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By J. B. Macelwane

Geophysics differs from geology and physics in in many respects. In the first place, geophysics is a complex science embracing the fields of seismology, geomagnetism, geoelectricity, geodesy, meteorology, vol-canology, physical oceanography, physical hydrology, tectonophysics and exploration geophysics. Geology is also a complex science and so extensive in its various fields that no one can master them all, and no part of geology deals in any sense with several of these fields of geophysics. In the second place, geophysics makes use of methods and instruments that are derived primarily from the science of physics. Geology, on the other hand, has methods of its own and it draws its borrowed techniques and its instrumental equipment not only from physics but also and perhaps primarily from chemistry and biology. The difference, therefore, between the geophysicist and the geologist lies partly in the phenomena that are observed, partly in the methods and instruments with which each carries on his exploration; but partly also, and perhaps principally, in the habitual attitude of mind and in the background of specialized training with which each approaches the problems presented by this planet of ours. The geologist as such, therefore, is no geophysicist. On the other hand, the physicist is not a geophysicist either. Isolation of each problem in a closed laboratow system under complete control is fundamental to the methods of the physicist. The geophysicist must apply physical instruments and physicomathematical reasoning to the study of physical quantities in their undisturbed natural environment. What, then, is a geophysicist? In the sense that he is a trained expert in all of the geophysical sciences, I do not believe that such a person ever existed. It would be beyond the possibilities of a single lifetime. I think there is confusion in our ideas and in our use of terms. We are not all thinking of the same thing when we say geophysics or geophysicist; yet we seem to talk as though we were. It is as absurd to say that the whole of geophysics belongs to geology because the field of a particular type of geophysicist—the exploration geophysicist —calls for some knowledge of geology as it would be to say that the whole of biology belongs to geology because a particular type of biologist—the paleontologist— needs some knowledge of geology. Development of a Geophysicist Since it is impossible to become an expert in all the fields of geophysics, and since students entering college seldom know the field they will choose as a career, what would we suggest as the best general preparation for work in geophysics, whether as a meteorologist, an oceanographer, a seismologist, a geodesist, a geomagneticist, a volcanologist, a tectonophysicist, a hydro1 ogist, or an exploration geophysicistp we may distinguish five phases in the development of a geophysicist: (I) his mathematical and scientific studies in high school; (2) the general mathematical and scientific

Jan 1, 1946

By J. B. Macelwane

Geophysics differs from geology and physics in in many respects. In the first place, geophysics is a complex science embracing the fields of seismology, geomagnetism, geoelectricity, geodesy, meteorology, vol-canology, physical oceanography, physical hydrology, tectonophysics and exploration geophysics. Geology is also a complex science and so extensive in its various fields that no one can master them all, and no part of geology deals in any sense with several of these fields of geophysics. In the second place, geophysics makes use of methods and instruments that are derived primarily from the science of physics. Geology, on the other hand, has methods of its own and it draws its borrowed techniques and its instrumental equipment not only from physics but also and perhaps primarily from chemistry and biology. The difference, therefore, between the geophysicist and the geologist lies partly in the phenomena that are observed, partly in the methods and instruments with which each carries on his exploration; but partly also, and perhaps principally, in the habitual attitude of mind and in the background of specialized training with which each approaches the problems presented by this planet of ours. The geologist as such, therefore, is no geophysicist. On the other hand, the physicist is not a geophysicist either. Isolation of each problem in a closed laboratow system under complete control is fundamental to the methods of the physicist. The geophysicist must apply physical instruments and physicomathematical reasoning to the study of physical quantities in their undisturbed natural environment. What, then, is a geophysicist? In the sense that he is a trained expert in all of the geophysical sciences, I do not believe that such a person ever existed. It would be beyond the possibilities of a single lifetime. I think there is confusion in our ideas and in our use of terms. We are not all thinking of the same thing when we say geophysics or geophysicist; yet we seem to talk as though we were. It is as absurd to say that the whole of geophysics belongs to geology because the field of a particular type of geophysicist—the exploration geophysicist —calls for some knowledge of geology as it would be to say that the whole of biology belongs to geology because a particular type of biologist—the paleontologist— needs some knowledge of geology. Development of a Geophysicist Since it is impossible to become an expert in all the fields of geophysics, and since students entering college seldom know the field they will choose as a career, what would we suggest as the best general preparation for work in geophysics, whether as a meteorologist, an oceanographer, a seismologist, a geodesist, a geomagneticist, a volcanologist, a tectonophysicist, a hydro1 ogist, or an exploration geophysicistp we may distinguish five phases in the development of a geophysicist: (I) his mathematical and scientific studies in high school; (2) the general mathematical and scientific

