Gold Road - Gruyere Style Mineralisation Discovered at YAM10 -SYJV
Gold Road Resources (ASX:GOR) has been buoyed by the results of aircore drilling on its South Yamarna Joint Venture tenements in Western Australia, with four target areas prioritised for follow-up RC drilling. The highest priority of these target areas is YAM10, where a best intersection of 19 metres grading 1.06 grams of gold per tonne was returned from 162 metres. Gold Road has identified YAM10 as analogous with the 6.2 million ounce Gruyere Gold Project on its North Yamarna tenements.
- Regional aircore drilling identifies gold in multiple targets
- Three separate prospects with bedrock intercepts greater than 0.5 g/t Au
- Hole16SYAC0691returned atotal interceptof19 metres at1.06 g/t Aufrom 62 metres at the YAM10 Prospect (including 3 metres at 5.16 g/t Aufrom 63 metres, and 1 metre at 2.90 g/t Au from 69 metres)
- GoldmineralisationhostedbyahighlyshearedandstronglyalteredGruyere‐style porphyry
Gold Road Resources Limited (Gold Road or the Company) is pleased to announce that a regional aircore (AC) drilling programme has recently been completed over its South Yamarna Joint Venture (SYJV) tenements at the Riviera‐Smokebush and Breelya‐Toppin Hill camp‐scale targets. Given the highly significant results a Reverse Circulation (RC) drilling programme will begin testing the priority targets in the December 2016 quarter. The SYJV is owned 50:50 by Gold Road and Sumitomo Metal Mining Oceania Pty Limited (Sumitomo).
The AC programme consisted of 328 holes for 16,500 metres of drilling designed to test RAB‐Interface anomalies identified through 2015 and 2016, and new conceptual structural targets not previously tested by drilling. The programme successfully intersected anomalous bedrock gold mineralisation over widespread areas, with 30 drill holes returning gold grades greater than 0.1 g/t Au.
Four target areas have been identified for priority follow‐up RC drilling, YAM10, Riviera, Yaffler South and Kingston North (Figure 1). The highest priority target is the YAM10 Prospect with a best intersection of 19 metres at 1.06 g/t Au from 62 metres, including 3 metres at 5.16 g/t Au from 63 metres (including 1 metre at 13.67 g/t Au from 65 metres) and 1 metre at 2.90 g/t Au from 69 metres. The mineralisation at YAM10 is hosted in a highly sheared and altered Gruyere‐style felsic porphyry intruding a basalt‐volcaniclastic sequence, and displays features most analogous to Gruyere so far found at South Yamarna. Planning for the follow‐up RC drilling at YAM10 and the three other targets is in progress.
Executive Director Justin Osborne said: “The results of this targeted aircore programme have proved very exciting. We set out to test a variety of geological settings, looking for both Gruyere analogue targets, and sheared mafic‐ hosted gold mineralisation more typical of Yilgarn gold deposits. The identification of the YAM10 Prospect as a true Gruyere look‐alike, although preliminary in nature, is extremely encouraging, and represents the combined efforts of the SYJV Geologists. Drill testing is expected to start shortly and we are looking forward to what we might learn from the next programme of RC drilling”.
The YAM10 Prospect, located approximately 4.5 kilometres east of the Smokebush Dolerite Prospect, comprises a Gruyere‐style felsic porphyry intruding a sequence of volcaniclastics and basalts. Previous exploration completed by Gold Road in 2014 identified a coincident gold and base metal (As, Mo, Pb, Zn) RAB Interface anomaly over the Prospect area. The initial 800 metre by 100 metre AC programme (2015) intersected scattered gold grades up to 1 g/t within Archaean saprolite. The recent programme added two 400 metre spaced AC lines of 100 metre spaced holes identifying high‐grade gold mineralisation. The best result was recorded in hole 16SYAC0691 which intercepted 19 metres at 1.06 g/t Au, including 3 metres at 5.16 g/t Au (with 1 metre at 13.67 g/t Au) from 63 metres, and 1 metre at 2.90 g/t Au from 69 metres (Figure 2). Mineralisation in this hole remains open at depth with the final metre intercepting 1 metre at 0.52 g/t Au from 80 metres (Figure 2). The combined drilling programmes have delineated gold mineralisation up to 1 g/t Au over a two kilometre long by one kilometre wide area.
This mineralisation is hosted by an intensely albite altered and strongly sheared Gruyere‐style felsic porphyry which appears to have intruded a large regional shear zone in predominantly mafic (basalt) country rock. The porphyry has the identical geochemical signature to the Gruyere Porphyry, which is host to the 6.2 million ounce Gruyere Deposit approximately 50 kilometres to the north‐east.
The intrusion of the mineralised felsic porphyry (“light rocks”) into the basalts (“heavy rocks”) forms a distinct gravity low signature within a surrounding gravity high (Figure 3). A large regional shear zone passes through the Prospect which is evidenced by strong shear fabric identified in the AC samples. Interpretation of aeromagnetic data suggests the mineralised intrusion to be located on a sharp flexure in this shear zone (Figures 4 and 5). The combination of gold mineralisation hosted in a felsic style porphyry within a flexure along a major shear zone, provides a geological setting similar to that of the Gruyere Deposit.
A follow up 3,000 metre RC drilling programme of 400 metres by 100 metre spaced drill holes is being planned to test the extent of mineralisation within the prospective porphyry and test for high‐grade mineralisation within the adjoining basalts along the intrusion’s sheared margins. This programme is scheduled to commence in the December 2016 quarter.
The Yaffler South Prospect consists of a linear gold‐arsenic‐molybdenum anomaly four kilometres in strike length at greater than 0.1 g/t Au defined by 800 metre spaced AC drill lines (Figure 6). Anomalous gold occurs within a mafic unit coincident with a discrete magnetic high. This unit shows structural offsets and demagnetised areas interpreted to represent cross cutting structures. The mafic sequence at Yaffler South is interpreted to be part of the same mineralised package that hosts the Toppin Hill Prospect located 10 kilometres to the south‐east.
A follow‐up AC programme will infill the gold anomaly to a 400 metre line spacing to identify a consistent bedrock gold anomaly greater than 100ppb and to test for elevated gold coincident with the interpreted cross structures. This will allow more detailed targeting and possible follow‐up RC drilling.