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Abdullah Arik 《Geotechnical and Geological Engineering》1990,8(4):305-318
Summary Reliable ore reserve estimates for deposits with highly skewed grade distributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods.This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters. 相似文献
2.
This paper presents a modified ordinary kriging technique referred to as the “Area Influence Kriging” (AIK). The method is a simple and practical tool to use for more accurate prediction of global recoverable ore resources in any type of deposit. AIK performs well even in deposits with skewed grade distributions when the ordinary kriging (OK) results are unreasonably smooth. It is robust and globally unbiased like OK. The AIK method is not intended to replace OK, which is a better estimator of the average grade of the blocks. Rather it aims to complement OK with its excellent performance in predicting recoverable resources that have been the major pitfalls of OK in many resource estimation cases. The paper details the methodology of AIK with a couple of examples. It also reports the results from its application to a gold deposit. 相似文献
3.
The Inkaya Cu-Pb-Zn-(Ag) mineralization, located about 20 km west of the Simav (Kütahya-Turkey), is situated in the northern part of the Menderes Massif Metamorphics. The mineralization is located along an E-W trending fault in the Cambrian Simav metamorphics consisting of quartz-muscovite schist, quartz-biotite schist, muscovite schist, biotite schist and the Ar?kayas? formation composed of marbles. Mineralized veins are 30–35 cm in width. The primary mineralization is represented by abundant galena, sphalerite, chalcopyrite, pyrite, fahlore and minor amounts of cerussite, anglesite, digenite, enargite, chalcocite, covellite, bornite, limonite, hematite and goethite with gangue quartz. Fluid inclusion studies on the quartz samples collected from the mineralized veins indicate that the temperature range of the fluids is 235°C to 340°C and the salinities are 0.7 to 4.49 wt. % NaCl equivalent. The wide range of homogenization temperatures indicates that two different fluid generations were trapped in quartz. Sulfur isotope studies of the sulfide minerals showed that all of the δ 34S values are between ?2.1 and 2.6 per mil. These values are a typical range for hydrothermal sulfide minerals that have sulfur derived from a magmatic source. Pyrite-galena and pyrite-chalcopyrite sulfur isotope fractionation is consistent with an approach to isotopic equilibrium, and calculated temperatures are 254.6 and 277.4°C for pyrite-galena and 274.7°C for pyrite-chalcopyrite. The microthermometric data and sulfur isotope thermometry indicate the existence of a hydrothermal fluid that circulated along the fault crossing the Simav metamorphics and Ar?kayas? formation. Fluid inclusion and sulfur isotope thermometry can be used in combination with ore petrographical and geological information to provide site-specific targets for meso-hypothermal metal concentrations. 相似文献
4.
Fetullah Arik 《Journal of the Geological Society of India》2012,80(6):855-868
Gözeçukuru As-Sb-Pb-Zn mine is located 1.2 km NW of Sahin village and 22 km west of Kütahya in NW Turkey. The aim of this study is to explain the genetic characteristics of the As-Sb deposits by using multivariate statistical analysis methods. Low-grade metamorphic rocks of the upper Paleozoic Sahin Formation occur as the basement of the study area. Cenozoic volcano-sedimentary units (Tavsanli volcanites and Emet Formation) overlie the Sahin Formation unconformably. The mineralization occurs mainly as veins and partly as disseminations and fillings of interstices in the rhyodacitic and rhyolitic tuffs of Tavsanli Volcanics. Common primary ore minerals are stibnite, realgar, galena, sphalerite, pyrite and arsenopyrite, and secondary minerals are orpiment, senarmontite and valentinite. Barite is the dominant gangue mineral, with a small amount of quartz, calcite and dolomite. Average As, Sb, Pb, Zn and Ba concentrations in the samples from the study area are 6.04%, 4938 ppm, 4589 ppm, 1.17% and 10.36 % respectively. Three significant groups appear in the cluster analysis of ore samples. First group consists of Pb-Ag and Zn-Cd. The second group consists of Sb-Tl-Hg and As. The last group is the Ba-Sr. There are three significant factors in the factor analysis. First factor reflects the formation of primary sulphide minerals, the second factor represents the formation of low temperature sulphide and sulphosalt minerals and the last factor depicts interstices-filling mineralization. Average homogenization temperature of the fluid inclusion in barites is 221 °C. Geological, petrographical and geochemical data suggest that the Gözeçukuru As-Sb deposit was formed under epithermal conditions. 相似文献
5.
