Narracoota Project E52/1496
Overview
The Narracoota project is located 80 km north of Meekatharra in Western Australia.
Latin Gold is earning a 50% interest in the project through the expenditure of $500,000 by no later than 31 December 2012. To date (November 2011) Latin has expended approximately $80,000 over the project area.
Historic exploration in and around the Narracoota project area focussed on the potential for shear or VMS hosted gold and copper deposits. In the early 2000's attention switched to copper and nickel exploration within the Bilyuin volcanic complex which lies on the eastern edge of the current tenement configuration. In 2009 attention shifted to the exploration for potential De Grussa repetitions within the underlying Narracoota Volcanics. Exploration drilling in 2010 discovered a gold anomaly under alluvial cover within ultramafic litholgies of the Narracoota Volcanics and in 2011 this anomaly was re-confirmed by drilling. In addition, a regional drilling programme in 2011 intersected thick sequences of ultramafic rocks across a wide area and with some intersections containing elevated nickel values to +0.3%.
The planned exploration programme for 2011 by Latin Gold was severely restricted because of the wet winter conditions. As a result only the first pass air core programme was completed together with extensive office and field based studies including a re-interpretation of the geology and a structural interpretation of the central and northern part of the tenement using geology and magnetics.
The confirmation of the gold anomaly and the elevated nickel results are highly encouraging and an active exploration programme is planned for 2012.
Tenure and Location
The Narracoota project is located around 80 km north of Meekatharra on Mt Padbury Station.
Access is from the sealed Great Northern Highway via a graded road to Ashburton Downs and Peak Hill, then station or exploration tracks of variable quality. Access off the tracks is excellent in dry weather particularly on the floodplains of the Murchison River where there is only sparse vegetation. In wet conditions access can however be severely restricted in the low lying areas.
In areas of thicker scrub in the extreme southern and northern parts of the tenement access restrict vehicle access but foot traverses can be easily carried out.
Water is available from isolated station bores or the Bilyuin waterhole within the main Murchison River channel. Camping facilities are occasionally available at the abandoned Narracoota Homestead.
The Narracoota Project comprises a single tenement, E52/1496. The tenement consists of 35 blocks, equivalent to 111 square kilometres. The tenement is owned 100% by Richmond Mining Limited.
| Tenement | Grant Date | Area |
| E52/1496 | 03.12.02 | 35 blocks (111 km2) |
Regional Geological Setting
The Narracoota project is located in the Proterozoic Bryah Basin, which onlaps the northern edge of the Archaean Yilgarn craton. The Bryah Group consists mainly of metasediments and mafic-ultramafic volcanic rocks emplaced in a back arc rift setting with regional metamorphism occurring during the 2200-1780 Ma Capricorn Orogen, as the Yilgarn and Pilbara cratons converged.
The major units of the Bryah Group in descending chronological age include:
- Horseshoe Formation: BIF, wacke, shale
- Ravelstone Formation: Quartz-lithic wacke
- Narracoota Formation: Mafic-ultramafic volcanic rocks and dykes, tuffs and intercalated sedimentary rocks
- Karalundi Formation: Conglomerate, quartz wacke
The Bryah group has a faulted contact with the older Yerrida Group (to the southeast of the project area) and an unconformable contact with the younger Padbury Group near the northern edge of the project area. Further north the Bryah Group is faulted against the older Peak Hill Schist. It unconformably overlies Archaean granite gneiss to the southwest of the project area.
Project Geology
Transported cover blankets the majority of the tenement with thicker alluvium developed in the palaeo-Murchison River floodplain. This alluvium is clay rich in places and in general terms is at its greatest thickness within the Murchison flood plan (10-15 metres) reducing to a few metres, with local development of laterite gravels, in the extreme north and southern parts of E52/1496.
Thicker sequences of lacustrine clays have been reported by previous explorers but appear to isolated and possible reflect narrow palaeo-tributary channels associated with the Murchison River.
Narracoota Volcanics cover the project area with the predominant rock type mafic and intercalated ultramafics and arenaceous metamorphosed sediments.
