Gravity

Ultramag offers Gravity Services using the CG5, CG3 and LaCoste gravity meters with resolution up to 0.005mGal for the CG5. We use walking, quad bike, 4WD and helicopter means to survey an area and provide color images of the graviity field.

Gravity data processing is undertaken in the field daily and backed-up by email. Intrepid and Carlson software is used with our in-house software to fastrack data processsing. We can provide output in any data format and projection.

We use the JAVAD Triumph 1 and Novatel DL4 RTK GPS systems and Carlson logging software.

Ultramag produces Bouguer anomalies using ustom Excel spreadsheet automation with automated output to Potent and Intrepid.

Bouguer anomalies can be terrain corrected in Intrepid using local grid and NASA's Shuttle Radar Topograpic  Mission (SRTM) elevations.

Gravity applications include:

  • Mineral Exploration - massive sulphides, porphyry's structure
  • Diamond Exploration - Kimberlitic pipes
  • Coal Exploration - basin structure, grabens, large faults
  • Dyke bulk density (Coal Hazard)
  • Petroleum - frontier basin mapping, diapirs
  • Locating void in Karst Topography
  • Engineering, tunneling, footings
  • Geodesy
  • Recreation - Speleology
Gravity data screenshot

Click Here for Gravity Case Studies
 Students
What is a Gravity Meter?
A gravity meter is a very sensitive instrument for measuring the downward (vertical) acceleration of gravity towards the centre of the earth.

Gravity aveages 9.81m/s/s on the earths surface, and varies by 0.5% over the surface of the Earth due to the elipsoidal shape and changes in crustal density.

Gravity allows us to measure the bulk density of rocks (and voids) beneath the meter to several kilometers depth - the deeper the 'more fuzzy' things look.

Gravity is measured in milli Gal [mGal] and our meters can resolve 0.01 mGal (arond 0.0000001 m/s/s) which is an elevation change of  25mm form the centre of the earth.

Surveys thus require very accurate heigh control. Ths is acheived using Real Time Kinematic (RTK) GPS.

Further reading
AGSO Best Practice in Gravity
Wikipedia
CG5 Gravity Meter
wiki ref: Gravimeter