EXPLORATION EXPLORATION TECHNIQUESTECHNIQUES

Virginia McLemoreVirginia McLemore

WHAT ARE THE OBJECTIVES IN WHAT ARE THE OBJECTIVES IN EXPLORATION?EXPLORATION?

WHAT ARE THE OBJECTIVES IN WHAT ARE THE OBJECTIVES IN EXPLORATION?EXPLORATION?

Establish baseline/background conditionsEstablish baseline/background conditions Find alteration zonesFind alteration zones Find ore bodyFind ore body Determine if ore can be mined or leachedDetermine if ore can be mined or leached Determine if ore can be processedDetermine if ore can be processed Determine ore reservesDetermine ore reserves Locate areas for infrastructure/operationsLocate areas for infrastructure/operations Environmental assessmentEnvironmental assessment Further understand uranium depositsFurther understand uranium deposits Refine exploration modelsRefine exploration models

STEPSSTEPS

Define uranium deposit modelDefine uranium deposit model Select areaSelect area Collect and interpret regional dataCollect and interpret regional data Define local target areaDefine local target area Field reconnaissanceField reconnaissance Reconnaissance drillingReconnaissance drilling Bracket drillingBracket drilling Ore discoveryOre discovery

Select AreaSelect Area

How do we select an area to look for How do we select an area to look for uranium?uranium?

Select AreaSelect Area

How do we select an area to look for How do we select an area to look for uranium?uranium?• Areas of known productionAreas of known production• Areas of known uranium occurrencesAreas of known uranium occurrences• Favorable conditions for uraniumFavorable conditions for uranium

COLLECT DATACOLLECT DATA

Historical dataHistorical data State, federal surveysState, federal surveys University research programsUniversity research programs ArchivesArchives Company reportsCompany reports Web sitesWeb sites Published literaturePublished literature Prospectors Prospectors

MethodsMethods Magnetic surveysMagnetic surveys Electromagnetic (EM, EMI), Electromagnetic (EM, EMI),

electromagnetic sounding electromagnetic sounding Direct current (DC)Direct current (DC) GPR (Ground penetrating GPR (Ground penetrating

radar potential) radar potential) Seismic Seismic Time-domain Time-domain

electromagnetic (TEM)electromagnetic (TEM) Controlled source audio-Controlled source audio-

magnetotellurics (CSAMT)magnetotellurics (CSAMT) Radiometric surveysRadiometric surveys Induced polarization (IP)Induced polarization (IP)

Spontaneous potential (SP)Spontaneous potential (SP) Borehole geophysics Borehole geophysics Satellite imagerySatellite imagery Imagery spectrometry Imagery spectrometry ASTER (Advanced space-ASTER (Advanced space-

borne thermal emissions borne thermal emissions reflection radiometer)reflection radiometer)

AVIRISAVIRIS PIMAPIMA SFSISFSI LIBSLIBS SWIRSWIR MultispectralMultispectral

REMOTE SENSINGREMOTE SENSING

Remote Sensing TechniquesRemote Sensing Techniques

Digital elevation model (DEM) Digital elevation model (DEM) Landsat Thematic Mapper (TM)Landsat Thematic Mapper (TM) ASTER (Advanced Spaceborne Thermal ASTER (Advanced Spaceborne Thermal

Emission and Reflection Radiometer)Emission and Reflection Radiometer) Hyperspectral remote sensing (spectral Hyperspectral remote sensing (spectral

bands, 14 and >100 bands)bands, 14 and >100 bands) NOAA-AVHRR NOAA-AVHRR ((National Oceanic and National Oceanic and

Atmospheric Administration - Advanced Atmospheric Administration - Advanced Very High Resolution RadiometerVery High Resolution Radiometer

Remote sensing is the science of Remote sensing is the science of remotely acquiring, processing and remotely acquiring, processing and

interpreting spectral information about interpreting spectral information about the earth’s surface and recording the earth’s surface and recording interactions between matter and interactions between matter and

electromagnetic energyelectromagnetic energy..

GROUND

Alumbrera, Ar

SATELLITE

AIRBORNE

CUPRITE, NVGoldfield, NV

Data is collected from satellite and airborne sensors. It is then calibrated and verified using a field spectrometer.

Field Spectrometer

LANDSAT

HYPERSPECTRAL

Sunlight Interaction with the Sunlight Interaction with the Atmosphere and the Earth’s SurfaceAtmosphere and the Earth’s Surface

The electromagnetic spectrum is a distribution of energy over specific wavelengths. When this energy is emitted by a luminous object, it can be detected over great distances. Through the use of instrumentation, the technique detects this energy reflected and emitted from the earth’s surface materials such as minerals, vegetation, soils, ice, water and rocks, in selected wavelengths. A proportion of the energy is reflected directly from the earth’s surface. Natural objects are generally not perfect reflectors, and therefore the intensity of the reflection varies as some of the energy is absorbed by the earth and not reflected back to the sensor. These interactions of absorption and reflection form the basis of spectroscopy and hyperspectral analysis.

Data is collected in contiguous channels by special detector arrays. Collection is done at different spectral and spatial resolutions depending on the type of sensor.

Each spatial element is called a pixel. Pixel size varies from 1/2 meters in some hyperspectral sensors to 30 meters in Landsat and ASTER, which are multispectral. Sensor spatial differences and band configurations are shown below.

Source: Bob Agars

ELECTROMAGNETIC SPECTRUM

HYPERSPECTRAL IMAGING SPECTROSCOPYHYPERSPECTRAL IMAGING SPECTROSCOPY

Source: CSIRO

Imaging spectroscopy is a technique for obtaining a spectrum in each position of a large array of spatial positions so that any one spectral wavelength can be used to make a coherent image (data cube).

Imaging spectroscopy for remote sensing involves the acquisition of image data in many contiguous spectral bands with an ultimate goal of producing laboratory quality reflectance spectra for each pixel in an image (Goetz, 1992b). The latter part of this goal has not yet been reached.

The major difference from Landsat is the ability to detect individual mineral species

and differentiate vegetation species.

This "image cube" from JPL's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) shows the volume of data returned by the instrument. AVIRIS acquired the data on August 20, 1992 when it was flown on a NASA ER-2 plane at an altitude of 20,000 meters (65,000 feet) over Moffett Field, California, at the southern end of the San Francisco Bay. The top of the cube is a false-color image made to accentuate the structure in the water and evaporation ponds on the right. Also visible on the top of the cube is the Moffett Field airport. The sides of the cube are slices showing the edges of the top in all 224 of the AVIRIS spectral channels. The tops of the sides are in the visible part of the spectrum (wavelength of 400 nanometers), and the bottoms are in the infrared (2,500 nanometers). The sides are pseudo-color, ranging from black and blue (low response) to red (high response). Of particular interest is the small region of high response in the upper right corner of the larger side. This response is in the red part of the visible spectrum (about 700 nanometers), and is due to the presence of 1-centimeter-long (half-inch) red brine shrimp in the evaporation pond.

Exploration Exploration Techniques:Techniques:

Geologic MappingGeologic Mapping

Leann M. GieseLeann M. GieseFebruary 7, 2008February 7, 2008

In the mine life cycle, geologic mapping falls under In the mine life cycle, geologic mapping falls under Exploration, but it effects all of the life cyclesExploration, but it effects all of the life cycles

Mining Life Cycle Mining Life Cycle (Spiral?)(Spiral?)

Exploration

Mine Development

Operations

Temporary Closure

Closure

Post-Closure

Future Land Use

Ongoing Operations

?????(McLemore, 2008)

What is geologic What is geologic mapping?mapping?

A way to gather & present geologic A way to gather & present geologic data. data. (Peters, 1978)(Peters, 1978)

Shows how rock & soil on the earths Shows how rock & soil on the earths surface is distributed. surface is distributed. (USGS)(USGS)

Are used to make decisions on how to Are used to make decisions on how to use our water, land, and resources. use our water, land, and resources. (USGS)(USGS)

Help to come up with a model for an Help to come up with a model for an ore body. ore body. (Peters, 1978)(Peters, 1978)

Figure 1. Graphic representation of typical information in a general purpose geologic map that can be used to identify geologic hazards, locate natural resources, and facilitate land-use planning. (After R. L. Bernknopf et al., 1993)

What is Geologic What is Geologic Mapping? (continued)Mapping? (continued)

•To better understand the geological features of an area•Predict what is below the earth’s surface•Show other features such as faults and strike and dips. (USGS (a))

Simplified Geologic Map of New Mexico

(from NMBGMR).

Topographic Map of the Valle Grande in the Jamez Mountains

Geologic Mapping Geologic Mapping EquipmentEquipment

Field notebooks Field notebooks Rock hammerRock hammer Hand Lens (10x or Hastings triplet)Hand Lens (10x or Hastings triplet) Pocket knifePocket knife MagnetMagnet Clip boardClip board Pencils (2H-4H) and Colored PencilsPencils (2H-4H) and Colored Pencils Rapidograph-type pens and MarkersRapidograph-type pens and Markers Scale-protractor (10 and 50 or 1:1000 and 1:4000)Scale-protractor (10 and 50 or 1:1000 and 1:4000) Belt pouches or field vestBelt pouches or field vest 30 meter tape measurer30 meter tape measurer Brunton pocket transitBrunton pocket transit GPS/AltimetersGPS/Altimeters CameraCamera

(Compton,1985)(Compton,1985)

                          

      

Mapping typesMapping types Aerial photographsAerial photographs

Topographical basesTopographical bases

Pace and CompassPace and Compass

ChainsChains

(Compton, 1985)

Map scalesMap scalesA ratio that relates a unit of measure on a A ratio that relates a unit of measure on a

map to some number of the same units of map to some number of the same units of measure on the earth's surface. measure on the earth's surface.

A map scale of 1:25,000 tells us that 1 unit A map scale of 1:25,000 tells us that 1 unit of measure represents 25,000 of the same of measure represents 25,000 of the same units on the earth's surface. One inch on units on the earth's surface. One inch on the map represents 25,000 inches on the the map represents 25,000 inches on the earth's surface. earth's surface.

One meter or one yard or one kilometer or One meter or one yard or one kilometer or one mile on a map would represent 25,000 one mile on a map would represent 25,000 meters or yards or kilometers or miles, meters or yards or kilometers or miles, respectively, on the earth's surface. respectively, on the earth's surface.