In the southern part of the project area a strong laterite duricrust has also been developed in places. This duricrust is iron rich and is generally only 1-2 metres thick.
A historical diamond drill hole intersected extensive proximal vent breccias in the Narracoota Volcanics in the southern half of the tenement area. These breccias are associated with a strong chlorite-calcite-quartz-albite-magnetite alteration system.
Within the project area pink-red albitic alteration, which is assumed to be related to the brecciation, is prominent in several locations with limited outcrop exposure.
Figure 1: Geology of Naracoota Project Area
Mineralisation
Most mineral deposits in the area (regionally) are structurally controlled, of mesothermal origin, and linked with compressional tectonics and metamorphism that have affected the Bryah Group and Peak Hill Schist.
While the role of compressional tectonics and metamorphism in the ore genesis is inferred from empirical evidence, the mechanisms responsible for mineralisation are unclear. The lode deposits are usually hosted in or along contacts of the metasedimentary and/or metavolcanic rocks. The lodes are associated with relatively narrow zones of hydrothermal alteration characterised by pyritisation and alkali metasomatism.
Four known prospects and mines lie very close to the Narracoota tenement boundaries. These include the prospects of Durack Well, Wembley, Mikhaburra and Cashman, with Cashman, Mikhaburra and Wembley producing some ore in the past.
The Durack Well gold deposit, located 12km south of Peak Hill, is hosted in the interfingered contact between the Narracoota Formation and Ravelstone Formation. The primary mineralisation is contained within stockworks of thin vertical quartz veins and hydrothermal alteration is pervasive consisting of quartz-chlorite-biotite-ankerite.
Pyrite has been recorded as occurring both as veins and disseminations and selvages of silica-pyrite-carbonate surround the mineralised zones. The supergene mineralisation is controlled by interpreted sub-horizontal redox fronts within the regolith. Grades of up to 5m @ 12 g/t Au have been reported, up to 45m either side of the primary zone.
The Wembley gold deposit, located 18km southwest of Peak Hill, has a reported average production grade of 17.5 g/t Au, but to date only 1,800 tonnes of ore are recorded as being extracted. The mineralisation is hosted in altered metabasite rocks within a major shear zone trending 120°. The mineralised zone strikes 255° with some quartz veining at 240°.
The Mikhaburra gold deposit, also known as Holdens Find, lies in volcanic rocks of the Narracoota Formation. The total recorded production of the Mikhaburra mine was about 226 kilograms of gold. The mineralisation is associated with a system of auriferous quartz veins emplaced along a shear zone trending ~130-150° and dipping 68° to the south. The volcanic rocks are mainly chlorite schists.
Cashman's includes a number of small mineral occurrences and deposits, which contain copper and copper-gold. The old Cashman copper mine is approximately 250m from the gold workings. This mine produced 7 tonnes of copper ore, grading 16.5% Cu. The copper mineralisation consists of a cupriferous limonite vein (~1m wide) striking 222°. Gold mineralisation is hosted in a quartz vein 10cm thick striking 295° with supergene enrichment present in a horizon about 30m wide and dipping 20° to the north.
In addition to these documented deposits, the most significant discovery made over recent years in the vicinity of the Narracoota project is Sandfire Resources' DeGrussa Cu-Au deposit at the Doolgunna project. Sandfire report the mineralisation style, chemistry and regional setting are consistent with a volcanogenic massive sulphide (VMS) base metal deposit. They also state the prospective stratigraphy which hosts the deposits is the volcano-sedimentary sequence at the top of the Narracoota Volcanics.
Previous Exploration
Numerous previous owners have explored with mixed success for different types and styles of mineralisation on and in the region of the Narracoota project. Historic exploration within the Narracoota project area has been hampered because of significant cover, both regolith and transported.
Historic work to date on tenement EL52/1496 includes:
- Aeromagnetic interpretation;
- Geological mapping;
- Soil geochemistry programmes;
- Petrological studies; and
- RAB, aircore and diamond drilling.
It is apparent that a large amount of past exploration at Narracoota has been ineffective as most of the project area is covered by alluvium with minor colluviums. As a result, surface geochemical testing is largely invalidated.
