Myrtle Deposit Geology
The Myrtle prospect was located in 1966 by Carpentaria Exploration Company (“CEC”). Hole MY1 intersected 35.7m @ 0.6% Zn, 0.09% Pb and 6 g/t Ag, and the prospective Barney Creek Formation was recorded to be over 100 metres thick. Further work then included geological mapping, rock chip sampling, gravity geophysics and further drilling (holes MY2 – MY5), resulting in the delineation of a number of subsidiary sub-basins within the Myrtle area.
No further work occurred until 2004 - 2005, after North Mining Limited acquired the ground. Drilling of holes MY6 and MY7 by former JV partner Anglo-American Plc intersected low-grade zinc mineralisation, similar to that drilled previously in hole MY 1.
It wasn't until hole MY8 was drilled, and intersected a wide interval of moderate grade mineralisation, that it was realised that holes MY6 and 7 were not deep enough, and so they were deepened, subsequently intersecting high grade mineralisation towards the base of the HYC Pyritic Shale Member. Holes MY10 and MY12 have also intersected mineralisation, and shown that the prospective mineralised horizon is widespread.
Anglo-American reported in 2005 that they had defined the limits of a major hydrothermal system of at least 3.3km x 1.6km (> 5.3km2), recommending detailed infill drilling, in particular to the north and south of holes MY6 and MY10 to define the highest grade central part of the system.
The region extending from Mt Isa in the southeast through McArthur River and for 500km to the northwest is probably one of the most well endowed zinc-lead regions on Earth. Myrtle now takes a place amongst the top 10 SEDEX zinc deposits in Australia (see table below). it is probably the most significant zinc deposit discovery for some 20 years or so (since the discovery of Century in 1990).
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Mt Isa - McArthur River Region
Table 1: Giant Sedex Zinc Deposits in Australia
|
Deposit
|
Mt Ore *
|
Mt
Zn + Pb
|
|
Broken Hill
McArthur River
|
280
227
|
51.8
30.4
|
|
Mount Isa
|
150
|
19.5
|
|
Hilton
|
120
|
20.3
|
|
George Fisher
|
107
|
17.7
|
|
Century
|
95
|
14.1
|
|
Dugald River
|
48
|
6.8
|
|
Cannington
|
44
|
7.0
|
|
Myrtle
|
44
|
2.2
|
|
Lady Loretta
|
14
|
3.1
|
|
|
|
|
Reward EL Geology and Prospect Locations
At Myrtle, and at McArthur River, base-metal (zinc and lead) mineralisation occurs within the HYC Pyritic Shale and the mineral bearing sequence occurs over an extensive area.
Drill Cross Section A - A' at 8167000N
Drilling to date, which is wide spaced but over an extensive area, has shown that the Myrtle deposit has the potential to be very large. The recent joint venture with Teck Resources of Canada will now enable the deposit to be drilled out to determine its ultimate size.
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Myrtle Prospect Drill Plan, showing interpreted geology, resource outline and soil anomalies
Myrtle Prospect Soil Sampling Plan