The earliest gold-mining operations in Ontario included the Cordova, Deloro, and Sophia mines north of Lake Ontario (see for example, Miller and Knight, 1914). The Cordova deposit, worked intermittently between 1891 and 1940, is reported to have yielded 22 774 oz of gold from 127 670 tons of ore averaging 0.19 oz/ton Au (Gordon et al., 1979). The property remained inactive for many years. In 1988, Gunnar Gold Inc. and Mill City Gold Inc. conducted a drilling program along the main Cordova vein. The present study is based on core from three drill holes through the Cordova gabbro (Fig. 1⇓) and the carbonate alteration zones enveloping the quartz-carbonate veins. The relatively narrow width of the alteration zone and the availability of continuous sections of core provided an opportunity to conduct a compact mineralogical-chemical study of carbonate alteration and its effect on the redistribution of rare earth elements (REEs). Although the Cordova deposit is not of great economic importance, this study has revealed a number of interesting features which are interpreted as resulting from processes that may be applicable to gold-bearing quartz vein deposits elsewhere. Fig. 1. Location and general geology of the Cordova area (after Bartlett and Moore, 1985). The Cordova gabbro is layered in places, varying from fine-to coarse-grained and in color from light gray (feldspathic) to dark gray-green (amphibolitic). However, layering within the section of the gabbro considered here and which hosts the Cordova gold deposit is mainly textural rather than compositional. Samples of unaltered gabbro selected for analyses were medium- to coarse-grained; amphibolitic and anorthositic phases were avoided as being less representative of the general chemical composition of the gabbro. The Cordova intrusion has undergone regional metamorphism and consists dominantly of actinolite and saus-suritized plagioclase with smaller amounts of granular clinozoisite and flaky chlorite; minor quartz, ilmenite, …
安大略省最早的金矿开采活动包括安大略湖以北的Cordova、Deloro和Sophia矿(例如，参见Miller和Knight, 1914)。Cordova矿床在1891年至1940年间间歇性开采，据报道从127670吨矿石中开采出22774盎司黄金，平均每吨金0.19盎司(Gordon et al.， 1979)。这块地产多年来一直闲置不动。1988年，Gunnar Gold Inc.和Mill City Gold Inc.沿着Cordova主矿脉进行了钻探计划。本研究基于穿过Cordova辉长岩(图1)的三个钻孔的岩心和包裹石英-碳酸盐脉体的碳酸盐蚀变带。相对狭窄的蚀变带宽度和岩心连续剖面的可用性为进行碳酸盐蚀变及其对稀土元素再分布的影响的紧密矿物学-化学研究提供了机会。虽然Cordova矿床的经济意义不大，但这项研究揭示了一些有趣的特征，这些特征被解释为可能适用于其他含金石英脉矿床的过程。1. Cordova地区的位置和一般地质(根据Bartlett和Moore, 1985)。科尔多瓦辉长岩在某些地方呈层状，从细粒到粗粒不等，颜色从浅灰色(长石)到深灰绿色(角长岩)不等。然而，在这里考虑的辉长岩段内的分层主要是质地而不是成分，它承载着Cordova金矿床。选择用于分析的未改变辉长岩样品为中至粗粒;由于角闪岩相和斜长岩相不能代表辉长岩的一般化学成分，因此避免使用。科尔多瓦岩体经历了区域变质作用，主要由放线石和斜长石组成，少量为粒状斜沸石和片状绿泥石;少量石英，钛铁矿，…
{"title":"CO2, Alkalies and REE Systematics in Hydrothermally Altered Gabbro Hosting the Cordova Gold-bearing Veins, Ontario","authors":"J. F. Davies, R. Whitehead","doi":"10.2113/0100321","DOIUrl":"https://doi.org/10.2113/0100321","url":null,"abstract":"The earliest gold-mining operations in Ontario included the Cordova, Deloro, and Sophia mines north of Lake Ontario (see for example, Miller and Knight, 1914). The Cordova deposit, worked intermittently between 1891 and 1940, is reported to have yielded 22 774 oz of gold from 127 670 tons of ore averaging 0.19 oz/ton Au (Gordon et al., 1979). The property remained inactive for many years. In 1988, Gunnar Gold Inc. and Mill City Gold Inc. conducted a drilling program along the main Cordova vein. The present study is based on core from three drill holes through the Cordova gabbro (Fig. 1⇓) and the carbonate alteration zones enveloping the quartz-carbonate veins. The relatively narrow width of the alteration zone and the availability of continuous sections of core provided an opportunity to conduct a compact mineralogical-chemical study of carbonate alteration and its effect on the redistribution of rare earth elements (REEs). Although the Cordova deposit is not of great economic importance, this study has revealed a number of interesting features which are interpreted as resulting from processes that may be applicable to gold-bearing quartz vein deposits elsewhere.\u0000\u0000\u0000\u0000Fig. 1. \u0000Location and general geology of the Cordova area (after Bartlett and Moore, 1985).\u0000\u0000\u0000\u0000The Cordova gabbro is layered in places, varying from fine-to coarse-grained and in color from light gray (feldspathic) to dark gray-green (amphibolitic). However, layering within the section of the gabbro considered here and which hosts the Cordova gold deposit is mainly textural rather than compositional. Samples of unaltered gabbro selected for analyses were medium- to coarse-grained; amphibolitic and anorthositic phases were avoided as being less representative of the general chemical composition of the gabbro.\u0000\u0000The Cordova intrusion has undergone regional metamorphism and consists dominantly of actinolite and saus-suritized plagioclase with smaller amounts of granular clinozoisite and flaky chlorite; minor quartz, ilmenite, …","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123085395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. R. Davis, J. M. Anderson, O. Tavchandjian, L. Cochrane
Resource modelling is a complex process involving different specialists with relevant experience using a multi-disciplinary approach and the best available technology and reviews by independent auditors. The reliability of the final resource estimate is highly dependent on the quality control exercised at each stage of the process. At each step in the resource modelling process it is necessary to define the specific objectives, the methodology proposed to achieve those objectives and to establish a set of checks and validation tools to assess the effectiveness of the proposed methodology. Designation of responsibility and authority for meeting these objectives must also be clearly identified. External audits must also be incorporated to review and validate the implementation of new procedures. Resource modelling is the basis for any economic appraisal of a mining project and includes a number of steps from data acquisition and validation to resource reporting, classification, and risk analysis.
