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1.
The dual geochemical character of paragenesis and fractionation between gold,arsenic and antimony in micro-disseminated gold deposits in southwestern Guizhou is discussed in terms of spatial distribution of independent deposits,lateral and vertical enrichment,mineralization stage and factor and correlation analyses.Thermodynamic calculations of solubility and speciation of gold and antimony minerals indicate that gold is transported in hydrothermal solution as Au(HS)-2 and antimony is mainly as Sb(OH)03 although HSb2S-4 may be of increasing importance in acid environment at low temperatures during the late stage of mineralization.Changes in physicochemical conditions hold the key to the association and fractionation between gold and antimony.Gold and antimony response differently to physicochemical variations because they are distinct from each other in soluble speciation and mineral solubility,leading to precipitation at different times and localities during hydrothermal evolution. 相似文献
2.
《Acta Geochimica》2021,(2)
One of the essential tasks accelerate the decision-making process in mineral exploration projects is ranking anomalous areas.In this study,we used fourteen geologic maps(at scale 1:100,000) in areas where systematic geochemical explorations were conducted in the Fariman-Kashmar axis in northeast Iran to conduct the anomaly ranking.On all these maps,samples were consistently prepared to be analyzed through statistical and geostatistical methods.At first,anomaly separation was carried out by fractal methods that resulted in the detection of 308 anomalous samples in 128 areas.These samples were classified into three groups of first,second,and thirdorder anomalies,whose number of anomalous samples were calculated based on this ranking technique.Three factors,including the average concentration of each anomaly,its surface area,and the number of its samples,were used to rank the areas.According to this technique,the maximum anomaly score obtained was 172 for the Taknar area,and the minimum score was 3 for several areas.To validate the ranking results,some exploration operations were carried out in some of these anomalous areas in which mining operations started later.Several significant gold anomalous areas were introduced,which is considered an important result of this study. 相似文献
3.
This paper reports the application of weights-of-evidence, artificial neural networks, and fuzzy logic spatial modeling techniques
to generate prospectivity maps for gold mineralization in the neighborhood of the Amapari Au mine, Brazil. The study area
comprises one of the last Brazilian mineral exploration frontiers. The Amapari mine is located in the Maroni-Itaicaiúnas Province,
which regionally hosts important gold, iron, manganese, chromite, diamond, bauxite, kaolinite, and cassiterite deposits. The
Amapari Au mine is characterized as of the orogenic gold deposit type. The highest gold grades are associated with highly
deformed rocks and are concentrated in sulfide-rich veins mainly composed of pyrrhotite. The data used for the generation
of gold prospectivity models include aerogeophysical and geological maps as well as the gold content of stream sediment samples.
The prospectivity maps provided by these three methods showed that the Amapari mine stands out as an area of high potential
for gold mineralization. The prospectivity maps also highlight new targets for gold exploration. These new targets were validated
by means of detailed maps of gold geochemical anomalies in soil and by fieldwork. The identified target areas exhibit good
spatial coincidence with the main soil geochemical anomalies and prospects, thus demonstrating that the delineation of exploration
targets by analysis and integration of indirect datasets in a geographic information system (GIS) is consistent with direct
prospecting. Considering that work of this nature has never been developed in the Amazonian region, this is an important example
of the applicability and functionality of geophysical data and prospectivity analysis in regions where geologic and metallogenetic
information is scarce. 相似文献
4.
