CLEVELAND UPDATE!
Highlights:
- Identification of exploration target along strike from historical mine workings
- Identification of additional exploration targets within the mine sequence
- Further potential is open along strike within untested mine sequence stratigraphy
- 3D modelling of magnetic anomalies to be used to further define drill targets
- Drilling work programme submitted to MRT for approval on shallow potential open cut targets
Elementos Limited (ASX: ELT) announce the identification of new exploration targets following the completion of a ground magnetic survey at Cleveland. The ground magnetic survey has identified a number of new exploration targets along strike from the historical workings and within the mine sequence to the north of the historical workings. The Company recently announced a new exploration strategy to define additional potential open cut resources for the proposed staged re-development of the Cleveland tin, copper and tungsten project in Tasmania. The completion of the ground magnetic survey is the first objective of that strategy. As has previously been highlighted, ELT’s Board of Directors have been working to define the optimum path to economically sustainable production where maximum shareholder value can be achieved.
Ground Magnetic Survey
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Figure 1. Cleveland Ground Magnetic Survey TMI Image
The ground magnetic survey was carried out under contract by Modern Mag in January 2017. The survey was completed using man portable magnetometers traversing a grid that had been constructed over the survey area. The survey covered a total of 32 line kilometres at a 30m line spacing. The narrow line spacing was used to maximise the potential to collect high resolution data from near surface features. Figure 1 is an image of the Total Magnetic Intensity after the original data was corrected for cultural objects left over from historical mining activities. The TMI image (Figure 1) displays the previously mined ore lenses projected to the surface (in white). These ore lenses were identified in a ground magnetic survey completed in 1954 by the Tasmanian Government prior to being mined by underground operations by Aberfoyle from 1968 to 1986.
Figure 1. Cleveland Ground Magnetic Survey TMI Image
The tin mineralisation at Cleveland occurs largely as cassiterite within a replacement sulphide orebody hosted by a carbonate rich sedimentary horizon. The sulphide mineralisation is predominantly pyrrhotite, which is magnetic. The ground magnetic data has been processed to highlight and better define magnetic responses, controlling structures and lithological variations. The enhanced magnetic images have been combined with pre-existing geological data to generate new exploration targets and are presented in Appendix 1 The pre-existing data included drill hole data, mineralised tin lode boundaries (pre-underground mining), underground development and mined stopes, and surface workings. Initial interpretation of the combined data has highlighted new exploration targets that warrant 3D modelling and drill testing.
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Figure 2. TMI magnetic image with new exploration targets highlighted.
A potential extension to the mineralised lodes has been identified from the ground magnetic survey to the east-northeast of the historical workings (Target No. 1, Figure 2). Previous workers have identified a significant fault that offsets the mineralised lodes in the historical underground workings. This feature and the effect it has had on the mineralised lodes can be seen in Figures 5 & 6. The fault has a north-northeast strike with a moderate dip to the southeast. Lesser southeast-northwest oriented structures, offsetting the mine sequence, have been identified within the images generated from the ground magnetic survey and confirm work recorded by previous workers. No exploration drilling has been recorded as being carried out in this area. This potential extension to the mineralised lode system is open to the east and held by Elementos under EL7/2005.
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Figure 3. Location of cross-sections depicted in Figures 4-6.
The three images in 3D depicted in Figures 4-6 are of sectional slices through the Cleveland deposit looking towards the northeast. The location of the sections are depicted in Figure 3.
Section 1 (Figure 4) shows the wireframe outlines of the original ore lenses (in red) before they were mined by Aberfoyle in underground mining operations between 1968 and 1986. The ore lenses have been projected to surface (white) and appear on a topographical surface with the enhanced magnetic image (1vd over 2vd RTP) draped over the topographical surface. The potential extension to the mineralised lodes is shown to the east of the historical workings.
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Section 2 (Figure 5), approximately 400m to the northeast of Section 1, shows the influence of a north-northeast striking fault zone on the mineralised lodes as it cross-cuts and displaces the lodes. The fault zone appears on sections and plans from the historical mine records.
Section 3 (Figure 6) depicts a separation of the lodes by the fault. The potential continuation of the lodes beyond the fault zone is highlighted to the east of this section.
Two magnetic anomalies (Target Nos. 2 & 3, Figure 2) have been identified approximately 300m to the north of the historically mined area. These anomalies display a similar orientation to the mineralised lodes previously mined at Cleveland, namely northeast striking with a south-easterly dip. These anomalies, if combined, occur over a strike length of approximately 400m and are open to the north east, beyond the current survey boundaries.
The orientation of the underground fault is sub-parallel to a strongly magnetic linear feature located in the southern portion of the recently completed ground magnetic survey. Geological mapping of this anomaly has identified a magnetically anomalous dolerite dyke that may have been intruded along a parallel structure.
3D modelling of all the anomalies, on a line by line basis, will be carried out to more accurately determine the orientation and depth of the anomalies prior to planning a drilling programme to test these anomalies for tin mineralisation.
Potential Open Cut Resource Extension Drilling Programme.
A proposal to carry out a 16-hole shallow diamond drilling programme, to locate near surface extensions to the existing open cut resource, has been submitted to Mineral Resources Tasmania for approval. The programme has been prepared utilising information from the recently completed ground magnetic survey, a geological mapping programme and historical drilling and mining data.
The Chief Executive Officer of Elementos, Mr Chris Creagh, said “the ground magnetic survey has identified several new exploration targets at Cleveland. These results are very encouraging and indicate a potential extension to the known mineralised horizon, plus the potential for additional new zones of mineralisation within the mine sequence. This represents a successful completion of the first phase of the new exploration programme at Cleveland. Elementos will drill test these new targets as soon as possible and commence planning to extend the ground magnetic survey to the east along strike from these new targets”.
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