{"title":"Quality Assurance/Quality Control (QA/QC) for Resource Estimation at Inco Technical Services Limited","authors":"C. R. Davis, J. M. Anderson, O. Tavchandjian, L. Cochrane","doi":"10.2113/0100303","DOIUrl":"https://doi.org/10.2113/0100303","url":null,"abstract":"Resource modelling is a complex process involving different specialists with relevant experience using a multi-disciplinary approach and the best available technology and reviews by independent auditors. The reliability of the final resource estimate is highly dependent on the quality control exercised at each stage of the process. At each step in the resource modelling process it is necessary to define the specific objectives, the methodology proposed to achieve those objectives and to establish a set of checks and validation tools to assess the effectiveness of the proposed methodology. Designation of responsibility and authority for meeting these objectives must also be clearly identified. External audits must also be incorporated to review and validate the implementation of new procedures.\u0000\u0000Resource modelling is the basis for any economic appraisal of a mining project and includes a number of steps from data acquisition and validation to resource reporting, classification, and risk analysis.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132510792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gold-bearing quartz reefs commonly show extremely erratic and unpredictable grade variation, although gross geological continuity may be good. This type of variation is often described as being nuggety or having a high nugget effect and can be measured quantitatively using the semi-variogram. Understanding of geological features such as reef texture and structure will provide improved models for the interpretation of assay data, drill core descriptions, etc. In this paper, a case study from the quartz-hosted gold occurrences in the Gwynfynydd mine, United Kingdom, is described. The work provides a starting point for models of lateral variation and demonstrates the types of structural and textural features that may be sought to give clues to the prediction of gold distribution in similar deposits. Gold deposition at Gwynfynydd is primarily associated with the reef footwall. The host veins form a discrete group of structures that may have been emplaced early in the sequence of quartz veins forming the reef. This potentially exposes them to a maximum number of dissection events during repeat dilations of the lode. Gold was deposited in the local porosity at extreme concentrations, equivalent to kg/t grades, when the host fissure had become filled with a porous framework of crystalline quartz and sulfides. Distribution of porosity varied laterally along the vein as the result of the formation of clump-like growths of minerals from the vein walls. The growth style is relevant to the distribution of gold although it may not be relevant to the occurrence of gold in a particular vein. The preservation of pores with some connectivity late in the vein fill sequence may be important in permitting continued but slow fluid flows. This facilitates effective fluid reaction with wall rock-derived methane, thus changing the relative rates of gold and quartz deposition in favor of gold. The textural studies explain the first-order control of nugget distribution at Gwynfynydd but do not allow for prediction and optimization of the resource estimation process. This is principally because of the very low geological continuity and poor predictability of the high-grade pockets. Nonetheless, the work does provide a clear geological explanation for the erratic nature of the gold. It indicates textures and structures that can be used to determine geological continuity of the gold-bearing elements within the gross reef envelope.
