bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Submillimeter Scale Variation of Oxygen Isotope of Vein Quartz at the Hishikari Deposit, Japan
Authors: HAYASHI Ken–ichiro , MARUYAMA Tohru , SATOH Hisao
Published: November 2008

Abstract: The physical and chemical mechanism of gold precipitation in the typical low‐sulfidation epithermal gold deposit at the Hishikari mine was quantified by submillimeter scale oxygen isotope analyses of vein quartz. In situ CO2 laser‐ablated fluorination was used to measure temporal δ18O excursions. The calculated oxygen isotopic compositions of the ore‐forming fluid indicate a dynamic process of epithermal vein formation. Intermittent opening of the vein allowed introduction of metal‐bearing deep fluid to the epithermal system, and associated boiling and subsequent mixing with meteoric water caused precipitation of precious metals.
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‰.
Zinc‐rich Pyrite from the TAG Active Mound, the TAG Hydrotherma Field, Mid‐Atlantic Ridge
Authors: Lee Su Young , Ohnishi Masatsugu , Shibata Yasuhiro , Wwatanabe Makoto , Hoshino Kenichi , Jige Mayumi , Gu Xiangping , Chiba Hitoshi , Oomori Tamotsu , Fujioka Kantaro , Rona Peter A.
Published: November 2008

Abstract: Pyrite rich in Zn, up to 3.1 wt%, was found in the TAG active mound of the TAG hydrothermal field, the slow‐spreading Mid‐Atlantic Ridge at 26°08'N and 44°49'W. The Zn‐rich pyrite is characterized by an optical homogeneity, a homogeneous distribution of Zn in the back‐scattered electron images, both at a magnification of about 500, a negative correlation between Fe and Zn contents of the pyrite and a rather small unit cell edge (a0 = 5.4117 ± 0.0008Å), strongly indicating that the detected Zn is present in the pyrite in solid solution. Such Zn concentrations are observed exclusively in dendritic pyrite, suggesting that the Znrich pyrite grew from hydrothermal fluids of a high degree of supersaturation due to quenching on the seafloor.
Hydrothermal Alteration and Fluid Geochemistry of the Tongonan Geothermal Field, Philippines
Authors: SCOTT Graeme L.
Published: November 2008

Abstract: The alteration mineralogy, the present‐day fluid chemistry, and some fluid inclusion data are used to make inferences on the chemical changes that have occurred in the fluids during the history of the Tongonan Geothermal Field. Thermal activity in the Tongonan area began in the Miocene when emplacement of many plutons forming a batholith contact metamorphosed the overlying volcanics to hornblende hornfels assemblages. In the early Pliocene, when tectonic uplift occurred along the Philippine Fault, about 2 mole % of mainly carbon dioxide and sulfur gas was released to a geothermal fluid and condensed in groundwater with geothermal steam. The condensate intensely altered the reservoir rock and formed an acid mineral assemblage, which was overprinted by a later, lower temperature, neutral‐pH assemblage. Some chlorite, epidote and illite in the reservoir rock formed at temperatures up to 100°C lower than present‐day temperatures possibly during the Plio‐Pleistocene uplift period, i.e., the system was heating up. The assemblage garnet‐anhydrite formed in fractures from a condensate after the gas had nearly completely separated from the deep, CO2‐rich fluid during vigorous boiling possibly during hydrothermal eruptions. The output of gas to the geothermal fluid decreased, while the salinity (10,000 mg/kg or ‐ 2 wt% NaCl) and the temperature of the geothermal fluid remained nearly constant throughout the Quaternary. When this neutral‐pH, alkali chloride fluid boiled, it initially precipitated albite or epidote on the rims then anhydrite at the center of fractures at high temperatures (‐250–300°C). At lower temperatures (‐150–250°C), adularia or wairakite and later calcite were deposited as the proportion of gas in the steam condensate increased. The origin of solutes is also discussed.
The Acoje Block Platiniferous Dunite Horizon, Zambales Ophiolite Complex, Philippines: Melt Type and Associated Geochemical Controls
Authors: YUMUL Graciano P.
Published: November 2008

