonitised. Fluorite ores occur in the monzonite and adjacent skarns.Recently presence of beryllium mineralization in this ore deposit was discovered with a beryllium detector. The mineralization occurs mostly in the monzonite and partly in the scheelite-feldspars-fluorite-iron-rich biotite skarn. The beryllium mineral contained in the skarn is exclusively phenacite which coexists with iron-rich biotite, plagioclase and potassium feldspar, filling the grain boundaries of fluorite crystals. A small amount of scheelite is also found in association with the minerals. On the other hand, danalite is the main beryllium mineral in the monzonite. It occurs as disseminated grains of euhedral or subhedral form, and is associated with violet fluorite and feldspars. Phenacite is also present in a trace amount. It is conspicuous that these phenacites are always corroded along cleavages and cracks, and also surrounded by danalite grains.Volumetric analyses of constituent minerals in thin sections by a point counter reveal that (1) danalite and phenacite are found in specific monzonite which contains fluorite and quartz more than 5.6% and less than 2.3%, respectively; (2) the quantity of modal danalite in such rocks ranges from 2.5% to 3.6%, and that of phenacite is less than 0.4%; and (3) the amount of quartz gradually decreases towards the adjacent skarn body, while total feldspars and fluorite increase in contrast. The degree of Al/Si order-disorder and the Or contents in potassium feldspars in biotite granite and monzonite were determined with powder X-ray diffractometry. Potassium feldspars in biotite granite have a tendency to become ordered and rich in Or component with coming close to monzonite, and the maximum ordering and Or contents are encountered where they coexist with danalite in monzonite. These results are correlative with the modal analysis data.From the results obtained, the genesis of this beryllium ore deposit may be summarized as follows : (1) Paleozoic rocks were partly metasomatised by the intrusion of Cretaceous biotite granite. (2) Migration of silica from the granite to the adjacent skarn body caused relative increases of alkali and alumina contents in peripheries of the granite, converting them to monzonite. (3) Only a small portion of beryllium contained in the granite could have moved to the skarn body to form phenacite at a limited part of the skarn. (4) The main portion of beryllium was precipitated as danalite crystals within the monzonite.

著者

尾関 規

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.11, no.45-46, pp.142-146, 1961-03-25 (Released:2009-06-12)

参考文献数

9

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The Gojo Mine is located southeast of Koya-san. The ore deposits are bedded cupriferous pyritic ones and their host rocks belong to the undifferentiated Mesozoic group which consists of shale, sandstone and green rock.In the vicinity of the mine, black shale is alternated with green rock or chert, forming a complex zone. The distribution of mineralized zone is closely related to the micro-basin structure of the complex zone.

著者

宮久 三千年 原田 進造 石橋 澄 渋谷 五郎 本村 慶信

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.25, no.133, pp.347-357, 1975-10-31 (Released:2009-06-12)

参考文献数

17

被引用文献数

1

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In this paper, the paragenesis of minerals in the Hoei mine is presented with some remarks on the mineralogical properties of kutnahorite.The Ichigo (no.1) ore body of the Hoei mine is a massive deposit of Sn, Zn and iron sulfide formed by replacement of the Silurian limestone bed. From this ore body, there have been found various kinds of ore and gangue minerals such as: garnet, clinopyroxene, axinite, tourmaline, vesuvianite, quartz, pyrrhotite, chalcopyrite, arsenopyrite, pyrite, marcasite, sphalerite, galena, native bismuth, herzenbergite, franckeite, jamesonite, cassiterite, stannite, malayaite, fluorite, sericite and carbonate minerals. The species of carbonate minerals are ferromanganoan dolomite, magnesian kutnahorite, kutnahorite, calcian rhodochrosite, ferroan magnesite and manganoan calcite, and they have been crystallized at the later stage of mineralization in this mine.The kutnahorite in this mine is white, yellow or pinkish in color, and platy or leaf-like in external shape, reaching to 5 cm in maximum length. Its specific gravity ranges from 2.98 to 3.18 by picnometer method. Optically negative, and some examples of refractive indices are ω=1.717-1.731, ε=1.524-1.529. Unit cell constants, a0 = 4.861-4.869 Å, c0=16.24-16.37 Å. The range of chemical composition of kutnahorite is fairly wide, as shown in Table 4 and 5.Judging from the mode of occurence, microscopic observations and the compositional changes detected by EPMA, the crystallization sequence of the carbonate minerals is suggested as follows : dolomite-ferromanganoan dolomite-magnesian kutnahorite-kutnahorite-calcian rhodochrosite-manganoan calcite.

著者

太田垣 亨

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.20, no.101, pp.222-236, 1970-07-11 (Released:2009-06-12)

参考文献数

23

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The epithermal ore deposit of Numanoue and Takatama Mine which has been worked mainly for gold and silver is thought to have deposited following continuous igneous activities, while the epithermal ore deposits of Oe and Kinkaseki Mines which have been worked principally for base metals accompanying gold and silver are understood to have deposited after geological structure movements.In this paper, the writer would present a report for these mines in regard to the following:i)The location where mineralization occurred.ii)The relation between first stage mineralization (rock alteration stage) and igneous activities.iii)The sequence of gangue and ore minerals.iv)The correlation among various stages of repeated mineralization.The mineralization appears to have repeated in all of these cases, but judging from the sequence of gangue minerals, ore minerals and minor elements, the mineralization in the cases of Takatamaa and Oe Mines is thought to have repeated from the identical ore magma while in the cases of Numanoue and Kinkaseki it is thought to have repeated from the different one.In all of these ore deposits, gangue and ore minerals of low, middle and high temperatures occur in paragenetic form showing a xenothermal tendency which is also true in the case of minor elements.In conducting a more detailed study on the sequence of gangue minerals, ore minerals and minor elements of these ore deposits hereafter, a consideration necessary should be on their geochemical and geophysical conditions.

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.36, no.195, pp.66-67, 1986-02-28 (Released:2009-06-12)

著者

柳生 六郎

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.1, no.1, pp.26-26, 1951-12-20 (Released:2009-06-12)

著者

津末 昭生 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.24, no.123, pp.13-30, 1974-03-04 (Released:2009-12-14)

参考文献数

42

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The iron-titanium oxides in the granitic rocks of Southwest Japan have been examined under the microscope and analyzed with the electron probe micro-analyzer. Ilmenite containing up to 4 mole percent hematite molecule is almost sole iron-titanium oxide present as an early accessory constituent of the granitic rocks in the Outer zone, Ryoke zone, and Sanyo. Naegi zone of Southwest Japan. While, magnetite, magnetite intergrown with ilmenite, and hemo-ilmenite containing up to 20 mole percent hematite molecule are present as early accessory constituents in the Sanin-Shirakawa zone.From the chemical composition of the granitic rocks of Southwest Japan, it is suggested that the granitic magmas in the Sanin-Shirakawa zone were more oxidized than those in other three zones.Residual ilmenite sand deposits derived from gabbroic rocks are found only in the Ryoke zone, while residual magnetite sand deposits originated in granitic rocks are found only in the Sanin-Shirakawa zone. Thus, the distribution of residual iron sand deposits well corresponds to the generalization stated above.

著者

津木 昭生

出版者

日本鉱山地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.24, no.1, pp.13-30, 1974-03