{"title":"The Occurrence of High-grade Gold Pockets in Quartz Reefs at the Gwynfynydd Mine, Wales, United Kingdom: A Geological Explanation for the Nugget Effect","authors":"I. M. Platten, S. Dominy","doi":"10.2113/0100249","DOIUrl":"https://doi.org/10.2113/0100249","url":null,"abstract":"Gold-bearing quartz reefs commonly show extremely erratic and unpredictable grade variation, although gross geological continuity may be good. This type of variation is often described as being nuggety or having a high nugget effect and can be measured quantitatively using the semi-variogram. Understanding of geological features such as reef texture and structure will provide improved models for the interpretation of assay data, drill core descriptions, etc. In this paper, a case study from the quartz-hosted gold occurrences in the Gwynfynydd mine, United Kingdom, is described. The work provides a starting point for models of lateral variation and demonstrates the types of structural and textural features that may be sought to give clues to the prediction of gold distribution in similar deposits. \u0000 \u0000Gold deposition at Gwynfynydd is primarily associated with the reef footwall. The host veins form a discrete group of structures that may have been emplaced early in the sequence of quartz veins forming the reef. This potentially exposes them to a maximum number of dissection events during repeat dilations of the lode. Gold was deposited in the local porosity at extreme concentrations, equivalent to kg/t grades, when the host fissure had become filled with a porous framework of crystalline quartz and sulfides. Distribution of porosity varied laterally along the vein as the result of the formation of clump-like growths of minerals from the vein walls. The growth style is relevant to the distribution of gold although it may not be relevant to the occurrence of gold in a particular vein. The preservation of pores with some connectivity late in the vein fill sequence may be important in permitting continued but slow fluid flows. This facilitates effective fluid reaction with wall rock-derived methane, thus changing the relative rates of gold and quartz deposition in favor of gold. \u0000 \u0000The textural studies explain the first-order control of nugget distribution at Gwynfynydd but do not allow for prediction and optimization of the resource estimation process. This is principally because of the very low geological continuity and poor predictability of the high-grade pockets. Nonetheless, the work does provide a clear geological explanation for the erratic nature of the gold. It indicates textures and structures that can be used to determine geological continuity of the gold-bearing elements within the gross reef envelope.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125144008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The often complex, erratic, and localized nature of gold is a common feature of many vein-style gold deposits. This style of mineralization is often referred to as being nuggety or possessing a high-nugget effect. As a result of these complexities resource estimation is difficult and in general, only Exploration Results can be provided or an Inferred Mineral Resource estimated from surface drilling data alone. Underground development, further drilling, and probably bulk sampling will be required to delineate Indicated and Measured Resources. Tonnages can generally be estimated from diamond drill and development information with a reasonable degree of confidence. Grade is much more difficult to define with confidence because it is commonly highly erratic and discontinuous in nature. The dependency of higher confidence Resource categories on development information may create a Catch 22 situation, with funding for such development often depending on the prior definition of at least Indicated Resources. There are no easy solutions to these challenges posed by high-nugget effect deposits, and it is important when classifying and reporting not to downplay the uncertainties often associated with Mineral Resource and Ore Reserve estimates for such deposits. However, in common with all deposit types, if the principles that underpin the estimation, classification, and reporting procedures are borne in mind and common sense applied, most issues can be satisfactorily resolved. This paper discusses the classification and reporting of Mineral Resources for high-nugget effect gold vein deposits within the framework of the JORC Code (JORC, 1999).
{"title":"Classification and reporting of mineral resources for high-nugget effect gold vein deposits","authors":"S. Dominy, P. R. Stephenson, A. Annels","doi":"10.2113/0100215","DOIUrl":"https://doi.org/10.2113/0100215","url":null,"abstract":"The often complex, erratic, and localized nature of gold is a common feature of many vein-style gold deposits. This style of mineralization is often referred to as being nuggety or possessing a high-nugget effect. As a result of these complexities resource estimation is difficult and in general, only Exploration Results can be provided or an Inferred Mineral Resource estimated from surface drilling data alone. Underground development, further drilling, and probably bulk sampling will be required to delineate Indicated and Measured Resources. Tonnages can generally be estimated from diamond drill and development information with a reasonable degree of confidence. Grade is much more difficult to define with confidence because it is commonly highly erratic and discontinuous in nature. The dependency of higher confidence Resource categories on development information may create a Catch 22 situation, with funding for such development often depending on the prior definition of at least Indicated Resources. There are no easy solutions to these challenges posed by high-nugget effect deposits, and it is important when classifying and reporting not to downplay the uncertainties often associated with Mineral Resource and Ore Reserve estimates for such deposits. However, in common with all deposit types, if the principles that underpin the estimation, classification, and reporting procedures are borne in mind and common sense applied, most issues can be satisfactorily resolved. This paper discusses the classification and reporting of Mineral Resources for high-nugget effect gold vein deposits within the framework of the JORC Code (JORC, 1999).","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127533989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Century mine in northwest Queensland, Australia, is a major sediment-hosted zinc-lead-silver orebody, located within the western Mount Isa Basin. Stratiform, carbonaceous shale-hosted mineralization is developed within Proterozoic shale and siltstone sequences of the Lawn Hill Formation. CRA Exploration Pty Ltd (CRAE) discovered the Century deposit in 1990 and open pit mine development commenced in 1998 under the ownership of Pasminco Century Mine Limited (PCML). The deposit contains an identified mineral resource of 105 Mt @ 12.1% Zn + 1.7% Pb + 46 g/t Ag (Broadbent and Waltho, 1998) which is currently being mined at a rate of 5 Mt/y. In December 1998, an exothermic reaction was observed between explosives spilt onto shale drill cuttings from a blasthole. This reaction is referred to as ‘reactive ground’ and has the potential to cause premature detonation of explosives in a charged blasthole with catastrophic consequences. The incident led to a subsequent geological and geochemical assessment of the different rock types at the Century deposit and their potential reactivity with ammonium nitrate-based (AN) explosive products. This assessment was conducted in an attempt to characterize zones safe for blasting with uninhibited AN-based explosive products. A direct result of this study is a set of procedures outlining the use of different AN-based explosives in areas defined as potentially reactive or non-reactive for the different lithologies present. Black shales contained in both the waste and mineralized sequences contain the sulfide mineral pyrite (FeS2), which is thermodynamically unstable with AN contained in commonly used explosives. The potential reactivity of partially weathered pyrite can ultimately result in the decomposition of an AN-based explosive. It was determined that only pyritic black shales showed any potential to react with AN, irrespective of their position in the stratigraphic sequence. Other lithologies present at Century, including Proterozoic sandstone and Cambrian limestone, are classified as non-reactive with AN. This is a geological risk management situation present at the Century mine.