Abstract: The Zambales Ophiolite Complex, a supra‐subduction zone ophiolite, is made up of the mid‐ocean ridge‐related Coto block and the island arc‐related Acoje block. This crust‐mantle sequence hosts platinum‐group elements (PGE) in the Acoje block. The melts responsible for the PGE‐bearing nickel sulfide and chromitite deposits are of magmatic origin characterized by high‐MgO basalt to boninitic composition which, being second or third‐stage melts, carry higher PGE budgets. Metal ratio diagrams, utilizing base and precious metals, reveal that the distribution and deposition of the PGE in the Acoje block are affected by olivine, chromite and sulfide crystallization. The generation, accumulation and segregation of the PGE, oxide and sulfide minerals from the melts are governed by the combined factors of high degrees of partial melting, multiple melt replenishment with concomitant magma mixing and fractional crystallization. Although previous sulfide segregation events could have occurred below the PGE‐bearing nickel sulfide horizon as shown by the Ni/Cu (>1), the Cu/Pd and Ni/Pd strongly suggest that the main platiniferous zone is confined within the Acoje block transition zone dunite.
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).
Tin–polymetallic Mineralization in the Southern Part of the Da Hinggan Mountains, China
Authors: WANG Jing Bin , WANG Yu Wang , WANG Li Juan , UEMOTO Takeshi
Published: November 2008

Abstract: The southern part of the Da Hinggan Mountains is the only tin‐polymetallic concentration area in northern China. Based on ore‐forming element assemblages, three metallogenic series, the Sn(W), paragenetic Sn–polymetallic, and poly‐metallic series, are recognized. The Sn(W) series, consisting of greisen, skarn and vein types, is associated with ilmenite–series, potassic feldspar (Kf)–granites. The polymetallic Pb–Zn–Cu series with porphyry, skarn and vein types, is related to magnetite–series, granodiorite – monzonite. On the contrary, the paragenetic Sn‐polymetallic series mineralization is associated with the coexisting igneous activities of Kf‐granite and granodiorite–monzonite, and it is suggested that the paragenetic Sn‐polymetallic series is caused by the superimposed mineralization with tin from ilmenite‐series magma and polymetallic elements from magnetite‐series magma–hydrothermal system. All the three series possess similar metallogenic age, concentrating on J3–K1 (130–150 Ma). The melting of high maturity and tin‐rich Xilinhot Proterozoic complex (micro–massif) during Mesozoic period, could generate the ilmenite–series, tin‐bearing felsic magma, and cause the tin mineralization in the southern part of the Da Hinggan Mountains.
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.
Mass Transfer, Oxygen Isotopic Variation and Gold Precipitation in Epithermal System: A Case Study of the Hishikari Deposit, Southern Kyushu, Japan
Authors: SHIKAZONO Naotatsu , YONEKAWA Noriyuki , KARAKIZAWA Takahumi
Published: November 2008

Abstract: Transportation of various kinds of elements occurred in wall rocks (Quaternary andesites) during the hydrothermal alteration accompanied by the Hishikari epithermal gold mineralization. For example, K2O and MgO contents of wall rocks decrease away from the gold‐quartz veins, while (CaO+Na2O) content increases, and SiO2 content is variable near the veins. Hydrothermal alteration zoning and bulk compositional variations in wall rocks suggest that the mixing of hydrothermal solution and acidic groundwater took place an important role as the cause for the hydrothermal alteration and bulk compositional variations. The relationship between dissolved silica concentration and temperature of hydrothermal solution mixed with groundwater is obtained based on precipitation kinetics‐fluid flow–mixing model, and the computed results are compared with the distribution of SiO2 minerals (quartz and cristobalite) in the hydrothermal alteration zones. This comparison suggests that the most reasonable flow rate of fluids migrating through hydrothermal alteration zones, and A/M (A: surface area of rocks interacting with fluid, M: mass of fluid) are estimated to be ca. 10‐4.2 m/sec, and ca. 0.10 m2/kg, respectively. The mixing of two fluids (hydrothermal solution and acidic groundwater) can also explain δ18O zoning in the altered country rocks, hydrothermal alteration zoning from K‐feldspar through K‐mica to kaolinite from the center (veins) to margin, and deposition of gold.
Isotopic Geochronology of the Late Paleozoic Kanggur Gold Deposit of East Tianshan Mountains, Xinjiang, NW China
Authors: ZHANG Lian–chang , LIU Tie–bing , SHEN Yuan–chao , LI Guang–ming , JI Jin–sheng
Published: November 2008

