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1.
Separated gold grains from 94 samples of the Vaal Placer, Klerksdorp gold field, South Africa have been analyzed for Au, Ag and Hg. Average gold grain compositions in these samples range from 80 to 95 weight percent Au, 4 to 18 weight percent Ag and 0.5 to 4 weight percent Hg with an average composition around Au 90, Au 8, Hg 2. Individual grains are homogeneous but significant differences exist between gold grains from single small samples and also between average compositions in separate samples. The data do not fit any simple model of gold compositional control by provenance or by metamorphic homogenization. 相似文献
2.
A.E. Kontorovich 《Russian Geology and Geophysics》2009,50(4):237-242
A probabilistic estimate of the global conventional recoverable oil resource was performed based on the concept of the Earth's sedimentary cover as a holistic system. A forecast for global oil production was made for the period till the end of the 21st century. It has been shown that the global oil production will most likely peak at 4.2–4.7 billion tons a year in 2020–2030. For that period, the top oil-producing regions in the world will be the Persian Gulf, West and East Siberia. The upstream sector at that time will turn its focus to the Arctic shelf. Annual oil production could be maintained at a level of 4.2–4.5 billion tons till the late 2040s. 相似文献
3.
The occurrence of potentially hazardous trace elements in five Highveld coals, South Africa 总被引：3，自引：3，他引：3
Permian coals of the southern hemisphere are generally considered to contain lower concentrations of sulfides, halogens, and trace elements when compared to northern hemisphere Carboniferous coals. Few studies have considered the trace element content in South African coals, and little or no work has been published for Highveld coals. Of the nineteen coal fields in South Africa, the Highveld coal field is one of the nine currently producing, and is second largest in terms of production. Five run of mine samples and a high ash middlings product from the Number 4 Lower seam were analyzed, totaling six sample sets. Fourteen trace elements (As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, V, and Zn) were selected for this study based on the global perception that these elements may be hazardous to human health and/or the environment when they are released during coal utilization. Several sample preparation techniques were tested using certified reference materials (SARMs 18, 19 and 20) to determine the most repeatable technique for these coals. The samples were analyzed by ICP-AES and CVAA (Hg only). Microwave digestion proved to be generally unreliable despite the utilization of several different methods. A slurry direct injection method into the ICP-AES provided good correlations with the reference material, but requires further development to enhance the confidence level in this relatively unexplored technique. Samples prepared based on three ASTM standards for the determination of trace elements in coal provided repeatable results in most instances, and were the preparation methods utilized for the Highveld coals.The trace element values determined for the Highveld coals are generally in good agreement with values available in literature for South African coals, with the exception of Hg, Mn and Cr. Hg values reported here are lower, Cr and Mn higher. Results generally agree well with analyses on the same samples conducted by the United States Geological Survey. When considering the global ranges for trace elements, the Highveld range values are within Swaine's range boundaries with the exception of Cr. Compared to the cited global average values for the fourteen trace elements determined, the values obtained for the Highveld coals generally fall below or well below these average values, with the exception of Cr and Mn. Concentrations of Cd and Cu are lower compared to global average values, and As, Mo, Pb, Se, Sb, and Zn can be considered low to very low. Arsenic is ten times lower compared to typical USA values. Concentrations of Co and Ni are similar to global averages, with V and Hg being very slightly higher. The middlings samples reported higher concentrations of most elements, related to the higher ash content of these samples. Of interest, the chalcophile elements determined are all depleted in the Highveld coals compared to global averages, and the siderophile elements are enriched or comparable to global averages.Risk-based health studies in the USA on coals with similar or higher Hg and significantly higher As contents have not reported negative health effects, and therefore it could be assumed that the mobilization of these trace elements from the five Highveld coals are unlikely to cause human health problems. Work is ongoing to determine the modes of occurrence of these HAPs and to address the partitioning behaviors and speciation states of these elements during coal utilization. 相似文献
4.
利用地震资料进行古地形恢复方法研究及应用 总被引：3，自引：0，他引：3
FENG Yan-zhuang )) SONG Wei-qi ) LIU Shi-you ) ) Nanjing Institute of Geology Palaeontology Chinese Academy of Sciences Nanjing ) Chunliang Oil Production of Shengli Oilfield Company SINOPEC Binzhou ) College of Geo-resources Information China University of Petroleum Dongying 《地层学杂志》2007,(Z2)
在讨论分析地质方法进行古地形恢复方法的基础上,研究了利用地震资料进行古地形恢复的技术方法。针对古地形恢复的几个技术关键问题:等时基准面的选取、压实校正系数的求取及差异构造校正进行讨论分析。综合利用各种基本地质成果,同时结合古构造、现今构造特点等,确定出研究区背景校正经验系数为0.2。就研究的方法对实际研究区目的层段进行了古地形的恢复。 相似文献
5.
