Walhalla

 

Gold Project



Orion Gold NL is an Australian gold exploration company focused on delivering value to shareholders through the successful exploration of the Company’s highly prospective tenement holdings located in the Walhalla goldfields of Victoria, shown in figure 1.


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FIGURE 1: Project Locality Plan 

 
Based on a review of geological data and historical mining records relating to the Walhalla Gold Project tenement area, Orion Gold has adopted a two part strategic plan being:
1.       Complete a technical review of all data relating to the highly prospective Walhalla Gold Project and determine priority
          targets to be drill tested.
2.       Progress a pre-feasibility study on the current gold resources within the Walhalla Gold Project.
Based upon the data from 130 years of exploration and mining activities including the previous work by Orion Gold, the Company has identified a number of highly prospective targets where additional resources may occur.  It is on these areas that the initial drill program, which commenced in November 2009 is focusing with the aim of establishing a near surface resource base leading to a mining operation in the medium term.

The numerous historic workings within the Walhalla Gold Project area are generally aligned in a linear, roughly north-south trending fashion.  These ‘lines of mineralisation’ have been exploited and or explored for well over 100 years and provide the Company with a ready window where new resources may be discovered.

The Company considers both the Cohen's and the Ross Creek Lines of mineralisation (see figure 2) to be highly prospective given the significant historic production (approximately 1.5 million ounces) and recovered grade (>1 ounce of gold per tonne) from the Cohen's Line.  In addition, there are numerous untested drill targets along the West 1 and West 2 Lines which are located in close proximity to the workings along the Cohen’s Line.  The Company’s existing resources at Tubal Cain and Eureka are located along the Ross Creek Line (RCL) which trends parallel to, but approximately two kilometres east of, the Cohen’s Line. Given the numerous historic workings along the RCL, some with significant production, this line of mineralisation is also considered highly prospective.



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FIGURE 2: Walhalla Gold Project Tenement Holdings
 


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FIGURE 3: Outline of established lines of mineralisation in the immediate Walhalla area.  Approximate area of workings on Cohen’s reef is shown in red.  Numerous other mine names and locations are not included. 

 
The Company has decided to adopt a ‘staged exploration approach’ to assist the systematic examination of various identified drill targets.  The Company is initially focused on shallower targets followed by progressively deeper, and more costly targets, with a focus on resource delineation and mining exploitation at progressively deeper levels within the Cohen’s area.  This decision has been made given the priority of initially delineating resources near surface which can be developed at a lower cost than deeper resources. Should this staged approach prove successful and near surface resources are developed, the Company will be better placed to drill test numerous deeper targets which could result in additional resources being delineated and developed at depth (See figure 4).

Exploration Programs

Although the Company considers its entire tenement package in the Walhalla region (730km2) to be prospective due to the numerous workings and the historic production in the area, the Company has decided to focus its initial exploration program on an area within a ten kilometre radius of the historic mines located on the Cohen’s Line which is referred to as the ‘proximal area’.
 
Within the ‘proximal area’ of focus there are clearly two stand-out areas, as set out below, based upon the first-pass prospectivity and metallogeny review. 

1.    The Cohen’s area, being essentially the area covering the West 1, West 2 and Cohen’s mineralised trends in the
       country west of the Walhalla township.

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FIGURE 4:  Cohen’s-Empress long section illustrating some potential exploration targets.  This figure illustrates the large number of possible exploration targets.  Areas shown in pink are regarded as potential blocks of remnant ore which require further drill testing to confirm.  The blue panels are zones considered to be prospective with the red circles denoting areas of specific interest.  The large red arrows indicate interpreted mineralised shoots.  The black dashed line is an interpreted fault within the plane of the diagram. 

The Cohen’s reef system (mined late 1800s to early 1900s) is Victoria’s highest single producing reef system, with production of ~1.5 Million ounces at a head grade approaching 40 g/t Au.  After approximately 40 years of mining many basic features of the system remain unknown or poorly defined, providing much scope for successful exploration.  As the spatial limits and disposition of the Cohen’s Reef system and associated mineralisation remains open in all directions, much prospective ground remains untested.  The high probability of remnant resources, the likelihood of discovery of extensions to known lodes and wholly new lodes, and unexploited ‘stockwork’ style mineralisation means that the chances of a significant resource being delineated based upon the Cohen’s reef system is regarded as very good.