Abstract: The Kanggur gold deposit lies in East Tianshan mountains, eastern section of Central Asia orogenic belt. The gold mineralization occurs on the northern margin of the Aqishan‐Yamansu Paleozoic island arc in the Tarim Plate. It was hosted mainly in Middle‐Lower Carboniferous calc‐alkaline volcanic rocks, and controlled by the distributions of syn‐tectonic intrusions and ductile shear zones. In order to determine ore‐forming age of the Kanggur deposit, samples were collected from ores, wall rocks, altered rocks and intrusions. The dating methods include Rb‐Sr isochron and Sm‐Nd isochron, and secondly 40Ar/39Ar age spectrum, U‐Pb and Pb‐Pb methods. Based on the mineral assemblage and crosscutting relationship of ore veins, five mineralization stages are identified. This result is confirmed by isotope geochronologic data.

The first stage featuring formation of pyrite‐bearing phyllic rock, is mineralogically represented by pyrite, sericite and quartz with poor native gold. The Rb‐Sr isochron age of this stage is 2905 Ma. The second stage represents the main ore‐forming stage and is characterized by native gold–quartz–pyrite–magnetite–chlorite assemblage. Magnetite and pyrite of this stage are dated by Sm‐Nd isochron at 290.47.2 Ma and fluid inclusion in quartz is dated by Rb‐Sr isochron at 282.35 Ma. The third mineralization stage features native gold–quartz–pyrite vein. In the fourth stage, Au‐bearing polymetallic sulfide‐quartz veins formed. Fluid inclusions in quartz are dated by Rb‐Sr isochron method at 25821 Ma. The fifth stage is composed of sulfide‐free quartz–carbonate veins with Rb‐Sr age of 2547 Ma. The first and second stages are related to ductile‐brittle deformation of shear zones, and are named dynamo‐metamorphic hydrothermal period. The third to fifth stages related to intrusive processes of tonalite and brittle fracturing of the shear zones, are called magmato‐hydrothermal mineralization period. The Rb‐Sr isochron age of 2905 Ma of the altered andesite in the Kanggur mine area may reflect timing of regional ductile shear zone. The Rb‐Sr isochron age of 28216 Ma of the quartz‐syenite porphyry and the zircon U‐Pb age of 2757 Ma of tonalite in the north of Kanggur gold mine area are consistent with the age of gold mineralization (290‐254 Ma). This correspondence indicates that the tonalite and subvolcanic rocks may have been related to gold mineralization. The Rb–Sr, Sm‐Nd and U‐Pb ages and regional geology support the hypothesis that the Kanggur gold deposit was formed during collisional orogenesis process in Late Variscan.
Gold‐bearing Quartz Veins and Hydrothermal Alteration of the Paleozoic Epithermal System in the Francis Creek Area, North Queensland, Australia
Authors: Harijoko Agung , Watanabe Koichiro , Motomura Yoshinobu , Izawa Eiji
Published: November 2008

Abstract. The Francis Creek area located at the Sybil graben in North Queensland, Australia, has some features of epithermal gold mineralization such as gold‐bearing quartz vein and silica body hosted in rhyodacitic rocks of the Late Carboniferous Hells Gate Formation. In order to understand the nature of the paleo‐hydrothermal activity in this area and to aid exploration for an economic gold deposit in this area, we carried out hydrothermal alteration mapping surrounding the veins and silica body, over an area of about 7 times 5 km2.

