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By Andrew Bellamy

A thorough appreciation of the origin, formation, preservation and geometry of marine sand and gravel deposits is central in demonstrating that their extraction by dredging does not affect coastal processes or marine life. Geological evaluation underpins wave, tidal and sediment transport modeling and assists in predicting the nature and extent of seabed change during and after dredging. Marine sand and gravel deposits in the English Channel, southern North Sea and parts of the Irish Sea are of predominantly periglacial fluvial origin and record long histories of valley and floodplain cut and fill associated with Quaternary climatic and sea level oscillations. In the Bristol Channel, the influence of marine transgression and tidal dominance in sorting proglacial outwash deposits is evident in the distribution of sandbanks, scoured channels and gravel lags of this region. These deposits are relict and are unrelated to coastal sediment dynamics. Their extraction leaves seabed depressions which monitoring shows remain unfilled. The resultant offshore bathymetric changes and sediment removal in over 10 m water depth are not transmitted to the coastal zone as beach drawdown, wave height increases or sediment starvation. Applications for new aggregate dredging permissions in UK waters must be accompanied by an EIA and need to make a convincing case that the dredging will not affect rare or declining species and communities of marine life. Seabed recovery rates post dredging are now investigated and understood with reference to geological setting and the uniqueness of the sediment/biological character (biotope). Investigation of the continental shelf by the Industry and others reveals the large extent of gravel-dominated biotopes relative to commercially viable deposits.

Jan 1, 2004

By B M. Guerin

In this paper, some of the constraints to applying bioremediation to the decontamination of polluted soils are introduced. Particularly, attention has been given to those associated with the geology of the polluted site. Areas which require further research have been addressed and indicate that geologists will play a key role, alongside microbial ecologists and engineers, in designing and implementing bioremediation strategies.

Jan 1, 1992

By Yves C. Lizotte, Malcolm J. Scobie

Blast fragmentation is affected by the physical and mechanical characteristics of the rockmass as determined by geology as well as the explosive energy, the partition of this energy, the actual amount of energy transmitted to the rockmass, the blast geometry and the detonation sequence. This paper reviews studies of the influence of geology on blast fragmentation, particularly structure, i.e. the in situ or inherent fragmentation arising from rock discontinuities. Prior structural studies have mainly been limited to comparing equivalent diameters of the in situ blocks with the size distributions of the blasted material. No criteria exist to integrate structure into blast design. This paper reviews on-going studies of the blasted fragment shape and size observed in different rockmasses aimed at analyzing geological control over blasting. Digital photoanalysis was applied {o measure size and shape distributions, to correlate results with block size distributions and shape parameters of the inherent fragmentation. An integrated and comprehensive fragmentation assessment procedure which accounts for geological control is proposed. The potential of this research is to provide a greater understanding of the true contribution of explosives to fragmentation, the effects of fragment shape on system productivity and the reduction of blast-induced damage.

Jan 1, 1994

By J. W. Mustard

The Macmillan Pass tungsten property (MacTung) is the largest known copper-tungsten, calcic, exoskarn deposit in the Western Hemisphere. Located on the border between the Yukon and Northwest Territories in northwestern Canada, the deposit crops out on Mt. Allen within the Selwyn Mountain Range. It was discovered in 1962 by a subsidiary of AMAX Inc. and has since been explored by 16,300 meters of surface and underground diamond drilling and by 800 meters of underground development. Geologic reserves are in excess of 30 million tons, grading slightly less than 1.0% WO3. Scheelite (CaWO3 ) is the main mineral of economic interest. Accessible by road, the property is not in production. Previously estimated reserves at MacTung have been unable to fully utilize all the geological controls on mineralization. In the past three years, however, an intensive program has been underway to improve our understanding of the deposit and to use the resulting information in a more precise way. This paper will discuss the key aspects of the geology as they specifically relate to reserve estimation and will demonstrate how these controls are being used in a geostatistical model of the deposit.

