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By Peter A. Rona

Investigations of the Gorda Ridge within the proclaimed U.S. Exclusive Economic Zone off northern California and southern Oregon, and the Mid-Atlantic Ridge extending along the center of the Atlantic Ocean, have received new impetus from the discovery of hot black smokers, sizeable polymetallic massive sulfide deposits, and vent animals at the Mid-Atlantic Ridge by the NOAA VENTS Program in 1985. Prior to that time, the oceanographic community focused investigations of seafloor venting at the faster-spreading oceanic ridges of the Pacific Ocean including the East Pacific Rise, the Galapagos spreading center and the Juan de Fuca Ridge because a consensus held that the faster spreading rates at these ridges were necessary to supply the heat to drive black smoker-type venting. As the only oceanic ridge in the Pacific with slow-spreading characteristics, the Gorda Ridge is an outlier of the slow-spreading ridge system that extends through the Atlantic Ocean and western Indian Ocean comprising more than half the 55,000-kilometer-length of the globe-encircling oceanic ridge system. In response to recent discoveries at the Mid-Atlantic Ridge the oceanographic community is shifting more of its activity to investigation of hydrothermal venting and related processes at slow-spreading oceanic ridges. The discovery cruise by a team of NOAA and university scientists followed by

Jan 1, 1988

By Richard H. T. Garnett

Marine mining on the continental shelf was first attempted in 1900 for gold off the beaches of Nome, Alaska. Attempts continued until 1990 with cutter-suction, airlift and bucket-ladder dredges. Offshore Thailand profitable production of tin resulted from clamshell, bucket-ladder and trailing suction hopper dredges. Today in Indonesia numerous bucket-ladder dredges continue to mine tin. Off the coast of Namibia and South Africa nearly a dozen large and medium sized vessels are engaged in diamond production. The obvious risk results from the working environment. Vessels and lives have been lost in the past. At best the availability of mining equipment is reduced. Leaving aside the marketing and financing aspects, otherwise the most important risks are technical. They manifest themselves as diamond production short-falls with obvious financial consequences. Bias and deficiencies in sampling equipment and procedures may result in misleading grade estimates, even serious under-estimation. Inadequate sampling in terms of sample support and density may result in over-optimistic grade determinations, especially if under-sized mining blocks are outlined. Quantitative measurement of the geotechnical characteristics of the sediments to be mined is an essential stage in a feasibility study. Without a full understanding of the bedrock profile and the overlying sediments the ease, completeness and speed of excavation during the mining process cannot be properly estimated. Both historically and at present the greatest negative discrepancies from production estimates result, not from grade shortfalls, but from significantly lower mining rates than thought possible by the operators. The learning curve in marine, production mining is steeper and longer than is generally recognised by newcomers to the industry. Examples are provided from tin, gold and diamond mining experiences.

Jan 1, 1998

By Frank Manheim

The purpose of this presentation is to review the history of offshore non- fisheries resource development since World War II, as an introduction to a planned symposium on offshore resources scheduled for the 1996 UMI Conference. After World War II the United States became the leader in offshore oil and gas production, deep ocean drilling technologies, offshore terminals, platforms and production systems, and natural gas recovery and transport. Wartime skills in acoustic profiling and antisubmarine warfare were transferred into commercially important geophysical exploration techniques. The application of ocean drilling and geophysical techniques permitted the recognition and elucidation of plate tectonics patterns, development of seafloor spreading theory, and the transformation of our knowledge of seabed and subseabed strata. After John Mero's studies and recommendations for developing marine manganese nodules in the late 1950's interest in nonfuel minerals grew rapidly. The formation of international deep sea mining consortia in the 1960's was accompanied by a flurry of ocean engineering development, minerals prospecting and associated environmental studies The Santa Barbara Oil Spill of 1969 resulted in a moratorium on both offshore energy and minerals leasing by the Depart- ment Interior, and catalyzed the development of new Federal legislation in 1972. In 1973 the offshore energy moratorium was lifted in response to the Arab oil embargo, and offshore energy activities surged for a time. Minerals were reopened to leasing following President Reagan's 1983 executive order implementing a 200 mile EEZ. Although interest was spurred by