Recent Exploration
Work completed by the current tenement holder, Richmond Mining Limited includes a detailed review of the historical exploration and results achieved by previous explorers such as Helix Resources and Geopeko over the Bilyuin magnetic anomaly as well as field based activities that included reconnaissance field checking, rock chip sampling and aircore drilling. In 2007, Richmond concluded that a large amount of the past exploration at Narracoota may not have been effective as the project area is predominantly covered by alluvium with minor colluvium, which may have masked any valid test of the mineralisation potential.
In 2008 Richmond Mining focused exploration on a fault zone located adjacent to and cutting an interpreted buried volcanic breccia complex with possible intercalated ultramafic rocks, which is covered by alluvial sediments of the Murchison River. The large magnetic feature (approximately 5km long and averages 1 km in width) associated with this complex is known as the Bilyuin anomaly.
Utilising existing magnetics, a structural re-interpretation was completed over the project with a particular focus on the southeastern corner of the tenement over the Bilyuin anomaly.
Field studies were undertaken to investigate the potential of outcrops within the broader project area, locate historic drill holes over the Bilyuin magnetic anomaly with reported elevated gold and nickel values, and locate and examine historic drill sample piles with reported carbonaceous and/or lignite-rich clays for potential roll front style uranium mineralisation.
Richmond Mining personnel carried out a number of traverses were completed over the tenement area. Outcrop is very poor and for the most part the surface cover appears to be an iron rich alluvial with, in places, plentiful angular colluvium. The only outcrop of any note are some quartzite ridges that flank the Murchison river in the northern part of the area and low hills of mafics just outside the southern boundary of the lease area.
The fieldwork confirmed the widespread nature of the transported cover throughout the project area, particularly covering the Bilyuin anomaly, and that much of the historical soil geochemical surveys were invalid.
Richmond Mining subsequently completed a 20 hole aircore drill programme to test the geochemical response of the weathered rocks beneath the extensive cover across a number of structural features associated with the breccia and fault zone within the Bilyuin magnetic anomaly. No significant Au, Ni or Cu results were returned.
Logging of aircore holes however confirmed Richmond's belief that much of the historical drilling on the tenement was probably ineffective, as a result of misinterpretation in the historic logs of alluvial clays as weathered bedrock.
The aircore drilling also tested an area of the old Murchison River flood plain where carbonaceous clays had been reported in historical drill logs. Richmond's drilling confirmed the reported carbonaceous clays were actually manganese rich layers in transported alluvium, thus downgrading the potential for roll front uranium mineralisation.
Exploration during the 2009 project year consisted of the finalisation of aircore logs from the late 2008 drilling programme with re-logging of chip trays, analysis of assay results received from the Bilyuin anomaly aircore drilling and regional rock chip sampling, a detailed project review of all work undertaken and results achieved for gold by all explorers on E52/1496 to date and a review to assess the potential for the tenement to host DeGrussa-style VMS mineralisation.
Up to that point Richmond Mining had been primarily exploring E52/1496 for potential shallow, epigenetic gold mineralisation in shear or fault zones associated with demagnetising alteration with exploration work focussed on the large 'Bilyuin' magnetic anomaly in the south-eastern section of the tenement.
In the latter half of 2009 more information becoming available on the significant Cu-Au discovery at the DeGrussa prospect, 130km north of Meekatharra and 75km northeast of E52/1496, which Sandfire Resources' reported as being hosted within rocks of the Narracoota Volcanics and showing characteristics consistent with a VMS deposit.
