Applications of exploration techniques using geochemistry in areas of residual soil, valley glaciation, and continental glaciation.

Abstract

This paper deals briefly with the principles of geochemical migration in the secondary (soil, sediment) environment, a knowledge of which is essential to a correct interpretation of exploration geochemical data. Examples are given which illustrate that the principles which apply in the more easily interpreted tropical areas, also apply in the more complicated glaciated regions. Any person employing exploration geochemistry in geomorphologically complicated areas, is well advised to study data from strictly residual soil areas where the fundamentals of geochemical migration are more easily observed.

Abstract

This volume summarizes the exploration geochemical conditions in the secondary environment, in the Canadian Cordillera and the Canadian Shield. This is achieved by a number of conceptual models which describe the principles and mechanisms of formation of anomalies, which govern the use of exploration geochemistry. These models have been constructed by drawing together information already existing in the literature plus 38 individual case histories contained in this volume.

Abstract

This volume summarizes the exploration geochemical conditions in the secondary environment, in the Canadian Cordillera and the Canadian Shield. This is achieved by a number of conceptual models which describe the principles and mechanisms of formation of anomalies, which govern the use of exploration geochemistry. These models have been constructed by drawing together information already existing in the literature plus 38 individual case histories contained in this volume.

Subjects: uranium; uranium geochemistry; Midnite Uranium Mine, Wash; geochemistry Area Idaho, Usa; United States Of America; Washington, USA

Abstract

The analysis of anion components of thirty natural water samples using an ion-chromatographic method were compared to analyses for F, Cl, NO3 and SO4 obtained by presently used techniques. Of these thirty samples, five were replicates.

Subjects analyses; stream sediment geochemistry; uranium; water geochemistry; Atlin Intrusives; Cache Creek Group; Coast Range Intrusives; Sloko Group; regional geology

Subjects trace element geochemistry; uranium; weathering; Nisling Range Alaskite; geochemistry

Subjects base metals; diffusion; equilibrium; geochemical dispersion; glaciolacustrine deposits; models; soil studies; geochemistry; surficial geology/geomorphology

This was part of a course seminar was held in Spokane, Washington.

This was part of a course seminar held in Spokane, Washington.

Sorry Not available; online CIM Bulletins only go back to 1997.

This was part of a course seminar held in Spokane, Washington.

Subjects analytical methods; chromatographic analyses; water geochemistry; geochemistry

A workshop compiled by J.A. Westgate

Sorry Not available; online CIM Bulletins only go back to 1998.

In: G.R. Parslow (Editor), Geochemical Exploration 1982.

Abstract

Ionic aureoles, overlying or contiguous to massive sulphide occurrences, are postulated to have been emplaced as a result of natural galvanic forces. The occurrences of these galvanic forces, most commonly referred to as the self-potential or spontaneous polarization phenomena, are well documented, but ionic migration in response to these electrical forces remained to be proven conclusively.

Ph.D. Thesis, Univ. New Brunswick. 477 p.

Abstract

Ionic aureoles, overlying or contiguous to massive sulphide occurrences, are postulated to have been emplaced as a result of natural galvanic forces. The occurrences of these galvanic forces, most commonly referred to as the self-potential or spontaneous polarization phenomena, are well documented, but ionic migration in response to these electrical forces remained to be proven conclusively.

Sorry Not available; online CIM Bulletins only go back to 1998.

Macmillian Pass, Yukon Territory In: Mineral Deposits of the Northern Cordillera.

Sorry Not available; online CIM Bulletins only go back to 1998.

At the Jason lead-zinc-silver-barium deposit, Yukon Territory

Abstract

The Macmillan Pass shale-hosted mineral district is located 400 km northeast of Whitehorse, Yukon Territory. On the Jason property, surface exploration based primarily on geological mapping and soil geochemistry has led to the discovery of three massive to laminated deposits rich in lead, zinc, silver, barium and iron. To date, diamond drilling has outlined geological reserves of 14.1 million tonnes grading 7.09% Pb, 6.57% Zn and 79.9 g/t Ag.

Copies available: http://www.appliedgeochemists.org/publications.html

Click to view article

Explore, 63, 12-14.

Those of us engaged in exploration geochemistry have undoubtedly faced difficulties in the interpretation of geochemical surveys for resistate minerals. Over the past ten years, nugget effects in elements such as tungsten, tin, and now gold have undoubtedly caused many headaches. The large amount of exploration currently under way for Au makes the nugget effects associated with Au particularly important for the exploration geochemist.

