Hello Doug Indeed GM-SYS would have been the approach to take with your model, the alternative approach with VOXI would be:
* Remove a linear background from your gravity data. Consequently you will be modelling the gravity contrast as opposed to absolute densities. * First set the Reweighting constraint to IRI=2 and run the inversion. If you do not find that the solution represents your geological knowledge then try the approach below. * Set the upper bound constraint using the basin depth o Create a grid that covers your area of interest of a constant value equivalent to the 650 m depth on your Z axis. o Generate an upper bound constraint using this grid and set the upper limit above this grid (basin fill) to the upper density contrast limit of the basin fill o Set the upper limit of the volume below the 650 m (bedrock) to a much larger value. o Set the Reweighting constraint to IRI=2 * Run the inversion Let me know how the above works, and if would you like further recommendations. Regards Elizabeth Baranyi Technical Product Manager, Geophysical GEOSOFT INC. freedom to explore T +1 416.369.0111 #356 C +1 647.504.6006 F +1 416.369.9599 Visit our site at www.geosoft.com From: [email protected] [mailto:[email protected]] On Behalf Of Doug Perkin Sent: Thursday, April 11, 2013 4:12 PM To: Geosoft Oasis montaj and Target Subject: [geonet] Gravity Modelling Hi Does anyone have experience using Voxi for 3D modeling of basins using gravity? I'm interested in getting a rough model with basin depth and a rough idea of its general geometry. I want to create a simple model with two density values: basin fill and bedrock. I also already know that the basin is at least 650m deep. I have tried using some of the constraints in Voxi, but have not gotten a reasonable model. I guess the hardest thing is just separating the response due to the basin from the rest of the Bouguer anomaly. I have tried polynomials, second order looks best. But just wondering if anyone else here has experience attempting this? I see GM-Sys is probably a better approach but don't have a license for that yet. Thanks, --- Forum archives can be accessed here: http://lyris.geosoft.com/read/?fourm=geonet You are currently subscribed to geonet as: [email protected]<mailto:[email protected]>. To subscribe or unsubscribe from any of our forums, select the User Forum selection on the Geosoft Community page: http://www.geosoft.com/support/community --- Forum archives can be accessed here: http://lyris.geosoft.com/read/?fourm=geonet You are currently subscribed to geonet as: [email protected]. To subscribe or unsubscribe from any of our forums, select the User Forum selection on the Geosoft Community page: http://www.geosoft.com/support/community
