EXPLORATION UPDATE, SANDSTONE PROJECT WESTERN AUSTRALIA
➢ Initial test of Maninga South IP target completed with one 348m deep RC hole
➢ 14 follow-up RC holes completed at Vanguard for total 1,173 metres
➢ 7 follow-up RC holes completed at Maninga Marley for total 616 metres. Assay results for all holes are awaited
➢ 20,000m aircore drilling program planned to cover various advanced targets, with Stage 1 (5,000m) planned for greater Vanguard area
➢ Major (3,000 sample) soil program commenced over 17 identified gold targets
➢ Program of Work submitted to Mines Dept for exploration at historic Hacks and Oroya mine sites. Work to include aircore and RC drilling, and auger sampling of historic mill sand deposits
Alto Metals Limited (ASX: AME) (“Alto”, “the Company”) wishes to advise that the first reverse circulation (RC) drill hole to test an extensive (1,200m x 300m) Induced Polarization (IP) chargeability anomaly south of the historic Maninga Marley gold workings was completed over the Easter weekend. 4m composite samples from the hole were submitted to the laboratory after Easter and results are awaited.
A further 21 RC holes were drilled at Vanguard and Maninga Marley to test interpreted along strike and down plunge positions of known gold mineralization. This program was completed on the 8th April and final samples will be delivered to the laboratory by end of this week.
A substantial aircore (AC) drilling program has been planned to follow up known oxide gold occurrences, existing geochemical soil anomalies and interpreted litho-structural targets. The first stage of this program will concentrate on defining the extent of the Vanguard - Vanguard North high-grade gold system, which currently extends over 1,200m of strike, and is open to the northwest and southeast.
Following compilation by Alto of a patchwork of soil sampling programs from various previous explorers, Alto has commissioned a modern soil sampling program (3,000 samples) over 17 target areas to “fill in the gaps”. This program commenced on 5th April 2018, and to date, 435 samples have been collected and submitted for analysis. No results have yet been received.
ALTO COMMENCES RC DRILLING TO TEST IP ANOMALY FOR NICKEL & GOLD, SANDSTONE WESTERN AUSTRALIA
- RC drill on site midday today to commence testing significant Induced Polarisation (IP) anomaly for Ni & Au
- IP target identified from 2011 IP survey, 1km south of Maninga Marley gold workings
- IP modelling suggests potential body ofsulphides at 200m-300m below surface, positioned up against a komatiitic unit interpreted from airborne magnetics and shallow RAB data
Alto Metals Limited (ASX: AME) (“Alto”, “the Company”) is pleased to advise that reverse circulation (RC) drilling of a significant IP anomaly south of the historic Maninga Marley gold workings will commence at midday. The RC drilling program will test an extensive IP target (1,200m x 300m) located by Western Areas NL (ASX: WSA) in 2011.
Troy Resources NL between 2000 and 2005 drilled 43 shallow RAB holes (av. depth 18m) around old workings nearby, but these holes were too shallow to test the modelled IP target. Refer Alto’s ASX release of 22 March 2018 and link below for further details.
The location of the Maninga South IP target is shown in Figure 2
- RC drilling program commencing week beginning 26 March to test significant Induced Polarisation (IP) anomaly for Ni & Au
- IP target (1,200m x 300m) 1km south of Maninga Marley gold workings identified from 2011 IP survey
- Survey was conducted as a “screening tool” as part of a nickel sulphide search
- Shallow RAB and aircore drilling by previous explorers deemed to be too shallow (av. depth 18m-39m) to intersect IP source(s)
- Modelling ofIP anomaly byAlto suggests potentialbody of sulphides at 200m-300m below surface
Alto Metals Limited (ASX:AME) (“Alto”, “the Company”) is pleased to advise that it has identified a significant IP anomaly south of the historic Maninga Marley gold workings, in an area of cover. Alto has planned a reverse circulation (RC) drill program to commence early in the week beginning Monday 26th March 2018 to test this extensive 1,200m x 300m IP target.
In 2011 Western Areas NL (ASX: WSA) conducted two IP surveys over the southern part of the Sandstone greenstone belt, under a joint venture agreement with Troy Resources NL, which was restricted to nickel and associated minerals (excluding gold).
