1 / 35

GG - Interim Technical Review Report

GG - Interim Technical Review Report. W. Mugomo, G.S Chagondah June 2013 Caledonia Mining Corporation Blanket Mine Division Gwanda, Zimbabwe. Preamble.

starr
Télécharger la présentation

GG - Interim Technical Review Report

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GG - Interim Technical Review Report W. Mugomo, G.S Chagondah June 2013 Caledonia Mining Corporation Blanket Mine Division Gwanda, Zimbabwe

  2. Preamble • Within Blanket Mine’s minerals claim portfolio are several satellite gold claims within the Gwanda Greenstone Belt that have been explored and developed to different stages . These blocks of claims are all within 50km radius of Blanket Mine. • GG and Mascot are gold prospects located 12km and 30km respectively from Blanket Mine. Technical information at Blanket Mine and in the public domain has indicated that GG and Mascot have produced 2500oz and 16280oz at a grade of 9.2g/t and 5.8g/t respectively. • At both Prospects gold in-soil sampling and IP exploration techniques were employed prior to extensive surface diamond drilling campaigns on the identified anomalies. A total of 6128.76m were completed at Mascot in 1998 on 26 drilling sites compared to 4704.41 metres drilled on 18 holes at GG. • At both localities significant intersections were encountered. • On the basis of the encouraging exploration results, past production records and infra-structure availability, GG and Mascot Prospects were selected and planned for production in view of the relatively low capital cost input and short-term duration to production.

  3. 2) Projects objective To upgrade GG resources to the mineable category in order to meet planned production schedules - GG 2013 Q3 and Mascot 2013 Q4.

  4. GG PROSPECT • 3.1) Location & Access • GG Prospect is located within the Gwanda Greenstone Belt approximately 8km west-northwest of Gwanda town, ( Matebeleland South Province -Zimbabwe). • Claims are in gently rolling relief. • Access to the Prospect is via an 9 km tarred road from Blanket Mine to the Kezi turn off from where a road seemingly heading towards Kezi immediately turns right into an all-weather dust road into the old Hotel Farm reaching the Prospect after approximately 3km (figure 1 and appendix 1).

  5. Figure 1. Location map of GG Mine

  6. 3.2) Ground Tenure Status • GG is one of the 21 satellite projects proximal to and held by Blanket Mine. • The ground is held in the form of gold claims which are The claim holding covers an area of 162.9ha and is registered in the Bulawayo Mining District.

  7. Work done previously includes: • Traditional geological mapping • Rock chip geochem – on surface outcrops • Gold in-soil geochem • Geophysical work- Induced Polarisation (IP) • Surface drill testing of selected targets • Resource estimation

  8. Figure 2: GG: Surface Drilling Plan and cross-section lines

  9. Figure 3. X section through holes GGD- 5, 9 &10 (looking 060)

  10. Figure 4. X section along holes GGD- 8, 1B &13 (looking 060)

  11. Figure 5. X section along holes GG- 2,3 6 & 11 (looking 060)

  12. Figure 6. X section through holes GGD 12,7 & 7b (looking 060)

  13. 4) Current Work • 4.1) Shaft and Underground Development • Shaft sinking commenced in July 2012 & is still in progress with a twofold objective: • Provision of exploration drilling platforms to locate & confirm the previous findings on the nature of mineralisation, the gold tenor and distribution of values. • Facilitate the blocking out of mineable Ore Reserves. • Exploratory drilling platforms have been established on 60mL. • Further drill platforms are also pencilled on 120mL.

  14. 60mL diamond drilling objective • The 60mL diamond drilling program was designed to: • Define a preliminary GG Prospect geology model so that useful information could be drawn and used to explore and develop subsequent levels. • Facilitate the blocking out of ore reserves for stoping to meet the 50t daily production call starting from June 2013. • The main target ore zones at GG prospect include: • North Main (underneath mined out pit) • South Main. • 60mL diamond drilling plan • Drill hole planning at 60mL targeted a coincident chargeability IP and Au in-soil geochemical anomaly (fig 6). • The chargeability IP and Au in - soil geochem anomalous zone (GG6, GG7 and GG8) trends north east, refer to appendix 2 and 3.

  15. Figure 7. GG coincident high IP chargeability & geochem Au anomaly

  16. Drilling at 60mL commenced in December 2012. • It comprises of strike perpendicular and fanned horizontal drill holes. • To date a total of 933.31metres has been completed over 11 holes as planned. • All horizontal holes were survey marked on each cubby prior to drilling. • Follow-up down holes at 20 degrees negative inclination are planned for selected sections with encouraging intercepts.

  17. 6) Findings Drilling Outcome Outlined below is a summary of the drilling outcome.

  18. Figure 8. 60mL drillhole & assay plan

  19. Figure 9.GG Inferred Positions of the mineralised zones

  20. Table 2: 60mL Drilling-Summary of Drill holes and Intersections

  21. Figure 10. 120mL development and assay plan from channel sampling.

  22. 6.3) Structure • Gold mineralization at GG prospect like in the entire Gwanda Greenstone Belt is restricted to selected shear zones and/or fault zones within a largely meta-basalt country rock (fig. 11). • The shear zones hosting mineralization at GG prospect are sub-parallel to the east-west regional foliation. • Two fault trends have been identified to be displacing and truncating mineralization (figure). • Both fault trends appear to be intruded by post mineralization mafic dykes.

  23. Figure 11. GG Geology Map

  24. GG Shaft ore body……A bonanza!!! • Underground development on 60mL, 90mL and 120mL has exposed a bonanza Shaft ore body or is it the South Parallel ore body???? • Anyway it has been established that the ore body is terminated on the west by a north-east trending and easterly dipping mafic dyke, refer to figure 12.

