Hi Elizabeth I was wondering if you have any other suggestions for the constraints? The problem with this upper limit one is that there is high density rock at the surface on the edges of the grid with low density fill in the middle of the grid. Also I was wondering what the Reweighting IRI=2 does?
Cheers, Doug From: [email protected] [mailto:[email protected]] On Behalf Of Elizabeth Baranyi Sent: Friday, April 12, 2013 4:04 AM To: Geosoft Oasis montaj and Target Subject: RE: [geonet] Gravity Modelling 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<http://www.geosoft.com> From: [email protected]<mailto:[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]<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 ************************************************************ Confidentiality Warning. The information contained in this e-mail is confidential and subject to certain laws pertaining to the protection of proprietary information. It is intended only for the use of the individual or entity named above. If the reader of this message in not the intended recipient, or the authorized agent thereof, the reader is hereby notified that retention or any dissemination, distribution or copying of this transmission is strictly prohibited. If you have received this e-mail in error, please notify us immediately by reply e-mail or by telephone, and delete all copies of the original message. Thank you. ************************************************************ --- 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
