bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incipient Stage of Ore Formation Process of the Kamioka Zn‐Pb Ore Deposit in the Hida Metamorphic Belt, Central Japan: Leaching and Precipitation of Clinopyroxene
Authors: KUNUGIZA Keitaro 
Published: November 2008

Abstract: Boundaries between the cpx Zn‐Pb ores of the Kamioka ore deposit and host clinopyroxene granitoid in the Hida metamorphic belt were examined to decipher the incipient stage of ore formation process. The boundaries are characterized by the compositional zoning of relic clinopyroxene with outward increase of XMg from 0. 5 to 0. 75 in the host rocks, and by the incline of XMg towards the ores, passing through the boundaries, reaching up to 0. 95. In the ores, relic clinopyroxene is rimmed by hedenbergite. Both clinopyroxenes show compositional zoning with outward decrease and increase of XMg and MnO, down to 0. 02 and to 3. 2 wt%, respectively. The presence of high magnesian clinopyroxene can be explained if hydrothermal fluid flow had leached hedenbergite component of relic clinopyroxene. The incline of XMg of clinopyroxene toward the ores was attributed to the degree of dissolution of clinopyroxene, and thus the total amounts of fluid to have passed. The outward decrease of XMg of clinopyroxenes in the ores was due to crystal‐fluid fractionation during precipitation.These mineralogical changes at the boundaries indicate the time‐integrated phenomena of hydrothermal ore forming process. Firstly, leaching of ore components by infiltrating fluid proceeded in host rocks, and enhanced the formation of a fluid channel. The condition of fluid changes through the fluid channel in P‐T space, and hence ore forming minerals precipitate at a remote place from the leaching one. This in turn caused the physicochemical change of fluid condition anyhow, and accelerated the precipitation of the minerals. This leaching‐precipitation sequence appears a basic process of hydrothermal ore‐forming system, and characterizes the incipient stage of ore formation process of the Kamioka Zn‐Pb ore deposit. Compositional zoning of clinopyroxenes defines Z‐shaped compositional trend in the Di–Hd–Jo diagram, each arm of which corresponds to the leaching and the precipitation stages, and the secondary dissolution of precipitated clinopyroxene.
Genesis of the Kamioka Skarn Deposits: An Important Role of Clinopyroxene Skarn and Graphite‐bearing Limestone in Precipitating Sulfide Ore
Authors: KATO Yasuhiro 
Published: November 2008

Abstract: A genetical relationship between skarn formation and mineralization is investigated for the Kamioka skarn deposits which are the largest Zn‐Pb producer in Japan. In the Mozumi deposit, one of main deposits in the Kamioka mining area as well as Tochibora and Maruyama, clinopyroxene skarn was generally subjected to later replacement by garnet or magnetite–calcite–quartz during the Zn‐Pb mineralization. The replacement of hedenbergitic clinopyroxene by andraditic garnet resulted in the formation of diopsidic clinopyroxene relicts. With the progress of replacement, the S/So value (So: an estimated area occupied by an original clinopyroxene grain in a thin section, S: a total area of relict clinopyroxene fragments) which is an index of the degree of replacement decreases from 0. 7 to 0. 1, and the hedenbergite mole percent of relict clinopyroxene decreases drastically from about 65 to less than 40. A close association of andraditic garnet and sphalerite suggests that heden‐bergitic clinopyroxene skarn played an important role to reduce the relatively oxic ore‐forming fluid enriched in Zn2+ and SO42– and to precipitate sphalerite from the fluid. Ferrous iron in the hedenbergitic clinopyroxene skarn was oxidized to form andraditic garnet. Besides this garnet formation, the mineral assemblage of magnetite–calcite–quartz replaced the clinopyroxene skarn at the time of mineralization. In both cases, the reduction of relatively oxic ore‐forming fluid by hedenbergitic clinopy‐roxene skarn at the later stage brought about the precipitation of sulfide minerals.In contrast, these types of later replacement are not found in the Tochibora deposit. Instead, graphite‐bearing crystalline limestone and relatively fresh clinopyroxene skarn are common. Mineralized clinopyroxene skarn has high graphite carbon contents relative to barren one, suggesting that the amount of graphite in the skarn was an important controlling factor for mineralization. It is very likely that the graphite played a role of reducing agent during the mineralization in the Tochibora deposit.
Characterization of Magnetically Zoned Pluton, Tsushima, Japan
Authors: SHIMADA Nobutaka , OHYAMA Youichi , IKEMI Hiroaki 
Published: November 2008