(from USGS (b))

Map scales (continued)Map scales (continued)Map ScaleMap Scale One cm on One cm on

the map the map representsrepresents

One km on One km on the Earth is the Earth is represented represented on the map on the map byby

One inch on One inch on the map the map representsrepresents

One mile on One mile on the Earth the Earth represented represented on the map on the map byby

1:2,0001:2,000 20 meters20 meters 50 50 centimeterscentimeters

166.67 feet166.67 feet 31.68 inches31.68 inches

1:25,0001:25,000 250 meters250 meters 4 4 centimeterscentimeters

2,083.33 2,083.33 feetfeet

2.53 inches2.53 inches

1:100,0001:100,000 1,000 1,000 metersmeters

1 1 centimetercentimeter

1.58 miles1.58 miles 0.634 inches0.634 inches

1:5,000,0001:5,000,000 50,000 50,000 metersmeters

0.02 0.02 centimeterscentimeters

78.91 miles78.91 miles 0.013 inches0.013 inches

(from USGS (b))

What to do first?What to do first? Most mineral deposits are found in districts Most mineral deposits are found in districts

where there has been mining before, an where there has been mining before, an earlier geologist has noticed something of earlier geologist has noticed something of importance there, or a prospector has filed importance there, or a prospector has filed a mineral claima mineral claim

Literature Search:Literature Search:• Library (University, Government, Engineering, or Library (University, Government, Engineering, or

Interlibrary loans)Interlibrary loans)• State and National bureaus of mines and State and National bureaus of mines and

geological surveys (may have drill core, well geological surveys (may have drill core, well cuttings, or rock samples available to inspect)cuttings, or rock samples available to inspect)

• Mining company information Mining company information • Maps and aerial photographsMaps and aerial photographs

Is the information creditable? Is it worth Is the information creditable? Is it worth exploring?exploring?

(Peters, 1978)

Where to go from here?Where to go from here?

Mapping is costly and time consuming, so an area Mapping is costly and time consuming, so an area of interest needs to be definedof interest needs to be defined

Reconnaissance helps narrows a region to a Reconnaissance helps narrows a region to a smaller area of specific interestsmaller area of specific interest

Reconnaissace in the U.S. usually begins at Reconnaissace in the U.S. usually begins at 1:250,000-scale1:250,000-scale

This large scale mapping can zone-in on areas of This large scale mapping can zone-in on areas of interest that can then be geologically mapped in interest that can then be geologically mapped in detail (this is usually done on a 1:10,000 or detail (this is usually done on a 1:10,000 or 1:12,000-scale). 1:12,000-scale).

Individual mineral deposits can be mapped at a Individual mineral deposits can be mapped at a 1:2,000 or 1:2,400-scale to catch its smaller 1:2,000 or 1:2,400-scale to catch its smaller significant features. significant features.

(Peters, 1978)(Peters, 1978)

Detailed Geological Detailed Geological MappingMapping

When mapping, we want to be quick, When mapping, we want to be quick, because time is money, but not too quick because time is money, but not too quick as to make a mistake or miss something.as to make a mistake or miss something.

Along with mapping occurs drilling, Along with mapping occurs drilling, trenching, geophysics, and geochemistrytrenching, geophysics, and geochemistry

Samples can be analyzed for Uranium Samples can be analyzed for Uranium concentrations. This gives a better idea of concentrations. This gives a better idea of where to explore more or drill in an area. where to explore more or drill in an area.

Uranium Deposit TypesUranium Deposit Types UnconformityUnconformity-related deposits-related deposits

• Metasedimentary rocks (mineralisation, fauletd, and brecciated) below Metasedimentary rocks (mineralisation, fauletd, and brecciated) below and Proterozoic SS. Above (pitchblende)and Proterozoic SS. Above (pitchblende)

Breccia complex depositsBreccia complex deposits• Hematite-rich breccia complex (iron, copper, gold, silver, & REE)Hematite-rich breccia complex (iron, copper, gold, silver, & REE)

Sandstone depositsSandstone deposits• Rollfront deposits, tabular deposits, tectonic/lithologic depositsRollfront deposits, tabular deposits, tectonic/lithologic deposits

Surficial depositsSurficial deposits• Young, near-surface uranium concentrations in sediments or soils Young, near-surface uranium concentrations in sediments or soils

(calcite, gypsum, dolomite, ferric oxide, and halite)(calcite, gypsum, dolomite, ferric oxide, and halite) Volcanic depositsVolcanic deposits

• Acid volcanic rocks and related to faults and shear zones within the Acid volcanic rocks and related to faults and shear zones within the volcanics (molybdenum & fluorine)volcanics (molybdenum & fluorine)

Intrusive depositsIntrusive deposits• Associated with intrusive rocks (alaskite, granite, pegmatite, and Associated with intrusive rocks (alaskite, granite, pegmatite, and

monzonites)monzonites) Metasomatite depositsMetasomatite deposits

• In structurally-deformed rocks altered by metasomatic processes In structurally-deformed rocks altered by metasomatic processes (sodium, potassium or calcium introduction)(sodium, potassium or calcium introduction)

(Lambert et al., 1996)

Metamorphic depositsMetamorphic deposits• Ore body occurs in a calcium-rich alteration zone within Proterozoic Ore body occurs in a calcium-rich alteration zone within Proterozoic

metamoprphic rocksmetamoprphic rocks Quartz-pebble conglomerate depositsQuartz-pebble conglomerate deposits

• Uranium recovered as a by-product of gold miningUranium recovered as a by-product of gold mining Vein depositsVein deposits

• Spatially related to granite, crosscuts metamorphic or sedimentary Spatially related to granite, crosscuts metamorphic or sedimentary rocks (coffinite, pitchblende)rocks (coffinite, pitchblende)

Phosphorite depositsPhosphorite deposits• Fine-grained apatie in phosphorite horizons; mud, shale, carbonates Fine-grained apatie in phosphorite horizons; mud, shale, carbonates

and SS. interbeddedand SS. interbedded Collapse breccia depositsCollapse breccia deposits

• Vertical tubular-like deposits filled with coarse and fine fragmentsVertical tubular-like deposits filled with coarse and fine fragments LigniteLignite Black shale depositsBlack shale deposits Calcrete depositsCalcrete deposits

Uranium-rich granites deeply weathered, valley-typeUranium-rich granites deeply weathered, valley-type OtherOther

Uranium Deposit Types Uranium Deposit Types (continued)(continued)

Some Minerals Associated Some Minerals Associated with Uraniumwith Uranium

Uraninite (UO2)Uraninite (UO2) Pitchblende (U2O5.UO3 or U3O8)Pitchblende (U2O5.UO3 or U3O8) Carnotite (uranium potassium vanadate)Carnotite (uranium potassium vanadate) Davidite-brannerite-absite type uranium titanatesDavidite-brannerite-absite type uranium titanates Euxenite-fergusonite-smarskite groupEuxenite-fergusonite-smarskite group Secondary Minerals:Secondary Minerals:

• GummiteGummite• AutuniteAutunite• SaleeiteSaleeite• TorberniteTorbernite• CoffiniteCoffinite• UranophaneUranophane• SklodowskiteSklodowskite

(Lambert et al., 1996)

Example of exploring a sandstone Example of exploring a sandstone Uranium depositUranium deposit

When looking for a sandstone-type uranium deposit When looking for a sandstone-type uranium deposit in an area that has had a radiometric survey, our first in an area that has had a radiometric survey, our first place to focus in on the areas where radioactivity place to focus in on the areas where radioactivity appears to be associated with SS. Beds. (We will appears to be associated with SS. Beds. (We will disregard potassium anomalies, below-threshold disregard potassium anomalies, below-threshold readings, unexplained areas, and radioactive readings, unexplained areas, and radioactive “noise”.)“noise”.)

We will then map the radioactive SS. units and other We will then map the radioactive SS. units and other associations with our model of a SS. uranium deposit. associations with our model of a SS. uranium deposit.

We will look for poorly sorted, medium to coarse We will look for poorly sorted, medium to coarse grained SS. beds that are associated with mudstones grained SS. beds that are associated with mudstones or shales.or shales.

Detailed mapping of outcrops on a smaller scale is Detailed mapping of outcrops on a smaller scale is now appropriate. Stratigraphic sections can be now appropriate. Stratigraphic sections can be measured and projected to covered areas. measured and projected to covered areas.

Other radioactive areas that were disregarded may Other radioactive areas that were disregarded may be given a second look for other possibilities for be given a second look for other possibilities for further investigations. further investigations. (Peters, 1978)

ReferencesReferences Compton, R. R. (1985). Compton, R. R. (1985). Geology in the Field. Geology in the Field. United States of America and United States of America and

Canada: John Wiley & Sons, Inc.Canada: John Wiley & Sons, Inc. Bernknopf, R. L., et al., 1993Bernknopf, R. L., et al., 1993

Societal Value of Geologic MapsSocietal Value of Geologic Maps, USGS Circular 1111. , USGS Circular 1111. Lambert,I., McKay, A., and Miezitis, Y. (1996) Lambert,I., McKay, A., and Miezitis, Y. (1996) Australia's uranium Australia's uranium

resources: trends, global comparisons and new developmentsresources: trends, global comparisons and new developments, Bureau of , Bureau of Resource Sciences, Canberra, with their later paper: Resource Sciences, Canberra, with their later paper: Australia's Uranium Australia's Uranium Resources and Production in a World ContextResources and Production in a World Context, ANA Conference October , ANA Conference October 2001. 2001. http://www.uic.com.au/nip34.htmhttp://www.uic.com.au/nip34.htm (accessed February 6, 2008). (accessed February 6, 2008).

McLemore, V. T. Geology and Mining of Sediment-Hosted Uranium McLemore, V. T. Geology and Mining of Sediment-Hosted Uranium Deposits: Deposits: What is Uranium?. What is Uranium?. Lecture, January 30, 2008; pp. 1-26. Lecture, January 30, 2008; pp. 1-26.

New Mexico Bureau of Geology and Mineral Resources. New Mexico Bureau of Geology and Mineral Resources. http://geoinfo.nmt.edu/publications/maps/home.html (accessed February 1, http://geoinfo.nmt.edu/publications/maps/home.html (accessed February 1, 2008). 2008).

Peters, W. C. (1978). Peters, W. C. (1978). Exploration and Mining GeologyExploration and Mining Geology. United States of . United States of America and Canada: John Wiley & Sons, Inc.America and Canada: John Wiley & Sons, Inc.

U.S. Geological Survey (a). U.S. Geological Survey (a). http://ncgmp.usgs.gov/ncgmpgeomaps (accessed February 1, 2008).http://ncgmp.usgs.gov/ncgmpgeomaps (accessed February 1, 2008). U.S. Geological Survey (b). U.S. Geological Survey (b).

http://id.water.usgs.gov/reference/map_scales.html (accessed February 6, http://id.water.usgs.gov/reference/map_scales.html (accessed February 6, 2008). 2008).

