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Greatland Gold announces positive IP results at Black Hills

Published by
Global Mining Review,


Greatland Gold plc, the precious and base metals exploration and development company, has announced that results of a high powered, deep sensing Induced Polarisation (IP) survey at its 100% owned Black Hills licence have successfully extended by a further 400 m the strike length of a chargeability anomaly spatially coincident with gold mineralisation identified at surface. The total length of the chargeability anomaly now exceeds 1400 m.

Systematic evaluation of new IP data and recent field geological reconnaissance has enabled new drill targets to be selected for Greatland’s upcoming maiden drill campaign at Black Hills. Due to the high level of exploration activity across the Paterson region and associated tightness in drill rig availability, drilling at Black Hills is now expected to commence by early July.

Key developments

  • Results of the recent IP survey confirm the location of the chargeability anomaly identified in 2018 and extend the anomaly a further 400 m to the southeast.
  • Total strike length of the chargeability anomaly has increased from approximately 1000 m of strike to approximately 1400 m.
  • Systematic evaluation of historic IP datasets, combined with new IP data and field geological reconnaissance, has enabled new drill targets to be selected.
  • New drilling plan has been designed to test the central parts of the Black Hills Dome where the IP chargeability anomaly and surface gold mineralisation are located, and the southern portion of the prospect where the IP anomaly has been extended by results of the recent IP survey.
  • Maiden drilling programme of approximately 6000 m, comprising more than 20 reverse circulation (RC) drill holes of depths up to 300 m, is expected to commence by early July.

Gervaise Heddle, Chief Executive Officer, commented: “We are very pleased by these results which further extend the length of the large chargeability anomaly to over 1400 m. The 1000 m of strike previously identified, which is spatially coincident with gold mineralisation identified at surface, has been successfully proven to continue for a further 400 m to the southeast, whilst still remaining open to the south. As a result of this positive outcome and recent field reconnaissance, we have been able to further refine target drill locations for Greatland’s first drilling campaign at Black Hills, which is expected to commence in the next four or five weeks.”

In June 2018, Greatland commenced it first exploration campaign at Black Hills. Multiple gold nuggets were found in thin sand cover within the first few days of the campaign, establishing the presence of high grade gold mineralisation at surface at the Saddle Reefs prospect. Results from additional rock chip sampling over the prospect returned many values over 10 g/t gold, peaking at 81.7 g/t gold, and these results approximately quadrupled the strike length of surface gold mineralisation from 200 m to 800 m.

In July - August 2018, a comprehensive IP survey was conducted covering a strike length of 1600 m over the zone of surface gold mineralisation at the Saddle Reefs prospect and immediate strike extensions. Modern 3D inversion models of resultant IP data were generated which outlined a large, coherent chargeability anomaly over 1000 m of strike, which is open to the southeast, and spatially coincident with gold mineralisation identified at surface.

Overview of Paterson project and Black Hills licence

The company’s Paterson project comprises the Havieron, Paterson Range East, and Black Hills licences, located in the Paterson region of Northern Western Australia. The three licences collectively cover more than 385 km2 and are prospective for Telfer style gold-copper deposits.

The Paterson region is currently one of the most active exploration areas in Australia. Recent exploration success achieved by Greatland Gold and Rio Tinto demonstrates the region has been under-explored, particularly the extensive areas under cover. As well as hosting several large gold and copper deposits such as Telfer and Nifty, more recent exploration has outlined several other deposits including Magnum (Au), Calibre (Au), O’Callaghans (W, Cu) and Maroochydore (Cu). The region is remote, however infrastructure is good, with several operating mines, roads, formed tracks and rail networks nearby which branch out from the regional industrial hub of Port Hedland 500 km to the west.

The Black Hills licence, E45/4512, lies 30 km east of the large Telfer gold mine. Black Hills is a granted exploration licence that covers 25 km2 and sits adjacent to the company’s Havieron exploration licence. The Black Hills licence is regarded as having high potential to host gold mineralisation, similar in style to that seen at Telfer. There has been a reasonable amount of historical exploration work at Black Hills with several discrete zones of mineralisation identified over 5 km of strike. Historical rock chip samples have returned up to 90 g/t gold, and commonly 20 g/t gold, with free (visible) gold in places. Historic drill intercepts include 3 m at 9.14 g/t gold from 26 m downhole (incl. 1 m at 21.2 g/t from 27 m (CBR073)), 1 m at 10 g/t gold from 16 m (CBH138), 1 m at 4.93 g/t from 12 m (CBH071) and 1m at 3.12 g/t from 37 m (NBH004). Historical RC drill spacing appears quite broad with holes at least 400 m apart, and some up to 600 m apart.

Gold prospects identified to date extend from Black Hills into the northwestern parts of the Havieron licence. Proterozoic sandstone and carbonate rocks of the Yeneena Group formations are present, including the Telfer Formation, in a domal structure which is the equivalent geology to that of the large Telfer gold deposit located 30 km to the west.