Abstract: Systematic measurements of magnetic susceptibility were carried out at the outcrops of the Uchiyama granitic pluton, Tsushima Islands. The pluton consists of hornblende‐biotite granodiorite and biotite granite. It intrudes concordantly along an anticline axis of the Taishu Group in middle Miocene (16. 10. 5 Ma), and crops out in five areas. The results show that the low magnetic susceptibility facies (LM–facies, <100A‐10‐6 emu/g) always occurs in the peripheral part of the pluton, while the high magnetic susceptibility facies (HM–facies, > 250 A 10‐6 emu/g) occupies the core through the medium magnetic susceptibility zone (MM–facies). It is pointed out that the pluton forms a magnetic zoning within a single plutonic body.Chemical compositions of the granitoids show no conspicuous differences in major elements among the LM–, MM–, and HM–facies. Biotites from the LM–, MM–, and HM‐facies also indicate uniform compositions with Fe/(Fe+Mg)=0. 6.The pluton is principally surrounded by black mudstones of the Lower Formation of the Taishu Group, which is deltaic to shallow sea sediments of the Eocene to early Miocene age, and the carbon contents in them were analyzed. The analyses show that carbon was mostly decomposed and lost in the hornfels zone, while mudstones in the non‐hornfels zone usually contain 0. 5 to 0. 7 % C.From these facts, it is concluded that the magnetically zoned pluton at Tsushima was formed by an external volatile buffer system such as CH4–CO2 during the solidifying magma process.
Sulfur Isotopic Study of the Toyoha Deposit, Hokkaido, Japan Comparison between the Earlier‐Stage and the Later‐Stage Veins
Authors: HAMADA Morihisa , IMAI Akira 
Published: November 2008

Abstract: The sulfur isotopic ratios (δ34S) of ore minerals from the Toyoha deposit, Hokkaido, one of the largest Pb–Zn–Ag polymetallic vein‐type deposits in Japan, were studied. More than 90% of the δ34S values of the studied sulfide minerals collected from the Toyoha deposit range from +5 to +9%, with an average of approximately +7% irrespective of the mineral species, veins, elevations, depth, mineralization stages and mineral assemblages. Relatively uniform δ34S values obtained in this study suggest that the reduced aqueous sulfur species predominated over the oxidized sulfur in the ore solution throughout the mineralization stages. Thus, the source of sulfur for the ore sulfides is postulated to be magmatic.The temperature obtained from the fluid inclusion study and the temperature of the sulfur isotopic geothermometer are not consistent. This suggests that each mineral precipitated under disequilibrated conditions with respect to the sulfur isotope.The change in redox conditions presumably encountered between the mineralization stages did not account for the isotopic fluctuations since the isotopic exchanges between the oxidized and reduced aqueous sulfurs are much slower than the rate of oxidation of the ore solution.
Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic‐Cenozoic Batholiths in Peru
Authors: ISHIHARA Shunso , HASHIMOTO Morio , MACHIDA Minoru 
Published: November 2008

Abstract: Plutonic rocks of the Coastal Batholith of Peru were evaluated in terms of the granitoid‐series classification using the bulk ferric/ferrous ratio from the literature and new measurements of magnetic susceptibility. The batholith is largely composed of magnetite‐series plutonic rocks; the magnetite series make up 85% by number of chemical analyses (n=130) and 80% by measurement of magnetic susceptibility (n=210). The ilmenite‐series rocks are mostly found in the felsic facies of the batholith. Asymmetrical distribution of magnetic susceptibility is not clear as in the Japanese Islands and Peninsular Range Batholith, but the magnetic susceptibility may decreases continentward (i. e., Peninsular Range type).The Cordillera Blanca Batholith and stocks are also composed of mainly magnetite series plutonic rocks, but ilmenite‐series rocks may be more predominant than in the Coastal Batholith, which is also indicated by the presence of Sn and W mineralizations.
Source Diversity of Ore Sulfur from Mesozoic‐Cenozoic Mineral Deposits in the Korean Peninsula Region
Authors: ISHIHARA Shunso , JIN Myung–Shik , SASAKI Akira 
Published: November 2008

