Land Magnetometer Training Course Magnetic Theory ½ day Hardware (G858/AP) ¼ day Software (MagMap / MagPick) ¼ day Hardware setup (858 and GPS) ½ day Survey ½ day Processing ½ day Review ½ day Slide
Geometrics, Inc. Premier Manufacturer of Land Magnetometers Slide
GEOMETRICS MAGNETOMETERS- tools for exploration Applications: • Map Geology for Mining, Oil/Gas Exploration • Environmental Survey for Tanks, Barrels • Locate Utilities, Pipelines • Military Uses, UXO-EOD, De-mining • Archaeology • Used in Land-Marine-Airborne Surveys
GEOMETRICS: a 30-year history of building magnetometers 1969: G-801 & G-803 marine and airborne proton magnetometers 1971: G-806 land and marine proton magnetometer 1973: G-816 portable proton magnetometer 1977: G-826 portable digital magnetometer 1981: G-856 portable memory magnetometer 1983: G-811 marine magnetometer 1991: G-822L military magnetometer 1992: G-825 military diver-held magnetometer 1992: G-822A airborne cesium magnetometer 1995: G-858 portable cesium magnetometer 1996: G-880 marine cesium magnetometer 1997: G-823A airborne cesium magnetometer with counter 1998: G-881 marine light-weight cesium magnetometer 2003: G-882 marine cesium magnetometer 2005: G-859 cesium mining magnetometer 2009: UAV, AUV testing 2013: G-860 land cesium magnetometer 2014: G-862RBS cesium base station
Magnetometer Configurations
UXO Magnetometer Configurations
Sensor Noise – Spin analysis
Sensor Noise – Tumble Analysis
Sensor Noise – Various Motions
Earth’s Magnetic Field Diagram
Earth’s Magnetic Field – Solar effects Earth’s Magnetic Field: detection of magnetic anomalies Earth’s Magnetic Field – Solar effects Earth’s dipole (N-S) magnetic field is produced by internal iron core dynamo effect. Charged particles from the sun cause a bow shock wave in the magnetosphere which leads to Diurnal Variations Earth’s dipole magnetic field is perturbed by relatively localized contrasts in magnetization. Magnetization contrasts are caused by ferrous debris, vessels, pipelines, communication cables, magnetic minerals (predominantly magnetite). With magnetometers, one can measure the total field to detect the magnetic anomalies associated with contrasts.
Earth’s Total Magnetic Field
Earth’s Magnetic Inclination
Diurnal Variations
Optional Diurnal / Base Station Monitor Use either G-858 or G-856 Magnetometers Monitor Magnetic Diurnal Variations Magnetometer in fixed location Synchronized clocks 1-30 second sample rate Use for correction of survey data Produce more accurate magnetic maps
Sensor Dead Zone Diagram
Sensor Diagrams - CSAZ
Sensor Dead Zone – 0 Degree Tilt
Sensor Dead Zone – 45 Degree Tilt
Results of Survey profile width
Anomaly patterns as a result of Inclination
Anomaly width versus depth
Depth estimate
Nomogram
Anomalies of common objects
Vertical Gradient Applications
Wearing the G-858
Gradiometer Transverse Layout G-858 CESIUM GRADIOMETER WITH agGPS-114/132 STEERING
Standard Survey Acquisition Swath Spacing
GPS Differential Corrections Coast Guard Beacon OmniStar (On shore only without special license) Racal (On shore only without special license) RTCM RTK Known Antenna and Satellite positions and frequencies
Data Processing Software – Magmap 2000
Software capabilities Import G-858 magnetometer (1 or 2 sensors) Convert GPS Lat / Long to UTM XY coordinates Correct for GPS offset from Magnetometer sensor Perform Spike filtering Import G-858 or G-856 base station data Merge Base Station data with survey Data Export in Surfer or Geosoft format
MagMap 2000 Destripping tool
Surfer Software Capabilities Windows based program for professional displays Grid and contour G-858 data Display sample locations on contour map Various types of displays for interpretation Export Windows Metafile and ASCII grid files for MagAID
Surfer Displays – Ft. Ross
Stanford Base Map
Surfer 3 dimensional display
Stanford shaded relief
Stanford Magnetic Contour Map
MagPick – Filtering theory RAW DATA MANUAL SMOOTHING 3 POINT RUNNING AVERAGE