INTRODUCTION TO UTM COORDINATES AND MAP DATUMS

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INTRODUCTION TO UTM COORDINATES AND MAP DATUMS
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UTM COORDINATES
300,000
700,000
500,000
105
108
102
105
ZONE CENTRAL MERIDIAN 500,000 m
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TRANSVERSE MERCATOR
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UTM ZONES UNITED STATES
NM
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UTM CARTISIAN COORDINATES
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USGS MAPS AND UTM
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COORDINATE SYSTEMS

• NAD 27 North American Datum, 1927
• NAV 29 North American Vertical, 1929
• NAD 83 North American Datum, 1983
• WGS 84 World Geodetic System 1984
• (ALL GPS)
• CORPSCON CONVERSION PROGRAM

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• INTRODUCTION TO MAGNETIC METHODS
• Earths Magnetic Field
• Rock Magnetism
• Geologic Models Magnetic Anomaly Sources
• Planning a Survey
• Examples

REFERENCE Sheldon Breiner, Applications Manual
for Portable Magnetometers www.georentals.co.uk/am
pm-opt.pdf
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TOTAL FIELD MEASUREMENTS
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EARTHS DIPOLE FIELD
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MAGNETIC ELEMENTS
North
F Total Field Intensity I Inclination D
Declination H Horizontal Component X North
Component Y East Component Z Vertical
Component
East
H F cos I Z F sin I H tan I X cos D Y
H sin D X² Y² H² X² Y² Z² F²
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TOTAL INTENSITY
50
25
50
70
X 1000 nTeslas
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GEOMAGNETIC INCLINATION
80N
60N
0
60S
80S
GEOMAGNETIC INCLINATION DEGREES OF ARC FROM
HORIZONTAL
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CHANGES IN DECLINATION AND INCLINATION AT LONDON
SINCE 1540SECULAR VARIATIONS
Declination
2008
Inclination
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SOLAR DIURNAL VARIATIONS
MID NORTHERN AND MID SOUTHERN LATITUDES
EQUATORIAL LATITUDES
50 nT
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MICRO PULSATIONS
10 minutes
10 nT
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TYPICAL MAGNETIC STORM
50 nT
1 day
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CORRECTING FOR TIME VARYING FIELDS

• F f(x,y,z,t)
• x Easting (Longitude)
• y Northing (Latitude)
• z Elevation (very small effect)
• t time
• FB Field at Base Station (time dependent)
• FR Field at Rover (space/time dependent)
• FC Time Correct Field at Rover FB FR
• GEOREF Geomagnetic Reference Correction

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AVERAGE MAGNETIC SUSCEPTIBILITIES
BASIC IGENOUS
Magnetic Susceptibility x 106 (c.g.s.)
ACID IGNEOUS
METAMORPHIC
SEDIMENTARY
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MEASURED SUSCEPTIBILITIES OF ROCK MATERIALS
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INDUCED VS REMANENT MAGNETIZATION

• Induced Magnetization
• Polarization in direction of Earths Field
• Remanent Magnetization
• Thermoremanent (Curie Temperature)
• Detrital (Depositional)
• Chemical

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GEOLOGICAL MODEL REPRESENTATIONS OF COMMON
MAGNETIC ANOMALY SOURCES
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Dipoles vs. Monopoles vs. Arrays of Poles
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ANOMALIES FOR GEOLOGICAL BODIES AT VARIOUS
ORIENTATIONS AND FIELD INCLINATIONS
? F F F ?F ?F
T N-S T E-W T N-S T E-W
1 2 3 4 5
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TOTAL INTENSITY INDUCED DIPOLE SIGNATURESAT
VARIOUS INCLINATIONS OF THE FIELD
Induced dipole Vertical Field (North or South
Poles)
Induced dipole (Inclination 60º)
Induced dipole Equatorial Field (Inclination 0º)
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REMANENT DIPOLE SIGNATURESMOMENT NOT PARALLEL TO
INDUCING FIELD
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EFFECT OF DEPTH ON ANOMALY WIDTH
The amplitude of the anomaly is maintained
constant By adjusting the size of the anomalous
body.
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DEPTH/AMPLITUDE BEHAVIOR OF DIPOLE ANOMALIES
Note Same Amplitude but Change in width
M
8M
M
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F
500
1 ton iron
100
nT
10
1
200
10
Ft
DISTANCE
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ANOMALIES OF COMMON OBJECTS

• OBJECT Ft/nT
  Ft/nT
• Automobile (1 ton) 30/40 100/1
• Ship (1000 ton) 100/300-700 1000/1
• Aircraft (light) 20/10-30
  50/1
• Pipeline (12) 25/50-200 50/12-50
• Wellhead 50/200-500 500/2-5
• Fenceline 10/15
  25/1-2
• Rifle 5/10-50
  10/ 2-10
• Revolver 5/10-20
  10/1-2

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TYPICAL MAGNETIC ANOMALIES OF COMMON
ARCHAEOLOGICAL FEATURES
Shallow grave or pathway
Humus-rich site of habitation
Kiln-baked brick wall
Sandstone wall in more magnetic soil
Bricks in disarray
Fire pit with bricks In original position
Shallow tomb
Deeply buried tomb
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PLANNING A SURVEY

• SIZE OF TARGET
• AERIAL EXTENT OF SEARCH
• GROUND OR AIRBORNE
• RESOLUTION OF SURVEY
• FIELD METHODS
• PITFALLS
• EXAMPLES

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TYPICAL SEQUENCES OF TRAVERSES DURING SEARCH
PROCEDURES
Object location
Total magnetic field contours (not known during
search)
Secondary Traverse
Primary Traverse
Primary Traverse
Primary Traverse
Final Traverse
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Maximum slope 5 m
52195 nT
52490 nT
GN
TN
52280 nT
Contour Interval 5 nT
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F
500
SOLUTION FOR BILLS CRATER
1 ton iron
100
nT
10
1
200
10
Ft
DISTANCE
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ESTIMATION OF DEPTH TO TOP OF ANOMALOUS BODIES
USING MAXIMUM SLOPE
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MAGNETIC EFFECT OF LATERAL SUSCEPTIBILITY CHANGE
VS STRUCTURE
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HIGH RESOLUTION AIRBORNE MAGNETIC MAP OF THE SAGE
2008 FIELD AREA
SAGE 2008 ARCH SITE
SAGE 2005 MT PROFILE
SAGE 2005 SEISMIC PROFILE