The dipole-dipole IP survey configuration used was considered the most appropriate method to target basement disseminated sulphide mineralisation within areas with conductive cover, and was used as a reconnaissance “screening method” in WSA’s search for massive Ni-Cu-Co sulphides.
Alto Metals has reviewed and re-modelled the IP data and targeted a significant IP chargeability and resistivity anomaly south of the Maninga Marley for drill testing.
Commenting on this target, Alto’s Managing Director Dermot Ryan said:
“The aerial extent, high chargeabilty and low resistivity nature of this anomaly, coupled with evidence fora komatiite hostin shallow drillingand downhole geochemistry,suggests that there is potentially a large sulphide body present.
The RC drill rig will give us the answer next week.”
IP SURVEYING & MODELLING
In 2007, Western Areas NL joint ventured into Troy’s southern Sandstone tenements to explore for nickel sulphides and in 2011 conducted two ground IP surveys (100m dipole-dipole array, lines 400mapart) centred over magnetic units interpreted to be komatiites south and southwest of Maninga Marley.
A 1.2km long IP chargeability anomaly was located, and later in 2011, Western areas completed
59 air-core holes with an average depth of 39m. Several deeper holes reached 107m depth and nickel values (average 1,500-2,000 ppm) correlated well with the logged ultramafic lithologies. No RC or diamond core drilling was conducted by Western Areas.
Alto’s consultantgeophysicist Bill Robertsonhas reviewed theIP data. Theprocessing and modelling has identified a high priority IP chargeabilityand resistivity anomaly south of the Maninga Marley Prospect.
The data for this survey was obtained from WAMEX Report A093563. Data were processed and presented using GeosoftMontaj IP module(refer IP pseudo-section inFigure 1 below). Subsequent 2D inversion modelling of the data was done using Zonge TS2DIP Smooth Model Inversion software. (refer Figure 2).
Figure 1. Maninga South IP Anomaly – IP Pseudo-Section Plot, Line 744,300mE (GDA94)
Figure 2. Maninga South IP Anomaly – 2D Inversion Model with Planned RC Holes Line 744,300mE
HIGH GRADE GOLD ASSAYS FROM 1 METRE PRIMARY ZONE RC SAMPLES, VANGUARD PROSPECT, SANDSTONE PROJECT, WA
Assays of 1 metre samples from reverse circulation (RC) drilling at Vanguard in February gave improved gold values over 4m composite samples
Fire assays from 1 metre samples from Vanguard primary zone include:
- SRC075 : [email protected] 3.8g/t Au from 85m
- incl. : [email protected] 6.4g/t Au from 89m
- and : [email protected] 7.0g/t Au from104m
- incl. : [email protected] 10.7g/t Au from106m
- SRC060 : [email protected] 3.7g/t Au from 81m
Alto Metals Limited (ASX: AME) (“Alto”,“the Company”) is pleased to advise that 50gmfire assays (FA’s) of1m individual RC samplesfrom February’s 15hole and 1re-entry (SRC071- SRC085, SRC060, total 1,912m) drilling program at the Vanguard prospect have been received. Refer Figure 1 below, where 2018 1m assay RC results are in yellow and 2017 RC results are in grey.
Three RC holesdrilled at IndomitableProspect (SRC086-SRC088, total468m) returned numerous 1m - 5m intervals of 0.5g/t Au to 1.95g/t Au, with a best result of 5m at 2.5g/t Au from 91m in hole SRC086
- 4.1% nickel identified in 2010 diamond drill hole during review of previous nickel exploration data at Sandstone
- Research work (2005) undertaken by Geological Survey of Western Australia and University of Western Australia first identified abundant komatiites in the Sandstone greenstone belt
- The research work highlighted the prospectivity for komatiite hosted nickel/copper/cobalt sulphide deposits at Sandstone
Alto Metals Limited (ASX: AME) (“Alto”, “the Company”) is pleased to advise that Alto will be assessing the nickel/copper/cobalt potential of the Sandstone komatiite sequence within Alto’sSandstone tenements.
Support for Ni-Cu-Co exploration at Sandstone comes from two sources. In 2010, Western Areas NL (ASX: WSA) made the first ever discovery at Sandstone of disseminated and semimassive nickel sulphides (26.2m at 0.4% Ni from 60m depth in hole WAD002), including a 20cm interval of semi-massive sulphide which assayed 4.1% Ni from 86.3m depth.
