Exploration in the Margaret Syncline

Abstract

Nord's exploration in the area is aimed at identifying targets where major stratiform base-metal deposits may have accumulated. In the Margaret Syncline a suitable palaeo-environment appears to have existed. Interpretation of regional gravity data (Tucker, Hone and Sampath in International Uranium Symposium on the Pine Creek Geosyncline Australia, 1979, p.206) confirms the Margaret Syncline as a relatively deep basin structure. Nicholson (1979) observes a facies change across the Golden Dyke dome, a gold-tourmaline association on the west side being absent on the east side. Instead geochemical lead, zinc and copper anomalies are present in the same stratigraphic position. The Margaret dome mirrors the facies variation with gold-bearing tourmalinites best developed on the east side, and lead, zinc, copper anomalies along the west side (Nord Resources current exploration in EL 1601). Search for major stratiform base metal deposits in the Pine Creek Geosyncline is given a new perspective when it is recognised that the 'geosyncline' may be an extensive shallow basin relatively little disturbed by folding. The deeper parts of any palaeotroughs, the potential sites of base metal accumulation, may never have been sufficiently up-tilted to expose visible evidence of major deposits. Targets may certainly be present, but must be identified by deductive reasoning followed by geophysical exploration and/or stratigraphic drilling. The presence of base metal anomalies and gossans at the base of the Gerowie Tuff in the southern part of the Margaret Syncline attracts attention for such an exercise. The fact that the strongest gossan development occurs at the keel of a local syncline structure encourages the view that mineralization strengthens with depth. Within the mineral claims, the target stratigraphic horizon and basin structure is probably in the depth range 100 to 1000 metres, well within the range of conventional, exploration.