Five principal sources of uncertainty in quantitative mineral resource estimation are listed and illustrated by means of a simple example (mosaic model) and a case history study for large copper deposits in the Abitib...Five principal sources of uncertainty in quantitative mineral resource estimation are listed and illustrated by means of a simple example (mosaic model) and a case history study for large copper deposits in the Abitibi area of the Canadian Shield.Abitibi copper potential originally was estimated on the basis of 1968 estimates of production and reserves totalling 3.12 Mt Cu.This prognostication now could be evaluated on the basis of 2008 copper production and reserves totalling 9.50 Mt Cu.An earlier hindsight study performed on the basis of 1977 data (totalling 5.23 Mt Cu) showed seven new discoveries occurring either in the immediate vicinities of known deposits or on broad regional copper anomalies predicted from the 1968 inputs.By 1977,the global geographic distribution pattern of large copper deposits in the Abitibi area had stabilized.During the next 30 years,new copper was essentially found close to existing deposits,much of it deeper down in the Earths crust.In this paper,uncertainties associated with copper ore tonnage are analyzed by comparison of 2008 data with 1968 data using (a) log-log plots of size versus rank,and (b) lognormal QQ-plots.Straight lines fitted by least squares on these plots show that 1968 slopes provide good estimates of 2008 slopes but 1968 intercepts are much less than 2008 intercepts.In each linear log-weight versus log-rank plot,the slope is related to fractal dimension of a Pareto frequency distribution,and in a lognormal QQ-plot it is determined by logarithmic variance.The difference between 2008 and 1968 intercepts represents the increase in copper ore production and reserves from 1968 to 2008.The Pareto model fits actual copper and massive sulphides increase over the past 40 years better than the lognormal frequency distribution model for 10 km×10 km cells on favorable environments in the Abitibi area.展开更多
The purpose of this contribution is to highlight four topics of regional and worldwide mineral resource prediction:(1)use of the jackknife for bias elimination in regional mineral potential assessments;(2)estimating t...The purpose of this contribution is to highlight four topics of regional and worldwide mineral resource prediction:(1)use of the jackknife for bias elimination in regional mineral potential assessments;(2)estimating total amounts of metal from mineral potential maps;(3)fractal/multifractal modeling of mineral deposit density data in permissive areas;and(4)worldwide and large-areas metal size-frequency distribution modeling.The techniques described in this paper remain tentative because they have not been widely researched and applied in mineral potential studies.Although most of the content of this paper has previously been published,several perspectives for further research are suggested.展开更多
It is well-known that the relatively rapid increase of the global atmospheric CO_(2) concentration value(currently≈422 ppm)during the previous two centuries has led to adverse worldwide climate changes.Although,curre...It is well-known that the relatively rapid increase of the global atmospheric CO_(2) concentration value(currently≈422 ppm)during the previous two centuries has led to adverse worldwide climate changes.Although,currently,the average atmospheric CO_(2) content is increasing more slowly than in the past,the development of cost-effective methods to reduce average atmospheric CO_(2) content by incorporating it into carbonates is becoming increasingly desirable.展开更多
文摘Five principal sources of uncertainty in quantitative mineral resource estimation are listed and illustrated by means of a simple example (mosaic model) and a case history study for large copper deposits in the Abitibi area of the Canadian Shield.Abitibi copper potential originally was estimated on the basis of 1968 estimates of production and reserves totalling 3.12 Mt Cu.This prognostication now could be evaluated on the basis of 2008 copper production and reserves totalling 9.50 Mt Cu.An earlier hindsight study performed on the basis of 1977 data (totalling 5.23 Mt Cu) showed seven new discoveries occurring either in the immediate vicinities of known deposits or on broad regional copper anomalies predicted from the 1968 inputs.By 1977,the global geographic distribution pattern of large copper deposits in the Abitibi area had stabilized.During the next 30 years,new copper was essentially found close to existing deposits,much of it deeper down in the Earths crust.In this paper,uncertainties associated with copper ore tonnage are analyzed by comparison of 2008 data with 1968 data using (a) log-log plots of size versus rank,and (b) lognormal QQ-plots.Straight lines fitted by least squares on these plots show that 1968 slopes provide good estimates of 2008 slopes but 1968 intercepts are much less than 2008 intercepts.In each linear log-weight versus log-rank plot,the slope is related to fractal dimension of a Pareto frequency distribution,and in a lognormal QQ-plot it is determined by logarithmic variance.The difference between 2008 and 1968 intercepts represents the increase in copper ore production and reserves from 1968 to 2008.The Pareto model fits actual copper and massive sulphides increase over the past 40 years better than the lognormal frequency distribution model for 10 km×10 km cells on favorable environments in the Abitibi area.
文摘The purpose of this contribution is to highlight four topics of regional and worldwide mineral resource prediction:(1)use of the jackknife for bias elimination in regional mineral potential assessments;(2)estimating total amounts of metal from mineral potential maps;(3)fractal/multifractal modeling of mineral deposit density data in permissive areas;and(4)worldwide and large-areas metal size-frequency distribution modeling.The techniques described in this paper remain tentative because they have not been widely researched and applied in mineral potential studies.Although most of the content of this paper has previously been published,several perspectives for further research are suggested.
文摘It is well-known that the relatively rapid increase of the global atmospheric CO_(2) concentration value(currently≈422 ppm)during the previous two centuries has led to adverse worldwide climate changes.Although,currently,the average atmospheric CO_(2) content is increasing more slowly than in the past,the development of cost-effective methods to reduce average atmospheric CO_(2) content by incorporating it into carbonates is becoming increasingly desirable.