{"title":"Ammonium Nitrate-Sulfide Reactivity at the Century Zn-Pb-Ag Mine, Northwest Queensland, Australia","authors":"Terry J. Briggs, I. Kelso","doi":"10.2113/0100177","DOIUrl":"https://doi.org/10.2113/0100177","url":null,"abstract":"The Century mine in northwest Queensland, Australia, is a major sediment-hosted zinc-lead-silver orebody, located within the western Mount Isa Basin. Stratiform, carbonaceous shale-hosted mineralization is developed within Proterozoic shale and siltstone sequences of the Lawn Hill Formation. CRA Exploration Pty Ltd (CRAE) discovered the Century deposit in 1990 and open pit mine development commenced in 1998 under the ownership of Pasminco Century Mine Limited (PCML). The deposit contains an identified mineral resource of 105 Mt @ 12.1% Zn + 1.7% Pb + 46 g/t Ag (Broadbent and Waltho, 1998) which is currently being mined at a rate of 5 Mt/y.\u0000\u0000In December 1998, an exothermic reaction was observed between explosives spilt onto shale drill cuttings from a blasthole. This reaction is referred to as ‘reactive ground’ and has the potential to cause premature detonation of explosives in a charged blasthole with catastrophic consequences. The incident led to a subsequent geological and geochemical assessment of the different rock types at the Century deposit and their potential reactivity with ammonium nitrate-based (AN) explosive products. This assessment was conducted in an attempt to characterize zones safe for blasting with uninhibited AN-based explosive products. A direct result of this study is a set of procedures outlining the use of different AN-based explosives in areas defined as potentially reactive or non-reactive for the different lithologies present. Black shales contained in both the waste and mineralized sequences contain the sulfide mineral pyrite (FeS2), which is thermodynamically unstable with AN contained in commonly used explosives. The potential reactivity of partially weathered pyrite can ultimately result in the decomposition of an AN-based explosive. It was determined that only pyritic black shales showed any potential to react with AN, irrespective of their position in the stratigraphic sequence. Other lithologies present at Century, including Proterozoic sandstone and Cambrian limestone, are classified as non-reactive with AN. This is a geological risk management situation present at the Century mine.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128674154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Prior to the development of the Diavik Diamonds Project, baseline studies were conducted to determine the geochemical characteristics of four kimberlite orebodies as an aid in the design of both the water-management system and the facilities for containment of processed kimberlite and ore stockpiles. Materials tested included field samples of volcaniclastic and pyroclastic kimberlite, processed kimberlite (i.e., kimberlite ore which had been screened and washed as part of the processing procedure), and sedimentary mudstone (a minor xenolithic unit which was assimilated during kimberlite emplacement). Approximately 200 samples of kimberlite materials were collected as part of the geochemistry program. Test-work included whole-rock chemical analyses, acid-base accounting, kinetic leach tests using columns, and mineralogical analyses. Diavik kimberlite has major oxide and trace-element concentrations consistent with global averages for kimberlite. The mean total-sulfur content of the kimberlite material is 0.22 wt% S, but with a significant range. The kimberlite has an excess of carbonate minerals over sulfide minerals (average CO 2 = 4 wt%, present mainly as calcite), and has a mean neutralization potential of 311 kg CaCO 3 equivalent/tonne. A reactive form of framboidal pyrite associated specifically with the mudstone xenoliths is the primary source of sulfide-sulfur. Long-term kinetic tests confirmed the preliminary interpretations that were made from the static-test results. Kimberlite and processed kimberlite are net acid-consuming materials that produce alkaline drainages and have low but detectable leaching rates for SO 4 and specific trace metals such as Al, Co, Cu, Ni, and Zn. If segregated from the kimberlite, mudstone xenoliths are acid-generating (pH = 3) and produce an effluent with elevated concentrations of SO 4 , Fe, Al, Cu, Ni, and Zn. The study demonstrates that xenolithic units in Diavik kimberlites have an important effect on the environmental geochemistry of the ore rock. The mineralogy and aqueous geochemistry of the kimberlite materials are such that they may not be suitable for general earthworks or as an alkaline agent and should report to an engineered facility to protect site water quality.