GEOPHYSICAL TECHNIQUESGEOPHYSICAL TECHNIQUES

Pedram RostamiPedram Rostami

Gravity TechniquesGravity TechniquesIntroductionIntroduction

Lateral density changes in the subsurface cause a Lateral density changes in the subsurface cause a changechange

in the force of gravity at the surface. in the force of gravity at the surface.

The intensity of the force of gravity due to a buried The intensity of the force of gravity due to a buried mass difference (concentration or void) is mass difference (concentration or void) is superimposed on the larger force of gravity due to the superimposed on the larger force of gravity due to the total mass of the earth. total mass of the earth.

Thus, two components of gravity forces are measured Thus, two components of gravity forces are measured at the earth’s surface: first, a general and relatively at the earth’s surface: first, a general and relatively uniform component due to the total earth, and second, uniform component due to the total earth, and second, a component of much smaller size which varies due to a component of much smaller size which varies due to lateral density changes (the gravity anomaly). lateral density changes (the gravity anomaly).

ApplicationsApplications

By very precise measurement of gravity and by By very precise measurement of gravity and by careful correction for variations in the larger careful correction for variations in the larger component due to the whole earth, a gravity component due to the whole earth, a gravity survey can sometimes detect natural or man-made survey can sometimes detect natural or man-made voids, variations in the depth to bedrock, and voids, variations in the depth to bedrock, and geologic structures of engineering interest.geologic structures of engineering interest.

For engineering and environmental applications, For engineering and environmental applications, the scale of the problem is generally small (targets the scale of the problem is generally small (targets are often from 1-10 m in size)are often from 1-10 m in size)

Station spacings are typically in the range of 1-10 Station spacings are typically in the range of 1-10 mm

Even a new name, microgravity, was invented to Even a new name, microgravity, was invented to describe the work.describe the work.

Gravity surveys are limited by ambiguity and the Gravity surveys are limited by ambiguity and the assumption of homogeneityassumption of homogeneity

A distribution of small masses at a shallow depth can A distribution of small masses at a shallow depth can produce the same effect as a large mass at depth.produce the same effect as a large mass at depth.

External control of the density contrast or the specific External control of the density contrast or the specific geometry is required to resolve ambiguity questions. geometry is required to resolve ambiguity questions.

This external control may be in the form of geologic This external control may be in the form of geologic plausibility, drill-hole information, or measured densities.plausibility, drill-hole information, or measured densities.

The first question to ask when considering a gravity survey The first question to ask when considering a gravity survey is “For the current subsurface model, can the resultant is “For the current subsurface model, can the resultant gravity anomaly be detected?”.gravity anomaly be detected?”.

Inputs required are the probable geometry of the Inputs required are the probable geometry of the anomalous region, its depth of burial, and its density anomalous region, its depth of burial, and its density contrast. contrast.

A generalized rule of thumb is that a body must be almost A generalized rule of thumb is that a body must be almost as big as it is deep. as big as it is deep.

Rock PropertiesRock Properties Values for the density of shallow Values for the density of shallow

materials are determined from materials are determined from laboratory tests of boring and bag laboratory tests of boring and bag samples. Density estimates may samples. Density estimates may also be obtained from geophysical also be obtained from geophysical well loggingwell logging

Table 5-1 lists the densities of Table 5-1 lists the densities of representative rocks.representative rocks.

Densities of a specific rock type on Densities of a specific rock type on a specific site will not have more a specific site will not have more than a few percent variability as a than a few percent variability as a rule (vuggy limestones being one rule (vuggy limestones being one exception). However, exception). However, unconsolidated materials such as unconsolidated materials such as alluvium and stream channel alluvium and stream channel materials may have significant materials may have significant variation in density.variation in density.

Field WorkField Work General General

Up to 50 percent of the work in a microgravity Up to 50 percent of the work in a microgravity survey is consumed in the surveying.survey is consumed in the surveying.

relative elevations for all stations need to be relative elevations for all stations need to be stablished to ±1 to 2 cm. A firmly fixed stake or stablished to ±1 to 2 cm. A firmly fixed stake or mark should be used to allow the gravity meter mark should be used to allow the gravity meter reader to recover the exact elevation. reader to recover the exact elevation.

Satellite surveying, GPS, can achieve the required Satellite surveying, GPS, can achieve the required accuracy, especially the vertical accuracy, only accuracy, especially the vertical accuracy, only with the best equipment under ideal conditions.with the best equipment under ideal conditions.

High station densities are often required. It is not High station densities are often required. It is not unusual for intervals of 1-3 m to be required to unusual for intervals of 1-3 m to be required to map anomalous masses whose maximum map anomalous masses whose maximum dimension is 10 m.dimension is 10 m.

Field WorkField Work General General

After elevation and position surveying, actual After elevation and position surveying, actual measurement of the gravity readings is often measurement of the gravity readings is often accomplished by one person in areas where solo accomplished by one person in areas where solo work is allowed. work is allowed.

t is necessary to improve the precision of the station t is necessary to improve the precision of the station readings by repetition.readings by repetition.

The most commonly used survey technique is to The most commonly used survey technique is to choose one of the stations as a base and to reoccupy choose one of the stations as a base and to reoccupy that base periodically throughout the working day. that base periodically throughout the working day.

The observed base station gravity readings are then The observed base station gravity readings are then plotted versus time, and a line is fitted to them to plotted versus time, and a line is fitted to them to provide time rates of drift for the correction of the provide time rates of drift for the correction of the remainder of the observations. remainder of the observations.

InterpretationInterpretation Software packages for the interpretation of gravity data Software packages for the interpretation of gravity data

are plentiful and powerful. are plentiful and powerful.

The geophysicist can then begin varying parameters in The geophysicist can then begin varying parameters in order to bring the calculated and observed values closer order to bring the calculated and observed values closer together.together.

Parameters usually available for variation are the Parameters usually available for variation are the vertices of the polygon, the length of the body vertices of the polygon, the length of the body perpendicular to the traverse, and the density contrast. perpendicular to the traverse, and the density contrast. Most programs also allow multiple bodies.Most programs also allow multiple bodies.

Magnetic MethodsMagnetic MethodsIntroductionIntroduction

The earth possesses a magnetic field caused The earth possesses a magnetic field caused primarily by sources in the core. primarily by sources in the core.

The form of the field is roughly the same, as would be The form of the field is roughly the same, as would be caused by a dipole or bar magnet located near the caused by a dipole or bar magnet located near the earth’s center and aligned sub parallel to the earth’s center and aligned sub parallel to the geographic axis. geographic axis.

The intensity of the earth’s field is customarily The intensity of the earth’s field is customarily expressed in S.I. units as nanoteslas (nT) or in an expressed in S.I. units as nanoteslas (nT) or in an older unit, gamma (g): 1 g = 1 nT = 10-3 μT. Except older unit, gamma (g): 1 g = 1 nT = 10-3 μT. Except for local perturbations, the intensity of the earth’s for local perturbations, the intensity of the earth’s field varies between about 25 and 80 μT over the field varies between about 25 and 80 μT over the coterminous United Statescoterminous United States

Many rocks and minerals are weakly magnetic or are Many rocks and minerals are weakly magnetic or are magnetized by induction in the earth’s field, and magnetized by induction in the earth’s field, and cause spatial perturbations or “anomalies” in the cause spatial perturbations or “anomalies” in the earth’s main field. earth’s main field.

Man-made objects containing iron or steel are often Man-made objects containing iron or steel are often highly magnetized and locally can cause large highly magnetized and locally can cause large anomalies up to several thousands of nT. anomalies up to several thousands of nT.

Magnetic methods are generally used to map the Magnetic methods are generally used to map the location and size of ferrous objects. Determination of location and size of ferrous objects. Determination of the applicability of the magnetics method should be the applicability of the magnetics method should be done by an experienced engineering geophysicist. done by an experienced engineering geophysicist.

Modeling and incorporation of auxiliary information Modeling and incorporation of auxiliary information may be necessary to produce an adequate work plan.may be necessary to produce an adequate work plan.

TheoryTheory The earth’s magnetic field dominates most measurementsz The earth’s magnetic field dominates most measurementsz

on the surface of the earth. on the surface of the earth.

Most materials except for permanent magnets, exhibit an Most materials except for permanent magnets, exhibit an induced magnetic field due to the behavior of the material induced magnetic field due to the behavior of the material when the material is in a strong field such as the earth’s. when the material is in a strong field such as the earth’s.

Induced magnetization (sometimes called magnetic Induced magnetization (sometimes called magnetic polarization) refers to the action of the field on the material polarization) refers to the action of the field on the material wherein the ambient field is enhanced causing the material wherein the ambient field is enhanced causing the material itself to act as a magnet.itself to act as a magnet.

The field caused by such a material is directly proportional The field caused by such a material is directly proportional to the intensity of the ambient field and to the ability of the to the intensity of the ambient field and to the ability of the material to enhance the local field, a property called material to enhance the local field, a property called magnetic susceptibility. The induced magnetization is equal magnetic susceptibility. The induced magnetization is equal to the product of the volume magnetic susceptibility and to the product of the volume magnetic susceptibility and the inducing field of the earth:the inducing field of the earth:

Theory(continue)Theory(continue) I = k FI = k F k = volume magnetic susceptibility (unitless)k = volume magnetic susceptibility (unitless) I = induced magnetization per unit volumeI = induced magnetization per unit volume F = field intensity in tesla (T)F = field intensity in tesla (T) For most materials For most materials k is much less than 1 and, in k is much less than 1 and, in fact, is usually fact, is usually

of the order of 10^-6 for most rock materials. of the order of 10^-6 for most rock materials. The most important exception is magnetite whose The most important exception is magnetite whose

susceptibility is about 0.3. From a geologic standpoint, susceptibility is about 0.3. From a geologic standpoint, magnetite and its distribution determine the magnetic magnetite and its distribution determine the magnetic properties of most rocks. properties of most rocks.

There are other important magnetic minerals in mining There are other important magnetic minerals in mining prospecting, but the amount and form of magnetite within a prospecting, but the amount and form of magnetite within a rock determines how most rocks respond to an inducing field. rock determines how most rocks respond to an inducing field.

Iron, steel, and other ferromagnetic alloys have susceptibilities Iron, steel, and other ferromagnetic alloys have susceptibilities one to several orders of magnitude larger than magnetite. The one to several orders of magnitude larger than magnetite. The exception is stainless steel, which has a small susceptibility.exception is stainless steel, which has a small susceptibility.