Jan 1, 1946

By Donald C. Branford

The place of geophysics in the curriculum of a college or an engineering school has been much discussed. There is uncertainty as to whether the graduate may be called a "geological geophysicist" or a "geophysical geologist." Some have used the term "geophysical engineer." The question of the specialized undergraduate curriculum versus a general undergraduate training in the parent sciences with the addition of cultural electives has been and is still being argued. The literature during the past Io years shows that there are two rather definite schools of thought on this subject. The prospective employer, engaged in active geophysical exploration, visualizes the graduate in terms of the routine work he will do in the field. The school administrator, grounded in many years of tradition in the cultural type of education, visualizes the graduate in terms of his position in a political and cultural society as well as in his work as a professional geophysicist. Both are right and both wrong. A third school of thought, that of the student himself, has been almost totally ignored. It would seem best, for the purpose of this paper, to treat these various points and allied material separately, and then to integrate the conclusions as a set of conditions that should be fulfilled as far as possible in the ideal curriculum. At the end the relationship of our findings to the curriculum that has been tentatively adopted at the University of Pittsburgh will be considered. Divisions in Definition or Field of Geophysics Geophysics is that field of science in which geological and earth problems are solved with the use of physical and chemical techniques. Altogether too much attention has been paid to the artificial separation in this science of the commercial applications from the so-called "pure" or academic geophysics. The only real difference in the two types of work is one of scale of operations. In the commercial field the scale is large in terms of fmancial backing, immediate economic importance, and speed of operations. In the academic field the scale is large in terms of breadth of interests, in eventual economic importance, and length of time allowable for theoretical investigations. In exploration work the scale is small in terms of dimensions, since the methods are applicable only to the outer 20,000 ft. or SO of the earth's crust. In academic work, the student is not pressed for results of immediate economic importance, and therefore can afford to spend more time on problems that seem unimportant at the time. In the sense of background knowledge of the parent sciences necessary to the geophysicist, no essential difference can be found. Physics, chemistry, geology, and mathematics together, and in their proper proportionate amounts, form the matrix from which geophysical ideas and methods may spring.

Jan 1, 1946

By Donald C. Branford

The place of geophysics in the curriculum of a college or an engineering school has been much discussed. There is uncertainty as to whether the graduate may be called a "geological geophysicist" or a "geophysical geologist." Some have used the term "geophysical engineer." The question of the specialized undergraduate curriculum versus a general undergraduate training in the parent sciences with the addition of cultural electives has been and is still being argued. The literature during the past Io years shows that there are two rather definite schools of thought on this subject. The prospective employer, engaged in active geophysical exploration, visualizes the graduate in terms of the routine work he will do in the field. The school administrator, grounded in many years of tradition in the cultural type of education, visualizes the graduate in terms of his position in a political and cultural society as well as in his work as a professional geophysicist. Both are right and both wrong. A third school of thought, that of the student himself, has been almost totally ignored. It would seem best, for the purpose of this paper, to treat these various points and allied material separately, and then to integrate the conclusions as a set of conditions that should be fulfilled as far as possible in the ideal curriculum. At the end the relationship of our findings to the curriculum that has been tentatively adopted at the University of Pittsburgh will be considered. Divisions in Definition or Field of Geophysics Geophysics is that field of science in which geological and earth problems are solved with the use of physical and chemical techniques. Altogether too much attention has been paid to the artificial separation in this science of the commercial applications from the so-called "pure" or academic geophysics. The only real difference in the two types of work is one of scale of operations. In the commercial field the scale is large in terms of fmancial backing, immediate economic importance, and speed of operations. In the academic field the scale is large in terms of breadth of interests, in eventual economic importance, and length of time allowable for theoretical investigations. In exploration work the scale is small in terms of dimensions, since the methods are applicable only to the outer 20,000 ft. or SO of the earth's crust. In academic work, the student is not pressed for results of immediate economic importance, and therefore can afford to spend more time on problems that seem unimportant at the time. In the sense of background knowledge of the parent sciences necessary to the geophysicist, no essential difference can be found. Physics, chemistry, geology, and mathematics together, and in their proper proportionate amounts, form the matrix from which geophysical ideas and methods may spring.