We defined two alteration zones and inferred the center of hydrothermal activity. Fluid inclusion shows the boiling feature, and the microthermometry analysis resulted in the trapping temperature of 240°C and low salinity. This temperature is consistent with the formation temperature of clay mineral in the host rocks. On the basis of whole‐rock composition, the silica body was identified as silicified rocks. Precious metal minerals such as electrum and acanthite coexist with sulfide minerals. Iodagylite was identified as a product of weathering. The sulfide minerals imply that the low‐sulfidation epithermal gold mineralization occurred in the Francis Creek area.
Gas Measurement of Fluid Inclusions from the Hishikari Epithermal Gold Deposit, Southern Kyushu, Japan, Using Laser Raman Microprobe
Authors: Etoh Jiro , Taguchi Sachihiro , Izawa Eiji
Published: November 2008

Abstract. Laser Raman microprobe analysis was performed on the fluid inclusions from the Honko‐Sanjin zone in the Hishikari epithermal gold deposit, southern Kyushu, Japan. Gas concentrations of fluid inclusions through the zone were below detection limits (e.g., 5 mmole/kg H2O for CO2), with an exception at shallow portion in which the CO2/N2 mole ratio was determined to be 5.3. Boiling of hydrothermal solutions probably separated gases from ore fluids at the deep portion of the deposit, and migration of gases to shallow portion resulted in CO2‐rich steam‐heated water and related acid alteration.
Geochemical Characteristics of the Akiyoshi Limestones, Japan and Their Bearing on Exploration for Blind Skarn Deposits
Authors: Nakano Takanori , Ishihara Shunso
Published: November 2008

Abstract. Carboniferous‐Permian limestones of the Akiyoshi Plateau, in the Inner Zone of southwestern Japan, are composed of essentially pure calcium carbonate containing only small amounts of other elements, and they are accompanied by marble and copper skarn deposits near the contact with late Cretaceous granitoids. The δ18O values of the Akiyoshi limestones range widely from 7.6 to 28.3% and are mostly lower than those of other areas of the same age (23–29%), whereas the differences among the δ13C values are small. The δ18O values are negatively correlated with Mn and Fe contents. Samples with high δ18O (>25%) and δ13C (>2%) values do not contain Fe, Zn, or Pb, but those with low δ18O values tend to be rich in these elements, indicating that these elements were introduced by interaction with H2O dominant fluids, possibly of magmatic origin. Potential scores for evaluating the degree of interaction with hydro thermal fluids were calculated for δ18O, δ13C, Fe, Mn, Zn, Pb, and Sr. Higher scores implying much hydrothermal interaction were evident in the Mt. Hananoyama area, where there are many skarn deposits, and along faults oriented mainly NNW‐SSE. Therefore, these are promising areas for exploring for blind deposits. It is likely that the hydrothermal fluid traveled through the limestones along fractures at the time of the granitic intrusions. However, the potential scores here are much smaller than those in the Pb‐Zn mineralized area of the Kamioka mine, so more detailed petrological and mineralogical investigations are necessary.
Implications of Analcime Hydrothermally Formed from Na‐alumino‐borosilicate Glasses Containing Cs and Sr for the Stability of High‐level Radioactive Waste Form
Authors: Sohn Wook , Shoji Tetsuya , Kaneda Hiroaki , Ishii Teruaki
Published: November 2008

Abstract. In order to know the behaviors of radioactive elements such as cesium and strontium during a hydrothermal alteration of borosilicate glass of radioactive waste, some alumino‐borosilicate glasses belonging to the systems Na2O‐Al2O3‐B2O3‐SiO2‐SrO, Na2O‐Al2O3‐B2O3‐SiO2‐Cs2O and Na2O‐Al2‐O3‐B2O3‐SiO2‐SrO‐Cs2O have been treated hydrothermally at 200d̀C under a vapor pressure of 1.54 MPa. The result shows that all glasses are changed into crystalline phases with running time up to 60 days, and that analcime‐type zeolite is formed as a major product. The formed zeolite is shown to contain cesium and/or strontium. Considering the fact that natural zeolite occurs in wide physicochemical conditions including hydrothermal one, the analcime‐type zeolite is expected to fix stably the radioactive elements in the disposal site. Since aluminum is necessary for the formation of the analcime‐type zeolite, the waste glass should have aluminum as one of major components.
Tectonic Controls on the Formation of the Liwu Cu‐rich Sulfide Deposit in the Jianglang Dome, S W China
Authors: Yan Dan‐Ping , Zhou Mei‐Fu , Song Hong‐Lin , Fu Zhao‐Ren , Sun Min
Published: November 2008

Abstract. The Liwu Cu‐rich sulfide deposit occurs within the Jianglang dome in the eastern margin of the Tibetan plateau. The dome consists of a core, a middle slab and a cover sequence. The main deposit is hosted in the core with minor ore bodies in the middle slab. The protolith of the core consists of clastic sedimentary rocks with inter‐layered volcanic rocks.