The importance of The importance of magnetite cannot be magnetite cannot be exaggerated. Some tests exaggerated. Some tests on rock materials have on rock materials have shown that a rock shown that a rock containing 1 percent containing 1 percent magnetite may have a magnetite may have a susceptibility as large as susceptibility as large as 10-3, or 1,000 times larger 10-3, or 1,000 times larger than most rock materials.than most rock materials.

Table 6-1 provides some Table 6-1 provides some typical values for rock typical values for rock materials. materials.

Note that the range of Note that the range of values given for each values given for each sample generally depends sample generally depends on the amount of on the amount of magnetite in the rockmagnetite in the rock

Theory(continue)Theory(continue) Thus it can be seen that in most engineering and Thus it can be seen that in most engineering and

environmental scale investigations, the sedimentary environmental scale investigations, the sedimentary and alluvial sections will not show sufficient contrast and alluvial sections will not show sufficient contrast such that magnetic measurements will be of use in such that magnetic measurements will be of use in mapping the geology. mapping the geology.

However, the presence of ferrous materials in However, the presence of ferrous materials in ordinary municipal trash and in most industrial ordinary municipal trash and in most industrial waste does allow the magnetometer to be effective waste does allow the magnetometer to be effective in direct detection of landfills. in direct detection of landfills.

Other ferrous objects which may be detected Other ferrous objects which may be detected include pipelines, underground storage tanks, and include pipelines, underground storage tanks, and some ordnance.some ordnance.

Field WorkField WorkGround magnetic measurements are Ground magnetic measurements are

usually made with portable usually made with portable instruments at regular intervals along instruments at regular intervals along more or less straight and parallel more or less straight and parallel lines which cover the survey area. lines which cover the survey area.

Often the interval between Often the interval between measurement locations (stations) measurement locations (stations) along the lines is less than the along the lines is less than the spacing between lines.spacing between lines.

The magnetometer is a sensitive instrument which is The magnetometer is a sensitive instrument which is used to map spatial variations in the earth’s magnetic used to map spatial variations in the earth’s magnetic field. field.

In the proton magnetometer, a magnetic field which is In the proton magnetometer, a magnetic field which is not parallel to the earth’s field is applied to a fluid rich in not parallel to the earth’s field is applied to a fluid rich in protons causing them to partly align with this artificial protons causing them to partly align with this artificial field.field.

When the controlled field is removed, the protons When the controlled field is removed, the protons precess toward realignment with the earth’s field at a precess toward realignment with the earth’s field at a frequency which depends on the intensity of the earth’s frequency which depends on the intensity of the earth’s field. By measuring this precession frequency, the total field. By measuring this precession frequency, the total intensity of the field can be determined. intensity of the field can be determined.

The physical basis for several other magnetometers, The physical basis for several other magnetometers, such as the cesium or rubidium-vapor magnetometers, such as the cesium or rubidium-vapor magnetometers, is similarly founded in a fundamental physical constant. is similarly founded in a fundamental physical constant. The optically pumped magnetometers have increased The optically pumped magnetometers have increased sensitivity and shorter cycle times (as small as 0.04 s) sensitivity and shorter cycle times (as small as 0.04 s) making them particularly useful in airborne applications.making them particularly useful in airborne applications.

The incorporation of computers and non-The incorporation of computers and non-volatile memory in magnetometers has volatile memory in magnetometers has greatly increased the ease of use and data greatly increased the ease of use and data handling capability of magnetometers.handling capability of magnetometers.

The instruments typically will keep track of The instruments typically will keep track of position, prompt for inputs, and internally position, prompt for inputs, and internally store the data for an entire day of work.store the data for an entire day of work.

Downloading the information to a personal Downloading the information to a personal computer is straightforward and plots of computer is straightforward and plots of the day’s work can be prepared each night.the day’s work can be prepared each night.

To make accurate anomaly maps, temporal To make accurate anomaly maps, temporal changes in the earth’s field during the period of the changes in the earth’s field during the period of the survey must be considered. Normal changes during survey must be considered. Normal changes during a day, sometimes called diurnal drift, are a few a day, sometimes called diurnal drift, are a few tens of nT but changes of hundreds or thousands of tens of nT but changes of hundreds or thousands of nT may occur over a few hours during magnetic nT may occur over a few hours during magnetic storms. storms.

During severe magnetic storms, which occur During severe magnetic storms, which occur infrequently, magnetic surveys should not be infrequently, magnetic surveys should not be made. The correction for diurnal drift can be made made. The correction for diurnal drift can be made by repeat measurements of a base station at by repeat measurements of a base station at frequent intervals. frequent intervals.

The measurements at field stations are then The measurements at field stations are then corrected for temporal variations by assuming a corrected for temporal variations by assuming a linear change of the field between repeat base linear change of the field between repeat base station readings. station readings.

The base-station memory magnetometer, The base-station memory magnetometer, when used, is set up every day prior to when used, is set up every day prior to collection of the magnetic data. collection of the magnetic data.

The base station ideally is placed at least 100 The base station ideally is placed at least 100 m from any large metal objects or travelled m from any large metal objects or travelled roads and at least 500 m from any power roads and at least 500 m from any power lines when feasible. lines when feasible.

The base station location must be very well The base station location must be very well described in the field book as others may described in the field book as others may have to locate it based on the written have to locate it based on the written description.description.

The value of the magnetic field at the base The value of the magnetic field at the base station must be asserted (usually a value station must be asserted (usually a value close to its reading on the first day) and each close to its reading on the first day) and each day’s data corrected for the difference day’s data corrected for the difference between the asserted value and the base between the asserted value and the base value read at the beginning of the day. value read at the beginning of the day.

As the base may vary by 10-25 nT or more As the base may vary by 10-25 nT or more from day to day, this correction ensures that from day to day, this correction ensures that another person using the SAME base station another person using the SAME base station and the SAME asserted value will get the and the SAME asserted value will get the same readings at a field point to within the same readings at a field point to within the accuracy of the instrument. accuracy of the instrument.

Interpretation.Interpretation.

Total magnetic disturbances or anomalies are highly Total magnetic disturbances or anomalies are highly variable in shape and amplitude; they are almost always variable in shape and amplitude; they are almost always asymmetrical, sometimes appear complex even from asymmetrical, sometimes appear complex even from simple sourcessimple sources

One confusing issue is the fact that most One confusing issue is the fact that most magnetometers measure the total field of the earth: no magnetometers measure the total field of the earth: no oriented system is recorded for the total field amplitude.oriented system is recorded for the total field amplitude.

The consequence of this fact is that only the component The consequence of this fact is that only the component of an anomalous field in the direction of earth’s main of an anomalous field in the direction of earth’s main field is measured. field is measured.

Figure 6-1 illustrates this consequence of the Figure 6-1 illustrates this consequence of the measurement systemmeasurement system

Anomalous fields that are nearly perpendicular to the Anomalous fields that are nearly perpendicular to the earth’s field are undetectableearth’s field are undetectable

Additionally, the induced nature of the Additionally, the induced nature of the measured field makes even large bodies measured field makes even large bodies act as dipoles; that is, like a large bar act as dipoles; that is, like a large bar magnet.magnet.

If the (usual) dipolar nature of the If the (usual) dipolar nature of the anomalous field is combined with the anomalous field is combined with the measurement system that measures measurement system that measures only the component in the direction of only the component in the direction of the earth’s field, the confusing nature of the earth’s field, the confusing nature of most magnetic interpretations can be most magnetic interpretations can be appreciatedappreciated

To achieve a qualitative understanding of what is To achieve a qualitative understanding of what is occurring, consider Figure in the next page.occurring, consider Figure in the next page.

Within the contiguous United States, the magnetic Within the contiguous United States, the magnetic inclination, that is the angle the main field makes inclination, that is the angle the main field makes with the surface, varies from 55- 70 deg. with the surface, varies from 55- 70 deg.

The figure illustrates the field associated with the The figure illustrates the field associated with the main field, the anomalous field induced in a narrow main field, the anomalous field induced in a narrow body oriented parallel to that field, and the combined body oriented parallel to that field, and the combined field that will be measured by the total-field field that will be measured by the total-field magnetometer. magnetometer.

The scalar values which would be measured on the The scalar values which would be measured on the surface above the body are listed. surface above the body are listed.

From this figure, one can see how the total-field From this figure, one can see how the total-field magnetometer records only the components of the magnetometer records only the components of the anomalous field.anomalous field.

Uranium ExplorationUranium Exploration

MagneticMagneticMagnetic. Palaeochannel magnetic Magnetic. Palaeochannel magnetic (either (either

positive or negative) anomalies may be positive or negative) anomalies may be defined if high-resolution surveys are used and defined if high-resolution surveys are used and if there are sufficient magnetic minerals in the if there are sufficient magnetic minerals in the channels or measurable magnetic contrast channels or measurable magnetic contrast between the channel sediments and bedrock.between the channel sediments and bedrock.

Cainozoic palaeochannels are not usually Cainozoic palaeochannels are not usually visible on regional magnetic data, as they are visible on regional magnetic data, as they are relatively shallow features, but careful use of relatively shallow features, but careful use of detailed surveys may assist in locating channel detailed surveys may assist in locating channel deposits.deposits.

GravityGravityGravity anomalies in the earth’s Gravity anomalies in the earth’s

gravitational field can in some cases be gravitational field can in some cases be used to define the thickness and extent used to define the thickness and extent of the fluvial sediments, and hence of the fluvial sediments, and hence palaeochannels, due to the contrast in palaeochannels, due to the contrast in density between the sediments and density between the sediments and fresh bedrock. For example, the density fresh bedrock. For example, the density of sand and clay is ~1.8g/cc and of sand and clay is ~1.8g/cc and granitic basement granitic basement is 2.7 g/cc (Berkman is 2.7 g/cc (Berkman 1995).1995).

Hoover et al. (1992)Hoover et al. (1992)

Hoover et al. (1992)Hoover et al. (1992)

GEOCHEMICAL SAMPLINGGEOCHEMICAL SAMPLING

Ground waterGround water Surface waterSurface water Stream sedimentsStream sediments SoilsSoils Biological Biological Ore samplesOre samples Radon Radon Track etch (identify radiaoactivity)Track etch (identify radiaoactivity)

Surface Sampling in Surface Sampling in ExplorationExploration

IntroductionIntroduction Sample? Sampling?Sample? Sampling? Sampling ProgramsSampling Programs Bias and Error in SamplingBias and Error in Sampling Quality ControlQuality Control Surface Sampling MethodsSurface Sampling Methods Sample HandlingSample Handling Documentation Requirements Documentation Requirements ConclusionConclusion ReferencesReferences

IntroductionIntroduction Sampling methods vary from simple Sampling methods vary from simple

grab samples on existing exposures grab samples on existing exposures to sophisticated drilling methods. to sophisticated drilling methods.