Jan 1, 1946

By F. McIntosh Galbraith

EMPLOYING geophysics to find ore was for a long time considered by the Canadian mining fraternity to be a performance of dubious value: in a category somewhere between the practice of sorcery, and using a divining rod to locate underground water. With increasing knowledge, however, and with constantly improving instruments, a solid speaking acquaintance with this adolescent science is becoming an integral part of the mining geologist's stock in trade. And quite properly so: for, in the established mining districts, the ore deposits which could be easily found, by ordinary prospecting methods, have already been located. There remain; however, in almost all of the principal mining camps, areas which are covered to varying depths by glacial debris; and it is here that the obvious opportunities exist for the successful application of geophysical methods. Geophysical results must always be considered in the closest possible relation to the local geology; and, in reality, the 'doodle-bugs' are simply additional tools for the geologist (in the same category with a plane table or a microscope). The Sudbury Basin is a shining example of precisely this state of affairs. Detailed geological mapping has not significantly altered the position of the outer norite contact as placed on Dr. Coleman's original map of the district. What detailed examination has done, of course, has been to reveal the accuracy with which the contact can be placed in different parts of the district, and to show up, in consequence, areas in which further work might reasonably be expected to disclose hitherto unknown or unsuspected ore. Viewed in this light, the proportion of the norite contact which is covered by substantial quantities of overburden is astonishingly large.

Jan 1, 1939

By Walter E. Heinrichs

To many, petroleum exploration and successful geophysics , are partly synonomous, This is not because natural petroleum is usually concentrated as a liquid, nor certainly not because oil can be detected directly. The reason is Chat geophysics helps to at least better understand and sometimes, to even explain the essential geology involved. That groundwater is similarly a liquid with all but a few of its basic geologic relationships practically identical to petroleum, seems to have escaped many of those most interested and responsible for complete geo-hydrologic knowledge. The paramount need to use every means at our disposal for maintaining and expanding our crustal resources reserves are generally obvious, However, in view of the rapidly mounting requirements, continual re-emphasis is worthwhile.

Jan 1, 1963

By Douglas C. Fraser

A DIGHEM survey was flown in the Belford-Montcalm Township area of Ontario in November 1975. This 600-linemile survey resulted in the detection of 134 EM anomalies. The Montcalm Township copper-nickel discovery yielded a single-line anomaly having a conductance of 154 mhos. This anomaly was highly visible because (a) it had the highest conductance in the survey area, (b) it correlated with a 175-gamma thumbprint-shaped magnetic anomaly and (c) it was isolated from long conductive bands. The deposit is a copper-nickel pyrrhotite body which occurs in gabbro and strikes north-south, parallel to the flight lines. The DIGHEM survey was flown north-south, because the exploration program was primarily concerned with locating copper-zinc sulphides in the east-west-striking felsic volcanics. The flight line passed close to the deposit and yielded a 9-ppm anomaly on the chart record. The computer analysis showed that a deposit of exceptionally high conductance (154 mhos) caused the relatively weak (9 ppm) anomaly. The ground follow-up program of magnetics and EM led quickly to the discovery drill hole, which penetrated the orebody in September 1976. Subsequent geophysical surveys consisted of horizontal-loop EM, pulse EM, magnetic and induced polarization surveys over an area of about 8 claims. In addition, a detailed DIGHEM" airborne survey was flown at a line spacing of 100 m to evaluate the entire property of 620 claims. This detailed survey yielded EM conductor maps and contour maps of resistivity, magnetics and enhanced magnetics.

