Dear Colleagues: Attached is the meeting notice for the next SAGA meeting this Friday. While I don't expect too many not already in RSA will be able to attend, Dave Hatch's talk should be an interesting one based on the abstract he provided below.
Regards Ken ------- Joel, I am sure all of us want to know whether you can make it or not... ------- SAGA Talk - Friday 22 November Venue: Fugro, 22 Packard St, Woodmead Time: 17h00 Refreshments will be served Cost Effective Delineation of Kimberlites by David Hatch, De Beers Africa Exploration In 2001, De Beers discovered 38 kimberlites worldwide. In order to turn these occurrences into deposits, the company must cost effectively determine which of those have economic potential. The early stage evaluation of these kimberlites involves the analysis of mineral chemistry and microdiamonds, which can indicate if the intrusion has sampled diamond-bearing mantle. A second factor that is critically important to this evaluation process is to determine the size of the body with an acceptable confidence and to provide a first pass geologic model. Kimberlites commonly consist of multiple intrusions that can possess different physical properties. A magnetic susceptibility database complied by De Beers indicates a high degree of variability of magnetic properties, both between the different facies (crater, hypabyssal, diatreme) and also within the same facies measured for different bodies. In the past, magnetic modelling has been used as the prime determinant of kimberlite size. However, it has been found that this data provides only what should be considered to be a lower limit of size as some phases can be non-magnetic. The collection of complementary geophysical data sets, such as, gravity can help provide a more complete picture of the size and complexity of the body. As the potential of a kimberlite is further increased, depth-sounding techniques can be used to provide more information on the 3-D shape and help optimize the cost effectiveness of delineation drilling. In an environment that does not have thick conductive cover, the CSAMT technique can be particularly useful as kimberlites are often more conductive than surround rock. Construction of a robust 3-D geophysical model enables drill sites to be established that optimally investigate the contact of the body and sample the main components of the kimberlite. An example of the geophysical delineation of the Thankane body in Botswana and results of the subsequent drilling will be presented. ----------------------- Condor Consulting, Inc. St 206, 4860 Robb Street Wheat Ridge CO 80033 Tel: 303.423.8475 Fax: 303.423.9729 Cell: 303.520.5732 www.condorconsult.com _______________________________________________________ List archive: http://www.mail-archive.com/[email protected]