All of the ore bodies are substantially controlled by an extensional detachment fault system. The ore bodies within the core are distributed along the S2 foliation in the hinge of recumbent fold (D2), whereas ore bodies with en echelon arrangement are controlled by the mylonitic foliation of the lower detachment fault. Ore bodies within the middle slab are oriented with their axes parallel to the mylonitic foliation. Pyrite and pyrrhotite from the ores contain Co ranging from 37 to 1985 ppm, Ni from 2.5 to 28.1 ppm, and Co/Ni ratios from 5 to 71. These sulfides have δ34S values ranging from 1.5 to 7.5 % whereas quartz separates have δ18O values of 11.9 and 14.3 % and inclusion fluid in quartz has δD value of‐88.1 %. These features suggest that the deposit was of hydrothermal origin.

Two ore‐forming stages are recognized in the evolution of the Jianglang dome. (1) A low‐temperature ore‐forming process, during the tectonic transport of the upper plate above the lower detachment, and the initial phase of the footwall updom‐ing at 192–177 Ma. (2) A medium‐temperature ore‐forming stage, related to the final structural development of the initial detachment at 131–81Ma. Within the core, the ore bodies of the first stage were uplifted to, or near, the brittle/ductile horizon where the ore‐forming metals were re‐concentrated and enriched. A denudation stage in which a compressional tectonic event produced eastward thrusting overprinted the previous structures, and finally denuded the deposit. The Liwu Cu‐rich sulfide deposit was formed during a regional extensional tectonic event and is defined as a tectono‐strata‐bound hydrothermal ore deposit.
The Fanshan Apatite‐Magnetite Deposit in the Potassic Ultramafic Layered Intrusion, North China
Authors: Cheng Chun , Sun Shihua
Published: November 2008

Abstract. This article reviews work carried out on the Fanshan layered apatite (‐magnetite) deposit, which occurs in the Fanshan complex, a potassic ultramafic‐syenite layered intrusion located in North China. The Fanshan complex intruded into Proterozoic sedimentary rocks in the early Triassic. The complex comprises First‐ to Third‐Phase Intrusives. The First‐Phase Intrusive includes rhythmic Units 1 to 9, which mainly consist of clinopyroxenite and biotite clinopyroxenite. The apatite (‐magnetite) deposit is situated near the top of rhythmic Unit no. 6 of the First‐Phase Intrusive.

The economical deposit comprises Orebody II and Orebody III. Orebody II, situated at the top of Unit no. 6, consists of two kinds of layer: one magnetite‐apatite rock layer at the top and a few apatite rock layers at the bottom. Orebody III is situated several meters below Orebody II, and consists of an apatite rock layer.

There is controversy over the ore formation mechanism, the temperature and pressure of the magma intrusion, and the origin of the magma (including the possibility of magma immiscibility). We review these problems of this unique apatite (‐magnetite) magmatic deposit.
Talnakhite Associated with Andradite Skarn at Fuka, Okayama Prefecture, Japan
Authors: Takechi Yasushi , Kusachi Isao , Nakamuta Yoshihiro , Kase Katsuo
Published: November 2008

Abstract. Talnakhite occurs in an andradite skarn forming adjacent to a leucocratic quartz monzonite dike intruded into limestone at Fuka. The mineral densely contains exsolution lamellae of chalcopyrite, and the talnakhite‐chalcopyrite inter‐growth is intimately associated with bornite that contains chalcopyrite as a lattice‐form exsolution. The chemical composition of the talnakhite acquired on an electron probe microanalyzer corresponds to Cu9.00Fe8.08S15.92, very close to the ideal chemical formula Cu9Fe8S16. Nickel is not detected. The X‐ray powder diffraction lines are well indexed on a body‐centered cubic cell with a = 10.589 Å. The characteristic (110) reflection of talnakhite is clearly observed at 7.49 Å. The present talnakhite retains the chalcopyrite‐like colored polished surface without tarnish in air more than a month.