Jan 1, 1978

By AIME AIME

ELECTRICAL methods of geophysical exploration attracted major attention at the three sessions devoted to geophysics on Monday and Tuesday. At the opening' meeting Monday morning Hans Lundberg gave the paper by himself and Folke Kihlstedt; he described the use of the Racom, discussed last year, and the method whereby it is possible to eliminate all but subsurface, effects in electrical exploration. In the discussion Theodor Zuschlag pointed out some of the theoretical considerations behind the field procedure. Karl Sundberg's paper on the effect of impregnating waters was presented by title only, and S. F. Kelly then gave an abstract of a paper on the electrical properties of ores, by J. J. Jakosky, R. N. Anderson and Clyde H. Wilson. , This dealt with an exhaustive series of laboratory tests on the variation of -conductivity of ore specimens with the frequency of the energizing current, and of the effect of moisture content in typical clays and gouges on their conductivities at various frequencies. Considerable discussion was provoked during which the authors came in for some-criticism on their measuring circuits and for their assumption that a solid conductor could be compared with linear ones. They were praised, however, for making a start toward a compilation of resistivities for ores and rocks. Dr. Slichter disagreed with them that the conductivity of an orebody was primarily capacitive. He also called attention to the fact that it was high time geophysicists adopted the standard physical expression of ohm-,centimeters or ohm-meters to express resistivities. This same point was the burden of the next paper,. "Uniform Expression for Resistivity," by Sherwin F. Kelly, presented by title only.

Jan 1, 1932

By L. W. Blau

THE entrance of geophysics and geochemistry into petroleum engineering may be viewed with apprehension by some engineers. They may not remember the time when "practical oil men" opposed the invasion of engineers into the field of petroleum production. By their excellent contributions they established themselves. In the popular mind, engis veers are practical men whereas physicists and chemists are suspected of being theoretical. It will be best to annihilate this misconception right now at the beginning of a closer relationship between petroleum engineers. geophysicists, and geochemists.

Jan 1, 1943

By A. A. Brant

Mining men, quite as exploration minded as petroleum interests, are in the position where most of the exposed crustal portions of the earth have been examined, where the demand for metals is high and likely to continue so, and yet where, perhaps, the tools fail for the economic exploration of many of the possible mineral areas more deeply covered with drift, alluvium, and later formations. At the same time the incentive exists to create acceptable substitutes for many of the duties of metal. The problem of the economic exploration of possible mineral-bearing areas is hence a vital one. In oil exploration, the absence of surface or shallow occurrences and the high cost of test drilling has led to the intensive study of geophysical techniques. Hence the development of the seismic method with its high certainty factor and its adaptability to standardized procedure.

Jan 1, 1949

By Sherwin F. Kelly

THIS is intended as a simple review of the principles and practice of geophysics, so will not be of interest to the geophysicist, who is hereby warned of its elementary character. The engineers for whom it is written are those who, having glimpsed the formidable formulas and discussions of the geophysicists, give all publications on the subject a wide berth. For a few years now the geo-physicists have had a tendency to be ingrowing at their meetings, going deeper and deeper into theory and instrument construction, and forgetting to present the topics that would interest the practicing engineer who desires merely to know how geophysics can help him, not why.

Jan 1, 1934

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for the industrial and defense sectors. In 2018, the U.S. Department of the Interior presented the final list of critical minerals that are vital to the U.S. economy and defense [1], which included REEs among other mineral commodities. REEs are not rare, despite their name, but economically viable deposits of REEs can be found only in certain geographical areas, and the political and social conditions characterizing these areas may not always be in favor of mining operations. Mining operations may be placed in great operational and financial risk if operations are planned in such areas. Erroneous decisions by decision makers may lead to a chain of events that can completely shut down a mining project. 

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for industrial and defense sectors. REEs are not as rare as the word “rare” portrays; yet, the exploitable and/or profitable deposits of REEs may be found only in certain geographical areas. The political and social conditions characterizing these areas may not always be in favor of mining operations. These conditions are imposing the need for extra consideration on the geopolitical constraints prior to any decision-making and before any mining project begins. This study assesses the risk related to mining projects for areas that feature REE deposits based on a geopolitical viewpoint. Probable ranking differences between the current assessment and a 2015 assessment are discussed. The comparative indicators used and the appraisal procedure applied in this comparison are based on a number of different geopolitical indicators. Several ranking changes occurred between 2015 and 2019.

