New Copper Targets Revealed by VTEM Survey
Sydney, Sep 17, 2014 AEST (ABN Newswire) - Thomson Resources Limited (ASX:TMZ) completed an extensive, 564 line kilometre, airborne "VTEM" survey (Versatile Time-domain Electro Magnetics) in June 2014 over some of its key prospects within NSW. The survey targeted volcanogenic massive sulphide deposits ("VMS") at the Havilah and Byrock projects as well as other sulphide-associated deposits in other project areas. The VTEM survey defined a number of bedrock conductors demanding immediate follow-up and drilling.
VTEM is widely considered the best helicopter borne TEM geophysical system for detecting and imaging massive sulphide deposits with notable successes including the discovery of the Mallee Bull deposit in the Cobar Basin (see reports by Peel Mining, ASX:PEX), and the recent Artemis discovery in Queensland by Minotaur Exploration (ASX:MEP). The VTEM system is flown using a helicopter that tows a powerful electromagnetic ("EM") transmitter and receiver which can detect conductive massive sulphide mineralisation.
Following completion of the survey in June, preliminary VTEM data was processed line by line comparing early, middle and late-time EM decay responses to identify potential bedrock targets. Throughout the survey areas two targets of high significance plus a further 27 second-order targets were identified from the VTEM data.
The Havilah base and precious metal project on EL 7391 is located approximately 20 kilometres southeast of Mudgee, central NSW. It lies within Silurian volcanics and volcaniclastic sediments of the eastern Lachlan Fold Belt, known to host high grade copper-lead-zinc-silver-gold VMS deposits such as Woodlawn, Captains Flat and Benambra.
The VTEM survey area covered zones of previously identified base metal sulphide mineralisation, including the Achaye prospect where historic drilling had tested a SIROTEM anomaly (at A1 on Figure 2). Gossanous rocks with old workings and copperzinc anomalism occur at surface along the NNW-SSE trend This trend was targeted by the 1979 drilling, recording strongly anomalous copper (up to 1% over 1m) and zinc (up to 2.2% over 1m) associated with sporadic massive pyrrhotite mineralisation. Appropriate EM responses were observed over the Achaye mineralisation (Figure 2 in link below), validating the survey technique and VTEM response over this type of mineralisation.
As well as confirming the A1 EM anomaly, the VTEM survey defined a stronger, deeper anomaly (A2 on Figure 3) around 400 metres west of Achaye. This new conductor has not been previously tested and represents a priority VMS target. The area will be followed up with detailed mapping (if practical), soil and rock chip geochemistry as well as a ground EM geophysics survey to confirm the geometry and dip of the conductor prior to drilling. Ground EM survey configurations can detect extensions of EM anomalies at depth, not seen in the airborne VTEM system.
WILGA DOWNS (BYROCK)
The Wilga Downs prospect on EL 8136, lies 35km west of Byrock in an area where both Silurian-Devonian Cobar Supergroup (mainly sediments) as well as older Ordovician rocks have been mapped. The area is believed to have potential for Tritton (VMS) type copper deposits. Tritton itself was discovered by ground EM (SIROTEM) and was also marked by a magnetic anomaly. The Wilga Downs area features several distinct magnetic anomalies, one of which has been drilled with two holes: one in 1971 by AMAX and one in 1978 by CRAE. Both holes returned anomalous copper (up to 0.2%) and zinc (up to 0.7%), but neither hole tested the full extent of the magnetic anomaly (they were too shallow and were drilled in opposite directions).
Of the several EM conductive anomalies identified in the area by the VTEM survey, the most prominent is coincident with this magnetic anomaly. The top of the conductor has been modelled as a shallowly south-dipping plate shaped body that falls between and below the previous drilling locations (Figures 4, 5). The anomaly is quite strong and persists from mid to late-response times suggesting a highly conductive zone possibly associated with sulphides.
In addition, several other second-order anomalies have been detected. All targets of significance will be assessed with further modelling and ground work ahead of design of a drill program.
VTEM results continue to be processed for the Furneys prospect (EL 8251), the Wilgaroon tin-tungsten prospect (EL 8011), and over Kenilworth (ELs 7642 and 7643). Several other second-order anomalies have been detected. All targets of significance will be assessed with further modelling and ground work ahead of design of a drill program.
To view figures and diagrams, please visit:
About Thomson Resources Ltd
Thomson Resources Ltd (ASX:TMZ) is an NSW active mineral explorer. Thomson has several tin projects (including an advanced project near Ardlethan), as well as gold, copper and zinc targets in a range of settings. Thomson has a good record of discovery, with multiple new Intrusion-Related Gold (gold with copper, lead, zinc, molybdenum, tungsten) systems discovered in the Thomson Fold Belt in the NW of the state.