CH7 Rare Earth Element Exploration – “Property X”, Canada


Gamma ray spectrometry can be used to accurately locate rare earth element-bearing rocks and, in this “top secret” example* (from somewhere in Canada), it can distinguish between tantalum-rich and niobium-rich end-member types of carbonatite. This could prove extremely useful during development of an exploration strategy.

*The identity of the study area has been removed at the request of the GamX Inc client.

In the example, several ~330 Ma carbonatite bodies have been emplaced as dikes and sills ranging up to 90 m thick and more than a kilometer long. They are either dolomitic (also referred to as rauhaugite or beforsite) or calcitic (sovite) and these may form bodies separately or both can occur within a single intrusion. Mineralization occurs as Nb and Ta bearing ferrocolumbite and pyrochlore.

Uranium and thorium occurring in trace concentrations within the carbonatites provide sufficient contrast with the host rocks to outline discrete airborne anomalies (not shown). Ground spectrometric measurements conducted on several of these show strong contrasts on eU-eTh and eTh-K bivariate plots, between the beforsitic and sovitic end members, as shown in the plots below. An eU/eTh ratio value of 3.4, and eTh/K ratio of 12, appear to separate the types. In addition, felsic intrusions are distinguished by their relative higher K and lower eTh/K ratios than the carbonatite phases.

GamX CH7 Property X U-Th Th-K Field Data charts

GamX Ground Spectrometry RSI BGO-230

The field measurements shown were taken during two days of field work in 2007, using an RS230-BGO spectrometer manufactured by Radiation Solutions Inc (www.radiationsolutions.ca), placed directly on outcrop exposures, . Access was by helicopter, underscoring the need to obtain accurate “real-time” field information as efficiently as possible. As many readings can be taken at each site, the cost and time required to collect, carry, ship and process rock samples for geochemical analyses, can be significantly reduced through use of the field spectrometry data.

 

 

 

 

 

 

Gamma ray spectrometry has been used elsewhere to separate different carbonatitic phases, as in the example below, from Fen, Norway (source: http://www.reeminerals.no).

GamX REE Fen Norway Example