Jan 1, 1985

By A. C. Noble, D. E. Ranta, J. W. Mustard

Skarn deposits present many unique problems in estimating ore reserves, including difficulties arising from the complex character of the mineralization and intricate ore body shapes resulting from structural complexity. Mineralization within skarns occurs in metasomatically altered carbonate horizons produced by magmatic hydrothermal fluids emanating from intrusive stocks. Deposit formation is controlled by both the presence of favorable host rocks and by proximity of these host rocks to a mineralizing intrusion. Ore controls must be defined to account for abrupt changes in grade that occur between miner- alized and unmineralized horizons. Gradational grade changes within the mineralized zones must also be defined in terms of skarn type and included barren rock to assist in reserve estimation. Defining mineralized limits can be further complicated by faulted, rotated, or folded strata affecting the morphology of an ore body. The MacTung copper-tungsten exoskarn deposit, located along the Yukon-Northwest Territories border in Northwestern Canada exhibits a number of unique properties that preclude a simple mathematical approach to ore re- serve estimation. This deposit is used to demonstrate methods for modeling geologic controls and geostatistical properties for a skarn deposit.

Jan 1, 1992

By A. J. Sinclair

"Abstract-Geology contributes essential information toward obtaining high-quality resource/reserve estimates. In this context, geology can be considered under the following overlapping topics: regional geology, detailed (deposit) geology, mineralogy, ore deposit models and continuity, with geological mapping being fundamental to all. Each of these topics is considered here in terms of potential contributions to "improved" mineral inventory estimation. Some of the principal conclusions are:1. Regional geological relations must be consistent with deposit geology. It is common that important geological relations are more clearly evident in various regional locales than in highly altered and/or highly deformed mineralized areas containing mineral deposit.2. Detailed geology provides information for a geometric model of a deposit, a model that serves as a basis for mine planning. It is important to distinguish fact from interpretation in such models. Substantial effort is required to characterize the geometric margins of a deposit and the relation of these margins to the simplistic geometric form that normally emerges as an interpretation.3. Mineralogical studies relate to many aspects of deposit evaluation including abundance of ore and deleterious minerals, spatial distribution of ore and deleterious minerals, grain size characteristics of important minerals, mill design, etc.4. Ore deposit models contribute substantially to confidence in developing a three-dimensional geometric model of a deposit for mine planning. Specifically, they are a basis on which to develop rules for interpolation and extrapolation of ore, and they contribute to recognition of domains, each with its own characteristic continuity and margin character.5. Continuity is dependent on mineralization style and may be controlled structurally and/or chemically. It is important to distinguish geological continuity and value continuity. A wide range of classical geological methods are useful in examining geological continuity; value continuity is best viewed as a statistical characteristic that is quantified by any of several measures of autocorrelation."

Jan 1, 1998

By T N. Little

This review paper presents an integrated and practical insight to blasting geology and its importance. This approach involves developing blasting objective up front and implementing geology specific blast designs. The author refers to this approach as ‘starting at both ends’. There are many human-imposed controls on blasting operations, such as: safety, security, legislative, company standards, heritage, and environmental constraints. Thus it is possible for some operators to lose sight of the controls imposed by nature. This paper demonstrates how site geology controls or influences many aspects of the rock breaking processes and how a focus on this aspect has potential to add considerable value to mining operations. It is obvious that mining companies concentrate their efforts on economic/ore geology (good rock geology). However it is the author’s experience that they also concentrate on engineering geology (bad rock geology) only when forced to do so by the ground conditions, but seem to run out of puff before they apply blasting geology (big rock geology). This paper contains five main sections. In the first section, the impact of geological controls on blasthole drilling is briefly discussed in terms of drill selection, penetration rates, bit wear, blasthole stability, blasthole deviation, and health precautions. In the second section the geological controls on aspects of geometric design are reviewed. These include: hazardous minerals, valuable minerals, selection of the blasting techniques, geological structures, blasting direction, and blasting geometry. Section three overlaps with the geometric design section and deals with aspects related to explosives. Topics addressed include selecting the explosive type based on geology, distribution of explosive charge in space and time, explosive performance, and the rock response to explosive loading. In the fourth section, examples are given of the operational complexity needed to implement a blast to cater for difficult bench geologies, environment constraints, past mining (voids) and need for a high degree of quality control. Section five demonstrates geological controls on blast results. Blasting results include the muck pile characteristics, downstream handling and processing, damage to the remaining rock, and blasting emissions.

