Greater Hemi Discovery Area Continues To Grow
De Grey Mining Limited (ASX: DEG) has defined significant new gold arsenic zones with its ongoing exploration activities at the Greater Hemi Intrusion targets, surrounding the Hemi Gold Discovery, located approximately 60km south of Port Hedland in Western Australia.
The Greater Hemi area is approximately 15km by 10km, excluding the Brierly Link zone, with the Greater Hemi Intrusion targets include Scooby to the east and Antwerp, Alectroenas and Shaggy to the west of Hemi.
The company has been undertaking exploration within the Greater Hemi area using systematic aircore drilling, geophysical and geochemical techniques to identify mineralised intrusions based on recent experience from the Hemi discovery.
Between January 2020 and early February 2021, the company has drilled 2,135 aircore holes for 140,532 metres. This includes discovery drilling at Hemi, Falcon, Diucon and Eagle together with widespaced reconnaissance drilling at Scooby, Antwerp, Alectroenas and Shaggy.
The aircore drilling has been an efficient discovery tool with over 20% of holes intersecting gold mineralisation >0.1g/t Au and 9% of holes defining zones >0.5g/t Au. These direct gold results together with our supporting geochemistry has been highly effective in defining the mineralised corridors for rapid follow-up RC drill testing.
Most recently, the discovery of the two new mineralised intrusions at Diucon and Eagle is a direct result of this exploration strategy. These two new zones did not show up as magnetic anomalies and were discovered using systematic aircore drilling. New geophysical techniques including induced polarisation (IP) are currently being trialled to provide additional targeting techniques due to the variation in magnetic responses. A combination of these exploration approaches is being used to identify and prioritise high prospectivity targets for follow up RC drilling at Scooby and Antwerp.
Scooby
At Scooby, aircore drilling has outlined a zone of anomalous gold and arsenic mineralisation of approximately 2km in strike and up to 1km wide with a coincident bedrock conductivity IP anomaly. The IP anomaly is interpreted to represent disseminated sulphide-rich mineralisation within the fresh bedrock at depth.
The anomalous gold and arsenic mineralisation is based on aircore drilling. The shallow high grade intercept of 3m @ 97.4g/t Au from 45m including 1m @ 264g/t Au and 2m @ 4.8g/t Auoccurs at the uppermost weathered bedrock interface with the transported cover sequence.
Aircore drilling at Scooby has been completed to an average depth of approximately 50 to 60 metres. This is due to the hardness of bedrock and aircore rig penetration. The shallow penetration of the aircore drilling provides information on only a relatively thin veneer of the underlying intrusion. In areas where deeper aircore drilling has been achieved, broad lower grade intercepts (i.e. 48m @ 0.2g/t Au) suggest wider zones of mineralisation and alteration occur.
Aircore drilling results at Scooby include:
- − 3m @ 97.4g/t Au from 45m in BXAC437 incl 1m @ 264g/t Au from 45m
- − 10m @ 2.1g/t Au from 48m in BWAC630 incl 1m @ 14.1g/t Au from 50m
- − 2m @ 4.8g/t Au from 39m in BXAC436 incl 1m @ 8.6g/t Au from 39m
- − 3m @ 1.5g/t Au from 48m in BWAC635
Antwerp
Wide spaced aircore drilling, on variably spaced lines 160m to 320m apart, has been completed at Antwerp. The more recent aircore drilling highlights a series of gold-arsenic intersections distributed throughout the Antwerp intrusion complex over an area 2km x 1km. The recent result of 23m @ 0.6g/t Aufrom 52m demonstrates potential for a broadly mineralised system. Drilling shows that the depth of cover significantly reduces to approximately 5m in the western portion of the prospect area.
To date, limited RC drilling has intersected quartz veined and altered intrusion with potentially mineralisation at shallow depths (<100m).
De Grey Technical Director, Andy Beckwith, said he recent encouraging gold mineralisation defined in RC drilling at the Eagle intrusion, to the immediate east, has the potential to link up with zones within the Antwerp intrusion complex. Step out RC drilling will test this potential.
He said the trial gradient array IP survey at Scooby has provided a new tool to target potential sulphide mineralisation. Accordingly, a gradient array IP survey is planned at priority areas – Antwerp, Diucon and Eagle – to aid targeting beneath the transported cover.
“Recent exploration activities at Scooby and Antwerp have identified widespread gold mineralisation in aircore drilling warranting follow-up RC drilling. This drilling will commence in the near future in parallel with resource delineation and extension drilling at Hemi, including at the recently discovered Diucon and Eagle zones,” Mr Beckwith said.
“The new IP target coincident with gold and arsenic mineralisation at Scooby are encouraging. The IP results potentially provide a new tool to identify and prioritise targets beneath the transported cover. Diucon, Eagle and Antwerp will be our next priority IP areas.”