地震波传播的褶积微分算子法数值模拟 总被引：2，自引：0，他引：2
为了解决地震波场数值模拟中的速度与精度的匹配及局部信息与全局信息的耦合等问题, 该文借助新推出的基于Forsyte广义正交多项式的褶积微分算子, 将计算数学中的Forsyte多项式褶积微分算子应用到地震波传播的数值模拟中.复杂非均匀介质模型数值模拟结果说明了该方法的可行性和优越性.该方法同时具有广义正交多项式褶积微分算子的高精度和有限差分短算子算法的高速度.通过对算子长度的调节及算子系数的优化, 可同时兼顾波场解的全局信息与局部信息. 相似文献
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The most generally used method for estimating the basin-wide sequence and scaling of first and last occurrences, based on
their occurrence in local sections, is Shaw’s graphic correlation method. The key step in this method is the determination
of the line of correlation (LOC), which represents the best estimate of the correlation between two local sections, or between
a local section and a composite standard. In general, available techniques for fitting the LOC for multiple sections are tedious,
subjective, or computationally expensive. A new method employing genetic algorithms can dramatically reduce the effort involved
in determining the LOC and produces stable biostratigraphic correlations and composite range charts objectively and efficiently.
Genetic algorithms are an artificial intelligence technique that excels in locating the optimum solution from a large number
of alternative choices. In the case of the LOC, the alternative choices are the number of line segments comprising the complete
line and the positions of each segment’s beginning and end points. For a given number of segments, a wide range of alternative
LOCs can be rapidly evaluated and a potential optimum fit determined. It is also possible to estimate the point when no further
refinement of the fit by adding line segments is necessary. Genetic algorithms can also be applied to other methods for quantitative
biostratigraphy. 相似文献
9.
In the paper, a novel inversion approach is used for the solution of the problem of factor analysis. The float-encoded genetic algorithm as a global optimization method is implemented to extract factor variables using open-hole logging data. The suggested statistical workflow is used to give a reliable estimate for not only the factors but also the related petrophysical properties in hydrocarbon formations. In the first step, the factor loadings and scores are estimated by Jöreskog’s fast approximate method, which are gradually improved by the genetic algorithm. The forward problem is solved to calculate wireline logs directly from the factor scores. In each generation, the observed and calculated well logs are compared to update the factor population. During the genetic algorithm run, the average fitness of factor populations is maximized to give the best fit between the observed and theoretical data. By using the empirical relation between the first factor and formation shaliness, the shale volume is estimated along the borehole. Permeability as a derived quantity also correlates with the first factor, which allows its determination from an independent source. The estimation results agree well with those of independent deterministic modeling and core measurements. Case studies from Hungary and the USA demonstrate the feasibility of the global optimization based factor analysis, which provides a useful tool for improved reservoir characterization. 相似文献
10.
针对流量资料极短时传统年径流频率分析方法——适线法不再适用的问题,分析了基于水文过程,由影响径流形成的因子推求年径流频率的一次二阶矩法的可行性,并讨论其在无流量资料流域应用中所存在的问题与解决方法。以江西省20个流域为研究对象,采用无参数Schreiber方程与单参数Fu-Zhang方程的水量平衡式作为年降雨—径流模型,结果表明:①一次二阶矩法的分析结果与实测年径流的经验频率较为吻合;②无流量资料流域中,忽略土壤含水量年间变化的作用,Fu-Zhang模型的分析结果比Schreiber模型好;③无流量资料流域中,Fu-Zhang模型中的参数ω可采用反距离权重法估计。 相似文献
11.
成都地区隐伏构造元素的地球化学特征 总被引：7，自引：0，他引：7
通过对成都市多目标地球化学资料的研究，认为深层样的Hg,W,Au,Sc和浅层样的Hg,W,Au,B可以指示隐伏构造，而深层样的指示作用优于浅层样，在深层样反映好的隐伏构造可能与地热发育有关。低温热液、农业有毒元素和油气指示元素指标在隐伏构造上表明明显。在今后多目标地球化学测量中，必需进行深层样的采样。 相似文献
12.
