Deep Sea Mining of Submarine Hydrothermal Deposits and its Possible Environmental Impact in Manus Basin, Papua New Guinea

The Manus back-arc basin host three distinct well known submarine hydrothermal deposits of Vienna Wood, Pacmanus and Onsen sites. The Vienna Wood site is a typical Cu-Zn type of mineralization consisting predominantly of pyrite, marcasite, sphalerite, wurtzite and chalcopyrite. The Pacmanus site is a polymetallic type of mineral deposit consisting of sphalerite, chalcopyrite, bornite, wurtzite, pyrite, marcasite, enargite, tennantite, galena, Pb-As-Sulphosalt, gold, covellite, digenite and chalcocite. The Onsen site is the first deep sea acid sulfate type of mineralisationconsisting ofenargite, covellite, chalcopyrite, pyrite and marcasite. The Papua New Guinea (PNG) Government has granted exploration license to Nautilus Mineral Cooperation to explore for submarin e hydrothermal deposit in the Manus Basin. It has done extensive exploration around the existing hydrothermal depos its of Vienna Wood, Pacmanus and Onsen site. This has resulted in the discoveries of well over twenty hydrothermal deposits (Solwara 1 to Solwara 20). Nautilus Minerals has done resource drilling on Solwara 1 and Solwara 12 deposit due to its polymetallic type of mineralization and its geochemicalsimilarities to the Pacmanus site. From resources drilling, Nautilus Minerals reported an indicated and inferred mineral resource of 1030 kt and 1540 kt respectively for the Solwara 1 project at 2.6% Cu equivalent cut off grade. The PNG government has granted mining lease (ML154) to Nautilus Minerals to mine the Solwara 1 deposit in January 2012. If mining activity commences at the Solwara 1 site then Nautilus needs to address possible environmental impacts of water usage and discharge, water quality, sedimentation and dewatering and preservation of hydrothermal vent communities

沖縄トラフ第四与那国海丘海底熱水系チムニーの錫を含む黄銅鉱と白金を含む輝蒼鉛鉱

The active sulfide chimney ore sampled from the flank of the active Tiger chimney in the Yonaguni Knoll IV hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, shalerite, galena, chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn 4+ Fe 2+ for Fe 3+ Fe 3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-310℃) and metasured end-member temperature of the vent fluids (325℃) indicate that the minerals are precipitated as metastable phases at temperature around 300℃. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite expess the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300℃