Talnakhite at Fuka is likely to be derived from breakdown of Cu‐rich intermediate solid solution (iss), which was in equilibrium with Fe‐rich bornite at elevated temperatures. Talnakhite thus formed has survived the subsequent cooling processes, probably because the ƒs2 was maintained in suitable levels preventing its decomposition into bornite and chalcopyrite.
Evidence of Microbial Activity in the Formation of Manganese Wads at the Asahidake Hot Spring in Hokkaido, Japan
Authors: Mita Naoki , Miura Hiroyuki
Published: November 2008

Abstract. Mt. Asahidake is an active volcano, with more than 90 active wells, in the Daisetsu volcanic group located in central Hokkaido, Japan. Wells along the Yukomanbetsu‐sawa River showed high manganese concentrations and associated manganese deposits. These deposits consist of manganese oxides, and the concentration of iron is very low except for one sample collected from the upper reach of the river. Most of the wet samples showed basal diffraction characteristic of todorokite (9.6 Å). Cultivation tests showed that microorganisms were responsible for the oxidation of dissolved Mn2+ in the Asahidake hot spring. The dissolved Mn2+ concentration in the sterilized hot spring water was unchanged after four days, whereas the Mn2+ concentration in the sterilized hot spring water with a small amount of fresh manganese wad was decreased to zero after three days, and manganese oxide formed. This result implies that the activity of microorganism oxidizes dissolved Mn2+ and forms manganese oxide at the Asahidake manganese deposits. In addition to Komanoyu hot spring and Yunotaki Falls, this is the third report of microbial activity forming considerable deposits of manganese oxides in hot spring waters.
K‐Ar Ages of Tin‐Polymetallic Mineralization in the Oruro Mining District, Central Bolivian Tin Belt
Authors: Sugaki Asahiko , Shimada Nobutaka , Ueno Hirotomo , Kano Shimpei
Published: November 2008

Abstract. K‐Ar age determinations were carried out on vein‐ and rock‐forming minerals from five vein‐type tin‐polymetallic ore deposits of the Oruro mining district in the central part of the Bolivian tin belt. The sericite from vein selvedges and an altered host rock provides good estimates of the ages of hypogene mineralization, and supergene alunite and jarosite provide ages for erosional and weathering episodes. It is concluded that hypogene mineralization in the Oruro mining district took place during the early to middle Miocene: 15.8±0.8 Ma at San José, 20.1±l.l Ma at Morococala, 20.5±1.0 Ma at Avicaya, and 19.6±1.0 Ma at Llallagua. Fine grained supergene alunite (δ34S = ‐10.1 960) and jarosite yield K‐Ar ages of 6.7±0.7 Ma at Avicaya and 3.9±0.7 Ma at Bolivar, respectively, suggesting that erosion and chemical weathering were active at those times.
A Study of Illite Kiibler Indexes and Chlorite “Crystallinities” with Respect to Shear Deformation and Alterations, Jinshan Gold Deposit, East China
Authors: Li Xiao‐feng , Hua Ren‐min , Mao Jing‐wen , Ji Jun‐feng , Wang Chun‐zeng
Published: November 2008

Abstract. This paper presents a measurement and study of Kübler Indexes (KI) of illite, “crystallinities” of chlorite (ChC), and apparent mean crystallite sizes and lattice strain of both illite and chlorite of the Jinshan ductile shear zone in the Jinshan gold deposit of East China. It is found that the KI values and apparent mean crystallite sizes of illite decrease and the lattice strain of chlorite apparently increase, whereas the apparent mean crystallite sizes of chlorite and the lattice strain of illite remain constant, from altered mylonite to altered and higher‐strained ultramylonite in the shear zone. Only slight decrease of ChC is observed.