Nov 8, 2011

By G. S. Camm

Gwynfynydd is a small, high-grade black shale-hosted vein-gold deposit. The Chidlaw Link Zone is the only area being mined and contains 24 000 t ore grading 15.2 g/t gold. Within the Link Zone a complex vein structure occurs consisting of a mother vein up to 5 m thick and narrow (less than 0.5 m) leader veins. The former shows minor variations in dip, strike and thickness, whereas the latter show marked changes in all three. The leader veins are hosted within the footwall zone of the mother vein and both are composed of quartz with galena, sphalerite, chalcopyrite, pyrite and minor arsenopyrite. The vein system is transected by a series of cross-vein and intra-vein dip-slip faults. Pockets of gold occur at vein intersections or branches and within the complex footwall zone and are often related to variations in vein attitude and/or geometry. The Chidlaw Link Zone displays a complex, erratic distribution of gold mineralisation and a multi-stage history of structural activity, fluid flow and mineral deposition

Jun 18, 1905

By John H. Duke

The success of most attempts to evaluate gold orebodies depends largely on the reliability and availability of representative sampling data and the accuracy of geological interpretation. An accurate prediction of the continuity of geology is paramount to a reliable prediction of gold reserves. Many of the problems encountered in gold mine evaluation and planning revolve around the difficulties in interpreting complex geology from sparse drilling data and the eagerness of mine financiers and promoters to start mining in order to derive an early cash flow. Following a program of sampling, geophysics, mapping and geological interpretation, a conceptual orebody model evolves in the minds of those working on the project. It is this model which is used typically in ore reserve computations and mine planning. Computer modelling techniques to represent and evaluate the conceptual model are now available. The main advantages of using computer modelling methods lie in being able to rapidly evaluate, modify and quantify the conceptual orebody model. Ore zones or domains can be recognised and defined both from geology and sampling results. Once these domains are defined as a series of boundaries, they may be modelled as two dimensional grid surfaces or as wire-framed three dimensional geometries, depending on the complexity of the orebody. It is the definition of these domains which provides the sound geological basis for reserves computation. To estimate reserves it is necessary to determine both volume of ore and grade of ore. The ore volume is calculated within each domain as defined by the confining surfaces or wire-frames. The ore

Jan 1, 1987

By Culshaw MG, Deaves AP, Bell FG

The accurate prediction both of the water ingress into sub-surface excavations and the nearby groundwater pressures is of fundamental importance to the control of the stability and flooding of tunnels or mines constructed below the water table. Predic- tions are usually based on laboratory and in situ permeability determinations together with observations of groundwater conditions in boreholes. Although established theoretical methods provide a basis for prediction, the actual ingress depends on many factors. The objective of this paper is to explore the geological controls on groundwater conditions, and the available methods of prediction of both groundwater flow and pressure are outlined. Salient points are emphasised by reference to a case history involving the construc- tion of a tunnel in a faulted and mixed sequence of sandstones, siltstones, shales and coals. Water ingress quantities have been monitored for a variety geological and geotechnical conditions including heavily faulted and mine disturbed ground. The overall results are discussed with reference to the relevant hydrological and geologi- cal conditions in terms of the geological structure, lithology and rockmass condition as well as the construction methods.

Jan 1, 1988

The geological features of the destructive plate margins of the southwest Pacific favour the formation of porphyry type deposits. The major controlling factor favouring the formation of gold-rich deposits of this type is a dense crust. This results in shallow intrusion of large magma bodies beneath andesite stratovolcanoes. Where the intrusives have near vertical sides, the comparatively low temperature of transfer of volatiles from the solidifying melt favours the partitioning of gold into bubbles of volatiles. They reduce the viscosity and density of the melt, resulting in the upward movement of a mineralised melt. With the drop of pressure with upward movement the bubbles separate into a two phase mixture, triggering freezing of the mineralised melt and the formation of a gold mineralised stockwork.