Jan 1, 1995

By Philomene Verlaan

Analysis of the relationship between environmental parameters and the content of Mn, Ni, Co, Cu, Fe and Zn in ferromanganese crusts permits improved identification of locations to prospect for crusts with commercially valuable concentrations of these metals. In this study we asked whether a statistically significant relationship exists between primary productivity of the overlying surface waters, the concentration of O2 in and depth of the O2 minimum layer on the metal content of non-hydrothermal ferromanganese crusts in the Pacific Ocean between 130o W and 175o E and 0o to 30o S (the study area). To further develop the interpretation of the results of the statistical analysis and to assess in detail the geographical expression of these parameters in terms of metal content in crusts, a geostatistical technique (kriging) was used to generate contoured values for metal content, primary productivity and O2 concentration in and depth of the O2 minimum layer in the study area.

Jan 1, 2001

By Andrea Koschinsky

Ferromanganese crusts have traditionally been considered a potential ore for Co, whereas ferromanganese nodules have typically been considered a potential ore for Ni and Cu. However, both nodules and crusts sequester high concentrations of many metals (Table 1) from sediment pore waters and seawater, many of which are essential for high-tech applications. The resource potential of these rare and valuable metals is poorly known and they are the subject of considerable current research. The need for adequate and dependable supplies of these metals is essential for the development of new technologies. The rare-earth elements have recently received much attention in the scientific and popular press because of their use in so many high-tech applications and because more than 95% of the production comes from China (e.g., Service 2010); consequently, there is concern about the possibility of a significant decrease or even curtailment in exports from China. The lack of a primary source and the inadequate supply of Te have prohibited the development of a Cd-Te photovoltaic solar-cell industry (Hein et al. 2010). Inadequate supplies of many of the elements listed in Table 1 are limiting the development of key high-tech industries, forcing the use of alternative metals that [ ] may result in less efficiency or less favorable properties for a product. The rare-earth elements, Te, and other elements listed in Table 1 occur in high abundances in marine hydrogenetic and diagenetic ferromanganese deposits. Here, we look at the mechanisms by which these rare and valuable metals are incorporated into different genetic types of marine ferromanganese deposits.

Jan 1, 2010

By Natalia Konstantinova, Kira Mizell, James R. Hein, Georgy Cherkashov

"Ferromanganese crusts and nodules from the Amerasian basin of the Arctic Ocean are characterized by a unique composition compared to crusts formed elsewhere in the global ocean (Konstantinova et al., 2017; Hein et al., 2017). One of the most significant differences from global ocean crusts is the high detrital mineral content; mass balance calculations show that it may be as high as 35% in some samples (Hein et al., 2017).These Arctic Ocean Fe-Mn crusts also typically have three distinct megascopic layers, except for thin crusts; less commonly, four layers are noted for thick crusts. The age of initiation of Fe-Mn crust growth in the Amerasia Basin varies from 14.8 Myr to 0.7 Myr ago based on the Manheim and Lane-Bostwick (1988) Co chronometer, Be isotopes, and Th excess methods (Dausmann et al., 2015; Konstantinova et al., 2017; Hein et al., 2017).Samples and MethodsFourteen Fe-Mn crust samples recovered on Russian and U.S. research cruises were chosen for analyses based on their morphology, composition, water depth, genetic type, and location in Amerasia Basin. Seven samples from four distant dredge sites along Mendeleev Ridge and seven samples from four locations on the Chukchi Borderland are included (Fig. 1). Dredge site water depths vary from 3850 to 2100 m with the deepest samples from the Chukchi Borderland. Many of the selected samples were described in previous publications (Konstantinova et al., 2017; Hein et al., 2017)."