The Western Areas work followed mapping and sampling of exploration drill samples by the Geological Survey of Western Australia (GSWA) in 2005 (Chen, 2005) which identified widespread but poorly exposed komatiites in the Sandstone greenstone belt, which represented the most significant occurrence of komatiites in the northern part of the Southern Cross Terrane in Western Australia. (Refer Figures 1 and 2 overleaf)
Commenting on this new initiative, Alto’s Managing Director Dermot Ryan said:
“We are very pleased to have secured Terry Streeter to the Alto board as he has a successful track record in finding and developing nickel sulphide deposits and, as a founder and former Chairman of Western Areas, has prior knowledge of the potential of the komatiites in the Sandstone greenstone belt to host nickel sulphides.
Alto is currently undertaking an extensive gold exploration program at Sandstone, and this NiCu-Co initiative is complementary to the gold exploration being undertaken.
Alto has flown modern detailed airborne magnetic and radiometric surveys, and has utilized the extensive historical drilling and geochemical database to develop an improved understanding of the bedrock geology and structure at Sandstone, which can be used in the search for gold and base metals. In addition, Alto has the benefit of access to the latest developments in electromagnetic (EM) techniques, which have proven to be effective in the recent discovery of massive sulphide deposits”.
The area covered by the Sandstone Gold Project was formerly part of Troy Resources Ltd’s (ASX: TRY) Sandstone Gold Operations, which was highly profitable up until the cessation of mining in late 2009.
Alto’s first obective at Sandstone is to delineate relatively shallow oxide gold mineralisation that can be economically mined and trucked to one of several gold treatment facilities in the region. The second objective is to delineate deeper and more extensive high-grade sulphide-hosted gold mineralisation using RC and diamond drilling.
To support these objectives, Alto commenced in late 2016 a variety of broader exploration initiatives including acquisition of high-resolution airborne magnetic and radiometric data, litho-structural interpretation and targeting, Induced Polarisation (IP) surveys, and established an external research advisory committee (ERAC).
The ERAC is chaired by Emeritus Professor David Groves and was established to oversee Alto’s research and development (R&D) activities. The committee consists of a multi-disciplinary team of geoscientists, and a primary researcher based at The University of Western Australia. The scope of the ERAC is to incorporate traditional and emerging exploration techniques and technologies for testing on Alto’s project areas. The Sandstone Belt has been the focus of limited research to date, in comparison with other similar greenstone belts. The team is developing an understanding of the mineralising systems of the Sandstone Greenstone Belt.
Alto considers that the robust Australian gold price and current competitive cost environment will enable it to consider several areas for early recommencement of mining.
Since the discovery of gold at the end of the 19th Century, the Sandstone Greenstone Belt has produced over 1.2 million ounces of gold from numerous underground and open pit mining operations. Of this, some 612,000 ounces was produced between 1994 and 2010 from the open-pit mining of shallow oxide ore by ASX listed companies Herald Resources Ltd and Troy Resources Ltd.
The numerous former open pits, prospects and gold occurrences now owned by Alto include Lord Nelson, Lord Henry, Havilah, Bull Oaks Reef, Vanguard, Ladybird, Maninga Marley, Sandstone North, Oroya, Tiger Moth, Musketeer, Piper and Bulchina.
Between 1994 and 2010, the exploration focus at Sandstone was largely on exploring for and mining shallow oxide ore to feed the Herald/Troy Nunngarra Mill, at a time when the Australian dollar gold price was substantially lower than it is today.
Alto’s Exploration Program
In late November 2016, Alto commenced a limited reverse circulation (RC) and aircore (AC) maiden drilling program (3,827 metre RC and RC/AC) to provide a preliminary test for possible extensions to shallow oxide gold mineralisation at the Indomitable and nearby prospects, previously identified by Troy Resources Ltd (Troy), and to test induced IP anomalies immediately north of the Lord Nelson and Lord Henry deposits for sulphide associated mineralisation. Refer ASX announcements for results of progressive drilling programs.
More extensive RC and AC drilling programs are planned to commence in March 2017.