Abstract: Sulfides from the Daebo Jurassic granitoids and some ore deposits from Korean Peninsula and Sikhote Alin occurring in different basement settings were analyzed for δ34S values. Highly positive values were obtained from Jurassic Mo skarn deposit at Geumseong of the Ogcheon belt (average +13. 0%), Au‐quartz vein deposits at Unsan, North Korea (+6. 7%), and late Paleozoic Sn‐F deposit at Votnesenka (+8. 2%), Khanka massif, Russia. Together with published data of that region, regional variation of δ34S values is shown across Korean Peninsula.Sulfur isotopic data published are compiled on 88 ore deposits, whose mineralization epochs belong to Cretaceous (58 deposits), Jurassic (25 deposits) and Precambrian (4 deposits) in South Korea. Average sulfur isotopic values vary across South Korea as follows: Cretaceous deposits in the Gyeongsang basin, +4. 8% ranging +1.2 ˜ +12.7‰ (n=28); Jurassic and Cretaceous deposits in the Sobaegsan massif, +3. 5% ranging 0.0 ˜ +7.8‰ (n=20); those of the Ogcheon belt, +6. 4% ranging ‐0.5 ˜ +15.4‰(n=19); those of the Gyeonggi massif, +5. 5% ranging +2.1 ˜ +9.0‰(n = 21).The δ34S values of South Korea tend to be concentrated around +5. 5 permil, exhibiting little, if any, a systematic variation across the geotectonic belts. This tendency is seen also in North Korea and Northeast China within the Cino‐Korean Block, and may be called as Cino‐Korean type. Sulfur of this type is derived mostly from the crystalline basement. Khanka massif of Russia seems to have features of the Cino‐Korean type. In contrast, paired positive/negative belts corresponding to magnetite‐series/ilmenite‐series granitic belts are overwhelming in the Japanese Islands, especially in Southwest Japan. The similar trend is also seen in southern Sikhote Alin and northern Okhotsk Rim, which may be called as Japanese type. Source of the sulfur in this type is likely in the subducting oceanic slab for positive value and accreted sedimentary complex for the negative value, respectively.The Daebo granitoids have an average rock δ34S value of +5. 3 permil, which should have reflected that of the source rocks in the continental crust. The ore sulfur heavier than this value may have been originated in other granitoids having even higher δ34S values, or the ore fluids interacted directly with sulfate sulfur of the host evaporites or carbonate rocks. Rock isotopic values of granitoids and basement rocks need to be examined in future from the above point of view in mind.
Sulfur Isotope Study and Re‐examination of Ore Mineral Assemblage of the Hol Kol and the Tul Mi Chung Skarn‐type Copper–Gold Deposits of the Suan Mining District, Korean Peninsula
Authors: Imai Akira , Anan Shinichi 
Published: November 2008

Abstract: Ore specimens collected by the late Professor Takeo Watanabe from the Hol Kol and the Tul Mi Chung deposits, Suan mining district, Korean peninsula, were examined. In addition, measurements of sulfur isotopic ratio of ores and preliminary fluid inclusion microthermometry were carried out. Ores from the New orebody of the Hol Kol deposit consist mainly of bornite, wittichenite and chalcopyrite presently, which exhibit lamellae intergrowth texture, associated with native bismuth and electrum. Bismuthian bornite solid solution is considered to be a principal initial phases, while native bismuth was nucleated as molten bismuth melt initially. The occurrence of cubanite, miharaite, carrollite, siegenite, hessite and geikielite are recognized from the New orebody. Ores from the Eastern orebody of the Hol Kol deposit consist chiefly of chalcopyrite, occasionally associated with trace amounts of pyrrhotite, pyrite, bismuthinite and rare tellurobismuthite, while an ore specimen from the Western orebody consists mainly of sphalerite associated with chalcopyrite, pyrite and galena. Ores from the Tul Mi Chung deposit consist mainly of chalcopyrite and pyrite, occasionally associated with magnetite, sphalerite, galena and rare molybdenite. Some portions of magnetite are revealed to be silician magnetite.Sulfur fugacity is supposed to be below the stability field of bismuthinite in the New orebody. A reducing condition is suggested by the occurrence of geikielite without Fe3+ content. The sulfur and oxygen fugacities for the Eastern and Western orebodies of the Hol Kol deposit and for the Tul Mi Chung deposit were higher than the New orebody of the Hol Kol deposit. On the other hand, the Suan granite (porphyritic granodiorite) and the Chil Sing Dai granite (biotite granite porphyry) from the Hol Kol area can be classified as weakly magnetic magnetite‐series. Polyphase fluid inclusions are observed in gangue diopside associated with Cu ore of two specimens. The dissolution temperatures of daughter crystals are 394±26°C and 442±45°C, while the disappearing temperatures of vapor bubble were 475±25°C and > 500°C. Highly saline fluids were responsible for the mineralization at the Hol Kol deposit. The δ34S values of ore sulfides of the Hol Kol and the Tul Mi Chung deposit range from +11. 5% to +16. 1%, having anomalous lower values mainly from the Tul Mi Chung deposit. Such anomalous lower 634S values can be caused by isotopic fractionation against oxidized sulfur species. The δ34S value of bulk sulfur in the ore solutions responsible for the Hol Kol and the Tul Mi Chung deposit is estimated to be +13.5±2.5‰.
Genesis and Age Constraints on Gold Deposits of the Daerae Mine, Sangju Area, Central‐Northern Sobaegsan Massif, Korea
Authors: YUN Seong–Taek , YOUM Seung–Jun , SO Chil–Sup , CHOI Seon–Gyu , ZHANG De–Quan , KOH Yong–Kwon 
Published: November 2008