A large amount of historical surface exploration data for the Black Hills area has been compiled and incorporated into the company’s database. Gold mineralisation has been outlined at several prospects throughout the licence including Saddle Reefs, Eastern, Rogers and Northern Granites (within an area of 6.5 x 2 km).

Strong surface gold mineralisation is present at the Saddle Reefs prospect with historical rock chips including 55.6 g/t, 20 g/t, 19.65 g/t, 18.45 g/t and 17 g/t over an area of approximately 1400 x 800 m. The zone has a northwestly trend and sporadic drilling with results including 3 m at 9.14 g/t gold from 26 m downhole, including 1 m at 21.2 g/t from 27 m, in hole CBR073. This zone is in the core of an anticlinal feature and, overall, is gold prospective over a strike length of approximately 3 km.

At the Eastern prospect, a linear zone of gold mineralised stratigraphy is apparent over a strike of approximately 4 km. Historical surface rock chip results include 1.9 g/t gold, 1.2 g/t gold and 1 g/t gold. Broad spaced drilling along the zone has returned results including 1 m at 10 g/t gold from 16 m (CBH138), 1 m a 4.93 g/t from 12 m (CBH071) and 1 m at 3.12 g/t from 37 m (NBH004). The mineralisation appears to track along a structural contact and the focus will be on identifying the higher grade mineralisation along this trend.

The other prospects of Rogers and Northern Granites show prospective gold mineralisation at surface with historical rock chip results including 50.2 g/t and 10.45 g/t at Rogers and 6.9 g/t at Northern Granites. Drill testing is limited but results have included 1 m at 1.48 g/t from 38 m (NBH008) at Rogers and 1 m at 2.35 g/t gold from 5 m (CBH253) at Northern Granites.

The company commenced field activities at Black Hills in mid-2018. Work focused on the Saddle Reefs and Rogers areas, collecting rock chip samples and locating historical access. The host sequence of Proterozoic sandstones and limestones outcrop through relatively thin sand cover. Numerous indications of mineralisation in bedrock are apparent. Gossanous samples were collected from outcrop, visible gold recovered from rock chip samples, and gold nuggets were found in thin sand cover at Saddle Reefs.

At Saddle Reefs, the mineralised sequence outcrops through a thin veneer of sand and gravel. Rock chip samples were collected over a strike length of approximately 800 m with results over 10 g/t including 81.7 g/t, 45.7 g/t, 37.6 g/t, 33.9 g/t, 28.2 g/t and 23.5 g/t. Many also showed high silver above 10 g/t up to a maximum of 106.1 g/t. Gold (and silver) mineralisation in bedrock has been identified over a strike length of approximately 800 m at Saddle Reefs.

A comprehensive IP programme over Saddle Reefs was undertaken during 3Q18. Total strike length covered was 1600 m. Transmitter and receiver lines were 100m apart and station spacing along lines was 20 - 40 m. Modern 3D inversion models of resultant IP data were generated. These models outlined a large, chargeability anomaly over 1000 m of strike spatially co-incident with gold mineralisation identified at surface. The body lies subparallel to the strike of gold mineralisation identified at surface and has dimensions of approximately 1000 m long, 200 m wide and 150 m thick. The body plunges gently southeast mirroring the overall structural plunge of the outcropping geology and is open to the southeast. Depth to top of the body ranges from 150 - 200 m below surface. The majority of historical drill holes at the Saddle Reefs prospect did not achieve these depths.

Greatland’s 2019 field programme in the Paterson commenced with a high powered, deep sensing IP survey at Black Hills. The survey continued southeast from the IP chargeability anomaly identified from the 2018 IP survey which remained open along strike. The recent IP programme consisted of two 3.4 km lines, 400 m apart; the northernmost line covered the southern extremity of the 2018 IP and the second line was sited 400 m to the south.

Results of the 2019 IP confirm the location of the chargeability anomaly identified in 2018 and extend the anomaly a further 400 m to the southeast. Total strike length of the chargeability anomaly has increased from approximately 1000 m of strike to approximately 1400 m. The body now has approximate dimensions of 1400 m long, 200 m wide and 150 m thick. Depth to the top of the body continues to range from 150 m to 200 m below surface and it remains open to the south.

Systematic evaluation of historic IP datasets, combined with new IP data and field geological reconnaissance, has enabled drill targets to be selected. Drilling has been designed to test stratigraphy over the Saddle Reefs prospect, including the central parts of the Black Hills Dome where the IP chargeability anomaly is located plus surface gold mineralisation, and the southern portion of the prospect (where the IP anomaly is also apparent). A drilling programme of approximately 6000 m comprising more than 20 RC drill holes of depths up to 300 m is proposed.

The company has received all required approvals from the Western Australian Department of Mines, Industry Regulation and Safety (DMIRS) for a drilling programme at Black Hills. Drilling is currently scheduled to commence by early July.

Read the article online at: https://www.globalminingreview.com/exploration-development/03062019/greatland-gold-announces-positive-ip-results-at-black-hills/

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