Jan 1, 2017

By Georgy Cherkashov

Shallow-water formation of marine ferromanganese nodules as well as their deep-water analogues is found throughout the global ocean. The Baltic Sea is a key province for the shallow-water type of marine minerals. The following main distribution areas of Fe-Mn nodules have so far been discovered in the Baltic Sea: the Gulf of Bothnia, the Gulf of Riga, Central Baltic area (Gdansk- Klaipeda) and the Gulf of Finland. The last area (Gulf of Finland/Finnish Bay) is the best studied from all aspects including geological prospecting and environmental assessment.

Sep 14, 2011

By Seung-Kyu Son

This study was investigated about physico-chemical parameter such as water temperature, salinity, inorganic nutrients and total organic carbon (TOC). CTD (Model: Sea-Bird 911 Plus) castings were carried out on two transects in the northeast equatorial Pacific Ocean. As a part of the Korea Deep-sea Environment Study (KODES), inorganic nutrients and TOC were determined at 41 stations located from 131° to 136°W along 10.5°N and from 17° to 5°N along 131.5°W (Fig. 1). We particularly chose KODES Long-term Monitoring Station (St. KOMO) to observe for the annually environmental baseline study in the contract area. [ ]

Jan 1, 2005

By James R. Hein

Barite and Fe-Mn-oxide deposits that occur along faults in the Southern California Borderland formed by low-temperature hydrothermal processes. The Borderland region consists of block-faulted continental crust within the broad transform boundary of the North American plate. The fault-bounded basins are anoxic and partially filled with hemipelagic and turbidite sediments. Barite was collected from four dredges and a submersible dive (DSV4-355) in the southern California Borderland, and was collected from two sea-cliff sites along the Palos Verdes Headlands near Los Angeles. Barite at these seven locations occurs along strike-slip and basin-margin faults from the shoreline to 1800 m water depth. Submersible observations showed a series of mounds up to 10-m high composed of friable, white barite associated with diffusely venting milky fluid; the mounds support large benthic colonies, including tube worms (Lonsdale, 1979). Barite samples recovered from dredges are brown, green, and white and range from porous, vuggy fragments to massive fragments cut by banded barite veins. Samples from two dredge sites contain fossil worm tubes 1-3 mm in diameter and >10 cm long. All the samples are nearly pure barite, with only minor to trace amounts of other minerals. Chemical analyses show 94-98 wt. % BaSO4, low total rare-earth element (REE) contents (<45 ppm), Sr contents from <2 to 10,000 ppm, and Hg contents up to 1 ppm. Chondrite and shale-normalized REE patterns show light REE enrichments and large positive Eu anomalies. These REE pattern characteristics are typical of marine hydrothermal fluids and minerals. Sulfur isotope ratios (d34SCTD) from +21.6 to +67.4? range from seawater values (+21?) to exceptionally high positive values. Strontium isotope ratios are lower than the modern seawater ratio as well as the seawater ratio that existed at the time of deposition of the host rocks.

Jan 1, 2002

By J. A. Jankowski

The situation in the raw material market has brought into consideration the commercial exploitation of the mineral deposits on the deep sea bed and in particular the manganese nodules. They occur generally in depths of 4000-5000 m, partially covered or buried in bottom sediments. The deposits and their potential recovery have been intensively explored and researched during the past twenty years (Bischoff 1979, Halbach 1988, Padan 1990). Although the present market situation limits the rentability of deep sea mining on an industrial scale, the mining technology is being further developed in many countries. The stagnation phase in the deep mining issue allows sufficient time for conducting research on the precautionary protection of the deep sea environment and for consultation in the development of technologies with the least possible impact on it. The subject has gained in importance since autumn 1994, when the United Nations International Law of the Sea was signed. This also regulates human activities in international waters from the environmental point of view. As fields tests have shown in the past, even with the most modern technologies, mining of the manganese nodules will inevitably be accompanied by a resuspension of some bottom sediments. The generated sediment plumes will be further transported with the ocean currents and in the worst case form stable turbidity layers in different depths (Ozturgut 1981a, Baturin 1991). One of the problems of the environmental impact assessment is the estimation of the plume persistence before it eventually dilutes to approximately the ambient concentration level or settles at the bottom (Lavelle 1981a, Lavelle 1981b, Lavelle 1982, Thiel 1991a, Thiel 1991b). The aim of the research is to develop a numerical sediment transport model in connection with potential manganese nodule mining in a reference area located in the southeastern equatorial Pacific Ocean off Peru (Peru Basin, Discol Experimental Area). In this region, a German mining claim is registered and interdisciplinary field works of the TUSCH (German: TiefseeUmweltSCHutz, deep sea environmental protection) research group are carried out in order to obtain the required scientific background for evaluating of the deep sea mining impacts and to provide the necessary supporting data for the modelling (Thiel 1991a, Thiel 1991h).