{"title":"Environmental Geochemistry of Kimberlite Materials: Diavik Diamonds Project, Lac de Gras, Northwest Territories, Canada","authors":"M. Baker, D. Blowes, M. Logsdon, J. Jambor","doi":"10.2113/0100155","DOIUrl":"https://doi.org/10.2113/0100155","url":null,"abstract":"Prior to the development of the Diavik Diamonds Project, baseline studies were conducted to determine the geochemical characteristics of four kimberlite orebodies as an aid in the design of both the water-management system and the facilities for containment of processed kimberlite and ore stockpiles. Materials tested included field samples of volcaniclastic and pyroclastic kimberlite, processed kimberlite (i.e., kimberlite ore which had been screened and washed as part of the processing procedure), and sedimentary mudstone (a minor xenolithic unit which was assimilated during kimberlite emplacement). Approximately 200 samples of kimberlite materials were collected as part of the geochemistry program. Test-work included whole-rock chemical analyses, acid-base accounting, kinetic leach tests using columns, and mineralogical analyses. Diavik kimberlite has major oxide and trace-element concentrations consistent with global averages for kimberlite. The mean total-sulfur content of the kimberlite material is 0.22 wt% S, but with a significant range. The kimberlite has an excess of carbonate minerals over sulfide minerals (average CO 2 = 4 wt%, present mainly as calcite), and has a mean neutralization potential of 311 kg CaCO 3 equivalent/tonne. A reactive form of framboidal pyrite associated specifically with the mudstone xenoliths is the primary source of sulfide-sulfur. Long-term kinetic tests confirmed the preliminary interpretations that were made from the static-test results. Kimberlite and processed kimberlite are net acid-consuming materials that produce alkaline drainages and have low but detectable leaching rates for SO 4 and specific trace metals such as Al, Co, Cu, Ni, and Zn. If segregated from the kimberlite, mudstone xenoliths are acid-generating (pH = 3) and produce an effluent with elevated concentrations of SO 4 , Fe, Al, Cu, Ni, and Zn. The study demonstrates that xenolithic units in Diavik kimberlites have an important effect on the environmental geochemistry of the ore rock. The mineralogy and aqueous geochemistry of the kimberlite materials are such that they may not be suitable for general earthworks or as an alkaline agent and should report to an engineered facility to protect site water quality.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121980970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accepted practice for the estimation of thin (2D) vein deposits recommends the use of the grade x thickness service variable (i.e., the accumulation). Grade estimates are obtained indirectly by the estimated accumulation/estimated thickness ratio. This practice stems from the varying support (thickness) problem and the resulting non-additive nature of the grade variable. We compare the actual performance of the direct grade estimation approach used by some practitioners to that of the indirect approach using accumulation. Our simulated and real data indicate that the direct approach is more accurate for point grade estimation where the grade-thickness correlation coefficient is positive (and vice-versa). Moreover, the relative gain of the direct method increases with the (positive) correlation coefficient. This finding contradicts common thinking that the indirect approach should be the preferred method where grade-thickness correlation is strongly positive. Also, for a given positive grade-thickness correlation, the relative gain of the direct method increases with the coefficient of variation of the grade and thickness. Resume — L’estimation de veines minces (2D) mineralisees est normalement realisee a l’aide de la variable auxiliaire epaisseur x teneur (i.e., accumulation). Les estimes des teneurs sont alors obtenus indirectement du rapport accumulation estimee/epaisseur estimee. Cette pratique decoule du probleme du support variable pour la teneur, l’epaisseur de la veine, qui fait que la teneur est alors une variable non-additive. Nous comparons les performances de l’estimation directe de la teneur, utilisee par certains praticiens, a celle de l’approche indirecte. Pour l’estimation ponctuelle des teneurs, nos donnees simulees et reelles indiquent une meilleure justesse de l’approche directe quand la correlation teneur-epaisseur est positive (et vice-versa). De plus, le gain relatif de la methode directe s’accroit avec la valeur de cette correlation (positive). Ce resultat contredit l’opinion repandue que l’approche indirecte devrait etre utilisee en presence de forte correlation positive de la teneur et de l’epaisseur. Nous montrons egalement que pour une correlation positive teneur-epaisseur donnee, le gain de l’approche directe augmente avec les coefficients de variation de l’epaisseur et de la teneur.