对安徽玉屏山、梅家洼１：５万区域金异常,开展了以Ｈｇ测量圈定异常区的构造格架,以Ａｕ的野外快速分析方法追踪评价异常的工作。迅速查明了区内断裂构造布局,Ａｕ的浓集地段。经探槽工程揭露发现了Ａｕ的矿化体,证明Ａｕ,Ｈｇ野外方法配合评价金异常,寻找金矿的技术是有效的。 相似文献
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Sewage sludges are potential targets for economic extraction of Au because of the documented Au content of sewage sludges worldwide, which are of the order of some ore deposits currently mined for Au. The sewage of Melbourne, Australia, was stockpiled in large, closed, lagoonal tanks from 1898 until 1980. Reeves, Plimer and Foster, 1999, have conducted, and published, an extensive and exhaustive study of the Werribee sewage reserves utilising RNAA, INAA, GFAAS, ICPMS, and FLAAS to determine 31 elements, including Au, Ag, Sb, As, Cd, Hg, Zn, Cu, and Pb. The study was initiated to determine Au, Ag and other metal variations in both space and time and to investigate the economics of chemical extraction of the precious metals. A total of 149 samples from over 50 hand-auger drillholes to a depth up to 4m were analysed from the stockpiles, with Au assays yielding remarkably consistent results. Average grades of 0.77 g/t Au and 18.8 g/t Ag have been documented for a measured resource of 770,000 m3. Laboratory-based extractive metallurgy of the Werribee sludges has demonstrated that Au, Ag, and Zn can be removed with relative ease by heap-leaching using modified conventional technology, albeit with prohibitive reagent consumption. The extraction of the precious metals also results in the variable removal of contaminant metals such as Cd, As, Sb, Hg and Cr which may render the sludges fit for sale as agricultural fertiliser, provided organic pollutants and pathogenic organisms are below governmental environmental protection limits. 相似文献
15.
Singer Donald A. 《地球科学》2011,36(2):201-208
For national or global resource estimation of frequencies of metals, a lognormal distribution has commonly been recommended but not adequately tested. Tests of frequencies of Cu, Zn, Pb, Ag, and Au contents of 1 984 well-explored mineral deposits display a poor fit to the lognormal distribution. When the same metals plus Mo, Co, Nb2O3, and REE2O3 are grouped into 19 geologically defined deposit types, only eight of the 73 tests fail to be fit by lognormal distribution, and most of those failures are in two deposit types suggesting a problem with those types. Estimates of the mean and standard deviation of each of the metals in each of the deposit types are provided for modeling. 相似文献
16.
西南大面积低温成矿域：研究意义、历史及新进展 总被引：8，自引：0，他引：8
我国西南大面积低温成矿域是目前世界上公认的2个大面积低温成矿域之一,其面积之大（约100万km^2）、包含的矿种之多（Au、Hg、sb、As、P、Pb—Zn、Ag以及萤石、冰洲石、水晶、分散元素等）、矿床组成和组合之复杂全球罕见,是我国重要的Au、Hg、sb、As、Pb—zn、Ag以及多种分散元素生产基地。国内外学者对该成矿域进行了近30年的研究工作,取得了大量高水平研究成果,同时也存在许多有待深人研究的科学问题。本文回顾了我国西南大面积低温成矿域的研究历史,总结了各研究阶段的主要研究内容、主要研究成果和存在的主要科学问题,同时介绍了近年来我国西南大面积低温成矿域研究新进展。 相似文献
17.
The main geochemical biological and reworking metallogenic models of the Lanmuchang independent Tl deposit 总被引：3，自引：0，他引：3
Thallium(Tl)is dispersed element and it seldom occurs in the form of independent minerals.So the element is hard to form any independent deposit.The world annual production of Tl is about 13 ton.most of which is recovered as by-product from non-ferrous metal metallurgical products.Reported in this paper is the only large-sized independent tl deposit in the world,of which the tl ores can be mined,ore-dressed and smelted independently.Bio-enrichment and hydrothermal reworking are the two important metallogenic mechanisms of this Tl deposit.This paper will give a discussion to the Lanmuchang Tl deposit in the following respects including its geolgical characteristics,element association of Tl,Hg,As and Au and W,sulfur isotopic composition.involvement of hallogens in metallogenesis and the metallogenic models. 相似文献
18.