Jan 1, 1995

By M. E. Holter

"Three main potash members are recognized within the Prairie Evaporite Formation of Saskatchewan and have been designated, in ascending order, the Esterhazy, Belle Plaine and Patience Lake members. Each is composed of sylvinite near the geographic center of the member and becomes increasingly carnallitic marginally. Each stratigraphically higher member has a narrower carnallitic margin. The sharp contact between carnallitic and non-carnallitic components of the formation describes a surface which may be traced regionally and is not related to bed-ding. The contact rises higher in the stratigraphic section toward margins of members. Within each of the three members, analyses indicate that carnallite becomes more abundant toward the north whereas sylvite and insolubles, increase toward the south. Within each member, areas rich in carnallite are coincident with areas in which the member as a whole is thicker than averag,e. The Belle Plaine Member contains the highest concentrations of carnallite, the Esterhazy the lowest. A maximum content of about 30 per cent sylvite is common to all three members. Insoluble contents increase in successively higher members.Map studies are combined to outline the economic potential of the potash beds in terms of depth to the top of the Prairie Evaporite, ""salt-back"" thicknesses and sylvite grades for each member."

Jan 1, 1971

By S. F. Emmons

THE first paper which appears in the published Transactions of our Institute is that read by our respected Secretary at its first meeting in Wilkes-Barre, in May, 1871. It is entitled The Geological Distribution of Mining Districts in the United States, and presents a brief but masterly review of what was known of the distribution of our deposits of useful minerals, particularly the metals, not only from a geographical but from .a geological stand-point. At the request of Dr. Raymond, I agreed, somewhat hastily, perhaps, to write for this occasion a brief sketch of the geological distribution of the deposits of the useful metals in this country, in the light of the increased knowledge of the present day. In the time given no personal investigation was possible, and as it was therefore out of the question to attempt to make anything that could be considered an original contribution to the history of our ore-deposits, I have been obliged to limit myself to an examination of such published data within my reach as bore upon this subject, and could be consulted in the brief time I have been able to give to it. Had the geological investigations undertaken by the Tenth Census been continued systematically by the United States Geological Survey or by the Eleventh Census, it might have been possible to make a fairly-complete review of the subject. As it is, the principal result of my examination 1 has been to show how very unequal

Jan 1, 1913

Interpreted geologic domains provide the geologic architecture of many current models used to estimate the potential economic resources in mineral deposits. The spatial extent of each domain is usually defined by a three-dimensional wireframe or triangulated surface.The set of geologic wireframes forming part of a resource model might generally be called a spatial interpretation of some set of geologic features coincident with the mineralisation, based primarily on logged and mapped properties of the samples and other exposures of the mineralisation. The interpreted spatial distribution of rock type, alteration and grade of drill hole samples above a particular grade threshold are commonly used criteria in constructing the geologic domain wireframes. Frequently, the grade threshold is closely related to the anticipated economic cut-off grade. The boundaries or spatial limits of different domains are most commonly defined as æhardÆ or æsoftÆ. A æhardÆ boundary usually means no dependent relationship of any kind is defined between the properties of samples inside a particular domain wireframe and those samples outside the wireframe. A æsoftÆ boundary commonly implies that some kind of dependent relationship does prevail between the properties of samples inside and outside the particular wireframe. Many ways are used to describe those relationships, few of which are based on spatial analysis of the continuity of sample attributes across the domain boundaries. In local estimation procedures such as ordinary block kriging, æhardÆ boundaries act as a total barrier to the influence of samples on either side of the boundary depending on the location of the block being estimated. In some instances, æsemi-permeableÆ boundaries are used in which the samples inside a domain wireframe are allowed to influence the estimates outside but not the reverse. This can lead to many undesirable effects in estimates of block grades.This paper discusses the value of this approach to geologic domaining from a viewpoint of model complexity, as well as in relation to the implications for both linear and non-linear estimation methods and contrasts it with alternatives. It also explores some important consequences of using æhardÆ and æsoftÆ geological boundaries with the commonly used modelling methods: excessive smoothing of estimates near domain boundaries and conditionally biased estimates of grade at the global and local scale.