空间自相似性与地球物理和地球化学场的分解方法 总被引：8，自引：2，他引：8
场的分解是应用勘查地球物理和地球化学数据所必不可少的数理处理工作，这项工作往往是为了分解不同的场来研究和了解不同的地质以及相应的地质过程，比如划分不同岩石类型以及识别和圈定矿化蚀变睡.闰定地质过程所产生的同类型的地质体并不简单地对应于相同的场值和频率，场的分布特征往往还与地质体的几何形态，。埋藏深度以及与其周围地质体的相对差异有关。然而，由于地质过程往往具有多期次和空间相关性等特点，所产生的地质体或者相应的场往往会呈现空间自相似性或统计自相似性。这种自相似性可以帮助分解不同地质过程所产生的同类地质体，文中所介绍的多重分形（multifractal)滤波方法（S－A）根据场的能谱分布的不同空间自相似性形成不规则甚至分形滤波器，并将场分解为不同同的组份，如局部异常和背景场，应用该方法对多处地球化学和地球物理场的处理结果表明，该方法对区分与矿有关的局部异常与背景场是很有效的，对加拿大NOVA SCOTIA省西南部航空放射性铀钍钾（U-Tn-K)数据处理所分解的异常对反映岩体中与铀－钨－锡（U－W－Sn)矿化有关的围岩饰变具有明显的效果。 相似文献
5.
《中国科学:地球科学(英文版)》2021,(9)
The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China. The mineralization shows common characteristics in their tectonic setting, ore-forming fluid and metallogenic system. Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation, both of which consume sulfur in the oreforming fluids. The escape of H_2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold, but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite. Quartz solubility shows strong dependence on temperature, pressure, and CO_2 content. The dependence of quartz solubility on pressure is weak at low temperatures, and progressively stronger at higher temperatures.Similarly, the temperature dependence of quartz solubility is relatively low at low pressures, but becomes gradually stronger at high pressures. The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the oreforming veins and the formation mechanism of different types of quartz veins. The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins. Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale. The trace elements(mainly the coupling of As-and Au-rich belt) and sulfur isotope composition also display a certain regularity. The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata, while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids. There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits. Water/rock reaction(sulfidation) was the main ore-forming mechanism of early gold mineralization, forming relatively high fineness gold, while significant pressure drop in the shallow part accompanied by fluid phase separation promoted the late gold mineralization, forming low fineness gold. Under cratonic destruction setting, dehydration of the amphibolite and granulite facies metamorphic lower-crust resulted in the formation of Au-CO_2-rich ore-forming fluids, which rose along the deep fault and secondary structure, and formed the largescale fault-controlled gold deposits in Jiaodong. 相似文献
6.
本文以标度变换法、相关函数法、最小二乘法分别计算时间分维D_t、空间分维D_s、强度分维D_m(b值),系统清理了云南地区1976年以来6级以上强震前时空强分维的变化特征,表明强震前的降维现象是普遍存在的,但各次强震前的异常三要素又表现出复杂的多样性。结果还表明,强震前小震活动在时间分布上的明显不均匀性主要表现在强震孕育地区,而在空间分布上的明显不均匀性却主要表现在强震孕育的外围地区。 相似文献
7.
为了探索播卡深部的找矿空间及找矿方向,本文在播卡矿区钻孔样品分析数据的基础上,研究了播卡金矿床的元素富集规律、元素组合、元素异常在地表及空间的分布特征,建立了播卡金矿的原生晕分带模型、地球化学勘查模式,提出了不同深度的原生晕判别指标,在此基础上对播卡金矿的深部隐伏矿体进行了预测。结果显示播卡金矿的深部及邻区具有寻找隐伏矿体的良好前景。 相似文献
8.
Widely-distributed lamprophyres in the Laowangzhai gold deposit were associated closely with gold ores. Phlogopite40Ar/39Ar dating suggests that the emplacement age of lamprophyric magma ranges from (30.8±0.4) to (34.3±0.2) Ma, and gold mineralization took place at (26.4±0.2) Ma. PGE geochemical tracing indicates that gold in the gold deposit did not come from the primitive lamprophyric magma. The tempo-spatial paragenesis between lamprophyres and mesothermal gold deposits along the Jinsha-Red River belt may be attributed to the fact that they formed in the same tectonic setting.
相似文献9.