As a rule, the surface of the As a rule, the surface of the mineralization is obscured by various mineralization is obscured by various types of overburden, or it is types of overburden, or it is weathered and leached to some weathered and leached to some depth, thereby obscuring the nature depth, thereby obscuring the nature of the mineralizationof the mineralization." ."

What is a sample?What is a sample? What is sampling? What is sampling?

A sampleA sample is a finite part of a statistical is a finite part of a statistical population whose properties are studied to population whose properties are studied to gain information about the whole (Webster, gain information about the whole (Webster, 1985). 1985).

SamplingSampling is the act, process, or technique is the act, process, or technique of selecting a suitable sample, of selecting a suitable sample,

oror a representative part of a population for the a representative part of a population for the

purpose of determining parameters or purpose of determining parameters or characteristics of the whole population.characteristics of the whole population.

Why Sample?Why Sample?

Sampling ProgramsSampling Programs Reconnaissance:Reconnaissance: (1) check status of land ownership, (2) physical (1) check status of land ownership, (2) physical

characteristics of area, (3) mining history of the area. characteristics of area, (3) mining history of the area. Field inspection:Field inspection: ssurface grab sampling over all exposures of gravel, urface grab sampling over all exposures of gravel,

ffew seismic cross section, ew seismic cross section, ggeobotanical study, and eobotanical study, and ssurvey for old workings. urvey for old workings.

Sampling PlanSampling Plan Special Problems Associated with Sampling:Special Problems Associated with Sampling: Sample Processing or Washing:Sample Processing or Washing: Data ProcessingData Processing Data processing consists of record keeping, Data processing consists of record keeping,

reporting values, and assay procedures. reporting values, and assay procedures.

Sampling PlanSampling Plan Defining the population of concern Defining the population of concern Specifying a sampling frame, a set of Specifying a sampling frame, a set of

items or events possible to measure items or events possible to measure Specifying a sampling method for Specifying a sampling method for

selecting items or events from the frame selecting items or events from the frame Determining the sample size Determining the sample size Implementing the sampling plan Implementing the sampling plan Sampling and data collecting Sampling and data collecting Reviewing the sampling process Reviewing the sampling process

Sample SizeSample Size The question of how large a sample should The question of how large a sample should

be is a difficult one. Sample size can be be is a difficult one. Sample size can be determined by various constraints such as determined by various constraints such as

Cost.Cost. nature of the analysis to be performednature of the analysis to be performed the desired precision of the estimates one the desired precision of the estimates one

wishes to achievewishes to achieve the kind and number of comparisons that the kind and number of comparisons that

will be made, will be made, the number of variables that have to be the number of variables that have to be

examined simultaneouslyexamined simultaneously

Bias and Error in SamplingBias and Error in Sampling A sample is expected to mirror the A sample is expected to mirror the

population from which it comes, however, population from which it comes, however, there is no guarantee that any sample will there is no guarantee that any sample will be precisely representative of the be precisely representative of the population from which it comes.population from which it comes.

biasedbiased:: when the selected sample is when the selected sample is systematically systematically

differentdifferent to the population. to the population. The sample must be a fair representation of the population we are interested The sample must be a fair representation of the population we are interested

in.in. Random errorsRandom errors The sample size may be The sample size may be too smalltoo small to produce a to produce a

reliable estimate. reliable estimate. There may be There may be variability in the population, variability in the population, the greater the greater

the variability the larger the sample size needed. the variability the larger the sample size needed.

Quality ControlQuality Control Responsibility for maintaining consistency Responsibility for maintaining consistency

and ensuring collection of data of and ensuring collection of data of acceptable and verifiable quality through acceptable and verifiable quality through the implementation of a QA/QC program. the implementation of a QA/QC program.

All personnel involved in data collection All personnel involved in data collection activities must have the necessary activities must have the necessary education, education, experience, and skills to perform their experience, and skills to perform their duties.duties.

Selecting Methods and EquipmentSelecting Methods and Equipment

Soil and sediment samples may be Soil and sediment samples may be collected using a variety of methods and collected using a variety of methods and equipment depending on the following:equipment depending on the following:

type of sample required type of sample required site accessibility, site accessibility, nature of the material, nature of the material, depth of sampling, depth of sampling, budget for the project, budget for the project, sample size/volume requirement, sample size/volume requirement, project objectives project objectives

Surface Sampling MethodsSurface Sampling Methods Near-surface samples can be Near-surface samples can be

collected with a spade, scoop, or collected with a spade, scoop, or trowel. trowel.

Sampling at greater depths or below a Sampling at greater depths or below a water column may require a hand water column may require a hand auger, coring device, or dredge. auger, coring device, or dredge.

As the sampling depth increases, the As the sampling depth increases, the use of a powered device may be use of a powered device may be necessary to push the sampler into necessary to push the sampler into the soil or sediment layers. the soil or sediment layers.

Sampling EquipmentsSampling Equipments Tube Sampler Tube Sampler Churn DrillsChurn Drills Tube Corers Tube Corers Hand Driven Split-Spoon Core SamplerHand Driven Split-Spoon Core Sampler Hand-Dug ExcavationsHand-Dug Excavations Backhoe Trenches; Bulldozer TrenchesBackhoe Trenches; Bulldozer Trenches Other Machine-Dug ExcavationsOther Machine-Dug Excavations AugersAugers Bucket or Clamshell Type ExcavatorsBucket or Clamshell Type Excavators

Surface SamplingSurface Sampling

Figure 13. Wet sieving of a stream sediment sample in the UK (Photo: Fiona Fordyce, BGS from Salminen and Tarvainen et al. 1998,

Floodplain sampling in southwestern Finland (Photo: Reijo Salminen, GTK).

Surface SamplingSurface Sampling

Figure 16. Humus sampling in Finland using cylindrical sampler, and the final humus sample. (Photographs: Timo Tarvainen, GTK).

Surface SamplingSurface Sampling

The alluvial horizons at the floodplain sediment sampling site 29E05F3, France.

The soil sample pit at the site 41E10T3, Finland.

Sample HandlingSample Handling Samples should be preservedSamples should be preserved to minimize to minimize

chemical or biological changes from the time of chemical or biological changes from the time of collection to the time of analysis. Keep samples in collection to the time of analysis. Keep samples in air tight containers. Sediment samples should also air tight containers. Sediment samples should also be stored in such a way that the anaerobic be stored in such a way that the anaerobic condition is preserved by minimizing headspace.condition is preserved by minimizing headspace.

If several sub samples are collectedIf several sub samples are collected, soil and , soil and

sediment samples should be placed in a clean sediment samples should be placed in a clean stainless steel mixing pan or bowl and thoroughly stainless steel mixing pan or bowl and thoroughly homogenized to obtain a representative homogenized to obtain a representative composite sample. composite sample.

Sample HandlingSample HandlingSample Label InformationSample Label Information – – Label or tag each sample containerLabel or tag each sample container with a with a

unique field identification code. If the samples are unique field identification code. If the samples are core sections, include the sample depth in the core sections, include the sample depth in the identification. identification.

Write the project nameWrite the project name or project identification or project identification number on the label.number on the label.

Write the collection dateWrite the collection date and time on the label. and time on the label. Attach the label or tagAttach the label or tag so that it does not so that it does not

contact any portion of the sample that will be contact any portion of the sample that will be removed or pouredremoved or poured from the container. from the container.

Record the unique field identification codeRecord the unique field identification code on all other documentation associated with the on all other documentation associated with the specific sample container. specific sample container.

Ensure all necessary information is transmitted to Ensure all necessary information is transmitted to the laboratory.the laboratory.

Documentation Documentation Thorough documentation of all field Thorough documentation of all field

sample collection and processing activities sample collection and processing activities is necessary for proper interpretation of is necessary for proper interpretation of results. All sample identification, chain-of-results. All sample identification, chain-of-custody records, receipts for sample custody records, receipts for sample forms, and field records should be forms, and field records should be recorded using waterproof, non-erasable recorded using waterproof, non-erasable ink in a bound waterproof notebook. ink in a bound waterproof notebook.

All Procedures must be documented.All Procedures must be documented.

Sample Data

From Sampling to Production From Sampling to Production PyramidPyramid

R_ MODEL&

PRODUCTION

CHEMICAL ANALYSIS&

GEOLOGICAL INTERPRETATION

SAMPLE PREPARATION &

GEOLOGICAL CLASSIFICATION

SAMPLING &

GEOLOGICAL OBSERVATION

FOUNDATION

1ST FLOOR

2ND FLOOR

3RD FLOOR

ConclusionConclusion

There are many ways to sample and There are many ways to sample and many methods to calculate the value many methods to calculate the value of a deposit. It is important to of a deposit. It is important to remember to use care in sampling remember to use care in sampling and to select the method that best and to select the method that best suits the type of occurrence that is suits the type of occurrence that is being sampled. being sampled.

ReferencesReferences Journal of the Mississippi Academy of Journal of the Mississippi Academy of

Sciences, v. 47, no. 1, p. 42. Sciences, v. 47, no. 1, p. 42. http://www.evergladesplan.org/pm/http://www.evergladesplan.org/pm/

pm_docs/qasr/qasr_ch_07.pdf pm_docs/qasr/qasr_ch_07.pdf http://www.gtk.fi/publ/foregsatlas/http://www.gtk.fi/publ/foregsatlas/

article.php?id=10article.php?id=10 http://www.socialresearchmethods.net/http://www.socialresearchmethods.net/

tutorial/Mugo/tutorial.htmtutorial/Mugo/tutorial.htm http://www.policyhub.gov.uk/http://www.policyhub.gov.uk/

evaluating_policy/magenta_book/evaluating_policy/magenta_book/chapter5.aspchapter5.asp

ThankThank youyou

Radiometric SurveyRadiometric Survey

Shantanu TiwariMineral Engineering

Feb 07, 2008

OutlineOutline1. Introduction to Radiometric Survey2. Radioactivity3. Use of Radiometric Survey4. Process5. Case Study6. Conclusion7. Refrences

IntroductionIntroduction1. Radiometrics : Measure of natural radiation in the Earth’s surface.

2. Also Known as Gamma- Ray Spectrometry (why?).

3. Who uses it?- Geologists and Geophysicists.

4. Also useful for studying geomorphology and soils.

RadioactivityRadioactivity 1. Process in which, unstable atom becomes stable through the process of decay of its nucleus.

2.Energy is released in the form of radiation; (a) Alpha Particle (or helium nuclei) - Least Energy- Travels few cm of air. (b) Beta Particle (or electrons)- Higher Energy- Travels upto a meter in air

(c) Gamma Rays- Highest Energy- Travels upto 300 meters in air.