Abstract: Gold mineralization of the Daerae mine represents the first recognized example of the Jurassic gold mineralization in the Sangju area, Korea. It occurs as a single stage of quartz veins that fill fault fractures in Precambrian gneiss of the central‐northern Sobaegsan Massif. The mineralogical characteristics of quartz veins, such as the simple mineralogy and relatively gold‐rich (65–72 atomic % Au) nature of electrum, as well as the CO2–rich and low salinity nature of fluid inclusions, are consistent with the ‘mesothermal‐type’ gold deposits previously recognized in the Youngdong area (about 50 km southwest of the Sangju area). Ore fluids were evolved mainly through CO2 immiscibility at temperatures between about 250 and 325 C. Vein sulfides characteristically have negative sulfur isotopic values (–1.9 to +0.2 %), which have been very rarely reported in South Korea, and possibly indicate the derivation of sulfur from an ilmenite‐series granite melt. The calculated O and H isotopic compositions of hydrothermal fluids at Daerae (δ18Owater = +5.2 to +5.9 %; δDwater = –59 to –67 %) are very similar to those from the Youngdong area, and indicate the important role of magmatic water in gold mineralization.The 40Ar–39Ar age dating of a pure alteration sericite sample yields a high‐temperature plateau age of 188.3 0.1 Ma, indicating an early Jurassic age for the gold mineralization at Daerae. The lower temperature Ar‐Ar plateau defines an age of 158.4 2.0 Ma (middle Jurassic), interpreted as reset by a subsequent thermal effect after quartz vein formation. The younger plateau age is the same as the previously reported K‐Ar ages (145–171 Ma) for the other ‘mesothermal–type’ gold deposits in the Youngdong and Jungwon areas, Korea, which are too young in view of the new Jurassic Ar‐Ar plateau age (around 188 Ma).
A Preliminary Study on Exhalative Mineralization in Permian Basins, the Southern Segment of the Da Hinggan Mountains, China – Case Studies of the Huanggang and Dajing Deposits–
Authors: LIU Jianming , YE Jie , LI Yongbing , CHEN Xusong , ZHANG Ruibin 
Published: November 2008

Abstract: The southern segment of the Da Hinggan Mountains is a well‐known tin–polymetallic metallogenic belt of North China with Jurassic‐Cretaceous volcanic–plutonic rocks widespread. Principally because of this, most of the deposits are regarded as epigenetic hydrothermal deposits in genetic connection with the Mesozoic magmatism. But nearly 90 % of the deposits occur in Permian strata, and show concordant stratiform mineralization with a spatial distribution constrained by sedimentary facies of the Permian strata. A close association between mineralization and Permian strata is recognizable.The Huanggang Fe‐Sn deposit was regarded as a standard skarn‐type deposit formed by magmatic hydrothermal solutions in connection with Mesozoic granites. But there are abundant fabrics indicating submarine hydrothermal exhalation both in magnetite ores and in skarns, including bedding/lamination, soft–deformation, synsedimentary brecciation, and collo‐form fabrics. The magnetite orebodies and skarn‐bodies are predominantly concordant stratiform, and extend nearly 20 km along certain stratigraphic horizon, that is, the upper section of the Lower‐Permian submarine volcanic rocks. The Mesozoic granitic rocks crosscut the magnetite and skarn zone. Instead of skarnization, they show strong greisenization associated with cassiterite‐quartz veins, distinct from the magnetite skarn‐ore with disseminated tin in the Permian rocks.The Dajing Sn‐polymetallic deposit is generally regarded as subvolcanic‐hydrothermal origin, principally because of the close spatial association between ores and some of the Mesozoic subvolcanic dikes (called rhyolitic porphyry). Detailed geological, fabric, petrographical and mineralogical study demonstrates that this very kind of subvolcanic rocks is actually a new type of exhalites (called ‘siderite‐sericite chert’ according to its mineral assemblage), formed by hydrothermal sedimentation during the evolution of the Later‐Permian lacustrine basin. There are, however, indeed some rhyolitic porphyry dikes that crosscut orebod–ies. The orebodies and their associated exhalite predate, and thus have no genetic relation, to the Mesozoic magmatic process.We thus conclude that subaqueous exhalative mineralization did occur during the basin evolution at the Permian time in the southern segment of the Da Hinggan Mountains, which is ignored and poorly understood, but might be as important as the hydrothermal mineralization connected with the Mesozoic magmatism.
Cu–Fe Bearing Zinc Sulfide from Laloki Stratabound Massive Sulfide Deposit, Papua New Guinea: Chemical Characterization
Authors: KULANGE Banda J. , KAJIWARA Yoshimichi , KOMURO Kosei 
Published: November 2008

