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Jul 2005 - Exploration in 3D

Exploration Advances into the 3rd Dimension

The use of 3 Dimensional IP by Kingsgate at its Chatree gold mine in Thailand represents a quantum leap in exploration techniques. The recent intersection announced on 7 July 2005 by Kingsgate of 12m at 30g/t gold (~1oz/t Au) and 318g/t silver (~10oz/t Ag) was in mineralisation that was parallel to and 200m further east from its existing A East (AE) orebody in Chatree North and was a direct result of the new technology.

We are all familiar with the use of 3d to depict orebodies with fly-throughs in presentations at conferences, having evolved from sections and plans through such orebodies. So it was just a case of time before exploration techniques such as IP took the next step and became 3-dimensional.

The use of IP to find orebodies or mineralisation is a well-known geophysical technique in which a pulse or signal bounces off conductive layers of rock and orebodies to form a contoured picture of different colours indicating where potential mineralisation or orebodies could occur.

It has been used very successfully for example by Sino Gold in China to determine potential mineralisation and orebodies at all their existing, new and emerging operations all with different geological settings such as Jianchaling in Shaanxi Province in Central China, Jinfeng in Guizhou Province in Southern China and White Mountain in Jilin Province in North Eastern China.

Sino Gold construct computer-based IP models comprised of sections and plans which do simplify interpretations of mineralisation. However, it is the latest 3d IP modelling (apparently only 3 to 4 months’ old) being used by Kingsgate at Chatree that really does take exploration up into another dimension.

Kingsgate’s (KCN) Chatree mine has recently shown that there is an excellent correlation between IP, resistivity and its mineralisation such that KCN has been able to determine that the main source of Chatree’s ore production since the mine was commissioned nearly 4 years’ ago (from pits C and H) appears to be located on the south western edge of a more than 2km long by almost 650m wide Mega-pit that has the potential to become a 5km long Super-pit averaging about 2.2g/t.

Contained within the Mega-pit is the AE orebody which is a newly discovered, higher grade, possibly stacked lode orebody. Something clearly “happens” in the A/AE area because the gold/silver ratios are significantly higher there increasing to 20 to 25 to 1 instead of their usual 5 to 10 to 1. There is speculation as to whether it signifies proximity to a feeder system.

Looking at IP plans and IP and geological sections, the interpretation was that the mineralisation at A/AE strikes NNW/SSE. However, 3d IP instead showed AE lying on a north-south striking ridge, and subsequent drilling north of AE has intersected mineralisation where none was contemplated or considered to be.

Amongst the structures, the 3d IP view shown in Figure 1, shows that there is a second ridge also striking north/south about 200m east of AE, with an as yet unexplained trough between the two ridges.

Drilling of the second ridge (which came purely from the 3d IP interpretation) resulted in the new mineralisation and potential orebody announced by Kingsgate on 7 July 2005. The 3d IP has generated a number of targets at Chatree which are being systematically followed up. Kingsgate have also extended their 3d modelling into Fracsis (Fractal Graphics) enabling geologically almost everything to be included in a 3d model.

Another 3d technique is EM torch which is being used by the Independence Group (IGO) to find nickel mineralisation through measuring the pulse response from nearby mining or drilling. This has been used extensively to establish the Victor South orebody and its link zone and possibly the new McLeay orebody, at their Long nickel mine near Kambalda. IGO have also been applying 3d modelling techniques that are capable of showing a simulation of how their Victor South orebody can be “mined” in sequence through drift and fill, cut and fill etc.

In addition, IGO are examining the use of Squid technology in a joint venture with Anglo American to determine nickel mineralisation beneath non-conductive cover like salt lakes. The Squid technology can reputedly distinguish the difference between sulphide and shale conductors.

It can be seen that geological exploration is continuing to evolve and with it the capability to find orebodies (and mine them) by taking them literally into another dimension through the advanced application of 3d.

Disclosure and Disclaimer : This article has been written by Keith Goode, the Managing Director of Eagle Research Advisory Pty Ltd, (an independent research company) who is an Authorised Representative with Taylor Collison Ltd, and with his associates, holds interests in some of the stocks mentioned in this article. The opinions expressed in this article should not be taken as investment advice, but are based on observations by the author. The author does not warrant the accuracy or completeness of any information and is not liable for any loss or damage suffered through any reliance on its contents.

  • Written by: Keith Goode
  • Friday, 01 July 2005