Radioactivity (Contd.)Radioactivity (Contd.)3. Energy of Gamma Ray is characteristic of the radioactive element it

came from.

4. Gamma Rays are stopped by water and other molecules (soil & Rock).

5. A radiometric survey measures the spatial distribution of three radioactive elements;

(a) Potassium (b)Thorium (c) Uranium

6. The abundance of these elements are measured by gamma ray detection.

Use of Radiometric SurveyUse of Radiometric Survey

1. Radioactive elements occur naturally in some minerals.

2. Energy of Gamma Rays is the characteristic of the element.

3. Measure the energy of Gamma Ray- Abundance.

ProcessProcess1. How we do radiometric survey?- By measuring the energy of Gamma

Rays.

2. Can be measure on the ground or by a low flying aircraft.

3. Gamma Rays are detected by Spectrometer.

4. Spectrometer- Counts the number of times each Gamma Ray of particular energy intersects it.

ProcessProcess

ProcessProcess5. The energy spectrum measured by a spectrometer is in MeV.

6. Range- 0 to 3 MeV.

7. The number of Gamma Ray counts across the whole spectrum is referred as the total count (TC).

ProcessProcessN

umbe

r of G

amm

a Ra

ys (p

er s

econ

d)

Energy of Gamma Rays

ProcessProcess

High

Low

Case StudyCase StudyGold Canyon Inc. (USA)- Bear Head Uranium Project

Bear Head Uranium Project- Red Lake Mining Camp(north-west Ontario)

Covers a 23 km strike-length of Bear Head Fault Zone

0.05% U3O8

ConclusionConclusion1. Good Technique

2. Large Area.

3. Better for plane areas.

ReferencesReferences1. http://www.goldcanyon.ca/

2. Suzanne Haydon from the Geological Survey of Victoria (Aus).

Thank youThank you

GROUND GEOPHYSICSGROUND GEOPHYSICS

EXPLORATION EXPLORATION TECHNIQUES TECHNIQUES

BYBY METALLURGICAL METALLURGICAL

SAMPLINGSAMPLINGGERTRUDE AYAKWAH GERTRUDE AYAKWAH

MINERAL ENGINEERING DEPARTMENTMINERAL ENGINEERING DEPARTMENTNEW MEXICO INSTITUTE OF MINING AND TECHNOLOGYNEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY

LEROY PLACELEROY PLACESOCORRO NMSOCORRO NM

February, 7February, 7thth, 2008, 2008

OutlineOutline

IntroductionIntroduction PurposePurpose SamplingSampling Sample PreparationSample Preparation Types of Metallurgical SamplingTypes of Metallurgical Sampling

a.a. Geochemical AnalysisGeochemical Analysis

b.b. Assay TechniquesAssay Techniques ConclusionConclusion ReferencesReferences

IntroductionIntroduction Exploration geology is the process and science of locating Exploration geology is the process and science of locating

valuable mineral or petroleum which has a commercial valuable mineral or petroleum which has a commercial value. Mineral deposits of commercial value are called ore value. Mineral deposits of commercial value are called ore bodies bodies

The goal of exploration is to prove the existence of an ore The goal of exploration is to prove the existence of an ore body which can be mined at a profitbody which can be mined at a profit

This process occurs in stages, with early stages focusing on This process occurs in stages, with early stages focusing on gathering surface data which is easier to acquire and later gathering surface data which is easier to acquire and later stages focusing on gathering subsurface data which stages focusing on gathering subsurface data which includes drilling data, detailed geophysical survey data and includes drilling data, detailed geophysical survey data and metallurgical analysismetallurgical analysis

PurposePurpose

The purpose of this presentation is to discuss The purpose of this presentation is to discuss

metallurgical sampling in exploration geologymetallurgical sampling in exploration geology

Soil and Stream Sample Soil and Stream Sample PreparationPreparation

Samples are reduced and homogenized into a form which Samples are reduced and homogenized into a form which can easily be handled by analytical personnelcan easily be handled by analytical personnel

Soil and stream sediment samples are usually sieved so Soil and stream sediment samples are usually sieved so that particles larger than fine sand are removed. that particles larger than fine sand are removed.

The fine particles are mixed and a portion is removed for The fine particles are mixed and a portion is removed for chemical analysischemical analysis

Rock Sample PreparationRock Sample Preparation

Rock samples are treated in a multi-step procedureRock samples are treated in a multi-step procedure

Rocks, cuttings, or core are first crushed to about pea-size in a Rocks, cuttings, or core are first crushed to about pea-size in a

jaw crusher, then passed through a secondary crusher to reduce jaw crusher, then passed through a secondary crusher to reduce

the size further - usually 1/10 inchthe size further - usually 1/10 inch

This crushed sample is mixed, split in a riffle splitter and reduced This crushed sample is mixed, split in a riffle splitter and reduced

to about one-half pound or 250 grams. This 250 grams is placed to about one-half pound or 250 grams. This 250 grams is placed

in a pulverizer where it is reduced further to -150 mesh for in a pulverizer where it is reduced further to -150 mesh for

analysisanalysis

Metallurgical SamplingMetallurgical Sampling

Types Types

• Geochemical AnalysisGeochemical Analysis

• Assay TechniquesAssay Techniques

Geochemical AnalysisGeochemical Analysis

Involves dissolution of approximately one gram of sample by Involves dissolution of approximately one gram of sample by

a strong acida strong acid

The solution which contains most of the base metals is The solution which contains most of the base metals is

aspirated into a flame as in atomic absorption spectroscopy aspirated into a flame as in atomic absorption spectroscopy

(AAS) or into an inductively coupled (ICP)(AAS) or into an inductively coupled (ICP)

AAS measures one element at a time to a normal sensitivity of AAS measures one element at a time to a normal sensitivity of

about 1 ppmabout 1 ppm

Geochemical Analysis (Cont’d)Geochemical Analysis (Cont’d) Whilst ICP 20 measure more elements at a time to ppm Whilst ICP 20 measure more elements at a time to ppm

levelslevels

The technique is low-cost, rapid, reasonably precise and can The technique is low-cost, rapid, reasonably precise and can be more accurate if the method is controlled by standards.be more accurate if the method is controlled by standards.

However accuracy is minor importance in geochemistry as However accuracy is minor importance in geochemistry as the exploration geologist seeks patterns rather than absolute the exploration geologist seeks patterns rather than absolute concentration concentration

Hence making geochemical analysis methods are considered Hence making geochemical analysis methods are considered to be indicators of mineralization rather than absolute to be indicators of mineralization rather than absolute measurement of mineralization.measurement of mineralization.

Assay TechniquesAssay Techniques

Wet ChemistryWet Chemistry

Fire AssayFire Assay

Aqua Regia Acid DigestionAqua Regia Acid Digestion

Assay TechniquesAssay Techniques

Assay procedures uses accurate representation of Assay procedures uses accurate representation of the mass of the sample being analyzed than in the mass of the sample being analyzed than in geochemical analytical techniques.geochemical analytical techniques.

Wet ChemistryWet Chemistry

““It's just an informal term referring to chemistry done It's just an informal term referring to chemistry done in a liquid phase. When chemists talk about doing "wet in a liquid phase. When chemists talk about doing "wet chemistry," they mean stuff in a lab with solvents, test chemistry," they mean stuff in a lab with solvents, test tubes, beakers, and flasks” (Richard E. Barrans Jr., tubes, beakers, and flasks” (Richard E. Barrans Jr., Ph.D)Ph.D)

It utilizes a physical measurement, either the color of a It utilizes a physical measurement, either the color of a solution, the weight or volume of a reagent, or the solution, the weight or volume of a reagent, or the conductivity of a solution after a specific reactionconductivity of a solution after a specific reaction

It is a preferred technique to determine element It is a preferred technique to determine element concentration in ore samplesconcentration in ore samples

Fire AssayFire Assay

It is used to analyzed precious metals in rock or soilIt is used to analyzed precious metals in rock or soil

Assay ton portion of the sample is put into a crucible Assay ton portion of the sample is put into a crucible and mixed with variety of chemical (lead oxide)and mixed with variety of chemical (lead oxide)

The mixture is fused at high temperatureThe mixture is fused at high temperature

During fusion, beads of metallic lead are released During fusion, beads of metallic lead are released into the molten mixtureinto the molten mixture

Fire AssayFire Assay The lead particles scavenge the precious metals and sink to The lead particles scavenge the precious metals and sink to

the bottom of the crucible due to the difference in density the bottom of the crucible due to the difference in density between lead and the siliceous component of the sample between lead and the siliceous component of the sample known as slag.known as slag.

On completion, the molten mixture is poured into a mold On completion, the molten mixture is poured into a mold and left to solidifyand left to solidify

After cooling, the slag is removed from the lead and the After cooling, the slag is removed from the lead and the lead bottom is transferred into a small crucible known as lead bottom is transferred into a small crucible known as cupel and placed back into a furnacecupel and placed back into a furnace

Fire AssayFire Assay

The lead is absorbed by the cupel leaving a bead The lead is absorbed by the cupel leaving a bead of the precious metals at the bottom of the cupelof the precious metals at the bottom of the cupel

Gold and silver is measured by weighing the bead Gold and silver is measured by weighing the bead on a balanceon a balance

Silver is dissolved in nitric acid and the bead is Silver is dissolved in nitric acid and the bead is weighed again to determine the undissolved goldweighed again to determine the undissolved gold

Silver is calculated by the differenceSilver is calculated by the difference

Aqua Regia Acid DigestionAqua Regia Acid Digestion

The same procedure is used as in fire assay but The same procedure is used as in fire assay but different method of measuring gold and silverdifferent method of measuring gold and silver

Atomic absorption is used to measure gold and silver Atomic absorption is used to measure gold and silver

Other forms of measurement include neutron Other forms of measurement include neutron activation analysis and flameless atomic absorptionactivation analysis and flameless atomic absorption

ConclusionConclusion

Geochemical analysis is considered to be Geochemical analysis is considered to be indicators of mineralization during the earlier indicators of mineralization during the earlier stages of explorationstages of exploration

Assay techniques is used to determine absolute Assay techniques is used to determine absolute measurement of mineralizationmeasurement of mineralization

It also determines if the ore deposit can be It also determines if the ore deposit can be processed by conventional milling or in situ processed by conventional milling or in situ leaching or some other wayleaching or some other way

ReferencesReferences

http://www.alsglobal.com/Mineral/ALSContent.aspx?http://www.alsglobal.com/Mineral/ALSContent.aspx?key=31#metallicskey=31#metallics

http://www.amebc.ca/primer3.htm#samplinghttp://www.amebc.ca/primer3.htm#sampling

http://www.newton.dep.anl.gov/askasci/chem00/http://www.newton.dep.anl.gov/askasci/chem00/chem00868.htmchem00868.htm

DRILLINGDRILLING

Samuel NunooSamuel Nunoo

New Mexico Bureau of Geology and New Mexico Bureau of Geology and Mineral ResourcesMineral Resources

New Mexico Institute of Mining and New Mexico Institute of Mining and Technology, Socorro, NMTechnology, Socorro, NM

77THTH FEBRUARY 2008 FEBRUARY 2008

DRILLINGDRILLING

OutlineOutline

IntroductionIntroduction

PurposePurpose

TypesTypes

IntroductionIntroduction

•Drilling is the process whereby rigs or hand

operated tools are used to make holes to

intercept an ore body.