Jan 1, 1995

By Rolf B. Pedersen, Filipa Marques

The extension of the Mid-Atlantic Ridge north of Iceland has collectively been referred to as the Arctic Mid-Ocean Ridges (AMOR). The AMOR extends from the northern shelf of Iceland, to the Siberian shelf in the Laptev Sea, passing en route through the Norwegian- Greenland Sea, the narrow gateway of the Fram Strait, and across the Eurasia Basin. The AMOR is 4000 km long and is divided into six super segments: 1) the Kolbeinsey Ridge, 2) the Mohns Ridge, 3) the Knipovich Ridge, 4) the Molloy Ridge, 5) the Lena Trough, and 6) the Gakkel Ridge. After continental rifting at 60-50 million years ago, around 2.5 million km2 of oceanic seafloor has formed by seafloor spreading - resulting in the formation of the Norwegian- Greenland Sea and the Eurasian Basin. This northernmost part of the global ridge system is anomalous in several ways: The seafloor spreading takes place at an ultraslow rate (less than 2 cm/y) with spreading rates decreasing northward to around 1 cm/y at the Gakkel Ridge - which is the most slow-spreading ridge on Earth. As a result, the volcanic activity along the northern part of the AMOR is low, the oceanic crust is unusually thin (around 3,5 km at the Knipovich Ridge, Kandilarov et al.2010), and the rift valley is deep (average water depth > 3 km). In the southern part of the AMOR, the ridge system is affected by the Icelandic plume and a hot spot below Jan Mayen. The ridge-plume interaction results in higher volcanic productivity, unusually thick oceanic crust (9-11 km, Kandilarov et al. 2012) and shallow ridge segments (1500-100 m). The AMOR also display contrasting spreading regimes, whereas some super segments are dominated by orthogonal spreading (Kolbeinsey and Gakkel Ridge) others are characterized by highly oblique spreading (Mohns and Knipovich ridges). Some ridge segment displays asymmetric spreading, like the Mohns Ridge where core complexes preferentially form along the northwestern flank. Together these variations in ridge characteristics results in large diversity of hydrothermal systems and associated mineral deposits.

Jan 1, 2018

By Sabrina Warwas, Thomas Kuhn

"Due to rising prices and increasing demand of raw materials over the last years, marine mineral resources including manganese nodules have become a focus of study for industry and science. Marine ferromanganese nodules consist of micro-layers of different chemical and mineralogical composition which incorporate metals of high economic interest (Ni, Cu, Co, Zn, Mo, Li, rare earth elements; Hein & Koschinsky, 2015).The varying composition of the layers depends on different growth processes, such as hydrogenetic (metal precipitation from the water column under oxic conditions; Mn/Fe = 3), diagenetic (metal precipitation from the sediment pore water) under oxic (Mn/Fe 3-10) or suboxic (Mn/Fe = 10) conditions; (Wegorzewski & Kuhn, 2014) or hydrothermal (metal precipitation from low-temperature hydrothermal fluids; Kuhn et al., 2003).METHODSIn this study, manganese nodules from three different locations of the Atlantic Ocean (Galicia Bank; Vema-Fracture-Zone and Brazilian Basin) were analyzed for their geochemical and mineralogical composition. Detailed information about the samples are given in table 1. The geochemical and mineralogical composition of bulk nodules were determined by XRF, ICP-MS/OES as well as XRD and the single micro-layers by high resolution analyses with electron microprobe and LA-ICP-MS."