{"title":"The Estimation of Mineralized Veins: A Comparative Study of Direct and Indirect Approaches","authors":"D. Marcotte, A. Boucher","doi":"10.2113/0100235","DOIUrl":"https://doi.org/10.2113/0100235","url":null,"abstract":"The accepted practice for the estimation of thin (2D) vein deposits recommends the use of the grade x thickness service variable (i.e., the accumulation). Grade estimates are obtained indirectly by the estimated accumulation/estimated thickness ratio. This practice stems from the varying support (thickness) problem and the resulting non-additive nature of the grade variable. We compare the actual performance of the direct grade estimation approach used by some practitioners to that of the indirect approach using accumulation. Our simulated and real data indicate that the direct approach is more accurate for point grade estimation where the grade-thickness correlation coefficient is positive (and vice-versa). Moreover, the relative gain of the direct method increases with the (positive) correlation coefficient. This finding contradicts common thinking that the indirect approach should be the preferred method where grade-thickness correlation is strongly positive. Also, for a given positive grade-thickness correlation, the relative gain of the direct method increases with the coefficient of variation of the grade and thickness.\u0000\u0000Resume — L’estimation de veines minces (2D) mineralisees est normalement realisee a l’aide de la variable auxiliaire epaisseur x teneur (i.e., accumulation). Les estimes des teneurs sont alors obtenus indirectement du rapport accumulation estimee/epaisseur estimee. Cette pratique decoule du probleme du support variable pour la teneur, l’epaisseur de la veine, qui fait que la teneur est alors une variable non-additive. Nous comparons les performances de l’estimation directe de la teneur, utilisee par certains praticiens, a celle de l’approche indirecte. Pour l’estimation ponctuelle des teneurs, nos donnees simulees et reelles indiquent une meilleure justesse de l’approche directe quand la correlation teneur-epaisseur est positive (et vice-versa). De plus, le gain relatif de la methode directe s’accroit avec la valeur de cette correlation (positive). Ce resultat contredit l’opinion repandue que l’approche indirecte devrait etre utilisee en presence de forte correlation positive de la teneur et de l’epaisseur. Nous montrons egalement que pour une correlation positive teneur-epaisseur donnee, le gain de l’approche directe augmente avec les coefficients de variation de l’epaisseur et de la teneur.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"42 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130671352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An application of logistic regression to mapping of gold potential in the Baguio district of the Philippines is described. Categorical map data such as lithologic units and proximity classes of curvi-linear features, based on spatial association analyses, are quantified systematically and used as independent variables in logistic regression to predict the probability for presence or absence of gold mineralization. Regression experiments to compare between using all independent variables that are associated spatially with the response variable and using only statistically significant independent variables are performed. The results of the regression experiments are similar; however, the use of all independent variables produces slightly optimistic results but better prediction rates for the known gold deposits in the test district. At least 68% of the ‘model’ large-scale gold deposits and at least 76% of the ‘validation’ small-scale gold deposits were predicted correctly. The predicted geologically favorable zones are also similar to delineated geochemically anomalous zones. The technique presented using logistic regression as a data integration tool is effective for geologically constrained technique of mapping mineral potential.
{"title":"Logistic regression for geologically constrained mapping of gold potential, Baguio district, Philippines","authors":"E. Carranza, M. Hale","doi":"10.2113/0100165","DOIUrl":"https://doi.org/10.2113/0100165","url":null,"abstract":"An application of logistic regression to mapping of gold potential in the Baguio district of the Philippines is described. Categorical map data such as lithologic units and proximity classes of curvi-linear features, based on spatial association analyses, are quantified systematically and used as independent variables in logistic regression to predict the probability for presence or absence of gold mineralization. Regression experiments to compare between using all independent variables that are associated spatially with the response variable and using only statistically significant independent variables are performed. The results of the regression experiments are similar; however, the use of all independent variables produces slightly optimistic results but better prediction rates for the known gold deposits in the test district. At least 68% of the ‘model’ large-scale gold deposits and at least 76% of the ‘validation’ small-scale gold deposits were predicted correctly. The predicted geologically favorable zones are also similar to delineated geochemically anomalous zones. The technique presented using logistic regression as a data integration tool is effective for geologically constrained technique of mapping mineral potential.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116874823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There are two main points stemming from Dagbert’s comments (2001). First, he indicates a bias occurs when estimating average grade for large blocks by combination of direct point grade estimates. Second, he proposes an “improved” indirect point estimate to minimize the problem of inconsistent point estimates (negative or huge point grade estimates) frequently observed with the indirect method. He concludes that the improved indirect method should be used for point estimation rather than the direct method even in the presence of positive grade-thickness correlation. Marcotte and Boucher (2001) results clearly indicate the indirect point grade estimates are more accurate in the case of negative grade-thickness correlation coefficient, whereas, the direct estimates are more accurate in the case of a positive grade-thickness correlation coefficient. From here on, we assume, otherwise indicated, a positive grade thickness correlation. The first point concerning