In light of this information, Richmond Mining initiated a project review to assess the potential for the tenement to host similar mineralisation. The review highlighted the potential was significantly enhanced, based on the following:
- The Narracoota tenement predominantly contains rocks of the Narracoota Volcanics and prospective stratigraphical horizon that hosts the Cu-Au mineralisation at DeGrussa;
- Small oxide gold deposits in the Bryah Basin may represent the surface expression of deeper Cu-Au systems;
- Albeit small, the Cashman Cu and Au mine, located less than 1km south of the southern tenement boundary, may represent a near surface expression of potentially deeper mineralisation on E52/1496;
- The Naracoota tenement has no historical record of geophysical exploration using electromagnetic technology, a key tool in the identification of electrical conductors at DeGrussa;
- A combination of thick transported cover blanketing all of the tenement and a deep weathering profile has resulted in the majority of historical exploration ineffectively testing for mineralisation;
- Historical exploration on and around E52/1496 has predominantly focussed on Au. The very limited exploration for Cu has been restricted to soil sampling and subsequent shallow RAB drilling, which has limited validity due to the areal extent and thickness of transported sediments within the project area;
- The area of historical exploration on the tenement is small compared to its size; and
- A review of all holes drilled on the tenement highlights some areas with weakly elevated Cu values that are up to 5x background values.
Following the review, Richmond Mining initiated a significant exploration programme to explore for DeGrussa style Cu-Au mineralisation on E52/1496. As the tenement is largely covered by transported sediments, initial exploration for VMS-style Cu-Au mineralisation was based on using proven geophysical technology that delineated the conductive bodies of Cu mineralisation at DeGrussa, followed up by ground electromagnetic surveys and drilling.
Sandfire Resources' successfully delineated conductors from trial reconnaissance ground EM surveying at the high grade DeGrussa Cu-Au prospect and subsequently flew a versatile time domain electromagnetic (VTEM) survey over its tenements from which they were able to identify a number of high priority targets concealed below transported cover.
The VTEM survey was flown in November 2009 and recorded 516 line kms of EM, magnetic and terrain elevation data on 250m spaced north-south flight lines. A 6km wide section of the tenement was not flown to avoid known conductive cultural features that exist on the ground surrounding the old Narracoota homestead.
The survey data from the VTEM programme was processed and interpreted during the March quarter of calendar 2010 and a total of 18 priority anomalies were defined for testing.
The underlying geology of these anomalies was determined to all be within the Narracoota Volcanics, which was a positive for the model being employed.
In addition, it was noted that from the limited historic drill programmes over the area, three of the anomalies were adjacent to drill holes with elevated Cu values in weathered bedrock.
The anomalies were prioritised geophysically using strength of signal persistence across channels and shape.
The anomalies were then further prioritised using geology and magnetics to determine which anomalies were in a favourable structural position.
As part of this review the magnetic data was interpreted and a number of bullseye and structural break targets determined.
In total, 9 reverse circulation holes were drilled as part of the initial drill programme. Holes planned over two southern anomalies were not possible because of restricted access. All holes were vertical and composite samples for assay were collected over 10 metre intervals.
Hole NRC5 was drilled to test a strong magnetic feature that was at the junction of two structural trends. The balance of the holes tested VTEM targets.
The VTEM anomaly in Hole NRC1 was likely caused by the sulphidic black shale.
In the other holes, the source of the VTEM anomaly was either not apparent or possibly caused through a combination of palaeochannels in the overlying transported profile or alternately weakly fractured zones within the fresh rock.
Samples were assayed for Au, Cu, Ni and Zn. Elevated Au values were recorded over 5 composite intervals.
Table 1: Selected Drilling Results
| Hole | Interval | Description | AU | CU | Ni | Zn |
| NRC2 | 11-22m | Brown clay | 0.18 | 53 | 232 | 16 |
| NRC3 | 90-100m | Volcaniclastic, rare magnetite | 0.09 | 82 | 781 | 81 |
| NRC5 | 10-20m | Mafic dyke?, highly magnetic | 0.33 | 105 | 74 | 107 |
| NRC5 | 20-30m | Mafic dyke?, variably magnetic | 0.12 | 127 | 96 | 111 |
| NRC5 | 40-50m | Mafic dyke?, variably magnetic, minor pyrite | 0.35 | 147 | 108 | 80 |
Au results in g/t, all other results in ppm, Au assayed by FA30, Cu, Ni and Zn assayed by AAS.
The base metal values across all holes showed only minor variability and this was interpreted to be the result of the differing lithologies intersected in the programme.
The Au results from Hole NRC5 were regarded as highly anomalous. This hole was sighted over a strong magnetic feature which lies at the intersection of three structural lineaments trending WNW, WSW and NW respectively.