The fractal properties of topography as controlled by the interactions of tectonic,lithological, and geomorphological processes 
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下载免费PDF全文 Landscape topography widely exhibits fractal structure. Because of the complexity of relief geometry this structure is not homogeneous in space, and the study of its spatial characteristics represents a powerful method for investigating the interrelationships between landforms and underlying processes. We explore these interrelationships using the digital elevation model (DEM) of an area located in central Italy, where landscape topography is strongly linked to its geological evolution, being characterized by alternating intermountain basins and mountain ranges trending NW–SE. A modified version of the method based on the standard deviation of relief elevations is used to evaluate the fractal parameters of relief after tiling the DEM in spatial units characterized by homogeneous fractal geometry, and statistical methods in conjunction with spatial analysis techniques are applied to the resulting terrain datasets. Both the lowest and (to a lesser extent) the highest values of fractal dimension are found to follow the ridge‐and‐valley trend. Low fractal dimension is observed in the mountain ranges characterized by massive strata of limestone, and along the fault scarps defining the contact between the intermountain basins and the surrounding slopes, where sediment deposition prevails. High fractal dimension is observed in regions characterized by highly erodible terrigenous lithology, and in areas where tectonic activity favors erosional processes mainly by rivers. The analysis of the (fractal) power law parameters also suggests that each major lithological complex has its own characteristic fractal signature. These results provide new insights into the link between the fractal properties of topography and the tectonic, lithological, and geomorphological features of the area, and show that the analysis approach proposed is useful to depict key aspects about the geomorphological and geological setting of an area, using only a DEM. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
10.
在模糊集理论与分形理论的基础上,引进了模糊分维的概念;给出了模湖容量维D0与模糊关联维D2的定义与确定方法;讨论了模糊分维与常用的分维（清晰分维）的关系.给出了模糊分维在地震研究中的应用结果: 1.根据模糊容量维D0随时间的上升趋势变化,可以划分出大地震活动的高潮期;由模糊容量维D0与模糊关联维D2随时间变化的曲线,可以分析识别大地震前的中长期前兆异常. 2.根据模糊容量维D0随空间和时间的变化,可以划分出未来大震所在的地区,并可发现大震前数年D0呈现增大或减小的趋势. 3.根据前兆数据的模糊时间分维D0随时间的变化,可以发现大地震的短期前兆异常. 相似文献
11.
Songtao Li Yong Xia Jianzhong Liu Zhuojun Xie Qinping Tan Yimeng Zhao Minghua Meng Lijin Tan Rong Nie Zepeng Wang Guanghong Zhou Haiyan Guo 《Acta Geochimica》2019,(4):587-609
The newly discovered Baogudi gold district is located in the southwestern Guizhou Province,China,where there are numerous Carlin-type gold deposits.To better understand the geological and geochemical characteristics of the Baogudi gold district,we carried out petrographic observations,elemental analyses,and fluid inclusion and isotopic composition studies.We also compared the results with those of typical Carlin-type gold deposits in southwestern Guizhou.Three mineralization stages,namely,the sedimentation diagenesis,hydrothermal(main-ore and late-ore substages),and supergene stages,were identified based on field and petrographic observations.The main-ore and late-ore stages correspond to Au and Sb mineralization,respectively,which are similar to typical Carlin-type mineralization.The mass transfer associated with alteration and mineralization shows that a significant amount of Au,As,Sb,Hg,Tl,Mo,and S were added to mineralized rocks during the main-ore stage.Remarkably,arsenic,Sb,and S were added to the mineralized rocks during the late-ore stage.Element migration indicates that the sulfidation process was responsible for ore formation.Four types of fluid inclusions were identified in ore-related quartz and fluorite.The main-ore stage fluids are characterized by an H2O–NaCl–CO2–CH4±N2system,with medium to low temperatures(180–260℃)and low salinity(0–9.08%NaCl equivalent).The late-ore stage fluids featured H2O–NaCl±CO2±CH4,with low temperature(120–200℃)and low salinity(0–7.48%Na Cl equivalent).The temperature,salinity,and CO2and CH4concentrations of ore-forming fluids decreased from the main-ore stage to the late-ore stage.The calculated δ^13C,d D,and δ^18O values of the ore-forming fluids range from-14.3 to-7.0%,-76 to-55.7%,and 4.5–15.0%,respectively.Late-ore-stage stibnite had δ^34S values ranging from-0.6 to 1.9%.These stable isotopic compositions indicate that the ore-forming fluids originated mainly from deep magmatic hydrothermal fluids,with minor contributions from strata.Collectively,the Baogudi metallogenic district has geological and geochemical characteristics that are typical of Carlin-type gold deposits in southwest Guizhou.It is likely that the Baogudi gold district,together with other Carlin-type gold deposits in southwestern Guizhou,was formed in response to a single widespread metallogenic event. 相似文献
12.