Given the historical production at Cohen’s, the other nearby lines of mineralisation (West 1 and West 2) have been subject to minimal exploration.  Importantly, previous mining has largely concentrated upon the Cohen’s Line, so the potential for near surface ore being delineated along the West 1 and 2 trends is considered high. This potential will be tested in the initial drill program which commenced in the December 2009 quarter.

The gold endowment of the West 1 and West 2 structures has the potential to be similar to that of the main Cohen’s structure, especially as cross-sections by the likes of Herman (1901) and Baragwanath (1918) interpret West 1 and West 2 as splays from the major reverse fault that constitutes Cohen’s reef.  Based on this interpretation, West 1, West 2 and Cohen’s appear to be part of the same mineralised system.  (See figure 5)

Geologically, the ore in the Cohen’s reef comprises continuous, roughly planar, laminated, auriferous quartz veining (colloquially referred to as a ‘reef)’.  This reef is situated within a reverse fault in a high-strain zone 10-50 metres wide hosted within sedimentary rocks.  Intermediate dykes are intimately associated with the reef and locally these may also bear auriferous veining.  Continuous reefs like Cohen’s are readily extracted by modern mining methods, and locating and defining continuous, high-grade primary reef mineralisation of this style is considered to be the main focus of exploration in the Cohen’s area.

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Figure 5: Cohen’s Deeps Cross Section (modified after Herman, 1901)

2.    The Ross Creek Line (RCL) located in the proximal area of interest includes the string of prospects (north to south)
       Shamrock – Bonanza – Centennial - North Coronation -Tubal Cain - Strusses – Eureka  - Walhalla Proprietary.

Geologically, the mineralisation established to date along the RCL is different in style to that of the Cohen’s area, largely being examples of the region’s classic ‘ladder reefs’ formed within dyke bulges, with lesser mineralisation hosted as laminated, breccia or ‘stockwork’ reefs in strained sediments adjacent to the dyke contacts.  The dyke-hosted nature has a number of ramifications on metallogeny and endowment: 

      • The individual ‘reefs’ or ‘floors’ are stacked vertically, and the spacing between them varies from 5 to 50 metres.

      • The quartz reefs are constrained by the host dyke, and the areal extent of a given reef is thus largely controlled by the size of the dyke bulge and the dyke that hosts it.  Individual reefs may traverse across the entire dyke contact into the surrounding wall rock.  There does not appear to be a clear relationship between overall dyke volume and gold endowment – the biggest dyke (Morning Star) is the biggest producer (of this style of mineralisation), however, the second biggest producer (the A1) is situated in one of the smaller dyke bulges.

      • Completion of the pre-feasibility study on the Tubal Cain and Eureka deposits will assist in determining the economics of such deposits and what future work should be undertaken by the Company.  

Given the potential for larger scale deposits being discovered along the Cohen’s Line, West 1 and West 2 Lines, the Company has elected to prioritise drill testing of targets in the Cohen’s area aimed at establishing a near surface resource base which will support the development of a mining operation in the short to medium term.

Initial Drill Program

The Company has recently commenced a 6,500 metre (16 hole) diamond core drilling program at the Company’s Walhalla Gold Project. 

The aim of the program is to test the continuity of mineralisation along the Cohen’s Line and parallel structures leading to the development of high grade near surface mineral resources based upon continuous, planar, laminated reef mineralisation similar in style to the Cohen’s Reef (see figure 3). 

If the initial drilling program is successful, later work may comprise an infill program to develop a JORC compliant resource and to further test encouraging drill results or other related targets.
 

Competent Person

Exploration information contained in the information above has been compiled and assessed under the supervision of Dr James Anderson, Orion Gold NL’s General Manager – Exploration, from historical records and field investigation. Dr Anderson is a member of the AusIMM (CP) and has extensive experience in the identification of gold mineralisation of this style. Dr Anderson consents to the public release of the information in the context contained within this release.
 

JORC Statement

The information above may include forward-looking statements. These forward-looking statements are based on management’s expectations and beliefs concerning future events. Forward-looking statements are necessarily subject to risks, uncertainties and other factors, many of which are outside the control of Orion that could cause actual results to differ materially from such statements. Orion makes no undertaking to subsequently update or revise the forward-looking statements made in this release to reflect events or circumstances after the date of this information.
 
 
Site updated 21st December 2009