SUMMARY OF STAGE ONE STRUCTURAL STUDY FOR BRONZEWING.
Forward
View Resource’s Bronzewing Operations in the Northeast Goldfields of Western Australia are contained within a well-mineralised greenstone belt that also includes other multi-million ounce gold mining operations, such as Newmont’s Jundee Mine and Barrick’s operations at Darlot.
Figure 1. Gold deposits of the Yandal belt.
Since gold was first discovered in the McClure area in the late 1980’s, the Bronzewing district, including the Bronzewing and McClure group of deposits has produced in excess of three million ounces of gold with presently nearly 800,000 ounces in resources. The Bronzewing region is similar to many other “mature” mining regions in the Western Australian goldfields, in that it has previously been subject to extensive exploration. However, outside of the immediate mine areas, much of this work has been of a reconnaissance nature with drilling generally on wide-spaced traverses and limited to testing for the presence of mineralisation within 100 metres of the surface.
View is of the firm opinion that exploration success in this region will depend on developing and integrating a coherent understanding of the detailed controls on mineralisation at individual deposits to the regional geology of district. View believes a successful exploration targeting strategy will come from a comprehensive understanding of the formation of known deposits in the area. Arguably, the most important feature determining the location and formation of lode gold deposits is structural geology. This is because geologic structures control the migration and trapping of the mineralising fluids that formed the gold deposits.
With this in mind View has engaged the well- respected international geology consulting firm SRK Consulting to undertake a structural investigation of the Bronzewing region. The principal aim of this study is to define “blind” gold exploration targets, that is they lie beyond the limits of current drilling.
The project has been undertaken in three stages. The first stage involved examining the geometry and structural geology of the Lotus-Cockburn and Bronzewing gold deposits, the most significant deposits in the area in terms of gold produced to date. The main objective was to provide a coherent understanding of the structural controls on gold mineralisation at these deposits that can be used in subsequent regional and near mine exploration targeting.
The second stage of the project, which has only recently been completed was more broadly focused and aimed to integrate the structural models for gold mineralisation defined in stage one with the regional structural geology. This has involved regional mapping and an interpretation of geophysical data.
The third and final stage of the project resulted in the definition of new exploration targets by combining the results of stages one and two. The key outcomes of stages two and three will be made available on View’s website once the findings have been analysed.
The following highlights from the Stage One interim report are released with the kind permission of SRK Consulting are provided below to indicate the benefits of this collaborative study between View Resources and SRK Consulting. The study to date has resulted in the delineation of near mine targets that we intend to test and are hopeful will lead to future exploration success.
Stage One Highlights.
The Project Team responsible for the Stage One study consisted of Toby Davis, Alison Morley, and Shane Kenworthy, all fulltime employees of SRK Consulting. Toby is a Senior Consultant (structural geology) and led the project team along with Terry Peachey, Exploration manager with View Resources. Alison is a Senior Consultant (resource geology) with extensive experience in mine geology and was responsible for deposit modeling, using Leapfrog™ software, that was the foundation of this study. Shane is a Consultant (geology), and was in charge of database management and assisted with field mapping.
The objective of this study was to determine the structural controls on gold mineralisation at the Bronzewing and Lotus-Cockburn deposits. The aim was to develop a coherent model to link mine-scale controls on mineralisation between the individual deposits in the district and to apply it to brownfields exploration targeting around these deposits.
Combining gold distribution modeling with pit mapping has resulted in the determination of the deposit-scale structural frameworks for the deposits in question, from which a model for the structural controls on mineralisation has been developed. This model is considered to be robust, coherent between the deposits and has been used to generate near mine exploration targets. The SRK model has been able to advance on earlier ones developed when these deposits were last mined.
Mineralisation and targets in the Lotus and Cockburn Areas.
SRK has identified an overall NNW-plunge to mineralisation, in addition to the previously known SSE-plunge to internal high grade shoots, along the Lotus Fault at the Lotus and Cockburn deposits. This has allowed the identification of structures thought to be implicated in localising the deposits and has resulted in identification of near mine exploration targets.
Figure 2. Long Section through the Cockburn deposit looking northeast. Diamond and RC drill data shown. Wireframes enclosing 1.5 g/t Au generated using Leapfrog™ that demonstrate the SSE plunge to high grade shoots.
SRK has proposed two strategies for near mine exploration targets in the Lotus-Cockburn area. These targets highlight the potential for mineralisation along extensions of the Lotus fault network as well along parallel structures that may exist nearby Prospective targets within the Lotus fault corridor are illustrated on figure 3.
Figure 3. Exploration Targets (numbered) within the Lotus-Cockburn Area.
Mineralisation and targets of the Bronzewing Mine Area.
The structural model for the Bronzewing deposit defined in the SRK study accounts observed geometric and structural features at a range of scales. It has been possible to determine the timing of mineralisation relative to the formation of specific structures.
Gold mineralisation at Bronzewing is located along a network of structures that formed in advance of mineralisation. The structures controlling the location of mineralisation along this network have been identified (figure 4). This has made it possible to identify areas with the potential to have a similar structural framework as the Bronzewing deposit.
Figure 4. Plan view of mineralised domains at Bronzewing. The top pair of figures illustrates mineralisation along folded D1 structures in the upper part of the deposit. The lower pair of figures show mineralisation developed along D2 structure at a lower level in the mine. North is toward the top of the page.
Structures that host gold mineralisation at the Bronzewing mine may extend to the east and west (figure 5). Drilling east of the mine suggests structures that host the ores continue there but are only weakly mineralised and unlikely to host economic ore deposits. However, there is only limited deep drilling west of the mine, meaning the potential of this area has yet to be fully assessed.
Figure 5. Conceptual target west of the Bronzewing Mine.
An area north of the mine has been identified as an exploration target in addition to the target to west. When viewed in sections looking east the orebodies at Bronzewing are contained within a gently north-plunging array. This arrangement of known orebodies shows increasing depth with distance to the north. Previous exploration has partially tested the area to the north of the mine but drilling does not appear have been deep enough to test for the presence of mineralisation greater than 600 metres directly north of the mine (figure 6).
Figure 6. Longitudinal projection and section through the Bronzewing deposit showing conceptual deep target (gold oval) north of the mine. The shoots comprising the existing Central and Discovery shoot are shown in red.
Conclusions
Mineralisation in the Bronzewing region has been linked to N-S-striking strain corridors. The structural geology and deposit geometry at Bronzewing and Lotus-Cockburn indicate that these deposits are localised where pre-existing structures intersect these corridors.
The structural model for mineralisation determined in this report presents a series of guiding principles to help direct near mine exploration. Consequently, there is potential for near mine locations to contain a structural framework conducive to mineralisation. Further assessment of the structural geology of these localities is required to assist in the evaluation of the potential for these sites to host mineralisation.
ACKNOWLEDGEMENT.
The information contained in this report is summarized from an unpublished document entitled “Stage 1: Deposit Scale Geometric Modeling and Structural Analysis” prepared for View Resources Limited by SRK Consulting. The principal author of the source document, Dr Toby Davis is a fulltime employee of SRK Consulting and is a member of the Australian Institute of Geoscientists. Dr Davis has sufficient experience which is relevant to the style of mineralization and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2004 Edition of the ‘Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves’. Dr Davis consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
|
