Annual report EL 674 Weaber Lagoon year ending 1-11-1977.

Abstract

A comprehensive geophysical programme has been completed on EL 674 in an attempt to follow stratabound lead-zinc mineralisation from the Sandy Creek area, which is in the adjacent EL 247. 4.25 km of seismic refraction and 23.5 km of induced polarization were employed. It is now believed that a narrow south-west trending band of mineralisation has been successfully delineated, and it is recommended that this trend be protected with mineral claims upon relinquishment of EL 674. Exploration this year, as in previous years, has been integrated with work on the adjacent EL 247 in an attempt to extend the 'Sandy Creek' type mineralisation (in EL 247) to the showings near Alpha Hill, in EL 674. To follow the mineralisation south-west from Sandy Creek, a geophysical programme was instigated for 1977 works. Geophysical methods employed were shallow seismic refraction and induced polarization (gradient array). A detailed survey was completed within EL 674 during 1977, by the contract surveyors Buxton, Tuder and Waugh. The purpose of this survey was to connect various stations (old drill holes etc) and the new 1977 works to the National 10,000 Metre Grid.

Tell urometer measurements were first made between 'Wicklow' and 'Weaber' with an agreement to computed distance of one part in 5400, and between 'Weaber' and 'S029' with an agreement of one part in 71000. Also, the angle measured at 'Weaber' between 'WicklowTM and '5029' was within 3 seconds of the cornputed value. Several geodimeter traverses were then made through EL 674, mainly to prepare the seismic refraction profiles. All stations connected to the National Grid have been cemented and tagged. Gradient Array Configuration - This configuration is derived from the E.S.I.P.E configuration where the current line length remains the same for the whole area and the receiver dipole is moved along the profile to measure the apparent resistivity and IP This method gives a good picture of the resistivity and IP variation at depth in the whole area and its geological interpretation can be quite accurate provided there is some E.S.I.P.E carried out to determine the origins of the resistivity and IP variations. Usually, the current line AB is at least 1,000m,, the receiver dipole l00m maximum, and the readings are carried out in a rectangle, with a maximum width along the current line of 1/3 of AB, and a maximum length of AB/2. On hard rock, it is often possible to extend its width since depth penetration variations are less important. CONCLUSIONS AND RECOMMENDATIONS - From the geophysical results, the geology can be described as follows; SW-NE fault downthrew the western compartment. The N-S faults, visible at Alpha Hill and Sandy Creek, also downthrew the western compartment and moved the eastern compartments northward. They are more recent than the SW-NE fault. The Cockatoo dips to the north or north-west under the Sandy Carbonates. From the most southern data, it is reasonable to assume that the NE-SW fault has a southern extension and it could be followed using the gradient array configuration with the same parameters as this year. The main interest in EL 674 is the SSW-NNE polarizable zone which appears to be a natural extension of the mineralised Sandy Creek trend. However, it appears that this trend could be weakening slightly southward, until intersected by the northerly fault from Alpha Hill, which divides the Enga Sandstone (Cle) and Cockatoo Sandstone (Duc) in outcrop. This fault has a zone of very high polarizability beneath the Enga Sandstone outcrop. Since the local dip seems to be NNW, this area is also a good target. It is recommended that diamond drilling be carried out on the anomalous trend SW from Sandy Creek, and in the Alpha Hill area. If drilling results then appear to be encouraging, more gradient array could be carried out further south-west from Alpha Hill. It was recommended that the above areas be: protected with mineral claims upon final reduction of E.L. 674, and, accordingly, twenty claims have been pegged.