An obvious negative correlation exists between KI and apparent mean crystallite sizes in altered mylonite with lower strain, whereas a positive correlation is found between ChC and apparent mean crystallite sizes in altered ultramylonite with higher strain. No any correlations between KI and lattice strain exist, whereas a negative correlation and a positive correlation between ChC and lattice strain occur separately in the altered mylonite and ultramylonite. It is suggested that illite Kiibler Indexes and chlorite “crystallinities” most likely reflect deformation behaviors and mechanisms of altered rocks although other factors involving water/rock ratio may apply as well.
Smectite‐Zeolite Envelope Surrounding the Tsukiyoshi Uranium Deposit, Central Japan: A Natural Analogue Study
Authors: Utada Minoru
Published: November 2008

Abstract. The Tsukiyoshi uranium deposit in Gifu Prefecture is the largest one in Japan. It is embedded in lower part of the Mizunami Group of Miocene age. Relating to the existence of this uranium deposit, the constituent minerals in sediments were studied by XRD and SEM, using many drilling cores. The most abundant authigenic mineral is smectite. The amount of smectite increases generally from upper to lower horizons, and a highly smectitized zone is situated around the uranium deposit. Smectitization predominated in mafic glassy grains of sediments, which was probably formed in early burial diagenesis. Zeolites including clinoptilolite‐heulandite, mordenite, analcime, chabazite and philipsite are secondly abundant authigenic minerals. They seem to have been formed at early to late diagenetic stages. Opaline silica is rather rare. Carbonate minerals, including cal‐cite, dolomite, siderite and rhodochrosite are common. They may be formed by diagenesis as well. Gypsum and pyrite occur in upper horizons and lower horizons, respectively. In particular, a highly smectitized zone including pyrite probably played an important role for retarding the migration of uranium and as a result keeping the uranium deposit for past one million years. This smectite‐zeolite envelope surrounding the Tsukiyoshi uranium deposit is regarded as a natural analogue of the buffer materials surrounding the high‐level radioactive waste repository.
Geochemical Process of Gas Hydrate Formation in the Nankai Trough Based on Chloride and Isotopic Anomalies in Interstitial Water
Authors: Tomaru Hitoshi , Matsumoto Ryo , Lu Hailong , Uchida Takashi
Published: November 2008

Abstract: Interstitial water expelled from gas hydrate‐bearing and ‐free sediments in the Nankai Trough are analyzed in terms of Cl‐, SO42‐, δ18O and δD. The baselines for the Cl‐ concentration and δ18O value are close to seawater values (530 mM and 0%), indicating that the interstitial water is of seawater origin. The δD values decrease with depth, implying isotopic exchange of hydrogen between upwelling biogenic methane depleted in D and interstitial water. The Cl‐ concentrations in gas hydrate‐bearing sediments are anomalously low, while the δ18O and δD values are both high, suggesting that the water forming these gas hydrates was poor in Cl‐ and enriched in 18O and D during gas hydrate formation. Calculation of the gas hydrate saturations using Cl “and δ18O anomalies gives results of up to 80 % in sand, and shows that the δ18O baseline is not consistent with the Cl” baseline. The δ18O baseline increases by +1% in gas hydrate‐free clay and silt. This is considered to be caused by clustering of water molecules after gas hydrate dissociation in response to the upward migration of the base of gas hydrate stability, as indicated by the presence of a double bottom‐simulating reflector at this site. The water clusters enriched in 18O are responsible for the increase in the δ18O baseline with normal Cl“. The abrupt shallowing of the base of gas hydrate stability may induce the dissociation of gas hydrates and the accumulation of gases in the new stability zone, representing a geological process that increases gas hydrate saturation.
Geochemistry and Petrogenesis of the Tongshankou and Yinzu Adakitic Intrusive Rocks and the Associated Porphyry Copper‐Molybdenum Mineralization in Southeast Hubei, East China
Authors: Wang Qiang , Zhao Zhen‐Hua , Bao Zhi‐Wei , Xu Ji‐Feng , Liu Wei , Li Chao‐Feng , Bai Zheng‐Hua , Xiong Xiao‐Lin
Published: November 2008