Jan 1, 2017

By Hal Palmer

A number of Articles contained in the United Nations Convention on the Law of the Sea III (UNCLOS) bear directly on legal issues related to the recovery of mineral deposits on the ocean floor. Mineral resources of the continental margin other than oil, gas and hydrates include, sand, gravel, shell, coral, gemstones and phosphorite. Jurisdiction over the exploration and exploitation of these deposits is determined either by the Territorial Sea claims of a coastal state or their recognized sovereign rights in the Exclusive Economic Zone (EEZ). At least 33 coastal states have the right under Article 76 (Continental Shelf regime) to claim seabed jurisdiction beyond 200 nautical miles (EEZ limit). In addition, several states have "Pioneer Investor" status with regard to seabed resources in international waters (The Area). A global maritime boundary database (GMBD) has been developed as a basic resource identifying the current claims of coastal states. It provides detailed information on existing boundaries and limits determined by the UNCLOS accords or by multi-lateral agreements which affect mineral exploration and exploitation. This paper will describe the GMBD and its construction and maintenance.

Jan 1, 2000

By Rahul Sharma

Although, mining of minerals such as polymetallic nodules and sulphides from the deep sea floor has been delayed due to the combination of factors such as current availability of Cu, Ni, Co, Mn (and other metals) on land and their fluctuating prices; these deposits are still considered as the alternative source for metals in the 21st century. Exclusive rights for exploration in the ?Area? (beyond the national jurisdictions of any country) given to eight countries and consortia by the International Seabed Authority and the estimated resource of 300 million tonnes in a typical area of 75,000 km2 is expected to yield about $17.5 billion (at December 2008 metal prices) in 20 years life span of a single nodule mine-site. In order to recover 3 million tonnes of nodules, an area of 300 sq km only will be mined annually (i.e. <1 km2/day) for an optimum abundance of 10 kg/m2. However, during mining, large quantity (22 tonnes/day) of sediments associated with nodules would be resuspended that could lead to certain environmental impacts on the benthic ecosystem. Several small-scale benthic impact experiments in the Pacific and Indian Oceans, have given some insight into the possible environmental impacts and the restoration processes, but the possibility of extrapolating these findings to a commercial mining scale remains an issue to be considered. An estimated capital expenditure of $1.05 billion and operating expenditure of $4.2 billion for a single deep-sea mining venture will have to be weighed against the availability of mineral ores on land as well as the metal prices in the world market. None-the-less, development of technologies for mining and metallurgical processing, as well as formulation of regulations and guidelines for potential ?contractors? to mine these minerals have been progressing consistently. These coupled with recent efforts by certain ?entrepreneurs? to initiate mining of seafloor massive sulphides in the EEZ of certain countries, indicate the continuing interest and support the perception that such deposits could well be the future sources of metals. This paper analyzes the current status and discusses the economic, environmental, and technical issues that need to be addressed for sustainable development of deep-sea minerals.

