(Au,Ag)Te2 Minerals from Epithermal Gold Deposits in Japan          下载免费PDF全文

Kosei Komuro  Masataka Nakata 《Resource Geology》2017,67(1):22-34

Chemical composition and mode of occurrences of (Au, Ag)Te₂ minerals such as calaverite (AuTe₂), sylvanite (AuAgTe₄) and krennerite ((Au, Ag)Te₂) in epithermal gold telluride ores from Suzaki, Kawazu and Teine are examined. In the ores from Suzaki, (Au, Ag)Te₂ minerals occur in microbands of tellurides and fine quartz. The minerals in telluride bands change from krennerite, via calaverite‐native tellurium, to sylvanite, in the order of crystallization. A sample from Kawazu contains sylvanite and native tellurium with stutzite, hessite and tetradymite in the coarser gray quartz part. The Teine sample also contains sylvanite and native tellurium with barite and quartz. The peak patterns of XRD of calaverite, krennerite and sylvanite from Suzaki are almost identical to that of JCPDS 43–1472, JCPDS 8–20 and JCPDS 9–477, respectively. The Te, Au, Cu, and Ag contents of calaverite from Suzaki range from 56.4 to 57.9 wt.%, from 41.6 to 42.6 wt.%, from 0.28 to 0.45 wt.% and from 0.14 to 0.31 wt.%, respectively, corresponding to the formula Au_0.97Ag_0.01Cu_0.02Te₂. The Te, Au, Ag, and Cu contents of krennerite from Suzaki range from 59.6 to 61.4 wt.%, from 31.3 to 33.6 wt.%, from 4.91 to 6.13 wt.% and from 0.66 to 0.80 wt.%, respectively, corresponding to the formula Au_0.71Ag_0.22Cu_0.05Te₂ with Au and Ag ranging from 0.68 to 0.74 and from 0.20 to 0.25, respectively. The Te, Au, Ag, and Cu contents of sylvanite from Suzaki range from 61.5 to 63.4 wt.%, from 24.1 to 27.4 wt.%, from 10.0 to 12.5 wt.% and from 0.00 to 0.12 wt.%, respectively. The Te, Au, Ag, and Cu contents of sylvanite from Kawazu range from 62.7 to 63.3 wt.%, from 23.5 to 24.1 wt.%, from 12.0 to 12.5 wt.% and from 0.09 to 0.16 wt.%, respectively. The Te, Au, Ag, Cu and Fe contents of sylvanite from Teine range from 61.8 to 63.5 wt.%, from 23.6 to 24.7 wt.%, from 11.9 to 13.3 wt.%, from 0.01 to 1.65 wt.% and from 0.00 to 0.02 wt.%, respectively. The average formulae of sylvanite from Suzaki, Kawazu, and Teine are expressed as Au_1.06Ag_0.94Cu_0.02Te₄, Au_1.00Ag_0.95Cu_0.02Te₄ and Au_1.01Ag_0.95Cu_0.06Te₄, respectively. Judging from the mineral assemblages of these ores and other localities, Au–Te mineralization in the Japanese Islands can be divided into four types: native gold–calaverite at Date and Agawa, krennerite(?native tellurium) at Osore‐zan and Mutsu, sylvanite–native tellurium–hessite at Teine, Kawazu, Kobetsuzawa, and Kato, and polyminerallic assemblages at Suzaki and Kushikino. The pH–Eh diagram of aqueous tellurium species and tellurium minerals at 250°C indicates that (Au, Ag)Te₂ minerals in epithermal gold telluride mineralization would have been formed under middle to low Eh and acidic (to intermediate) pH conditions. It is possible that dilute tellurium‐containing fluid would scavenge dilute gold.  相似文献   

High-beta plasma blobs in the morningside plasma sheet   总被引：1，自引：0，他引：1  

G. Haerendel  W. Baumjohann  E. Georgescu  R. Nakamura  L. M. Kistler  B. Klecker  H. Kucharek  A. Vaivads  T. Mukai  S. Kokubun 《Annales Geophysicae》1999,17(12):1592-1601

Equator-S frequently encountered, i.e. on 30%0of the orbits between 1 March and 17 April 1998, strong variations of the magnetic field strength of typically 5–15-min duration outside about 9R_E during the late-night/early-morning hours. Very high-plasma beta values were found, varying between 1 and 10 or more. Close conjunctions between Equator-S and Geotail revealed the spatial structure of these “plasma blobs” and their lifetime. They are typically 5–10° wide in longitude and have an antisymmetric plasma or magnetic pressure distribution with respect to the equator, while being altogether low-latitude phenomena (<15°). They drift slowly sunward, exchange plasma across the equator and have a lifetime of at least 15–30 min. While their spatial structure may be due to some sort of mirror instability, little is known about the origin of the high-beta plasma. It is speculated that the morningside boundary layer somewhat further tailward may be the source of this plasma. This would be consistent with the preference of the plasma blobs to occur during quiet conditions, although they are also found during substorm periods. The relation to auroral phenomena in the morningside oval is uncertain. The energy deposition may be mostly too weak to generate a visible signature. However, patchy aurora remains a candidate for more disturbed periods.  相似文献   