In addition, the results are from a hole that was in effect purely reconnaissance and sited in an area which is completely alluvial covered and has not been previously drilled or tested through soil geochemistry.
There is also possible significant magnetite destruction proximal to the drill hole, as evidenced from the aeromagnetic data.
In 2011 the plan was to actively explore the NRC 5 anomaly and extend this investigation into areas of apparent structural complexity along strike and adjacent to this anomaly.
The unusually wet winter in the Meekatharra region however significantly curtailed exploration access such that it was not until late August that drilling equipment could be taken into the area.
A 25 hole aircore programme was drilled by Latin Gold as the first pass test of these targets and confirmed the Au anomaly at NRC 005 as well as discovering elevated Ni values up to 0.3% in a number of lines drilled across buried structural targets.
The drilling across the gold anomaly confirmed the previous anomalous results with a best intersection of 6 metres grading 2.35g/t.
Initial petrological work suggests the host rock to this gold anomaly could be a high magnesium ultramafic rather than a mafic intrusive as originally identified.
These drill results are very encouraging as the intersection in NAC 001 which bulks out at 10 metres grading 1.6g/t is open along strike and down dip.
It also appears to be surrounded by a wide but low grade halo which could indicate a larger mineralised zone is present.
Table 1: Selected Drilling Results
| Hole | Co-ordinates | Azimuth/Inclination | Interval | Au assay (g/t) |
| NRC5 | 66100mE 7133990mN | Vertical | 10-20m | 0.33 |
| 20-30m | 0.12 | |||
| 40-50m | 0.35 | |||
| NAC 001 | 661605mE 7134004mN; | 60/180 | 15-17m | 0.41 |
| 17-23m | 2.35 | |||
| 23-25m | 0.52 | |||
| NAC 002 | 661604mE 7134019mN | 60/180 | 18-22m | 0.09 |
| NAC 003 | 661605mE 7134044mN | 60/180 | 20-30m | 0.06 |
| 30-35m | 0.05 | |||
| NAC 004 | 661616mE 7133979mN | 60/360 | 12-20m | 0.06 |
| 20-30m | 0.12 |
As discussed, a large part of the 25 hole aircore programme was directed towards providing stratigraphic information in areas of transported alluvial cover. In the central part of the Narracoota project area there is zero outcrop over the interpreted and prospective Narracoota Volcanics.
As a first pass regional test of this area and prospective lithologies, vertical aircore holes to blade refusal were drilled across 2.5 kms of strike focusing on areas where the magnetic suggested significant structural dislocation and/or possible magnetite destruction.
Subject to final petrological examination the large majority of these regional holes bottomed in ultramafic rocks with a number of intersections returning highly anomalous nickel values. These values ranged as high as 3113 ppm Ni (0.31%) and were all in the saprolite zone or weathered basement rocks where there were no obvious signs of any secondary enrichment.
| Hole | Interval | Description | Nickel assay (ppm) |
| NAC 006 | 23-33m | Saprolite clay, minor ultramafic chips | 1003 |
| 33-43m | Ditto | 1026 | |
| NAC 010 | 40-47m | Ditto | 3009 |
| NAC 011 | 37-54.5m | Ditto | 1313 |
| NAC 024 | 40-50m | Ditto | 1091 |
| 50-60m | Ditto | 1965 | |
| 60-63m | Ditto | 1346 | |
| NAC 025 | 20-30m | Ditto | 1369 |
| 30-35m | Ditto | 3113 |
From the assay data the background nickel values for the ultramafics in this part of the project area are in the range 250-300ppm.As a result of these drill intersections it is planned to carry out a 25 hole air core programme to grid drill the Au anomaly to determine the orientation and strike and width of the mineralisation. In addition, another 25 holes are planned to drill test across the zones of elevated Ni values to test the extent of these anomalies.
It is also planned to carry out a more detailed magnetic interpretation of the Au and Ni anomalous areas with a particular focus on structure and possible magnetite destruction.
Following from this work it is likely that a deep reverse circulation drilling programme in conjunction with possible IP will be carried out over the Au and Ni anomalies.