Summary of technology for a comprehensive geophysical exploration of gold mine in North China Craton
《中国科学:地球科学(英文版)》2021,(9)
The North China Craton is the oldest continental block, and has suffered from large-scale lithospheric thinning and destruction, which in turn led to gold deposits in northern China. The decratonic gold deposits in the North China Craton became the most important gold deposits in China, and geophysical methods are key means to detect and discover gold deposits there. In this paper, based on the geological and petrophysical characteristics of the North China Craton, the geological model of the decratonic gold deposits is transformed into a geophysical model. At present, two methods of geophysical exploration of decratonic gold deposits are in use: rapid and efficient exploration on the scale of the ore concentration area, and large depth exploration on the scale of the deposit area. In detail, the airborne electromagnetic,magnetic and gravity methods are used to detect the shallow(1,500 m) anomaly area on the scale of the ore concentration area.Through the ground-controlled source electromagnetic and ground magnetotelluric methods, explorations for targets at significant depth(5,000 m) are carried out in the mining area. Then, taking the Liaodong ore concentration area as an example,geophysical methods are used to discover two prospecting areas around the Jianshanzi Fault in the Qingchengzi ore concentration area, Baiyun-Xiaotongjiapuzi deep prospecting area, and Qingchengzi deep prospecting area. Next, three prospecting areas are delineated around the Jixingou Fault in the Wulong mining area, Wulong deep prospecting area, Weishagou deep prospecting area, and Chang'an deep prospecting area. The anomalies in the ore concentration area and mining area are revealed by means of three-dimensional exploration methods, thereby providing technical support for the exploration of metal minerals such as decratonic gold deposits. 相似文献
13.
在石庙子沟金矿勘查中,运用了物化探综合方法测量。各方法在金矿体上均有不同的异常反映,异常的吻合程度较好。经槽探工程验证,实测异常分布特征与矿（化）体吻合。表明采用物化探综合方法测量寻找金矿体是行之有效的找矿方法。 相似文献
14.
Au-Sb association and fractionation in micro-disseminated gold deposits, southwestern Guizhou—geochemistry and thermodynamics 总被引：3，自引：0，他引：3
The dual geochemical character of paragenesis and fractionation between gold, arsenic and antimony in micro-disseminated gold
deposits in southwestern Guizhou is discussed in terms of spatial distribution of independent deposits, lateral and vertical
enrichment, mineralization stage and factor and correlation analyses. Thermodynamic calculations of solubility and speciation
of gold and antimony minerals indicate that gold is transported in hydrothermal solution as Au(HS)-
2 and antimony is mainly as Sb (OH)
3
0
although HSb2S4 may be of increasing importance in acid environment at low temperatures during the late stage of mineralization. Changes
in physicochemical conditions hold the key to the association and fractionation between gold and antimony. Gold and antimony
response differently to physicochemical variations because they are distinct from each other in soluble speciation and mineral
solubility, leading to precipitation at different times and localities during hydrothermal evolution. 相似文献
15.
