Key points
- The Atlantis II basin lies in the Red Sea about 115 kilometres west of Jeddah, roughly 2,000 metres below sea level.
- A historical resource of 89.5 million tonnes grading 2.06 per cent zinc, 0.45 per cent copper and 38.4 ppm silver was calculated from 587 core samples, but DFI has not classified it as a current mineral resource.
- High-grade zones returned assays up to 20.1 per cent zinc, 3.6 per cent copper and 338 parts per million silver.
- A Preussag prepilot test mining program processed 15,000 cubic metres of seafloor sediments and brines from four test sites in the Atlantis II basin.
Diamond Fields International Ltd. has released a futher update on the Atlantis II Red Sea Deeps project (see DFI’s Stockwatch
press release dated June 4, 2010). DFI is developing the project with its Saudi joint venture partner, Manafa International.
The Atlantis II basin containing the Atlantis II deposit is located in the Red Sea, approximately 115 kilometres west of Jeddah. The Atlantis basin comprises four interlinked subbasins lying approximately 2,000 metres below sea level. Base and precious metal mineralization contained within the sediments have attracted considerable exploration interest since their discovery in 1965. It is estimated that more than $28-million (U.S.) in 1970s dollars was spent on exploring the deposit. The historical work has shown the economic potential of the deposit by evidencing extensive and continuous mineralization of zinc, copper, silver, gold, lead and other metals.
In the mid-1970s, the Saudi-Sudanese Red Sea Commission was established with the directive of assessing the economic potential of these resources. Preussag AG was commissioned by the RSC to conduct a five-year geological exploration program and technical feasibility study. This process concluded in 1982 with positive results. Together with Manafa, DFI has obtained the documented records and hard data generated during the study. DFI has located the original Preussag sediment cores. It is analyzing the data and modelling the deposit, using the latest technology, and otherwise moving forward with the preliminary steps necessary to develop the project.
The Preussag coring program on average sampled only the uppermost 8.5 metres of the sedimentary sequences. The program demonstrated that mineralization is open at depth and extends over an area of approximately 57 square kilometres. Composited one-metre core assays showed a variable grade in the top seven to 11 m of sediments, with high-grade areas yielding results up to 20.1 per cent zinc, 3.6 per cent copper and 338 parts per million silver. The underlying sediments were also shown to be mineralized in all of the samples that were taken extending into this unit. The thickness of these underlying sediments is currently unknown, but high-resolution seismic studies undertaken by Preussag suggest that it may attain thicknesses of up to 28 m.
Deep-tow seismic data commissioned as part of the Atlantis II investigation indicate that sediments in some parts of the Atlantis basin may attain a total thickness of up to 160 m. The composition of these deeper sediments is currently unknown, but they offer potential to host a further significant resource. On the basis of the data from the Preussag study, DFI estimates that only a minor portion of infilling sediments contained within the Atlantis II Deeps have been sampled.
A historical resource figure based on 587 core samples taken only from the uppermost unit and the first m of the underlying sediments (an average of 8.3 m in thickness) estimated the deposit to contain 89.5 million tonnes of sediment at a grade of 2.06 per cent zinc, 0.45 per cent copper and 38.4 ppm silver on a dry salt-free basis. DFI has not done sufficient work to classify the historical estimate as current mineral resources. Accordingly, the company is not treating the historical estimate as current mineral resources and the historical estimate should not be relied upon.
A prepilot test mining study undertaken by Preussag successfully demonstrated that the mineralized mud of the Atlantis II Deeps can be continuously mined and concentrated at sea, using conventional flotation techniques. During test mining operations, 15,000 cubic m of sea floor sediments and brines from four test sites in the Atlantis II basin were processed. Metal grades derived from this operation proved to be higher than those predicted by the Preussag resource modelling, with grades varying from 2.51 per cent to 4.91 zinc, 0.47 per cent to 4.91 per cent copper and 59.43 ppm to 111.24 ppm silver (DSF).
“The potential of the Atlantis II deposit is vast and represents the largest known polymetallic Sedex marine orebody in the world,” said Ian Ransome, DFI’s chief executive officer.
The geological information in this press release has been reviewed by Mr. Ransome, BSc (honours), PriSciNat, who is a qualified person in terms of National Instrument 43-101 regulations.
Support for the historical geological data for this release came from the Atlantis II Red Sea data and reports generated by Pressaug and other sources.
