Jamina, I agree with Isobel Clark and Tomislav. Further, I'd suggest to study the geology thorouhgly and define your domains with ONE lithology. But if atered (what is usually the case in Porphyry deposits), then you can define domains as per alteration types. The goal is NOT to mix up the variable of interest ( I assume Cu in your case) from two different domains.
This exercise may help you get rid of Zonal anisotropy. In addition to what Dr Clark suggested, zonal anisotropy may suggest more than one geologic events, such as mixing of data from hypogene mineralization and supergene mineralization. About anisotropy, I'd suggest to do VARIOGRAM MAPs for each domain individually to choose the most prominent directions of anisotropy. Again, be aware of mathematical artifacts that may result due to clustering. Hope this helps. Abani Denver, USA ************************************************************ ----- Original Message ---- From: Isobel Clark <[EMAIL PROTECTED]> To: Jamina Dogic <[EMAIL PROTECTED]>; [email protected] Sent: Monday, January 14, 2008 3:45:25 AM Subject: Re: AI-GEOSTATS: Variogram Jamina Different software packages have different requirements for defining anisotropy. Some will allow you to define completely a model for each major axis of the anisotropy ellipse. The simplest (geometric anisotropy) just accept anisotropy 'factors' for the range of influence. In my experience, "zonal" anisotropy usually indicates geological non-homogeneity and/or discontinuities. For example, you may have a fult line which increases the apparent sill when you cross it. Or you may have different geological zones, again increasing the sill when you cross from one to the other. Isobel http://www.kriging.com Jamina Dogic <[EMAIL PROTECTED]> wrote: Dear experts, I¢ll be very grateful if you can help me with following question. I am geologist, and I need to use variogram for ore estimation process. I have problem with managing data in variography. I am looking at variation of cooper content in porphyry type of deposit and I did variograms in 4 directions. 0, 45, 90 and 135 degrees. I have both geometric and zonal anisotropy. My question is connected with final variogram model, does it means that I need to produce only one model of variogram which will be suitable for all 4 directions, some kind of average variogram model for all direction. Thanks in advance Jasmina Beljic Belgrade, Serbia Never miss a thing. Make Yahoo your homepage. Never miss a thing. Make Yahoo your homepage. ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping
