cbh resources limited the geology of the endeavor mine - an update - peter nicholson, don smith and...

CBH Resources Limited

The Geology of the Endeavor Mine

- an update -

Peter Nicholson, Don Smith and Vanadis Mares

History


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


At June 2005 Resources: 17.7 MT

4.9% Pb, 8.7% Zn, 69 g/t AgReserves: 11MT

4.9% Pb, 7.9% Zn, 66 g/t AgMine Production: ~24MT

At present, production is ramping up to a rate of 1.4 MT per annum

Production

Cobar Basin – Mineralisation


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


Rhyolite100m

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


Structural Corridor

Cobar TMICorridor is defined by

mineralisation, coincides with

magnetic, gravity and geological fabric


Basement Protrusions

Cobar Basin Gravity

Basement protrusions indicated by gravity low anomalies and

doming of sediments

Cobar Basin

Summary


Protrusion of basement into Cobar Basin

Endeavor

CSA

The Peak

Hera

CBH Tenure

Triako Tenure

145

3131

147

3232

0 25 50structural corridor


Endeavor Mine

7000N Cross Section

surface

sulphide stringers

upper shale

lower shale

high-grade massive sulphide

9600RL

200m

limestone

49

00

E

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


Endeavor Mine7000N 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


9600RL

200m

limestone

49

00

E


Endeavor Mine

7075N Cross Section

Sandstone/shale

Lower shale

PO/PY/SIPY

VEIN 6-10%PbZn

MINA 1-6%PbZn

20m


sulphide stringers


Main Lode

200m

N

7000N

6500N4900

EEndeavor Orebody

9400RL plan

• Mineralisation in anticline axial plane

• Low-grade halo of sulphide stringers

open along strike• N and NNE faults

truncate


Endeavor Mine Schematic

Long Section 7000N

Partially defined concordant mineralisation

9000RL

200m

limestone

Main Lode

upper shale

lower shale

9600RL


Metal Zonation (long section slices)

Ag

100 m

1.0-2.0

>9.0%

30-40

>400g/t

Cu

0.04-0.1

>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

Zn Cu100m


Metal Zonation - Cross Section 7080N

Cu

0.04-0.1

>0.6%

Ag

30-40

>400gt

Zn

1-2

>9%

100 m

Endeavor Mine Mineralisation Textures


Axial Plane MineralisationMassive textured and bandedBanding sub parallel to contactsOften rapid transition from altered sedimentsConcordant MineralisationQuartz-siderite veins along strikeLow grade material composed of discordant

veins and concordant replacements


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



20 mm



sphalerite

galena

10 mm

sphalerite

Endeavor Mine – Exploration


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 defined100m

Endeavor Mine Exploration


Drilling planned to

test mineralisation

adjacent to the

limestone contactlimestone

lower

shale

Planned drillholes

50m

Endeavor Geology Update - Summary


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

cbh resources limited the geology of the endeavor mine - an update - peter nicholson, don smith and...

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