In headwater catchments, streamflow recedes between periods of rainfall at a predictable rate generally defined by a power–law relationship relating streamflow decay to streamflow. Research over the last four decades has applied this relationship to predictions of water resource availability as well as estimations of basin‐wide physiographic characteristics and ecohydrologic conditions. However, the interaction of biophysical processes giving rise to the form of these power–law relationships remains poorly understood, and recent investigations into the variability of streamflow recession characteristics between discrete events have alternatively suggested evapotranspiration, water table elevation, and stream network contraction as dominant factors, without consensus. To assess potential temporal variability and interactions in the mechanism(s) driving streamflow recession, we combine long‐term observational data from a headwater stream in the southern Appalachian Mountains with state and flux conditions from a process‐based ecohydrologic model. Streamflow recession characteristics are nonunique and vary systematically with seasonal fluctuations in both rates of transpiration and watershed wetness conditions, such that transpiration dominates recession signals in the early growing season and diminishes in effect as the water table elevation progressively drops below and decouples with the root zone with topographic position. As a result of this decoupling, there exists a seasonal hysteretic relationship between streamflow decay and both evapotranspiration and watershed wetness conditions. Results indicate that for portions of the year, forest transpiration may actively compete with subsurface drainage for the same water resource that supplies streamflow, though for extended time periods, these processes exploit distinct water stores. Our analysis raises concerns about the efficacy of assessing humid headwater systems using traditional recession analysis, with recession curve parameters treated as static features of the watershed, and we provide novel alternatives for evaluating interacting biological and geophysical drivers of streamflow recession. 相似文献
6.
Abdullah Arik 《Mathematical Geology》2002,34(7):783-796
This paper presents a modified ordinary kriging technique referred to as the Area Influence Kriging (AIK). The method is a simple and practical tool to use for more accurate prediction of global recoverable ore resources in any type of deposit. AIK performs well even in deposits with skewed grade distributions when the ordinary kriging (OK) results are unreasonably smooth. It is robust and globally unbiased like OK. The AIK method is not intended to replace OK, which is a better estimator of the average grade of the blocks. Rather it aims to complement OK with its excellent performance in predicting recoverable resources that have been the major pitfalls of OK in many resource estimation cases. The paper details the methodology of AIK with a couple of examples. It also reports the results from its application to a gold deposit. 相似文献
7.
Quantitative reconstruction of lake conductivity in the Quaternary of the Near East (Israel) using ostracods 总被引：2，自引：1，他引：1
Steffen Mischke Ahuva Almogi-Labin Reuven Ortal Arik Rosenfeld Markus J. Schwab Ian Boomer 《Journal of Paleolimnology》2010,43(4):667-688
Surface sediments, water samples and environmental data from 37 lakes, ponds and streams in Israel were analysed to determine
the main variables controlling ostracod species distributions. Multivariate statistical analysis revealed that the greatest
amounts of variation in the distribution of the ostracod taxa among the 37 water bodies were explained by the host water δD
value (12.9%), water temperature (11.0%), mean January air temperature (10.5%), electrical conductivity (9.5%), and the Mg
and NO3 concentrations (7.8 and 7.1%, ion concentrations as % of the anions or cations). A supplementary data set comprising ostracod
species composition and electrical conductivity readings for 24 water bodies was available from previous research and was
merged with the 37 samples data set to develop an ostracod-based transfer function for the reconstruction of electrical conductivities.
A weighted averaging partial least squares regression (WA-PLS) provided the best results with a relatively high coefficient
of determination (r
2) between measured and inferred electrical conductivity values of 0.73, a root mean square error of prediction of 0.13 (13.4%
of gradient length) and a maximum bias of 0.24 (23.9% of gradient length), as assessed by leave-one-out cross-validation based
on 56 water bodies. The application of the EC transfer function onto (sub)fossil ostracod assemblages from Holocene and early
to mid Pleistocene lake sediments provided EC values consistent with other proxies and demonstrated that Quaternary ostracod
assemblages from subaqueous sediments can now be used to trace the hydrological history of water bodies in the Near East.
A better understanding of past hydrological conditions in response to the natural climate variability is crucial in regions
that face restricted water resources and rising demands in times of rapid climate and environmental change. 相似文献
8.
Restricted kriging for mixture of grade models 总被引：2，自引：0，他引：2
A modified type of kriging, referred to as restricted kriging (RK), is proposed in this study. The method incorporates constraints on different grade classes to restrict the influence of the samples having different likelihoods in estimation. RK is motivated by the estimation of mineral reserves when grades have highly skewed distributions. Ordinary kriging tends to produce an overly smoothed interpolated surface by underestimating high grades and overestimating low grades. The fact that ordinary kriging gives a uniform prior treatment to all samples independent of their values is a major factor associated with this smoothing effect. The new approach differentiates each grade portion by preselected cutoffs. RK is developed for a single cutoff and then extended into a general form for any finite number of cutoffs. Restricted cokriging (RCK) is also formulated to simultaneously estimate a set of random functions with restriction conditions. Methods are suggested for determination of the probabilities of occurrence of different grade portions. Finally, the new approach is demonstrated on a case study of an epithermal gold deposit. 相似文献
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