the large block bias constitutes a necessary and useful reminder as indeed the combination of direct point estimates is biased for large block grade. To see this, consider the true block grade: batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v} = frac{frac{1}{v}{int}_{v}T(x)G(x)dx}{frac{1}{v}{int}_{v}T(x)dx} = frac{frac{1}{v}{int}_{v}A(x)dx}{frac{1}{v}{int}_{v}T(x)dx}] end{document}(1) where T(x) and G(x) are the thickness and the grade at point x; A(x) is the accumulation. The combination of direct point estimates gives: batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v,dir}{ast} = frac{frac{1}{v}{int}_{v}T{ast}(x)G{ast}(x)dx}{frac{1}{v}{int}_{v}T{ast}(x)dx}] end{document}(2) where the * indicates an estimate. Each term in the integral of the numerator of equation (2) is a biased estimate of the corresponding term in equation (1). It can be shown (Journel and Huijbregts, 1978), that the bias term in the numerator of equation (2) is approximately E[eT(x)eG(x)], where eT(x) = T(x)−T*(x) and eG(x) = G(x)−G*(x). Thus, batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v} {int}_{v}T{ast}(x)G{ast}(x)dx) end{document} underestimates batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}T(x)G(x)dx) end{document} by the quantity batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}[e_{T(x)}e_{G(x)}]dx) end{document} which is normally positive for positive grade-thickness correlation. Note that for point estimation, the integrals disappear and the dire
There are two main points stemming from Dagbert’s comments (2001). First, he indicates a bias occurs when estimating average grade for large blocks by combination of direct point grade estimates. Second, he proposes an “improved” indirect point estimate to minimize the problem of inconsistent point estimates (negative or huge point grade estimates) frequently observed with the indirect method. He concludes that the improved indirect method should be used for point estimation rather than the direct method even in the presence of positive grade-thickness correlation.Marcotte and Boucher (2001) results clearly indicate the indirect point grade estimates are more accurate in the case of negative grade-thickness correlation coefficient, whereas, the direct estimates are more accurate in the case of a positive grade-thickness correlation coefficient. From here on, we assume, otherwise indicated, a positive grade thickness correlation.The first point concerning the large block bias constitutes a necessary and useful reminder as indeed the combination of direct point estimates is biased for large block grade. To see this, consider the true block grade:batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v} = frac{frac{1}{v}{int}_{v}T(x)G(x)dx}{frac{1}{v}{int}_{v}T(x)dx} = frac{frac{1}{v}{int}_{v}A(x)dx}{frac{1}{v}{int}_{v}T(x)dx}] end{document}(1) where T(x) and G(x) are the thickness and the grade at point x; A(x) is the accumulation. The combination of direct point estimates gives:batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v,dir}{ast} = frac{frac{1}{v}{int}_{v}T{ast}(x)G{ast}(x)dx}{frac{1}{v}{int}_{v}T{ast}(x)dx}] end{document}(2) where the * indicates an estimate.Each term in the integral of the numerator of equation (2) is a biased estimate of the corresponding term in equation (1). It can be shown (Journel and Huijbregts, 1978), that the bias term in the numerator of equation (2) is approximately E[eT(x)eG(x)], where eT(x) = T(x)−T*(x) and eG(x) = G(x)−G*(x). Thus, batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v} {int}_{v}T{ast}(x)G{ast}(x)dx) end{document} underestimates batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}T(x)G(x)dx) end{document} by the quantity batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}[e_{T(x)}e_{G(x)}]dx) end{document} which is normally positive for positive grade-thickness correlation. Note that for point estimation, the integrals disappear and the direct point grade
{"title":"Authors’ Reply to “Comments on The Estimation of Mineralized Veins: A Comparative Study of Direct and Indirect Approaches,” by M. Dagbert","authors":"D. Marcotte, A. Boucher","doi":"10.2113/0100245","DOIUrl":"https://doi.org/10.2113/0100245","url":null,"abstract":"There are two main points stemming from Dagbert’s comments (2001). First, he indicates a bias occurs when estimating average grade for large blocks by combination of direct point grade estimates. Second, he proposes an “improved” indirect point estimate to minimize the problem of inconsistent point estimates (negative or huge point grade estimates) frequently observed with the indirect method. He concludes that the improved indirect method should be used for point estimation rather than the direct method even in the presence of positive grade-thickness correlation.\u0000\u0000Marcotte and Boucher (2001) results clearly indicate the indirect point grade estimates are more accurate in the case of negative grade-thickness correlation coefficient, whereas, the direct estimates are more accurate in the case of a positive grade-thickness correlation coefficient. From here on, we assume, otherwise indicated, a positive grade thickness correlation.\u0000\u0000The first point concerning the large block bias constitutes a necessary and useful reminder as indeed the combination of direct point estimates is biased for large block grade. To see this, consider the true block grade:\u0000\u0000batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v} = frac{frac{1}{v}{int}_{v}T(x)G(x)dx}{frac{1}{v}{int}_{v}T(x)dx} = frac{frac{1}{v}{int}_{v}A(x)dx}{frac{1}{v}{int}_{v}T(x)dx}] end{document}(1) \u0000\u0000where T(x) and G(x) are the thickness and the grade at point x; A(x) is the accumulation. The combination of direct point estimates gives:\u0000\u0000batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} [G_{v,dir}{ast} = frac{frac{1}{v}{int}_{v}T{ast}(x)G{ast}(x)dx}{frac{1}{v}{int}_{v}T{ast}(x)dx}] end{document}(2) \u0000\u0000where the * indicates an estimate.