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81.
82.
The enrichment ratio (ER), defined as the ratio of grade of a metal element in a deposit to the crustal abundance of the metal, is proposed for assessing mineral resources. According to the definition, the enrichment ratio of a polymetallic deposit is given as a sum of enrichment ratios of all metals. The relation between ER and the cumulative tonnage integrated from the high ER side of about 4750 deposits in the world is approximated by the combination of three exponential functions crossing at ER values of 16 · 103 and 600. High ER deposits are expected for the commodities Ag, Pb, and Au+Ag, and for epithermal, mesothermal, unconformity-related and vein types. In contrast, low ER deposits are typical for the commodities Cu, Mn, Mo, Ni, and U, and for chemically precipitated, Cyprus, laterite, orthomagmatic, pegmatite, placer, porphyry, and sandstone deposits. The critical ER value of the low ER class (the differential metal amount decreases with decreasing ER in the regions lower than the value) is 250 in all deposits, 610 in W+Mo, 2800 in Pb+Zn and 360 in Au+Ag, 530 in massive sulfides, 160 in the orthomagmatic type, 170 in placers, 220 in the porphyry type, 1900 in the replacement type, 580 in the stratabound type, 3400 in the unconformity-related type, and 1700 in vein type deposits. The frequency proportion determined by a keyword and a commodity provides valuable suggestions for mineral exploration: for example, the exploration target for chromite is a deposit characterized as orthomagmatic, whereas the expected commodity of a newly developed orthomagmatic deposit is chromite. 相似文献
83.
Alan D. Ziegler Junjiro N. Negishi Roy C. Sidle Takashi Gomi Shoji Noguchi Abdul Rahim Nik 《地球表面变化过程与地形》2007,32(13):1947-1970
Measurements of saturated hydraulic conductivity (Ks) and diagnostic model simulations show that all types of logging road/trail in the 14·4 ha Bukit Tarek Experimental Catchment 3 (BTEC3) generate substantial Horton overland flow (HOF) during most storms, regardless of design and level of trafficking. Near‐surface Ks(0–0·05 m) on the main logging road, skid trails and newly constructed logging terraces was less than 1, 2 and 34 mm h?1, respectively. Near‐surface Ks on an abandoned skid trail in an adjacent basin was higher (62 mm h?1), owing to the development of a thin organic‐rich layer on the running surface over the past 40 years. Saturated hydraulic conductivity measured at 0·25 m below the surface of all roads was not different (all <6 mm h?1) and corresponded to the Ks of the adjacent hillslope subsoil, as most roads were excavated into the regolith more than 0·5–1 m. After 40 years, only limited recovery in near‐surface Ks occurred on the abandoned skid trail. This road generated HOF after the storage capacity of the upper near‐surface layer was exceeded during events larger than about 20 mm. Thus, excavation into low‐Ks substrate had a greater influence on the persistence of surface runoff production than did surface compaction by machinery during construction and subsequent use during logging operations. Overland flow on BTEC3 roads was also augmented by the interception of shallow subsurface flow traveling along the soil–saprolite/bedrock interface and return flow emerging from the cutbank through shallow biogenic pipes. The most feasible strategy for reducing long‐term road‐related impacts in BTEC3 is limiting the depth of excavation and designing a more efficient road network, including minimizing the length and connectivity of roads and skid trails. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
84.
Ishimaru Satoko; Arai Shoji; Ishida Yoshito; Shirasaka Miki; Okrugin Victor M. 《Journal of Petrology》2007,48(2):395-433
85.
Nagayoshi Katsuta Masao Takano Shin-ichi Kawakami Shoji Togami Hitoshi Fukusawa Mineo Kumazawa Yoshinori Yasuda 《Journal of Paleolimnology》2007,37(2):259-271
Event-related sedimentary layers, which are deposited occasionally due to volcanic eruptions, earthquakes or heavy rains,
are often contained in the rhythmical sequences of lacustrine and marine sediments. We have developed an analytical method
for separating the sedimentary rhythms and the event layers identified using the scanning X-ray analytical microscope (SXAM)
and obtained sequential profiles of seven elements Al, Si, K, Ca, Ti, Mn, and Fe in the lacustrine sediment from Lake Suigetsu,
Japan. Two types of event layers could be detected from the elemental composition of 33 layers of sediment: three known volcanic
ash layers and 30 clay layers containing 12 turbidites. The recurrence interval of the latter, which may potentially be initiated
and archived by locally important earthquakes, is estimated to be an average of 640 ± 160 years by using Sompi event analysis
(SEA) based on an autoregressive (AR) model. After removing those portions that represented event layers from the elemental
profiles, we obtained event-removed (ER) temporal profiles based on the tephrochronology of the three volcanic ash layers.
The ER temporal profiles of manganese and iron, probably representing the siderite content, showed a millennial-scale variation
in the Holocene that corresponded well with ice-rafting events in the North Atlantic. 相似文献
86.
Dania Tristá-Aguilera Fernando Barra Joaquin Ruiz Diego Morata Oscar Talavera-Mendoza Shoji Kojima Fernando Ferraris 《Mineralium Deposita》2006,41(1):99-105
The Lince–Estefanía stratabound copper deposit in the Michilla district is one of the most important deposits in the Coastal Cordillera of northern Chile and is one of the most representative of this type of deposit. Chalcocite and bornite characterize the main stage of hypogene copper sulfide mineralization. Rhenium and osmium isotopes are used here to constrain the age of hypogene mineralization and the source of osmium contained in these ore minerals. A Re–Os isochron yielded an age of 160±16 Ma (2σ), with an associated initial 187Os/188Os ratio of 1.06±0.09 (mean square of weighted deviates=1.8). This age is consistent with available geochronological data from volcanic rocks that host the mineralization and associated alteration phases. The high initial 187Os/188Os ratio indicates a lower crustal component for the source of Os and, by inference, the Cu sulfides that contain this Os. Late hematite occurs as an isolated phase or, more commonly, is associated with the chalcocite–bornite and supergene chalcocite–covellite associations. Analyses performed on pure hematite indicate a disturbance of the Re–Os system, and hence, this mineral phase is not useful as a Re–Os geochronometer. 相似文献
87.
