Annual report on EL 25406 Fog Bay for the period 12 April 2007 to 12 April 2008

Abstract

EL25406 'Fog Bay' covers an area of 77 sq. km and has little outcrop apart from a ridge of Proterozoic Depot Creek Sandstone that strikes north-south through the tenement with a maximum height of 50m above the surrounding plains. ELA 26439 Fog Bay East is an easterly 23 km extension to EL 25406. The tenement extends to the south as the Finniss River and Delissaville-Wagait-Larramia Aboriginal Reserve boundary. The area occupies part of the Litchfield Region at the western end of the Pine Creek Orogen. Drilling shows the geology to be structurally complex with isoclinal folding and metamorphic grade extending to amphibolite facies. The older higher-grade metamorphics, now known as Fog Bay Metamorphics, contain a calc-silicate and graphitic sequence towards its base termed the Sweet?s Member. This is considered a stratigraphic correlative of the Cahill Formation in the Alligator Uranium Field in the far east of the Pine Creek Orogen, and is the main target of present exploration. Amphibolite layers in the metamorphics lie above the calc-silicates and are magnetic markers. The Depot Creek Sandstone of the Tolmer Group lies above the 1800 Ma unconformity and correlates with the Kombolgie Sandstone of the Katherine River Group. A previous regional airborne magnetic-radiometric survey was flown along northsouth lines generally parallel to regional stratigraphy. The contract for a new survey was awarded to UTS and this was completed in late December 2007. Flight lines were oriented east-west and flown at a height of 50m. Contouring of original data highlights 3 magnetic anomalies A, B and C. Anomalies A and B are directly on or underneath the Depot Creek Sandstone unconformity in Palaeoproterozoic metamorphics. Anomaly A is spatially related to a N-S and NW-SE fault intersection. Anomaly C is a linear feature several kilometres long and passes out of the tenement to the south. It is located on a major postulated fault with outcropping quartz breccia. A ground magnetic and radiometric survey of anomalies is recommended. Fence drilling and collection of fresh bedrock samples for magnetic susceptibility measurements is also recommended. This will aid geophysical modelling and an estimate of depth of anomalies.