CBH Resources Limited The Geology of the Endeavor Mine - an update - Peter Nicholson, Don Smith and Vanadis Mares
History CBH Resources Limited 1973: Discovered by EZ - bullseye mag anomaly with coincident Pb/As in soil 1983: Production begins from Elura Mine 1998: Intersection of mineralisation close to limestone at ~1200m depth 2003: Purchased by CBH Resources Ltd. and renamed Endeavor Mine
CBH Resources Limited At June 2005 Resources: 17.7 MT 4.9% Pb, 8.7% Zn, 69 g/t Ag Reserves: 11MT 4.9% Pb, 7.9% Zn, 66 g/t Ag Mine Production: ~24MT At present, production is ramping up to a rate of 1.4 MT per annum Production
Cobar Basin – Mineralisation CBH Resources Limited Generally polymetallic discordant veins hosted by siliciclastic turbidites Often in anticlines adjacent to competent lithologies Concentration of shows within structural corridor on E margin Transfer structures often present Largest deposits adjacent to basement protrusions into Basin
CBH Resources Limited Rhyolite 100m 500m Rhyolite 25640E 200m Limestone Endeavor 9600RL 4900E Cobar Basin Mineralisation Generally polymetallic discordant veins hosted by siliciclastic turbidites Often located in anticlines adjacent to competent lithologies, e.g. limestone at Endeavor, rhyolite at The Peak, basic intrusive at Louth The Peak after Lawrie and Hinman 1998
CBH Resources Limited Structural Corridor Cobar TMI Corridor is defined by mineralisation, coincides with magnetic, gravity and geological fabric
CBH Resources Limited Basement Protrusions Cobar Basin Gravity Basement protrusions indicated by gravity low anomalies and doming of sediments
Cobar Basin Summary CBH Resources Limited Protrusion of basement into Cobar Basin Endeavor CSA The Peak Hera CBH Tenure Triako Tenure structural corridor
CBH Resources Limited Endeavor Mine 7000N Cross Section surface sulphide stringers upper shale lower shale high-grade massive sulphide 9600RL 200m limestone 4900E 1200m siliclastic turbidites overlie limestone breccia Tuffs and two shale rich units markers South plunging anticline Early concordant and steep NNW faults Later steep N and NNE faults cut mineralisation
CBH Resources Limited Endeavor Mine 7000N Cross Section Above 900m depth within anticline axis Truncates against shales Offset by N and NNE faults Sub vertical pipes within sheet Below 900m mineralisation bifurcates into two concordant zones that dip down anticlinal limbs Alteration Siderite clots and replacement forms halo several tens of metres around sulphide stringers. Preferentially replaces siltstone/sandstone Silicification and chloritisation intense in places surface sulphide stringers upper shale lower shale high-grade massive sulphide 9600RL 200m limestone 4900E
CBH Resources Limited Endeavor Mine 7075N Cross Section Sandstone/shale Lower shale PO/PY/SIPY VEIN 6-10%PbZn MINA 1-6%PbZn 20m
CBH Resources Limited sulphide stringers high-grade massive sulphide Main Lode 200m N 7000N 6500N 4900E Endeavor Orebody 9400RL plan Mineralisation in anticline axial plane Low-grade halo of sulphide stringers open along strike N and NNE faults truncate
CBH Resources Limited Endeavor Mine Schematic Long Section 7000N Partially defined concordant mineralisation 9000RL 200m limestone Main Lode upper shale lower shale 9600RL
CBH Resources Limited Metal Zonation (long section slices) Ag 100 m >9.0% >400g/t Cu >0.6% Zinc Highest grade (8-10%) in centre of pipes. Pb similar Silver Concentrated on upper/outer margins. Up to 1000ppm Copper Up to 4% in small pods at base of pipes ZnCu 100m
CBH Resources Limited Metal Zonation - Cross Section 7080N Cu >0.6% Ag >400gt Zn 1-2 >9% 100 m
Endeavor Mine Mineralisation Textures CBH Resources Limited Axial Plane Mineralisation Massive textured and banded Banding sub parallel to contacts Often rapid transition from altered sediments Concordant Mineralisation Quartz-siderite veins along strike Low grade material composed of discordant veins and concordant replacements
CBH Resources Limited Face showing near- horizontal bedding in lower shale unit with siltstone layers replaced by pyrite, sphalerite & galena Vein at the centre of the photo sub parallels cleavage & measures ~20cm Mineralisation Textures
CBH Resources Limited Mineralisation Textures 20 mm
CBH Resources Limited Mineralisation Textures sphalerite galena 10 mm sphalerite
Endeavor Mine – Exploration CBH Resources Limited Massive sulphide zones open up dip, down dip & to N of current workings Mineralisation near limestone contact to be tested from W High metal prices have encouraged investigation into mining zones of stringer mineralisation Stringer zone open along strike to N & S, down dip on both limbs. May contain more massive sulphide or lower grade zones
Endeavor Mine Exploration stringers open sulphide open Limestone Massive Sulphide sulphide & stringers open sulphide & stringers open Contact mineralisation partially defined 100m
Endeavor Mine Exploration CBH Resources Limited Drilling planned to test mineralisation adjacent to the limestone contact limestone lower shale Planned drillholes 50m
Endeavor Geology Update - Summary CBH Resources Limited Mineralisation localised in zones of competency contrast on both regional and local scale Shale-rich sequences appear to truncate axial plane mineralisation Concordant mineralisation may be important Better understanding of mineralisation controls and high metal prices has expanded exploration opportunities