Sep 26, 2011

By Kasimcan Koruk, Julian M. Ortiz

A geological model accounting for uncertainties possesses important advantages for resource estimation. Machine learning algorithms (MLAs) employed on multivariate geochemical datasets open up ways to new methodologies for such geological models with ease in comparison to traditional geostatistical methods. This article proposes a two-step MLA with an ensemble implementation to define geological domains and their uncertainties based on geochemical data. The proposed workflow is applied hierarchically on a dataset from a porphyry copper deposit to perform binary classification that can be attributed to alteration domains.

Mar 1, 2024

By Kasimcan Koruk, Julian M. Ortiz

Building a geological model is important in resource estimation, as it defines the extent of domains for estimation. Geological models are built by assigning a domain to the samples, based on logging of different features related to lithology, alteration, and mineralization. Then, the extent of these domains is determined using geometric or geostatistical tools. However, these models should account for uncertainty, since the actual extent of these domains is not known and must be extrapolated from the labelled samples. With the availability of geochemical datasets and machine learning techniques, employing multiple variables to build resource models should be considered. This article proposes a two-step machine learning approach with an ensemble implementation to define geological domains and their uncertainties. First, an unsupervised binary clustering method labels the geochemical samples into two domains. These labelled samples are used to inform a geological domain model built by support vector classification. This application is repeated with subsets of variables and subsets of samples, leading to an ensemble learning method. Weak models are produced with each subset of samples and variables, and combined to devise a stronger learner. The final model accounts for uncertainties thanks to the ensemble implementation. The proposed workflow is demonstrated on a dataset from a porphyry copper deposit, applied hierarchically to define four domains. Performance is comparable with traditional methods, but provides the advantage of allowing domain knowledge in the selection of the variables, and generates domain boundaries that can be controlled in terms of their continuity and smoothness.

Oct 11, 2023

By James N. Gundersen

Geological Engineering can be all-encompassing and it necessarily overlaps many applications of economic and applied geology. Other review articles will cover specific developments in rock mechanics, open-pit and underground mining, geology, geochemistry, geophysics and geohydrology- all of which overlap many fields of economic and applied geology. Nevertheless, there still remains a diversity of new and innovative applications of geology to engineering works through the activities of federal and state agencies, college and university departments, and industrial or consultant firms-particularly with respect to the properties of earth materials and their behavior "as-is" in nature or under the stress of engineering works. Governmental Agencies: Federal John T. McGill (Chief: Engineering Geology Branch; USGS, Denver) relates that recently the Engineering Geology Branch, together with several other branches of the Office of Environmental Geology, has undertaken the production of interpretive maps of unusual character. These maps are commonly called special-purpose or single concept maps. A folio, or series of maps, is prepared for each topographic quadrangle or area selected for study. The individual maps in a given series are printed on standard-size sheets so that they can be bound together if desired.

Jan 3, 1974

By Daniel R. Stewart

The function of the geological engineer is to assist in mine planning and operations by collecting, interpreting, and applying geologic data to the solution of engineering problems. The geologist supports this effort by collecting additional geologic information specifically useful to the engineer. This use of geologic information reinforces the value of mine geology to the mining process beyond the traditional role of orebody definition. Work discussed includes: evaluation of caving strategies at the Climax and Henderson mines; support definition and slope stability at the Climax mine; and some uses of geology in cavability estimation for the Mount Emmons project.

Jan 1, 1983

By Daniel R. Stewart, Ralph R. Sacrison

The function of the geological engineer is to assist in mine planning and operations by collecting, interpreting, and applying geologic data to the solution of engineering problems. The geologist supports this effort by collecting additional geologic information specifically useful to the engineer. This use of geologic information reinforces the value of mine geology to the mining process beyond the traditional role of orebody definition. Work discussed includes: evaluation of caving strategies at the Climax and Henderson mines, support definition and slope stability at the Climax mine, and some uses of geology in cavability estimation for the Mount Emmons project.