Abstract. The late Jurassic Tongshankou and Yinzu plutons in southeast Hubei have been investigated for their contrasting metal mineralization features. The former is closely associated with porphyry Cu‐Mo mineralization, while the latter is barren of metal mineralization, althouth both are located very close to each other. The Tongshankou granodiorite porphyries and the Yinzu granodiorites are geochemically similar to adakites, e.g., high Al2O3 and Sr contents and La/Yb and Sr/Y ratios, enriched in Na2O, depleted in Y and Yb, very weak Eu anomalies and positive Sr anomalies. However, different geochemi‐cal characteristics exist between the two plutons: the Tongshankou adakitic rocks (1) are relatively enriched in SiO2, K2O, MgO, Cr, Ni, and Sr and depleted in Y and Yb; (2) have higher degree REE differentiation; (3) have positive Eu anomalies in contrast with very weak negative or unclear Eu anomalies in the Yinzu rocks; and (4) isotopically have relatively higher ePNd(t) values (‐5.19 to ‐5.38) and lower initial 87Sr/86Sr ratios (0.7060 to 0.7062), while the Yinzu adakitic rocks have relatively lower ePNd(t) values (‐7.22 to ‐8.67) and higher initial 87Sr/86Sr ratios (0.7065 to 0.7074).

The trace element and isotopic data demonstrate that the Tongshankou adakitic rocks were most probably originated from partial melting of delaminated lower crust with garnet being the main residual mineral whereas little or no plagioclase in the source. On the contrary, the Yinzu adakitic rocks were likely derived from partial melting of thickened lower crust, with residual garnet and a small quantity of plagioclase and hornblende in the source. Interactions between the adakitic magmas and mantle peridotites possibly took place during the ascent of the Tongshankou adakitic magmas through the mantle, considering that MgO, Cr, and Ni contents and ePNd(t) values of the adakitic magmas were possibly elevated and initial 87Sr/86Sr ratios were possibly lowered due to the contamination of mantle peridotites. In addition, the Fe2O3 of the adakitic magmas was likely released into the mantle and the oxygen fugacities (ƒo2) of the latter were obviously possibly raised, which made metallic sulfide in the mantle oxidized and the chalcophile elements such as Cu were incorporated into the adakitic magmas. The ascent of the adakitic magmas enriched in Cu and Mo will lead to the formation of porphyry Cu‐Mo deposit. Nevertheless, the Yinzu adakitic magmas were possibly lack of metallogenetic materials due to not interacting with mantle peridotite, and thus unfavorable to metal mineralization.
Rhythmic Layering in the Apatite (‐Magnetite) Deposit in the Fanshan Complex, North China
Authors: Cheng Chun , Sun Shihua , Mao Qian
Published: November 2008

Abstract. The Fanshan complex consists of three (First‐ to Third‐) Phases of intrusion. The First‐Phase Intrusive is composed of rhythmic layers. The Fanshan apatite (‐magnetite) deposit is situated near the top of no. 6 rhythmic Unit of the First‐Phase Intrusive. Two sketch maps were drawn through the deposit along no. 25 cross‐cut on 425 mL and no. 1 crosscut on 491 mL in the Fanshan mine. Through this mapping, a small‐scaled rhythmic layering (called sub‐rhythmic layering) was newly found. The sub‐rhythmic layering consists of five typical rocks: biotite clinopyroxenite, biotite rock, biotite‐apatite rock, alternation biotite‐apatite rock and apatite rock. The thickness of layers varies from four millimeters to several meters. Six units of sub‐rhythmic layering were distinguished. Each unit consists of biotite clinopyroxenite (or biotite rock and biotite‐apatite rock) layer at the bottom and apatite rock layer at the top.

Major element compositions of biotite and clinopyroxene were analyzed. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*: total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub‐rhythmic unit. A general trend, however, through the whole sub‐rhythmic layering sequence shows that the both minerals become relatively magnesian upwards. The hypotheses of liquid immiscibili‐ty, gravitational settling and magma mixing are against with the results obtained in the present study. This study suggests that the apatite (‐magnetite) deposit is formed through fractional crystallization process.