Summary:
Davyhurst Operation consist of several Deposits: Missouri, Sand King, Riverina Area, British Lion, Waihi, Callion, Golden Eagle, Iguana, Forehand and Silver Tongue.
Missouri & Sand King
There are two alteration events at Missouri and Sand King, including an initial pervasive greenschist alteration event related to metamorphism, and a later hydrothermal alteration event related to shearing. The shears have acted as conduits to hydrothermal fluids causing localised alteration and gold mineralisation. Alteration associated with mineralisation is commonly an assemblage of minerals namely biotite-carbonate-feldsparpyrrhotite-pyrite. The mineralisation is within distinctive alteration haloes around quartz vein arrays. Thickness of the alteration zones varies from centimetres to several metres. A sharp transition is evident between altered, mineralised basalt and unaltered, unmineralised basalt.
Dimensions Misssouri
The Misssouri deposit extends for 550m in both a north-south and east-west direction. The deposit extends for 280m below the surface RL of 420m AHD.
Dimensions Sand King
The Sand King deposit extends for over 800m in NE-SW direction and approximately 300m in a SE-NW direction. The Resource extends for 280m below the surface RL of 420m AHD.
Riverina South and British Lion
Mineralised structures are roughly N-S striking, sub-vertical to steeply east dipping. The main lodes at Riverina extend south into Riverina South and British Lion. Minor sinistral offsets appear to offset the lodes though these have not been modelled given the wide drill spacing.
The geology of the Riverina South area consists of an interlayered sequence of meta-basalts, meta-sediments and ultramafics, rarely cross-cut by narrow pegmatite dykes. The local stratigraphy strikes roughly N-S with primarily steep east to sub-vertical dips. The area has been affected by upper greenschist to lower amphibolite grade metamorphism with many minerals exhibiting strong preferred orientations. All rock units exhibit strain via zones of foliation, with strongly sheared zones more common in ultramafic lithologies. Contemporaneous strike faults and late stage thrust faults have dislocated the stratigraphy and hence, mineralisation.
Dimensions
The Riverina South deposit is defined over 1000m strike length and to depths of 130m below surface. A southern portion is centred around the British Lion prospect and has a strike length of 560m. The northern portion of Riverina South is the southern extension of Riverina deposit, particularly Main lodes. This northern portion of Riverina South has a strike length of approximately 200m. Between this area and British Lion is a less well drilled portion of the deposit with only minor lodes defined thus far.
Riverina
In mineralised zones, quartz veins are surrounded by visible wall-rock alteration haloes typically <2 wide, which are relatively small. Depending on vein density and silicification intensity, the alteration haloes may overlap or, where the veins are more widely spaced, the haloes may be separated by unaltered country rock. The common mineralisation assemblage is silica-sericite-pyrite-arsenopyrite. Dominant sulphide minerals include pyrrhotite and pyrite, with pyrrhotite often replacing pyrite. Arsenopyrite has been observed in localised areas in the highest gold grade intervals.
Riverina is characterised by three distinct mineralised shear systems, from west to east Main, Murchision and Reggie.
Dimensions
The main lodes at Riverina are geologically continuous over 1km in a N-S direction and defined to a depth of 320m below surface. A single deep diamond hole has confirmed main lode mineralisation at a depth of 470m below surface.
The central Murchison and East (Reggie) lodes extend for a similar strike length but are not as depth extensive. The deposit extends for 320m in an E-W direction.
Iguana
Regional alteration of upper greenschist to mid amphibolite is evident at Iguana. Local hydrothermal alteration, associated with the mineralising event is variable but intense biotite-hornblende-silica alteration is proximal to the ore zones. Gold is present in quartz veins and the associated biotite alteration of the amphibole schist. The veins were sited within a narrow zone where the amphibolites have been boudinaged. Arsenopyrite is the main ore mineral, and gold is in these grains (SEM imaging). Gold has also been imaged in one of several potassium feldspar veinlets that brecciates the main shear fabric. The veinlets are not sheared or rotated, indicating that mineralisation took place after the foliation developed.
Dimensions
The Iguana deposit extends for over 750m in NW-SE direction and approximately 150m across strike. The Resource extends for 200m below the surface RL of 520m AHD.
Callion
The geology of the system and the gold distribution is modelled as a set of sub-parallel, NNW-SSE striking, steeply dipping narrow lodes.
Dimensions
The reported mineralised corridor extends 1200m NNW-SSE, up to 40m east/west (in multiple narrow lodes) and up to 350m vertically. Mineralised structures are present at surface for some lodes and have been mined by both open pit and underground methods.
Waihi
Mineralised structures at Waihi strike from 320o to 345o and are steeply west dipping. Mineralised lodes at Homeward Bound strike 325o and are steep east dipping. The main Waihi lodes are interpreted to be the west limbs of a tightly folded antiform. Homeward Bound lodes are the east limbs of the same antiform. Late stage E-W structures have been mapped and may offset the mineralised lodes slightly. These structures have also been exploited by thin pegmatite dykes.
Dimensions
The main lodes at Waihi are geologically continuous over 0.9 km in a N-S direction and defined to a depth of 200m below surface. The Homeward Bound Lodes are continuous over 0.3 km in a NW-SE direction and defined from surface to a depth of 230 m below surface.
Forehand
Mineralised structures are roughly N-S striking, sub-vertical to steeply east dipping. The lodes appear to terminate at the postulated location of a NE striking fault, observed in the SAM imagery. There is a lack of drilling north of this and lodes may continue north, possibly with a sinistral offset across the NE fault.
Dimensions
The lodes at Forehand are defined over 350m in a N-S direction and defined to a depth of 180m below surface. The deposit extends for >100m in an E-W direction.
Silver Tongue
Mineralised structures are roughly N-S striking, sub-vertical to steeply east dipping. A single quartz lode hosts most of the mineralisation with minor lodes in the hangingwall and footwall. A late NE fault appears to sinistrally offset the mineralisation. Minor sinistral offsets of up to 5m are noted in underground workings at Riverina Mine approx. 1km to the west.
Dimensions
The lodes at Silver Tongue are defined over 250m in a N-S direction and defined to a depth of 180m below surface. The deposit extends for 90m in an E-W direction.