Jan 1, 1992

By P. J. Shenon

ENROLLMENT in geological and mining engineering curricula is declining at an accelerated rate despite the greatest need for trained men ever extant in the minerals industry. Industrial and military demand is mounting, but the number of freshmen selecting the mineral field continues to fall. Estimates on the needs of industry range as high as 30,000 new engineers a year. The current deficit is more than 60,000 engineers less than the 350,000 to 450,000 which eventually will be needed. The indisputable fact is that the colleges are turning out fewer and fewer engineers despite the greatest enrollment in colleges and universities ever experienced in the United States. In 1950 a record 52,000 young men stepped out of the confines of ivy covered walls with engineering degrees in their hands. By 1951, however, the number dropped to 41,000 and present enrollment indicates a national graduating class of only 25,000 for 1952. No letup in the drop is forecast. About 19,000 can be looked for in 1953 and 1954 may reach an unhappy 12,000. It becomes clear that something must be done to attract high school graduates to engineering. One immediate possibility could be to make the course burden carried by the engineering student somewhat lighter. The prescribed curriculum in many schools is such that the student takes the path of least resistance, and instead of training for an engineering future, studies for a vocation which will allow him to learn and at the same time get at least a nominal enjoyment out of college life. Review geological and mining curricula of 20 colleges and it will be found that the engineering student is a veritable pack mule compared to a lad taking liberal arts or some other non-technical program of study. The curriculum for geological engineering at one school calls for 202 semester hr, with almost 23 hr carried per semester. Multiply this figure by three hr, the minimum supposedly to be devoted to a credit and you get 69 hr per week. With a bare minimum of 84 hr for sleeping and eating, about two hours a day remain for recreation. However, the load of other schools investigated is about 19 hr. The University of Utah requires 238 quarter hr for graduation with a degree in geological engineering, while requiring only 183 quarter hr for baccalaureate degree from University college, Utah's liberal arts school. It can be stated with a measure of surety that the same proportions exist in other universities. The first step would be for ECPD to review its requirements for mining and geological engineering. It must recognize that mining and geological engineers operate in a specialized field, as do other types of engineers. Although a geological engineer may not design a bridge, as pictured by the ECPD Committee on Engineering Schools, his field of design calls for similar engineering precision, a knowledge of materials, construction methods, economic considerations, and financing. Six schools have been accredited by the ECPD. What is the basis for approval and can the requirements be modified and still be kept in line with the needs of the geological engineer? Course work from school to school varies with the exception of mathematics, chemistry, and physics. Even in those courses the not inconsiderable variation lends dubious creditability to the mean. One accredited school requires 7 1/3 semester hr of chemistry, compared with 24 hr required by another, making an average for the six schools of 17 1 /3 hr. Required credit hr in mechanics ranges from 4 to 18 and in surveying from 2 to 15. Several non-accredited schools require more hr than do the accredited schools in some courses. Why is the engineering student forced to carry such a back-breaking load? The answer is of course fairly obvious. He is irrevocably set apart from the rest of the student body because of the nature of his life's work. He is training for a place in a world where technology is becoming increasingly involved. He must be prepared to do a job now-and not later. Mining and geological engineering require the same essential backgrounds as other engineers, and more. The "more" is a knowledge of mining methods, metallurgy and geology for the mining engineer. The geological engineer must know in addition, mineralogy, petrography, and geophysics. The load is compounded finally by the addition of liberal arts courses. Should anything be done to relieve the situation? Today's engineer must be a whole man, capable of handling the tools of communication and with an understanding of the economics of industry. He must be able to write clear simple English, and he must be man who can think from some other position than bent over a work table. He must be aware of the history of his country and to some extent that of the world. Not all schools share this view. Only two of the accredited schools require history courses. However, five of the non-accredited schools make it mandatory. Four accredited and five of the nonaccredited schools require economics. Courses in mathematics, physics, and chemistry are fundamental in engineer training. The average for the accredited schools could serve as a guide in

Jan 1, 1952