By Andrew C. Katen

The mining industry faces increasing geopolitical risk in the coming decades. Constraints such as resource nationalism, corruption and social license could grow to outweigh fundamental limitations like geology or supply and demand (Ernst & Young, 2013; Verrastro et al. 2010). Lurking beneath these more immediate and palpable concerns, however, may be more significant risks entrenched in geography and history. Deep-rooted cultural and strategic forces that emerge slowly ? or erupt suddenly and unexpectedly ? can generate momentous and far-reaching political, social and economic changes. While multinational enterprises routinely assess for political risk, the nature of minerals extraction means long-term and systemic geopolitical conditions are especially important for mining companies to identify and understand. Mine development is a decades-long process that binds companies to the land and makes changing course to avert emerging threats a difficult and costly option. Consequently, geopolitical assessment is a pertinent and valuable tool that mining companies can use to more comprehensively evaluate strategic threats and opportunities. Geopolitics is the study of society, politics and strategy through the lens of geography (Gray, 1996). Its emphasis on relatively permanent physical features of the earth makes geopolitics a uniquely valuable tool for assessing political risk. Topography, climate and natural resources have shaped, constrained and motivated peoples and governments throughout history. These influences transcend regimes, policies and borders ? and even states themselves ? which, by contrast, change often and dramatically. Framing politics against mountains, deserts and rivers supports identification of historical patterns and forecasts of emerging trends. In other words, the physical map provides an objective and consistent model for studying a subjective and dynamic subject such as politics (Sloan and Gray, 1999). Consequently, geopolitical assessment can highlight threats and opportunities that go unaddressed by other risk methodologies that emphasize current conditions (Glancy, 2012). Taken together, the permanence of geography, hindsight afforded by centuries of political history, and interconnectedness of world events makes geopolitical assessment a valuable approach for conceptualizing strategic risk.

Mar 1, 2014

By G S. B Karunatillake

Following a pre-feasibility study, Mount Isa Mines commenced a feasibility study on the deposit of the George Fisher Mine in May 1997. Board approval was granted in May 1998 to construct a 2.5 million tonne per annum mine and to upgrade existing concentrator and smelter facilities. The world-class George Fisher zinc-lead-silver deposit is located approximately 22 kilometres north of the city of Mount Isa, in north-west Queensland and is 2.6 kilometres north of the existing Hilton Mine. It will be a large-scale underground mine, sustaining a profitable zinc-lead-silver business in Mount Isa for at least ten years. This paper will outline the details of the mine that was developed during the feasibility and design phase. It will include a description of the mining methods, ventilation, fill, ore handling, services and infrastructure. The utilisation of existing assets and the development of innovative ideas were essential to the successful economic development of the George Fisher Mine.

Jan 1, 2000

By C Itotoh, K O’Halloran, L Karlson

Global methods used to explore for minerals have progressed relatively slowly since the development of the first diamond core drill in 1863. Since then, key developments such as wireline geophysics (1920s), the tricone drill bit (1930s) and aeromagnetic surveys (1940s) all occurred in response to global events. In this project, BHP’s WAIO Geoscience operations team hypothesise that a global movement towards a greener future as well as an increasing intolerance for safety events will drive another step change in exploration methods. We have leveraged our relationships with exploration contractor partners and industry leaders to develop a realistic vision for 2033 and beyond, where drill rigs, earthworks and geophysical units are operated and maintained remotely; emissions of dust and waste are eliminated; hazardous energy sources are controlled; procurement is based on sustainability rather than cost and carbon emissions are tracked with the same rigour as production metrics. We have combined these visions into a series of graphical illustrations with the aim of inspiring ourselves, our vendors and our peers to collaborate further on producing a step change in our industry.