Comparison of stable isotopes,ratios of Cl/Cl and I/I in brine and deep groundwater from the Pacific coastal region and the eastern margin of the Japan Sea     

Yasunori Mahara  Tomoko Ohta  Tomochika Tokunaga  Hiroyuki Matsuzaki  Eiji Nakata  Yuki Miyamoto  Yukihiro Mizuochi  Toshiharu Tashiro  Masahiro Ono  Toshifumi Igarashi  Keisuke Nagao 《Applied Geochemistry》2012

Fifty-three samples, including brines associated with oil and natural gas reservoirs and groundwater samples from deep boreholes, were collected from the Pacific and Japan Sea coastal regions in Japan. The ¹²⁹I/¹²⁷I and ³⁶Cl/Cl ratios, and stable isotopes (δD and δ¹⁸O) are compared to investigate differences related to the geotectonic settings of the two regions. The δD and δ¹⁸O data indicate that brine and groundwater from the Pacific coastal region reflect mixing of meteoric water with connate seawater in the pores of sedimentary rocks. On the other hand, brine and groundwater from the Japan Sea coastal region have been hydrothermally altered. In particular, brines associated with petroleum accumulations at Niigata and Akita showed the same isotopic characteristics as fluids found in the Kuroko deposits of the Green Tuff region in northeastern Japan. There is little difference in the ³⁶Cl/Cl ratios in brine and groundwater from the Pacific and Japan Sea coasts. Most brine and some deep groundwater, except those from the Pleistocene Kazusa Group, have already reached the average secular equilibrium ratio of 9.9 ± 2.7 × 10⁻¹⁵ for their mudstone and sandstone reservoirs. There was no correlation between the ³⁶Cl/Cl ratios and differences in geotectonic setting between the Pacific and the Japan Sea coast. The molar I/Br ratio suggests that the I in all of water samples was of biogenic origin. The average ¹²⁹I/¹²⁷I ratio was 290 ± 130 × 10⁻¹⁵ to 294 ± 105 × 10⁻¹⁵ in both regions, showing no relationship to the different geotectonic settings. The uncontaminated brine and groundwater samples are likely to have retained the original ¹²⁹I/¹²⁷I ratios of marine I released from the old organic matter stored in sedimentary rock.  相似文献   

Multicomponent observation of crustal activity in the DPRI 800 m borehole close to the Nojima Fault   总被引：1，自引：0，他引：1  

Hiroshi Ishii  Atsushi Mukai  Kunio Fujimori  Shigeru Nakao  Shigeo Matsumoto  Yasuhiro Hirata 《Island Arc》2001,10(3-4):282-287

Abstract An 800 m borehole was drilled near the Nojima Fault, on which a strike–slip larger then 1 m occurred during the 1995 Hyogo-ken Nanbu earthquake ( M = 7.2). Crustal activity near the fault has been observed since May 1996 using a multicomponent instrument installed at the bottom of the borehole. Data of three components of strain, two components of tilt and temperature observed from May 1996 to December 1998 were analyzed. Long-term changes of strain and tilt show a north-east–south-west extension and southwards subsidence. As for the Earth tides and atmospheric effect, orientation of the principal axis of strain was mainly east-west and orientation of the maximum subsidence was mainly north-south. The observational data of strain had variations corresponding to a change in temperature at a depth of 800 m. The thermal expansion coefficient of the crust was calculated to be approximately 2.0 × 10⁻⁶/°K.  相似文献   

Interannual variations of the occurrence of epipelagic fish in the diets of the seabirds breeding on Teuri Island, northern Hokkaido, Japan     

Tomohiro Deguchi  Yutaka Watanuki  Yasuaki Niizuma  Akifumi Nakata 《Progress in Oceanography》2004,61(2-4):267

The diets of breeding seabirds can be a good monitor of marine environmental changes. From 1984 to 2001 we monitored the diets of black-tailed gulls (Larus crassirostris) (“surface foragers”), rhinoceros auklets (Cerorhinca monocerata) (“epipelagic divers”), and Japanese cormorants (Phalacrocorax filamentotus) (“bottom divers”) that breed on Teuri Island at the northern boundary of the Tsushima Warm current in the Sea of Japan/East Sea. Between 1984 and 1987, both the gulls and the auklets foraged on the sardine (Sardinops melanostictus), but after 1992, they switched to the anchovy (Engraulis japonica). This change might reflect the collapse of the sardine stock in the late 1980s. In the 1990s, the year-to-year variations of the percentage of anchovy in the diets of the three seabird species showed similar trends: High in 1994 and 1998–2001; and low in 1992–1993 and 1995–1997. The estimated stock size of the anchovy population in the Tsushima Current area was positively correlated with the percentage of mass of anchovy in the seabirds’ diets. Thus, the short-term annual changes of the total anchovy availability, which might reflect SST or the volume transport of Tsushima Current, possibly affected the seabirds diets on this island.  相似文献   

