Final Report for Victoria River Downs Project 7 March 2007 to 6 March 2013

Abstract

During the first year of tenure, data from the open file reports pertaining to the Victoria River Basin (VRB) Project area was used to construct a robust, validated database. Anglo reprocessed the geochemical data and Geotem, gravity, aeromagnetics and landsat images. The NTGS completed a regional gravity survey. Interpretation of this gravity data in conjunction with other imaged data sets generated robust interpretations showing major lineaments, which correlate with faults mapped by the NTGS. Major structural features which had not been previously documented, were evident on imaged early time channel data. Southern Geoscience reprocessed AGSO gravity data, which showed the presence of basement highs and linear gravity lows, the resolution of which would be refined by infill gravity readings in areas of specific interest. Anglo undertook a regional reconnaissance geochemical sampling program (i.e. stream sediment, rock chip and soil samples). This work successfully confirmed the robustness of previous anomalies identified and highlighted prospective areas of interest in the vicinity of the Victoria River Downs Homestead. The statistically processed geochemical data showed a zoning of the base metal occurrences, from principally lead domains to zinc-copper domains. This work highlighted a distinct zinc-copper domain along the western and southern margins of the VRB. By contrast lead-copper anomalism dominates the central-eastern portion of the VRB. Areas of strong base metal anomalism are generally associated with the calcareous sediments of the Bullita Group and major structural corridors. During the second year of tenure the data from an airborne GEOTEM EM survey completed ~1996 was re-processed by Southern Geoscience Consultants. The survey detected one good quality, discrete, late time anomaly (A68) plus numerous, lower quality response. A total of 68 anomalies were identified. The majority of these anomalies appeared to be related to conductive surficial (regolith) or possibly shallow, flat dipping bedrock stratigraphic units rather than being discrete bedrock conductors. The only late time anomaly interpreted as a possible bedrock conductor (A68) coincides with litho-structural target 5E, defined by Anglo. This target is characterized by the triple point intersection of major faults trending N-S, NE-SW and NW-SE. Some of the stratigraphic conductors might have potential for stratiform-stratabound sulphide mineralisation as they may be related to thick sulphidic shale (basinal) sequences. In the third year of tenure Anglo conducted a helicopter-supported gravity survey in two areas. The northern part of the survey (based on readings spaced 1 km x 1 km) was designed to target a major north south fault and associated splay faults and domes over a strike length of 50 km near Victoria River Downs Station. The southern half of the survey in the Mt Sanford area (100 km south west of Victoria River Downs Homestead) was also conducted initially on a 1 km x 1 km basis and then infilled to 500m x 500m. The gravity data assisted in the interpretation of the geology and the development of targets. The most promising targets were developed in the Mt Sanford area where a broad gravity low is highlighted, sub-parallel to and east of a major NW trending fault (Pear Tree Fault). This area was interpreted to be a potential shale basin. In the fourth year of tenure the interpreted gravity targets were followed up with stream sediment and rock chip samples. No evidence of outcropping mineralisation was discovered. Stream sediment samples collected in the vicinity of the gravity targets were 1 to 2 times above background in Zinc (i.e. moderately anomalous). The highest values were collected in streams overlying the B1 and B2 target areas which contained sediments dominated by weathered Cambrian volcanics. Southern Geoscience reviewed the gravity data which showed an open ended 2-5km wide gravity low sitting on the eastern flank of a fault zone (named Pear Tree Fault). This low is interpreted as basin dominated by low density lithologies such as shales. Further interpretations concurred with Southern Geoscience's gravity interpretation and highlighted the visibility of a strike extensive NW-SE structure on a continental scale. No exploration work was completed during the fifth and sixth years of tenure (i.e. 2011-2013), as Anglo was seeking a joint venture partner to advance the project and then MMG Australia Ltd was focussing exploration efforts on other tenements. The Victoria River Downs tenement was not found to meet MMG's prospectivity criteria, and given its expenditure status, it was decided to relinquish the tenement.