Sep 18, 2023

By Ross Cutts

As a public servant geotechnical engineer, I observed how costly and valuable geotechnical field explorations are to the success of every project. Often however, the field exploration is a long and complex process that is made less efficient by the difficulty of retrieving and utilizing nearby internal or external historic geotechnical datasets. As an employee of a public agency, we would often start our investigations for every project from scratch, given the difficulty of locating and utilizing historic geotechnical data. This is an ethical and technical failing of our profession. When we start subsurface explorations from scratch, not only do we often duplicate investigations, we are also likely defaulting to reapplying tradi- tional test methods that yield con- servative geotechnical parameters, resulting in overly conservative and potentially costly construction. To address this issue while working as a public servant, I started a research program with Yunfeng Zhang, Ph.D., of the University of Maryland, to build a tool that could compile internal historic geotechnical data and extract additional value from it, using machine learning. This tool was able to provide, upon request, nearby historic geotechnical data, estimated soil parameters and recommendations for geotechnical test methods best suited for a given project site. This prevented common field ex- ploration problems such as, requesting duplicate data, requesting test methods that were not applicable for the project geology, not realizing presence of karsts, missing permits for wetlands, private property and others. This tool allowed for more efficient field investigations with regards to time and money saved. There was one problem with this tool: it could only be used by internal employees of a single state's depart- ment of transportation (DOT) for which this data was compiled. I realized at that point that it would be of tremendous value to make this concept universally accessible to the geotechnical engi- neering profession. I left public service to devote time to building a platform that would host historic geotechnical data from publicly funded sources throughout the country. The tool I helped build as a public servant was the foundation of Geosetta, a nonprofit company dedicated to serving the geotechnical profession. The nonprofit structure was adopted to prevent acquisition by a for-profit company and to ensure that Geosetta remains an independent steward of our profession's valuable data. Geosetta provides a GIS (geographic information system) platform that enables users to view historic geo- technical data and extract value from it with machine learning-based predictions and visualization tools. This data is provided in an open and interchangeable format called DIGGS, which stands for Data Interchange for Geotechnical and Geoenvironmental Specialists, making it easy for users to integrate it into their workflows. Geosetta is collaborating with the American Society of Civil Engineers' Geo-Institute and other sponsors to extract public data at no cost to the agency and provide the profession with free access to the existing data and access to advanced tools through a subscription to support the nonprofit mission.

Nov 1, 2023

This paper describes a detailed geostatistical study of producing copper orebodies at Mount Isa Mines Limited in Queensland, Australia. As a result of this work, kriging has been adopted for grade estimation for final stope design at Isa Mine. Extensive variogram and back analysis studies indicate that one relative variogram model can be used to give optimal kriged grade estimates from production sampling throughout the 100 million tonne copper orebody complex. The kriging method replaces a computer technique used at [sa Mine based on inverse distance weighting using parameters chosen from experience.Comparative stope designs based on 10 million tonnes of ore indicate a 16% increase in minable ore tonnage at a grade well above the cut-off, as a result of the geostatistical work.Although this paper is written as a practical description with simple explanations of geostatistical concepts, the theory and use of relative variograms has been expanded. A possible link is suggested between relative variograms and first order kinetics of natural mineral concentration processes.

Jan 1, 1982

By Donald E. Scheck, Da-Rong Chou

The application of geostatistics to coal reserve analysis is discussed. One problem in particular, the selection of the optimum locations for exploratory drill holes, is considered in detail. A new interactive program to help the geologist determine the best locations is described and applied to a specific property. The steps in the process are described and then illustrated using a mine's actual data. First, a variogram is selected based on graphical displayed information from the known sample data. Kriging estimates are made for the region of interest and the blocks within the region. The location of future exploratory drill holes is selected based on the criterion of minimizing the region estimation variance for a given number of exploratory holes. The least number of exploratory holes required to meet a specified upper limit on the regional variance is also determined. The computer generated recommendations for the exploratory drill holes are compared to a manually prepared drilling plan. The post- drilling analysis of the results is compared to the predicted values.

Jan 1, 1983

By D. Rucker

Flow models are used to predict the extraction efficiency of metals in rock piles. These models typically use hydraulic parameters obtained through column studies, which assume that the material in the column wholly represents the entire pile and the parameters can be upscaled several orders of magnitude for model evaluation. This assumption fails for parameters that are spatially variable or scale dependent. To overcome these issues, measurements made directly on the heap at the appropriate model scale can be made with the electrical resistivity method. The method aims to map the variations in the electrical resistivity, which can be associated with moisture content, degree of fines, metal content, and leachate concentration. We present an example of calibrating the resistivity with borehole measurements of moisture using geostatistics to show how the resistivity method can be used to obtain a spatial moisture distribution. It was shown that cokriging the resistivity and moisture together gives a more reliable distribution.

Jan 1, 2010