The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus)     

Kang  Donhyug; Mukai  Tohru; Iida  Kohji; Hwang  Doojin; Myoung  Jung-Goo 《ICES Journal of Marine Science》2005,62(4):779-789

  相似文献   

Feeding Strategy of Japanese Sand Lance Larvae in Relation to Ciliated Protozoa in the Vicinity of a Thermohaline Front   总被引：1，自引：0，他引：1  

Naoki Nagano  Yukio Iwatsuki  Yuji Okazaki  Hideaki Nakata 《Journal of Oceanography》2001,57(2):155-163

Larval feeding and survival strategies are described on a Japanese sand lance, Ammodytes personatus Girard, collected in the vicinity of a thermohaline front in the Ise Bay, in comparison with those of other predominant larvae, Hexagrammos spp. and Sebastiscus marmoratus (Cuvier). First-feeding A. personatus larvae (3.1–3.9 mm NL) fed primarily on tintinnid ciliates, subsequently switching to copepod nauplii (4.0–7.9 mm NL larvae) and post-naupliar copepods (8.0–11.3 mm NL larvae). First-feeding Hexagrammos spp. larvae (6.5–6.9 mm NL) fed primarily on post-naupliar copepods, and first-feeding S. marmoratus larvae (<4.0 mm NL), mostly on copepod nauplii. The different food preferences of these species at first-feeding were related to their different mouth widths (0.15–0.19, 0.52–0.56 and 0.32–0.40 mm, respectively) and/or body size (3.1–3.9, 6.5–6.9 and 3.2–3.9 mm NL, respectively). Ciliate-feeding by first-feeding A. personatus larvae was strongly related to the convergence of the larvae and their prey near the thermohaline front, densities of both being greater on the inshore side of the frontal zone. In conclusion, the aggregation of ciliates near the thermohaline front may have improved feeding conditions and survival of first-feeding A. personatus larvae.  相似文献   

A comparative study of the photosynthetic activity among three temperate seagrass species in Northern Japan   总被引：1，自引：0，他引：1  

Maria Luisa Sasil-Orbita  & Hiroshi Mukai 《Marine Ecology》2006,27(4):388-396

The photosynthetic activity of Zostera marina, Zostera asiatica and Phyllospadix iwatensis shoots from populations of Hokkaido (Northern Japan) was determined using the pulse amplitude modulated (PAM) fluorometer. Several fluorescence parameters were measured as a function of irradiance and leaf age: electron transport rate (ETR), quantum yield, photochemical quenching (qP) and non‐photochemical quenching (NPQ). The leaf age determined by the leaf position in the shoot bundle strongly influenced the photosynthetic activity of Z. marina, Z. asiatica and P. iwatensis. Young leaves had the maximum electron transport rate (Zm: Leaf 1 = 15.7, Leaf 2 = 16.3; Za: Leaf 1 = 13.0, Leaf 2 = 12.2; and Pi: Leaf 1 = 12.5, Leaf 2 = 11.7) and showed higher photoprotection (NPQ) than old leaves. Among the studied seagrass species, Z. marina had the highest photosynthetic activity (ETR_max = 15.3), in accordance with the highest production in the field in comparison with the other two seagrass species. The PAM fluorometry technique showed to be effective in determining intraspecific (among‐leaves) and interspecific (among‐species) variation in seagrass photosynthetic activity.  相似文献   

Accretion disc evolution in cataclysmic variables (the 1988 international time project in La Palma     

P. A. Charles  M. J. Arévalo  J. Baruch  R. Biernicowicz  P. Callanan  J. Casares  V. Dhillon  A. Giménez  I. González  R. González  E. Harlaftis  B. Hassall  C. Hellier  P. Johnson  D. Jones  M. Kidger  C. Lázaro  K. Mason  K. Mukai  T. Naylor  V. Reglero  R. Rutten  J. L. Sedano  J. van Paradijs 《Astrophysics and Space Science》1990,169(1-2):147-148

A summary of data collected during a sixty night international campaign devoted to cataclysmic variables is presented.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

Aerosol properties and air pollutants over an urban area   总被引：2，自引：0，他引：2  

Sonoyo Mukai  Itaru Sano  Mutsumi Satoh  Brent N. Holben 《Atmospheric Research》2006,82(3-4):643

For a better understanding of urban aerosols, sun/sky photometry has been undertaken at the Kinki University campus in Higashi-Osaka as a NASA/AERONET station since 2002. A new instrument, the SPM-613D (Kimoto Electric), has been taking measurements at the same site since March 15, 2004. The relationship between aerosol properties obtained from radiometry with AERONET and the SPM measurements is examined. It is found that there is a linear correlation between SPM concentrations and aerosol properties, which indicates that aerosol characteristics can be estimated from SPM data, and vice versa.It is also shown that the air quality of the Higashi-Osaka site is poor due to not only the anthropogenic particles by local emissions, such as diesel vehicles and chemical industries, but also due to the dust particles coming from continental desert areas by large scale climatic conditions.  相似文献