\u0000\u0000Each term in the integral of the numerator of equation (2) is a biased estimate of the corresponding term in equation (1). It can be shown (Journel and Huijbregts, 1978), that the bias term in the numerator of equation (2) is approximately E[eT(x)eG(x)], where eT(x) = T(x)−T*(x) and eG(x) = G(x)−G*(x). Thus, batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v} {int}_{v}T{ast}(x)G{ast}(x)dx) end{document} underestimates batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}T(x)G(x)dx) end{document} by the quantity batchmode documentclass[fleqn,10pt,legalpaper]{article} usepackage{amssymb} usepackage{amsfonts} usepackage{amsmath} pagestyle{empty} begin{document} (frac{1}{v}{int}_{v}[e_{T(x)}e_{G(x)}]dx) end{document} which is normally positive for positive grade-thickness correlation. Note that for point estimation, the integrals disappear and the dire","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116653536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enigmatic hydrothermal vein/breccia/replacement Cu-Au deposits with magnetite and/or hematite are well-represented in Australian 1850 Ma to 1500 Ma terrains and associated with different-aged synorogenic intrusions in the Tennant Creek Block (ca. 1850 Ma); the Gawler-Curnamona region (1640 Ma to 1590 Ma); and the Cloncurry district (Mount Isa Eastern Fold Belt, 1540 Ma to 1500 Ma with a possible earlier event at ca. 1600 Ma). No deposits are known to be coeval with various 1780 Ma to 1610 Ma anorogenic intrusions. Deposits are hosted by many different rock-types with varying metamorphic grade including granites and various supracrustal rocks. Depth of mineralization varied from many kilometers in semiductile crust (e.g., Cloncurry deposits) to very shallow (e.g., Olympic Dam). Ore deposition near Cloncurry occurred in brittle-ductile shear zones from geochemically variable and complex, CO2-rich, 300°C to 500°C, high salinity fluids with magmatic stable isotopic signatures. Recently published studies of a giant granitoidhosted magnetite vein complex at the Lightning Creek prospect (>1000 Mt magnetite) suggest it is a product of internal differentiation and endogenous Fe and Cu-rich hydrous-carbonic fluid phase generation within a quartz monzodiorite-monzogranite intrusion. Coupled with other field relationships, this points to a possible genetic relationship with intermediate (55 to 65 wt% SiO2) members of an alkaline and partly shoshonitic granitoid supersuite which appears to have both mantle and crustal source components from eNd evidence. In constrast, main-phase mineralization at Olympic Dam in the Gawler Craton is distinguished by hematite-phyllosilicate alteration and chalcopyrite-bornite-chalcocite zoning, reflecting fluid mixing in a high level (<250°C) system with a probable large component of meteoric water. Early high-temperature parageneses and fluid inclusions imply that the extensive hematitic breccias overprinted an older magnetite system which may have had similarities with those at Lightning Creek and Ernest Henry in the Cloncurry district. Deposits of this family are inherently difficult to find and evaluate as even within a single district, there is no reliable relationship between the location of ore and any specific combination of geophysical characteristics. Diverse alteration assemblages, geochemistry and physical characteristics suggest the deposits reflect the interaction of multi-sourced fluids with different host rocks in a wide range of geological environments. Recent discoveries and research in the Cloncurry district have extended the range of deposit models available and aid the development of a rudimentary classification in which economic and exploration characteristics can be linked to variations in the mechanisms and environments of ore formation.
{"title":"Australian Proterozoic Iron Oxide-Cu-Au Deposits: An Overview with New Metallogenic and Exploration Data from the Cloncurry District, Northwest Queensland","authors":"P. Williams, P. Pollard","doi":"10.2113/0100191","DOIUrl":"https://doi.org/10.2113/0100191","url":null,"abstract":"Enigmatic hydrothermal vein/breccia/replacement Cu-Au deposits with magnetite and/or hematite are well-represented in Australian 1850 Ma to 1500 Ma terrains and associated with different-aged synorogenic intrusions in the Tennant Creek Block (ca. 1850 Ma); the Gawler-Curnamona region (1640 Ma to 1590 Ma); and the Cloncurry district (Mount Isa Eastern Fold Belt, 1540 Ma to 1500 Ma with a possible earlier event at ca. 1600 Ma). No deposits are known to be coeval with various 1780 Ma to 1610 Ma anorogenic intrusions. Deposits are hosted by many different rock-types with varying metamorphic grade including granites and various supracrustal rocks. Depth of mineralization varied from many kilometers in semiductile crust (e.g., Cloncurry deposits) to very shallow (e.g., Olympic Dam). Ore deposition near Cloncurry occurred in brittle-ductile shear zones from geochemically variable and complex, CO2-rich, 300°C to 500°C, high salinity fluids with magmatic stable isotopic signatures. Recently published studies of a giant granitoidhosted magnetite vein complex at the Lightning Creek prospect (>1000 Mt magnetite) suggest it is a product of internal differentiation and endogenous Fe and Cu-rich hydrous-carbonic fluid phase generation within a quartz monzodiorite-monzogranite intrusion. Coupled with other field relationships, this points to a possible genetic relationship with intermediate (55 to 65 wt% SiO2) members of an alkaline and partly shoshonitic granitoid supersuite which appears to have both mantle and crustal source components from eNd evidence. In constrast, main-phase mineralization at Olympic Dam in the Gawler Craton is distinguished by hematite-phyllosilicate alteration and chalcopyrite-bornite-chalcocite zoning, reflecting fluid mixing in a high level (<250°C) system with a probable large component of meteoric water. Early high-temperature parageneses and fluid inclusions imply that the extensive hematitic breccias overprinted an older magnetite system which may have had similarities with those at Lightning Creek and Ernest Henry in the Cloncurry district.\u0000\u0000Deposits of this family are inherently difficult to find and evaluate as even within a single district, there is no reliable relationship between the location of ore and any specific combination of geophysical characteristics. Diverse alteration assemblages, geochemistry and physical characteristics suggest the deposits reflect the interaction of multi-sourced fluids with different host rocks in a wide range of geological environments. Recent discoveries and research in the Cloncurry district have extended the range of deposit models available and aid the development of a rudimentary classification in which economic and exploration characteristics can be linked to variations in the mechanisms and environments of ore formation.","PeriodicalId":206160,"journal":{"name":"Exploration and Mining Geology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122220340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：