•Drilling is the ultimate stage in exploration.

PurposePurpose

The purpose of drilling is;

•To define ore body at depth

•To access ground stability (geotechnical)

•To estimate the tonnage and grade of a

discovered mineral deposit

•To determine absence or presence of ore

bodies, veins or other type of mineral

deposit

TypesTypes

Drilling is generally categorized into 2 types:

•Percussion Drilling

This type of drilling is whereby a hammer

beats the surface of the rock, breaks it into chips.

-Reverse Circulation Drilling (RC)

•Rotary Drilling

This is the type of drilling where samples are recovered by rotation

of the drill rod without percussion of a hammer.

- Diamond Drilling

- Rotary Air Blast (RAB)

- Auger Drilling

Percussion DrillingReverse Circulation Drilling (RC)

1. This type of drilling involves the use of high pressure compressors, percussion hammers that recover samples even after the water table.

2. The end of the hammer is a tungsten carbide bit that breaks the rock with both percussion and rotary movement .This mostly follows a RAB intercept of an ore body.

3. The air pressure of a RC rig can be increased by the use of a booster. This allows for deeper drilling.

4. Samples are split by special sample splitter that is believed to pulverize the samples. This is done to avoid metal concentrations at only section of the sample. Contamination is checked by cleaning the splitter after every rod change either by brush or high air pressure from rig’s air hose.

5. RC drilling is mostly followed by diamond drilling to confirm some of the RC drilling ore intercept.

6. This type of drilling is faster and cheaper than diamond drilling

http://www.midnightsundrilling.com/reverse_circulation.html

Rotary DrillingRotary Air Blast Drilling (RAB) 1. This type of drilling is common in green-field exploration and in mining pits.

2. This drilling mostly confirms soil, trench or pit anomalies.

3. It involves an air pressure drilling and ends as soon as it comes into contact with the water table because the hydrostatic pressure is more than the air pressure.

4. Samples cannot be recovered after the water table is reached.

5. Mostly a 4meter composite sampling is conducted. Every 25th sample is replicated to check accuracy of the laboratory analysis.

6. RAB drilling in the mine is mostly done for blast holes.

Rotary Drilling (Cont’d)Diamond Drilling 1. This type of drilling uses a diamond impregnated bit that cuts the rock by rotation with

the aid of slimy chemicals in solution such as; - DD200, expan-coarse, expan-fine, betonite and sometimes mapac A and

B for holes stability.

2. Drill sample are recovered as cores sometimes oriented for the purpose of attitude measurement such as dip and dip directions of joints, foliation, lineation, veins.

3. Sampling involves splitting the core into 2 equal halves along the point of curvature of foliations or along orientation lines. One half is submitted to the lab for analysis and the other left in the core yard for future sampling if necessary.

4. Standards of known assay values are inserted in the samples to check laboratory accuracy. Mostly high grade standards are inserted at portions of low mineralization and low grade standards into portions of high mineralization.

5. Diamond drilling is usually the last stage of exploration or when the structural behavior of an ore body is to be properly understood.

http://www.almadenminerals.com/geoskool/drilling.htmlhttp://en.gtk.fi/ExplorationFinland/images/ritakallio_diamond_drilling.jpghttp://www.istockphoto.com/file_closeup/

Rotary Drilling (Cont’d)Auger Drilling1. This is a type of superficial drilling in soils and sediments. It could machine powered

auger or hand powered (manual).

2. It is mostly conducted at the very initial stage of exploration. That is after streams sediments, soils or laterite sampling.

http://www.geology.sdsu.edu/classes/geol552/sedsampling.htm

Thank You !!!!

GEOPHYSICAL LOGGINGGEOPHYSICAL LOGGING

Frederick EnninFrederick EnninDepartment of Environmental Department of Environmental

EngineeringEngineering

INTRODUCTIONINTRODUCTION Geophysical logging is the use of physical, radiogenic or Geophysical logging is the use of physical, radiogenic or

electromagnetic instruments lowered into a borehole to gather electromagnetic instruments lowered into a borehole to gather information about the borehole, and about the physical and information about the borehole, and about the physical and chemical properties of rock, sediment, and fluids in and near the chemical properties of rock, sediment, and fluids in and near the borehole borehole

Logging: “make record” of somethingLogging: “make record” of something

First developed for the petroleum industry by Marcel and Conrad First developed for the petroleum industry by Marcel and Conrad Schlumberger in 1972.Schlumberger in 1972.

Schlumberger brothers first developed a resistivity tool to detect Schlumberger brothers first developed a resistivity tool to detect differences in the porosity of sandstones of the oilfield at differences in the porosity of sandstones of the oilfield at Merkwiller-Perchelbrom, eastern France.Merkwiller-Perchelbrom, eastern France.

Following the first electrical logging tools designed for basic Following the first electrical logging tools designed for basic permeability and porosity analysis other logging methods were permeability and porosity analysis other logging methods were developed to obtain accurate porosity and permeability developed to obtain accurate porosity and permeability calculations and estimations (sonic, density and neutron logs) and calculations and estimations (sonic, density and neutron logs) and also basic geological characterization (natural radioactivity)also basic geological characterization (natural radioactivity)

THE BOREHOLE ENVIRONMENTTHE BOREHOLE ENVIRONMENT

Different physical properties used to Different physical properties used to characterized the geology characterized the geology surroundingsurrounding a borehole-drillinga borehole-drilling

Physical properties: porosity of gravel bed, Physical properties: porosity of gravel bed, density, sonic velocity and natural gamma density, sonic velocity and natural gamma signalsignal

Drilling can perturb the physical properties of Drilling can perturb the physical properties of the rockthe rock

Factors influencing properties of rocks:Factors influencing properties of rocks: Porosity and water contentPorosity and water content Water chemistryWater chemistry Rock chemistry and minerologyRock chemistry and minerology Degree of rock alteration and mineralisationDegree of rock alteration and mineralisation Amount of evaporitesAmount of evaporites Amount of humic acidAmount of humic acid TemperatureTemperature

APPLICATIONSAPPLICATIONS

Became and is a key technology in Became and is a key technology in the petroleum industry.the petroleum industry.

In Mineral industry: In Mineral industry: Exploration and monitoring Exploration and monitoring

grade control in working mines.grade control in working mines.Ground water exploration:Ground water exploration: delineation of aquifers and delineation of aquifers and

producing zonesproducing zonesIn regolith studies:In regolith studies: provides unique insights into provides unique insights into

the composition, structure and the composition, structure and variability of the subsurfacevariability of the subsurface

Airborne electromagneticsAirborne electromagnetics used for ground truthing used for ground truthing

airborne geophysical data sets.airborne geophysical data sets.

GEOPHYSICAL LOGGING METHODSGEOPHYSICAL LOGGING METHODS

MECHANICAL METHODSMECHANICAL METHODS

caliper loggingcaliper logging

sonic loggingsonic logging

ELECTRICAL METHODSELECTRICAL METHODS

resistivity loggingresistivity logging

conductivity loggingconductivity logging

spontaneous potential loggingspontaneous potential logging

induced polarisationinduced polarisation

RADIOATIVE METHODSRADIOATIVE METHODS

natural gamma rays loggingnatural gamma rays logging

neutron porosity loggingneutron porosity logging

MECHANICAL METHODSMECHANICAL METHODS

Caliper loggingCaliper logging

caliper used to measure the caliper used to measure the diameter of a borehole and its diameter of a borehole and its variability with depth.variability with depth.

motion in and out from the borehole motion in and out from the borehole wall is recorded electrically and wall is recorded electrically and transmitted to surface recording transmitted to surface recording equipmentequipment

Sonic loggingSonic logging

works by transmitting a sound through works by transmitting a sound through the rocks of the borehole wall the rocks of the borehole wall

Consists of two parts:Consists of two parts:

transmitter and receivers separated transmitter and receivers separated by rubber connector to reduce the by rubber connector to reduce the amount of direct transmission of amount of direct transmission of acoustic energy along the tool from acoustic energy along the tool from transmitter to receivertransmitter to receiver Crosshole Sonic Logging method with various kinds of defects.  (Blackhawk

GeoServices, Inc.)

ELECTRICAL METHODSELECTRICAL METHODSUsed in hard rock drillingUsed in hard rock drilling

ResistivityResistivity probes measure voltage drop by passing current through rocks probes measure voltage drop by passing current through rocks

ConductivityConductivity measurements induction probes via electromagnetic induction measurements induction probes via electromagnetic induction either in filled or dry holeseither in filled or dry holes

Spontaneous potential (SP)Spontaneous potential (SP) - oldest E-method - oldest E-methodMeasures small potential differences between down Measures small potential differences between down hole movable electrode and the surface earth connectionhole movable electrode and the surface earth connectionUses wide range of electrochemical and electrokinetic processesUses wide range of electrochemical and electrokinetic processes

Induced polarisation (IP)Induced polarisation (IP)Commonly used in surface prospecting for minerals and downhole Commonly used in surface prospecting for minerals and downhole

applications.applications.Uses transmitter loop to charge the ground with high currentUses transmitter loop to charge the ground with high currentTransmitter loop turned off and voltage change with time is recorded.Transmitter loop turned off and voltage change with time is recorded.