These two realizations were collected with sample sizes such that an an average of 0.25 and 1 grain per sample (Figures 2b and 2c, respectively) were collected over the anomaly.

A third realization of an unknown groundtruth (with sample sizes corresponding to 0.25 grains per sample) was presented in Figure 2d.

In: Exploration geochemistry of tropical environments, MDRU Short Course, University of British Colombia. (Seminar/Workshop)

In: A workshop on exploration geochemistry in areas of present and past tropical and sub-tropical climates.

Queen's University, Kingston Ontario. (Seminar/Workshop)

ABSTRACT

A challenge for the geochemist is to develop and test transport theories and near surface sampling techniques for use in areas overlain by cover of exotic origin, i.e., where the surficial cover is not in any way related to the underlying bedrock. Selective extraction methods that dissolve certain minerals or attack specific binding sites in soil suppose that some form of upward migration of ions must be taking place. Chemical components related to mineralization must travel from the bed-rock-overburden interface to the surface, where they are immobilized, or change the surface chemistry in some detectable fashion. Upward migration is likely caused by a combination of diffusion down a concentration gradient, capillary action or "wicking" from the water table to the dry surface, osmotic action carrying ionic species, vegetation roots carrying elements to the surface portions of the plant, then back to the soil, or electrical fields transporting ions through the soil by cation exchange.

Available online to subscribers of the Northern Miner at:
http://www.northernminer.com/issues/verify.asp

Northern Miner, June 16, v. 83, No.16

Abstract

Mineral exploration is extending into geologically prospective areas which are overlain by surficial cover. Geochemical techniques using chemical reagents or analytical procedures that selectively dissolve certain minerals or attack specific ion-binding sites in soil have been suggested to enhance the detection of buried mineral deposits. Few of these techniques have been tested one against the other in a controlled environment, and no mechanism of transporting elements through overburden cover has been proposed that explains observed patterns. A geochemical orientation survey over two buried epithermal Au deposits at Marigold, Nevada was completed during 1994-95 in an attempt to determine the effectiveness of various analytical extractions, and develop a theory to explain observed geochemical responses.

Multi-element geochemical data can be effectively interpreted through the use of multivariate statistical techniques, imaging methods and merging with digital topographic information. This is illustrated using the results of a geochemical sampling program in Indonesia. Difficulties were encountered when the interpretation of selected elements was attempted. Patterns appeared to be discontinuous and erratic. However the application of multivariate statistical methods identified two distinct geochemical associations: recent volcanic ash, and a saprolitic soil profile containing a_mineralized zone of Cu associated with mafic volcanic rocks. Maps and figures are shown on Page 20.

In: Workshop on quality control methods in mineral exploration.

Association of Exploration Geochemists, Vancouver. B.W. Smee ed. (Seminar/Workshop)

In: Setting New Standards, Companion Volume B.

Introduction

Weak chemical extractions on soils are being promoted throughout the exploration world as a method for detecting mineralization that is blind to surface (Clark, J.R., 1993, Mann, A.W. et al, 1995). These techniques are being used in a wide variety of geological and climatic terrains, with apparently little regard for geological substrate, or changing soil conditions.

Workshop on Quality Control in Mineral Exploration,

19th IGES, Vancouver.

using multivariate methods and digital topography.

Abstract

Multi-element geochemical data can be effectively interpreted through the application of multivariate statistical techniques, imaging methods and integration with digital topographic information. These techniques have been applied to a suite of 1665 soil samples collected in a sampling program from the central Sumatra area of Indonesia. The selected samples were analyzed for Au, Cu, Pb, Zn, As, Sb, Ba, Ca, Cd, Co, Cr, Fe, Ga, K, La, Li, Mg, Mn, Nb, Ni, Sc, Sr, Ti, V, Y, Zr and Hg using aqua-regia digestion followed by ICP–IES determination.

CIMM Annual Meeting Abst.

Sorry, CIMM Annual Meeting proceedings not available to the public.

In: Mineria, Centro de Excelencia en Mineria (Centre of Excellence in Mining).

NOTE: Arthur Andersen Consulting now doing business as Accenture;

Sorry, no archived publications or reports available.