Nguyen Dinh Duong Shoji Takeuchi 《ISPRS Journal of Photogrammetry and Remote Sensing》1997,52(6):253-260
The image analysis system ASEAN (Advanced System for Environmental ANalysis with Remote Sensing Data) was designed and programmed by a software development group, ImaSOFr, Department of Remote Sensing Technology and GIS, Institute for Geography, National Centre for Natural Science and Technology of Vietnam under technical cooperation with the Remote Sensing Technology Centre of Japan and financial support from the National Space Development Agency of Japan. ASEAN has been in continuous development since 1989, with different versions ranging from the simplest one for MS-DOS with standard VGA 320×200×256 colours, through versions supporting SpeedStar 1.0 and SpeedStar PRO 2.0 true colour graphics cards, up to the latest version named WinASEAN, which is designed for the Windows 3.1 operating system. The most remarkable feature of WinASEAN is the use of algorithms that speed up the image analysis process, even on PC platforms. Today WinASEAN is continuously improved in cooperation with NASDA (National Space Development Agency of Japan), RESTEC (Remote Sensing Technology Center of Japan) and released as public domain software for training, research and education through the Regional Remote Sensing Seminar on Tropical Eco-system Management which is organised by NASDA and ESCAR In this paper, the authors describe the functionality of WinASEAN, some of the relevant analysis algorithms, and discuss its possibilities of computer-assisted teaching and training of remote sensing. 相似文献
88.
Tomoaki Morishita Yoshito Ishida Shoji Arai Miki Shirasaka 《Geostandards and Geoanalytical Research》2005,29(1):107-122
To understand and/or avoid small-scale chemical heterogeneities within geological materials prepared as normal thin sections, in situ multiple trace element determination coupled with the simultaneous microscopic observation of the sample during analysis is preferable. We have examined fifty trace elements in thin (< 30 μm) layers of the NIST SRM 614 and 616 glass reference materials by LA-ICP-MS using different pit diameters and internal standard elements (Ca and Si). Compositional heterogeneities of Tl, Bi, As and Cd were found in NIST SRM 614 and 616 at the spatial resolution of ca. 10 0 μm. Except for these elements, the RSDs of six determinations for most elements were better than 10% in NIST SRM 614 when ablation diameters were < 50 μm. The measured concentrations for most elements in NIST SRM 614 and 616 agree with previous values in the literature at the 95% confidence level with the exception of W and Bi. New LA-ICP-MS data for K, As and Cd are also reported. The results support the view that the latest LA-ICP-MS is a powerful and flexible analytical technique for the determination of multiple ultra-trace element compositions in geological materials prepared as normal thin sections of the type that has been used for polarising optical microscopic observations since the end of the 19th century. 相似文献
89.
Metasomatized harzburgite xenoliths from Avacha volcano as fragments of mantle wedge of the Kamchatka arc: Implication for the metasomatic agent 总被引:6,自引:0,他引:6
Abstract Abundant peridotite xenoliths have been found in pyroclasitics of Avacha (Avachinsky) volcano, the south Kamchatka arc, Russia. They are mostly refractory harzburgite with or without clinopyroxene: the Fo of olivine and Cr/(Cr + Al) atomic ratio of spinel range from 91 to 92 and from 0.5 to 0.7, respectively. They are metasomatized to various extents, and the metasomatic orthopyroxene has been formed at the expense of olivine. The metasomatic orthopyroxene, free of deformation and exsolution, is characterized by low contents of CaO and Cr2 O3 . The complicated way of replacement possibly indicates low viscosity of the metasomatic agent, namely hydrous fluids released from the relatively cool slab beneath the south Kamchatka arc. This is a good contrast to the north Kamchatka arc, where the slab has been hot enough to provide slab-derived melts. High content of total orthopyroxene, 40 vol% on average, in metasomatized harzburgite from Avacha suggests silica enrichment of the mantle wedge, and is equivalent to some subcratonic harzburgite. Some subcratonic harzburgites therefore could have been formed by transportation of subarc metasomatized peridotites to a deeper part of the upper mantle. 相似文献
90.
L.G Austin K Shoji V.K Bhatia F.F Aplan 《International Journal of Mineral Processing》1974,1(2):107-123
The Alyavdin equation for batch grinding data is: where P(χ,t) is the weight fraction less than size χ after grinding time t, c (χ) is constant with t and p is a constant close to one. It is shown that this equation is illogical (except for a single size of feed) unless c (χ) varies with P(χ,0), which makes the equation of little utility. A new empirical equation is developed for finite size intervals: which reduces to the Alyavdin equation for a single size of feed, and which gives consistent computations for any feed size distribution. Techniques are given for determining Ki, γ values from sets of batch grinding data. The values are then used to predict size distributions for other times and other feed size distributions. The equation was quite successful in predicting size distributions in batch milling: (a) providing the feed size distribution was not un-natural, that is, not truncated or (b) if a truncated feed was used, the values of Ki and γ are determined from size distributions of grinding of the same type of feed. Thus, Ki, γ are not, unfortunately, completely independent of the starting feed size distribution. 相似文献