RADIOATIVE METHODSRADIOATIVE METHODS

Natural Gamma loggingNatural Gamma logging simplest, high penetration distance through simplest, high penetration distance through

rocks (1-2 m)rocks (1-2 m) Depends on initial energy level and rock Depends on initial energy level and rock

densitydensity Records levels of naturally occurring gamma Records levels of naturally occurring gamma

rays from rocks around boreholerays from rocks around borehole

Signals from isotopes: K-40, Th-232, U-238 Signals from isotopes: K-40, Th-232, U-238 and daughter products- and daughter products- provides geologic informationprovides geologic information

Sophisticated tools records emission from Bi-Sophisticated tools records emission from Bi-214 and214 and

Tl-208 instead of U-238 and Th-232 Tl-208 instead of U-238 and Th-232 provides detailed chemistry of rocks in provides detailed chemistry of rocks in

boreholeborehole

Successfully used to search for roll front Successfully used to search for roll front uranium deposit in regolithuranium deposit in regolith

Gamma-ray Borehoole Logging Probe (Lead Shielded)/System for measurement of high-grade ore in borehole

Secondary uranium minerals associated with Gulcheru quartzite from Gandi area, Andhra

RADIOATIVE METHODSRADIOATIVE METHODS

Neutron Porosity LoggingNeutron Porosity Logging Measures properties of the rock close to Measures properties of the rock close to

the borehole the borehole Very useful tool for measuring “porosity”Very useful tool for measuring “porosity” free neutrons almost unknown in the free neutrons almost unknown in the

EarthEarth

Neutron emission sourceNeutron emission source Active source emits into rocks around a Active source emits into rocks around a

boreholeborehole Flux of neutrons recorded at the detector Flux of neutrons recorded at the detector

is used as indicator of conditions around is used as indicator of conditions around surrounding rocks. surrounding rocks.

Neutron logging provides data Neutron logging provides data under a variety of conditions in under a variety of conditions in cased and uncased boreholes. cased and uncased boreholes. ..

RADIOATIVE METHODSRADIOATIVE METHODS

Effects:Effects: Hydrogen Exception:Hydrogen Exception:

neutrons rapidly loose energy due neutrons rapidly loose energy due to collision with hydrogen nuclei to collision with hydrogen nuclei

(thermal neutron”-like diffusing (thermal neutron”-like diffusing gas)gas)

Changes in Diameter of boreholes Changes in Diameter of boreholes affects resultsaffects results

Calibrated with limestone samples Calibrated with limestone samples of differing water-filled porosities of differing water-filled porosities (equivalent limestone porosities)(equivalent limestone porosities)

Used in conjunction with other Used in conjunction with other logging logging

methods in mineral geophysical methods in mineral geophysical logging in hard rock (lower logging in hard rock (lower porosities)porosities)

PROBLEMS AND LIMITATIONPROBLEMS AND LIMITATION

ProblemsProblemsBiggest is the need for a “well” (ie. a borehole) to operateBiggest is the need for a “well” (ie. a borehole) to operateHigh cost of drilling meaning boreholes are always High cost of drilling meaning boreholes are always not available hence GWL will not be possible for a particular not available hence GWL will not be possible for a particular

study.study.Colapse of holes in regolith systems Colapse of holes in regolith systems while wireline logs are running solved with foam drilling while wireline logs are running solved with foam drilling or plastic casing insertion.or plastic casing insertion.

LimitationsLimitationsRecognition that each method has weaknesses and strengths.Recognition that each method has weaknesses and strengths.PVC casing- prevents electrical logging & neutron logging PVC casing- prevents electrical logging & neutron logging

(hydrogen) (hydrogen)

CONCLUSIONSCONCLUSIONS

Geophysical well logging provides many different Geophysical well logging provides many different opportunities to investigate the material making opportunities to investigate the material making up the wall of a borehole, be it regolith or up the wall of a borehole, be it regolith or crystalline rock. crystalline rock.

A widen range of different sensors provide A widen range of different sensors provide information which complementary in nature. Best information which complementary in nature. Best results are obtained by running a suite of logs results are obtained by running a suite of logs and analyzing their similarities and differences.and analyzing their similarities and differences.

REFERENCESREFERENCES Hallenburg, J.K., 1984. Geophysical logging for mineral and Hallenburg, J.K., 1984. Geophysical logging for mineral and

engineering applications. PennWell Books, Tulsa, Oklahoma, 254 engineering applications. PennWell Books, Tulsa, Oklahoma, 254 pp.pp.

Keys, W.S., 1988. Borehole geophysics applied groundwater Keys, W.S., 1988. Borehole geophysics applied groundwater investigations. U.S Geol. Surv. Open File Report 87-539, Denver.investigations. U.S Geol. Surv. Open File Report 87-539, Denver.

McNeill, J.D., Hunter, J.A and Bosnar, M., 1996. Application of a McNeill, J.D., Hunter, J.A and Bosnar, M., 1996. Application of a borehole induction magnetic susceptibility logger to shallow borehole induction magnetic susceptibility logger to shallow lithological mapping. Journal of Environmental and Engineering lithological mapping. Journal of Environmental and Engineering Geophysics 2: 77-90Geophysics 2: 77-90

Schlumberger, 2000. Beginnings. A brief history of Schlumberger Schlumberger, 2000. Beginnings. A brief history of Schlumberger wireline and testing, www site: wireline and testing, www site: http://www.1.slb.com/recr/library/wireline/brochure/beginnings.htmlhttp://www.1.slb.com/recr/library/wireline/brochure/beginnings.html

Sheriff, R.E., 1991. Encyclopedic Dictionary of Exploration Sheriff, R.E., 1991. Encyclopedic Dictionary of Exploration Geophysics, Society of Exploration Geophysicists, Tulsa, Oklahoma, Geophysics, Society of Exploration Geophysicists, Tulsa, Oklahoma, 376 pp.376 pp.

Keys, Scott, MacCary, L. M., 1971 Application of Borehole Keys, Scott, MacCary, L. M., 1971 Application of Borehole Geophysics to Water-Resources Investigations, Techniques of Geophysics to Water-Resources Investigations, Techniques of Water-Resources Investigations Book 2, Chapter E1, Water-Resources Investigations Book 2, Chapter E1, http://pubs.er.usgs.gov/usgspubs/twri/twri02E1http://pubs.er.usgs.gov/usgspubs/twri/twri02E1

Keys, W. S., 1990, Techniques of Water-Resources Investigations, Keys, W. S., 1990, Techniques of Water-Resources Investigations, Book 2, Chapter E-2, U. S. Geological Survey, Book 2, Chapter E-2, U. S. Geological Survey, http://pubs.er.usgs.gov/usgspubs/twri/twri02E2 http://pubs.er.usgs.gov/usgspubs/twri/twri02E2

REFERENCESREFERENCES

Stevens, H. H. Jr., Ficke, J. F., and Smoot, G. F., 1976, Techniques of Water-Resources Stevens, H. H. Jr., Ficke, J. F., and Smoot, G. F., 1976, Techniques of Water-Resources Investigations Book 1, Chapter D1, Water Temperature—Influential Factors, Field Investigations Book 1, Chapter D1, Water Temperature—Influential Factors, Field Measurement, and Data Presentation, U.S. Geological Survey, Measurement, and Data Presentation, U.S. Geological Survey, http://pubs.er.usgs.gov/usgspubs/twri/twri01D1http://pubs.er.usgs.gov/usgspubs/twri/twri01D1

http://images.google.com/imgres?imgurl=http://id.water.usgs.gov/projects/INL/http://images.google.com/imgres?imgurl=http://id.water.usgs.gov/projects/INL/images/therm_1.gif&imgrefurl=http://id.water.usgs.gov/projects/INL/images/therm_1.gif&imgrefurl=http://id.water.usgs.gov/projects/INL/geophys.html&h=472&w=474&sz=11&hl=en&start=13&um=1&tbnid=U3z2Z4OhRFgeophys.html&h=472&w=474&sz=11&hl=en&start=13&um=1&tbnid=U3z2Z4OhRFxj5M:&tbnh=128&tbnw=129&prev=/images%3Fq%3DPICTURES%2BOFxj5M:&tbnh=128&tbnw=129&prev=/images%3Fq%3DPICTURES%2BOF%2BGEOPHYSICAL%2BLOGGING%26um%3D1%26hl%3Den%26rls%2BGEOPHYSICAL%2BLOGGING%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:*:IE-SearchBox%26rlz%3D1I7GGIC%3Dcom.microsoft:*:IE-SearchBox%26rlz%3D1I7GGIC

http://images.google.com/imgres?imgurl=http://www.nga.com/graphics/http://images.google.com/imgres?imgurl=http://www.nga.com/graphics/Geo_ser_Borehole_logging(sketch).gif&imgrefurl=http://www.nga.com/Geo_ser_Borehole_logging(sketch).gif&imgrefurl=http://www.nga.com/Geo_ser_Borehole_logging_tech.htm&h=292&w=350&sz=11&hl=en&start=1&um=1Geo_ser_Borehole_logging_tech.htm&h=292&w=350&sz=11&hl=en&start=1&um=1&tbnid=yn-xod1ZgFgn3M:&tbnh=100&tbnw=120&prev=/images%3Fq%3DPICTURES&tbnid=yn-xod1ZgFgn3M:&tbnh=100&tbnw=120&prev=/images%3Fq%3DPICTURES%2BOF%2BGEOPHYSICAL%2BLOGGING%26um%3D1%26hl%3Den%26rls%2BOF%2BGEOPHYSICAL%2BLOGGING%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:*:IE-SearchBox%26rlz%3D1I7GGIC%3Dcom.microsoft:*:IE-SearchBox%26rlz%3D1I7GGIC

METALURGICAL SAMPLINGMETALURGICAL SAMPLING

MethodsMethods Magnetic surveysMagnetic surveys Electromagnetic (EM, EMI), Electromagnetic (EM, EMI),

electromagnetic sounding electromagnetic sounding Direct current (DC)Direct current (DC) GPR (Ground penetrating GPR (Ground penetrating

radar potential) radar potential) Seismic Seismic Time-domain Time-domain

electromagnetic (TEM)electromagnetic (TEM) Controlled source audio-Controlled source audio-

magnetotellurics (CSAMT)magnetotellurics (CSAMT) Radiometric surveysRadiometric surveys Induced polarization (IP)Induced polarization (IP)

Spontaneous potential (SP)Spontaneous potential (SP) Borehole geophysics Borehole geophysics Satellite imagerySatellite imagery Imagery spectrometry Imagery spectrometry ASTER (Advanced space-ASTER (Advanced space-

borne thermal emissions borne thermal emissions reflection radiometer)reflection radiometer)

AVIRISAVIRIS PIMAPIMA SFSISFSI LIBSLIBS SWIRSWIR MultispectralMultispectral

OTHER TECHNIQUESOTHER TECHNIQUES

Fluid inclusion analysesFluid inclusion analyses Stable and radiometric isotopesStable and radiometric isotopes Computer modelingComputer modeling

STEPSSTEPS

Define uranium deposit modelDefine uranium deposit model Select areaSelect area Collect and interpret regional dataCollect and interpret regional data Define local target areaDefine local target area Field reconnaissanceField reconnaissance Reconnaissance drillingReconnaissance drilling Bracket drillingBracket drilling Ore discoveryOre discovery