LI Yonggang ZHAI Mingguo YANG Jinhui MIAO Laicheng & GUAN HongInstitute of Geology Geophysics Chinese Academy of Sciences Beijing China Correspondence should be addressed to Li Yonggang 《中国科学D辑(英文版)》2004,47(2):115-121
The Anjiayingzi gold deposit in Chifeng County, Inner Mongolia is located in the central part of the gold mineralization belt of the northern margin of the North China Craton (NCC), and is adjacent to the Paleozoic Inner Mongolia-Da Hinggan Mountains orogenic belt in the north. The Chifeng-Kaiyuan fault, which separates the NCC from this orogenic belt, is considered to be a regional ore-controlling structure. The Anjiayingzi gold deposit is a mediate-size quartz lode-gold deposit and is hosted by the Anjiayingzi quartz monzonite that was emplaced into the basement composed of early Precambrian gneisses. Rhyolitic and porphyritic dikes are generally associated with the gold mineralization. Zircon U-Pb analyses suggest that the Anjiayingzi granite was emplaced from 132 Ma to 138 Ma, while the rhyolitic dikes that occupy the same fracture system as the gold-bearing quartz veins and locally crosscut the gold lodes crystallized from 125 Ma to 127 Ma. These results constrain the mineralization age between 126 相似文献
16.
Multifractal modelling and spectrum analysis: Methods and applications to gamma ray spectrometer data from southwestern Nova Scotia, Canada 总被引：1，自引：0，他引：1
CHENG Qiuming . State Key Lab of Geological Processes Mineral Resources China University of Geosciences Wuhan China . Department of Earth Space Science Engineering Department of Geography York University Keele Street Toronto Ontario MJ P Canada 《中国科学D辑(英文版)》2006,49(3):283-294
Multifractal theory was developed for handling scale invariant fields instead of geometry only[1―4]. From a multifractal point of view, some fractal models, ordinary physical processes and relevant probability distribution types can be considered as special cases of multifractal models which provides new insight into the interrelationships between systems and subjects. For example, the low order moment exponents τ (0), τ (1), τ (2) or τ ″(1) obtained by means of the moment method determi… 相似文献
17.
赣东南大墩地区铜金多金属矿化主要产于晚三叠世黑云正长花岗岩与南华系接触带附近,受南华系浅变质岩地层岩性及断裂破碎带控制明显。本文以该区1：5万矿产远景调查项目大墩靶区成功找矿为例,基于M APG IS软件系统,对勘查区进行了化探数据处理、化探异常剖析、元素聚类分析、元素定量统计分析、剥蚀程度定量评价等综合定量评价。工作成果表明,勘查区显示铜金为主要矿种、银铅锌为伴生矿种的中低温热液型矿床特征,矿化类型主要为石英脉型,矿床可达小型-中型规模。在风化剥蚀面显露出金铜等近矿地球化学原生晕指示元素。根据地球化学勘查综合定量指标分析,认定大墩地区为面积约15 km2具有中型铜金多金属矿产地勘查前景的找矿靶区。应用以上成果,该区已取得明显找矿效果。 相似文献
18.
Recently biogeology develops rather quickly. Some new subdisciplines have come into being, such as biometallogenesis[1,2] and geomicrobiology. Attention is also paid to the related geo-bio- techniques such as biohydrometallurgy and bio-exploration which a… 相似文献
19.
20.
A procedure is proposed for geochemical mapping of the water area bottom based on the subdivision of raw data into two components, i.e., systematic (regional) and random (local). The former is used to determine regional characteristic of the spatial radionuclide distributions in bottom sediments to be utilized to identify large radiogeochemical regions, while the latter is used to identify local anomalies and evaluate their characteristics. The systematic component of the radiogeochemical field is determined by trend analysis. Next, cluster analysis, i.e., hierarchic clusterization of the results of trend analysis followed by associative classification, is used for radiochemical zoning of the water area. After that, maps are constructed, showing contour lines of the local component of radiogeochemical fields, represented by deviations of the value in the given point from the trend. The result is a single map showing the radiogeochemical regions with contour lines of normalized anomalous activities of the radionuclides under study. The practical application of the method is illustrated by radiogeochemical mapping of the bed in the Eastern Gulf of Finland. 相似文献