Vancouver MEG Workshop notes

Workshop/Seminar

Abstract

The development of low-cost, rapid multi-element analytical techniques has generated large geochemical databases in many exploration programs. When a sampling program consists of several thousand samples, the resulting data matrix is enormous and effective interpretation using all of the elements individually becomes burdensome. However, the application of multivariate statistical techniques can extract geochemical patterns related to the underlying geology, weathering, alteration and mineralization. Imaging the results over topography enhances the interpretation of these patterns. Examples of this approach are shown from mineral exploration programs in Canada, Mexico and Indonesia.

Introduction

Auditing resource databases and exploration data sets over the past several decades has exposed the lead author to many instances of data averaging of multiple analyses from a single sample. These data sets were comprised of pulp or reject analyses that showed poor precision upon re-analyses. Some organizations produced a final concentration in their database that was an arithmetic average of all analyses. It was this average concentration that was used in resource grade estimation, or in anomaly definition. In these cases the reason for the re-analyses was a "rare grain" or "nugget" effect in the element being sought, usually gold.

Introduction

The controversy about the use of selective or weak extractions (SWE) to detect buried or blind mineralization continues unabated. Proponents of the methods often appear to be associated with the companies that offer the analytical services (Birrell, 1996; Clark, 1993; Mann et.al., 1998) whilst studies that reveal the difficulties in using such methods are primarily from arms-length institutions (Bajc, 1998; Gray et.al., 1999; Seneshen et.al., 1999; Smee, 1997). I expect the debate will continue into the foreseeable future.

Response to Reply. Article “Theory behind the use of soil pH measurements as an inexpensive guide to buried mineralization, with examples” by Barry Smee in Explore 118, Jan 2003.

Abstract

The development of low-cost, rapid multielement analytical techniques has generated large geochemical databases in many exploration programs. When a sampling program consists of several thousand samples, the resulting data matrix is enormous and effective interpretation using all of the elements individually becomes burdensome.

Introduction

During recent audits of numerous commercial laboratories, the first author has noticed that many laboratories prepare pulp samples from rock, drill core and drill cuttings of approximately 3 kg mass using large, fixedbowl, shatter box-type, vibratory pulverizers. This preparation method is referred to by the laboratories as "total preparation', because the complete 3 kg sample submitted by the geologists is pulverized before sub-sampling. During these laboratory audits, each laboratory manager was asked if this 3 kg pulverizing equipment produced a pulp equal to or better in quality than the smaller 1 kg shatter box pulverizers also in common use by commercial laboratories. Each of the laboratory managers indicated that the large pulverizer actually produced a pulp product that was inferior in grain size specifications to the 1 kg shatter box pulverizers. The laboratory managers furthermore admitted that the larger pulverizers were used solely because the clients requested the 3 kg pulp in the belief that it results in significantly better sub-sampling (preparation) precision than a 1 kg pulp. This purportedly improved precision was thought to be especially important for samples containing a significant "rare grain' or nugget effect.

1. Dr. Francois-Bongarcon first suggests that Poisson statistics cannot be used to model sampling error in gold ores because the gold is typically not liberated. This comment ignores the work of Clifton et al. (1969), that has long formed the basis of sampling protocols for rare grains in applied geochemistry. This U.S.G.S. Professional Paper details how the effective nugget size and the effective number of nuggets can be calculated from the relative error of replicate samples of a given size, and how these can be used to estimate the relative error of samples of different sizes. Clifton et al.'s (1969) approach makes no attempt to exactly mimic non-ideal sample characteristics (such as full liberation, or constant grain size and shape), but rather employs an ideal 'equant grain model' that exhibits exactly the same variance structure of the material under examination. Using this Poisson-based model, predictions regarding the magnitude of sampling error can be made for samples of different size.

Workshop on partial leaches in exploration and environmental geochemistry, IGES, Perth.

Workshop/Seminar

Workshop on Geochemistry in Mineral Resource Development, in Wealth Creation in the Minerals Industry, SEG, Keystone, Colorado.

Workshop/Seminar

Exploration 2007 Workshop.

Workshop/Seminar

Abstract

Sampling error is the degree to which the concentration of an element differs from the true element concentration of the material from which the sample was collected. Gold mineralization commonly exhibits sampling errors as large as 50–100%. As a result, collection and preparation of drill samples from Au mineralization can provide significant challenges for the geoscientist, largely because of the coarse particulate nature of Au. To avoid this, geoscientists have opted to collect and prepare larger drill samples to reduce the magnitude of this ‘nugget effect’.