Abstract: A strange, unidentified, Cu‐Fe bearing zinc sulfide occurs in the Laloki massive sulfide deposit, Papua New Guinea. The mineral is optically uniform in texture but is chemically variable and zoned even within a single grain. Copper contents vary from 0.1 up to 8.85 wt%. Iron reaches 18.31 wt% at maximum and decreases as Cu increases. It is remarkable, however, that the total Fe+Cu remains essentially unchanged between roughly 18 and 20 wt%. Zn and S are least variable, giving 45.85–47.84 wt% and 33.48–34.58 wt%, respectively. Other trace elements such as Cd and Mn are in general less than 0.2 wt%. It is strongly suggested that the mineral in question constitutes a unique Fe‐Cu substitutional solid solution series belonging essentially to the Zn–Fe–Cu–S system.The ideal chemical formula of the solid solution series can well be presented as Zn10(Fe, Cu)5S15 or Zn2(Fe, Cu)S3, where Fe is always greater than Cu. It is intriguing that chalcopyrite blebs are recognizable restrictively only in nearby portions of the Cu‐rich end member with the ideal composition close to Zn10Fe3Cu2S15. It has been confirmed by vacuum‐sealed heating experiments that this mineral is decomposed to produce chalcopyrite and Fe‐bearing normal sphalerite at temperatures below 200C. This would provide another evidence for the existence of such distinct phase as suggested here.
Microbial Diversity in Hydrothermal Systems and Their Influence on Geological Environments
Authors: ISHII Kousuke , MARUMO Katsumi 
Published: November 2008

Abstract: Microorganisms found at terrestrial and seafloor hydrothermal systems are classified based on their optimum growth temperatures. Prokaryotes exhibiting optimum growth temperatures above 45C are defined as thermophiles, while those with optimum growth temperatures above 80C are called hyperthermophiles. Hyperthermophiles have chemically and thermodynamically stable cytoplasmic‐membrane consisting of ether–lipids. Hyperthermophiles observed at temperature up to 113C in seafloor hydrothermal areas should have thermostable proteins. Presumably, the thermostable proteins are replacing certain amino acid residue by proline instead of alanine in order to increase hydrogen bonds and salt bridges.Microorganisms inhabiting terrestrial and seafloor hydrothermal areas obtain energy mainly by use of chemical disequilibrium, so that their habitat may be restricted to the redox boundary between ambient water and reduced hydrothermal fluids. Among more than 200 species of cultivable thermophiles and hyperthermophiles, hyperthermophiles mainly obtain energy by sulfur reduction, because this reaction can produce energy efficiently at > 80C.Some hyperthermophilic sulfur reducers can reduce Cr(VI), Mn(IV), Fe(III), Co(III), As(V), Se(VI), Tc(VII), Au(III) and U(VI) through hydrogen or organic compounds that act as reducing agents for yielding energy. Some hyperther‐mophiles use W instead of Mo for activating their enzymes. Bacteria can pump out toxic metal ions from their cells, however toxic metal resistance systems of archaea, including hyperthermophiles, have not yet been studied.Methane producing hyperthermophiles can yield energy by the autotrophic reaction, when sufficient carbon dioxide and molecular hydrogen can be supplied and methane can be removed from hydrothermal systems. If nitrogen can be supplied into a hydrothermal system, hydrogen oxidization by nitrogen species (e.g. NO3‐, NO2‐, NO and N2O) may be expected through the metabolism of some hyperthermophiles.