  25. Figure 12.GG Shaft ore body longitudinal section and associated development

  26. 6.4) Alteration and mineralization • Chloritization, silicification and carbonation appear to be the dominant alteration types associated with shear zones and mineralization. • The gold mineralization is confined to a predominantly sheared and bleached grey-khakish phyllitic unit (magnesium basalts?) and chlorite schists with the foliation following the regional shear, refer to figure 11 above. • Mineralization is hydrothermal in origin and is associated with smokey grey to blackish quartz-carbonate veins which are also foliation parallel in places. • The major sulphide mineral is acicular arsenopyrite with pyrite and pyrrhotite being subsidiary. • In places, mafic dykes are mineralized with an average gold tenor of 1.5 - 2.5g/t

  27. 6.5) Geology Footprint • The drilling program on 60mL is largely successful as it is intercepting significant intersections. • To date, the campaign has confirmed presence of a broad alteration and mineralized zone as earlier outlined by a coincident high chargeability IP and Au in-soil geochemical anomaly. • On 60mL, correlation of drill intersections in the broadly altered and mineralized shear zones has been difficult. • The ore zones appear to be of limited strike. This development could be resulting from a combination of complex structural deformations/alterations associated with mafic dyke intrusions and faulting or the zone could simply be a broad sub-surface alteration zone that is not persistent with depth. • A drilling platform on 120mL will be designed to try and pick common trends from the 60mL unconformities thereby resolving the non-correlations in the broad anomalous zone and improve on the overall understanding of GG Prospect ore zones.

  28. 7) Conclusions • The 2007 surface drilling highlighted the existence of two consistent major reefs: North Main and South Main. • The reefs extend in depths to beyond 150m vertical distance from surface returning significant gold values with little variations being recorded with depth. • Resource polygons from the year 2007 surface drilling campaign indicate a resource of 524 320 tonnes at 3.41g/t over an average true width of 2,93m for North Main and 501 400 tonnes at 4.02 g/t over an average true width of 2.55m for South Main. • This resource if successfully upgraded to reserves, represents 34 months of production at 30 000 tonnes per month. This resource is exclusive of the recently discovered bonanza shaft ore body which is still the subject of the current evaluation. • 60mL drilling outcome collaborated the findings of the 2007 drilling campaign to a limited extent. • On-reef development at 60mL, 90mL and 120mL have confirmed the presence of the Shaft ore body. This discovery of the shaft ore body is indicative of the growing potential of the GG Prospect. • Underground development and diamond drilling from surface to 120mL have successfully confirmed that IP chargeability and Au in-soil geochemical surveys (GG6, GG7 and GG8) are effective techniques in identifying zones of sulphide mineralization at GG prospect.

  29. 8) Recommendations 8.1 There is merit in extending the current planned shaft depth to beyond 120mL. 8.1.1 GG has a significant resource estimate of 450 000 tonnes at a tenor of 3.5g/t below the 120mL. Table 1 and Figures 3, 4, 5 and 6 show indications of the mineralisation on the vertical extensions beyond the 120mL planned depth. 8.1.2 In view of the need for a shaft safety margin (15m radius), a significant amount of the shaft ore body will remain unmined in the event that the shaft is not deepened beyond the planned 120mL.The shaft ore body footwall contact in the west is defined by a steep easterly (±85˚) dipping mafic dyke beyond which there is no mineralisation. Although the shaft ore body appears more developed to the east of the shaft from about 100mL, there is still need to confirm the presence, morphology and attitude of the ore body at 120mL before a decision to deepen the shaft is made. This cautionary step is particularly important if one considers the uncertainty and risk that the presence of the dyke poses. 8.1.3 The shaft when deepened will provide drilling platforms to confirm the 60mL findings and similarly track the footprints of the established reefs at depth. The difficulty in correlation of 60mL short strike length drill intersections associated with broad altered and mineralized shear zones with coincident chargeability IP and Au in-soil anomaly would be resolved by collating information gathered from surface drill holes and 60mL and trending this to 120mL after drilling along carefully selected section lines. This will in turn block out mineable ore reserves between 60mL and 120mL.

  30. 8.2) The North Main and South Main ore bodies have been defined to a good extent by surface drilling. It is recommended that cross cuts to the two ore shoots be mined off the current shaft at 120 metre level. These positions of the cross cuts will be marked shortly by the Exploration Department and will also facilitate the positioning of further drill holes to confirm the positions of the reefs. 8.3) Other targets developed from gold in-soil sampling and IP exploration techniques e.g. GG4, GG5 and GG10 which have similar signatures to GG6, GG7 and GG8 and are proximal to the current shaft should be pursued by underground developments. 8.4) In line with general laboratory practice it is recommended that the accuracy and precision of the laboratory be periodically checked.

  31. References Mikhailov, A. (1998), Geological map of GG Prospect, Boss Resources (Pvt) Ltd, (Unpublished internal company report). Mpofu, P., (2006). Induced Polarization Surveys, Blanket Mine (1983) Pvt Limited Gwanda, Zimbabwe, Geophysics GPR (Zimbabwe) (Pvt) Ltd, (Unpublished internal company report). Nyagumbo, J., Thomson, B., (2005). Request for Authority to Fund Expenditure (AFE) for GG claims - Drilling, AFE No. BN-05-54, (Unpublished internal company report). Tyndale-Biscoe, R., (1940). The geology of the country around Gwanda, Southern Rhodesia Geological Survey, Bulletin No. 36, 204p. Zizhou, A. P., Sakala, A. E. (2007), GG drill hole sections.

  32. Appendix 1. Gwanda Greenstone Belt showing location of Blanket Mine claims

  33. Appendix 2. Gradient array IP survey chargeability map

  34. Appendix 3. GG area soil Au geochem

More Related