油气成藏期断层古侧向封闭能力的强弱对于油气的聚集和分布有着重要的影响,目前尚无有效的评价方法用于定量分析断层古侧向封闭性,并且在利用断层侧向封闭油气SGR(Shale Gouge Ratio)下限方法预测油柱高度过程中,发现断层侧向封闭油气能力与油气分布呈现部分不吻合现象,即井在预测范围之内,但是该井却不含油气.经过深入研究表明:这种现象可能是由于在油气成藏期断层古侧向封闭能力弱(达不到侧向封闭油气下限)造成的.因此,在断层侧向封闭油气SGR下限方法的基础上,通过恢复油气成藏期的古地层厚度、断层古断距、古泥质含量曲线,建立一套断层古侧向封闭性的评价方法,并以冀中坳陷文安斜坡文13断圈为例,利用断层古侧向封闭性评价法对断圈的古侧向封闭能力进行定量评价.结果表明:文13断圈在油气成藏期侧向封闭油气高度为0 m,与井试油结论相吻合,表明该方法用于定量评价断层古侧向封闭性是可行的,对于准确评价断圈封闭油气能力、降低断圈油气钻探风险以及丰富和完善断层侧向封闭理论均具有实践和理论意义. 相似文献
19.
《Applied Geochemistry》2002,17(1):21-28
A simulated stream sediment bed was constructed in a laboratory to determine whether dissolved Hg could be transported through sediment and deposited as amalgam on Au grains. Metallic Hg was placed in a sump at one end of a tank filled with gravel (quartz sand, granules, and pebbles), and Au grains were buried in the gravel at the other end. Water was circulated in a continuous closed loop over the Hg and through the gravel that included the Au grains for more than 850 days. The Hg content of the water increased from nil at the beginning to approximately 0.5 μg/l after approximately 22 days. The Hg content on the rims of Au grains went from nil to approximately 0.2 wt.% over 22 days reaching a maximum 0.48 wt.% Hg after 14 days. Subsequent measurements indicated a persistent decrease of the maximum Hg on Au grains to ⩽0.19 wt.% Hg at 552 days and to ⩽0.05 wt.% at 851 days. Deposition of Hg on the Au grains indicates that amalgams can form without actual contact of Hg on Au in stream sediments. Why Hg first deposited on Au and then dissolved from the Au is unknown, but a paucity of microbiota early in the experiment and subsequent development of microbiota that could facilitate dissolution of Hg is suspected. The simulated Au placer, with its coarse sediments and free water flow, is analogous to streams that have measurable (>0.2 μg/l) Hg in the water and no amalgams on Au grains within the sediments. An example of a Au mining region with similar water concentrations of Hg would be the Amazon Basin, although information on the presence of amalgam rims on Au grains is lacking, as for most regions. Lower but still measurable (⩽0.55 μg/l Hg) concentrations of Hg in stream water and a lack of amalgams on Au grains occur in Au placers near Talladega, Alabama. The opposite case would be streams with less-than-measurable (<0.2 μg/l) Hg in the water but amalgams on Au grains, where conditions are less aerated and Hg would be more likely to remain in the substrate. This situation is analogous to Au placers in the North Carolina Piedmont (South Mountains, Robbins, and High Point), where Hg is not detected in stream water (<0.2 μg/l) and Au grains possess amalgamated rims. Mercury concentrations in the air over the tank (41–465 ng/m3) varied inversely with barometric pressure (1012–1033 mb @ SL), with a positive response to light, which is consistent with the work of other researchers. The positive photo effect on Hg concentration in the air was obvious at lower barometric pressures (∼ave. 1015 mb @ SL) but subdued or nonexistent at higher barometric pressures (∼ave 1025 mb @ SL). Mercury concentrations were as much as 3 times as high during daylight hours compared to nighttime concentrations over the tank at relatively low barometric pressures. The Hg content of the water remained relatively low (<1 μg/l) through the first 200 days and then abruptly increased where it oscillated between 4 and 17 μg/l to the end of the experiment (851 days). Meanwhile, the rate of loss of Hg from the tank averaged approximately 1 μg/cm2 day with a high of 1.54 μg/cm2 day. Apparently the release of Hg is little affected by the Hg content of the water, as long as a minimum amount of Hg is maintained in the water. The release rate of Hg from the tank experiment is approximately 10 times higher than those reported by other workers but probably represents a maximum due to ideal, oxidizing, high water flow conditions in the tank. 相似文献