Jan 1, 2010

By Carsten Rühlemann, David Friedmann, Bernd Friedrich, Thomas Kuhn

"This paper explores the option of direct reduction smelting of the nodules from the German license area in the equatorial NE Pacific in a submerged arc furnace (SAF). An optimized slag design is proposed to separate the larger Mn-bearing stream from the valuable metals (i.e. Ni, Cu, Co, Mo). The slag optimization allows a maximum of Mn to be retained in the manganese-silicate slag on the one hand and a maximized metal recovery in a FeNiCuCo alloy on the other. This way, the goal is to make use of the complete nodules (“zero-waste”) instead of extracting only the metals Ni, Cu, and Co, which make up about 3 wt%. The process closely relates to the “Inco Process” by the Ocean Management Inc. (OMI) of the late 1970s, which was a consortium of INCO (International Nickel Company, CAN; today Vale Canada), Preussag AG & Metallgesellschaft AG (GER), DOMCO (JPN), and Sedco (USA). However, the manganese containing slag is investigated in more detail to recover FeMn, FeMnSi and/or SiMn. To optimize the process modern tools such as thermo-chemical modeling in FactSage™ have been used. [1,2]Polymetallic deep-sea manganese nodules may offer a decreased dependency of raw material imports for Germany and the EU. Currently, four European countries (United Kingdom, Belgium, Germany, and France and an Eastern European consortium (InterOcean Metal)) hold exploration licences for these nodules in international waters in the equatorial NE-Pacific. The license areas each cover 75 000 km2 of the seafloor and are located in the Clarion Clipperton Fracture Zone (CCZ) south east off Hawaii at water-depths between 4000 and 6000 m. The nodules may be used as a resource for industrially important metals such as Cu, Ni, Mn as well as for technology metals like Co, Mo, V and Zn. The average chemical composition of nodules from the German license area is presented in Table 1. [3,4]"

Jan 1, 2017

Although Mn, Fe, Cu, Ni, and Co have been the main interests since the ferromanganese nodules had been found, the other major components such as Si and Ca might be very important controlling factors in the processing due to the locally variable content. It is because of the fact that SiO2 and CaO are added to decrease the smelting temperature in the reduction-smelting method for manganese nodule processing. We have compiled the 707 chemical data for KODOS (Korea Deep Ocean Survey) ferromanganese nodules, which have been acquired from 1994 to 2001 and have been also standardized from 2001 to 2003 to avoid the discrepancy between the data sets. All 707 chemical data were used for the hierarchical cluster analysis to get the elemental correlations and also classified by the morphological types. The averages from each station were classified by the facies groups (Fig. 1) and the localities. Then all data are plotted on the SiO2-CaO-MnO phase diagram at 1773°K to compare with the best compositional area in the nodule smelting. Variations and distributions of SiO2 and CaO as well as those of Mn, Fe, Cu, Ni and Co in KODOS ferromanganese nodules were also reviewed. The mineral phases assigned by the cluster analysis are CFA (Carbonate Fluorapatite), Fe-oxide, Al-silicate, and Mn-oxide. MnO contents are generally higher than SiO2 contents in most of the morphological types except for the Is- and It-type. The Dt- and Tt-type show wider range and the E-types show high anomaly in their CaO contents. The stations which belong to facies group A and B show generally higher MnO contents than SiO2 contents, however, the stations of facies group C and D show wide range in their MnO and SiO2 contents.

Jan 1, 2004

By Olav Rune Godø

We present a science-based infrastructure for continuous online monitoring of the ocean interior including benthic, pelagic and the demersal habitats. It will reduce expensive ship based monitoring costs associated to offshore and coastal industries. We combine established Norwegian cabled observatory technology and German mobile seafloor robotic technology and thus supports the transition from local to spatial ecological monitoring. Both technologies are developed through science - industry partnerships. In Norway, the Institute of Marine Research has worked with Statoil ASA and Metas AS to install and operate the LoVe cabled observatory. The German technology is developed by iSeaMC and Kraken Robotik, two spinoff enterprises of the Helmholtz Alliance “ROBEX”. GEOMAR has recently developed a lander-based deep-sea crawler that operates autonomously based on the original iSeaMC crawler system using the Kraken Autonomy. Combined with the Spanish image processing and modelling expertise in the SME Deusto Sistemas SA the consortium hosts the capacity to establishing a complete semi-autonomous real-time monitoring system. Merging of existing technologies into one operational autonomous product through the unique competence of partners’ support international ambitions (e.g. Blue Growth, GES, Horizon 2020), and renew monitoring that assess impact of human use of the marine environment. The consortium has been invited to contribute to technology/science programs for the Yellow Sea and for European mining and offshore decommissioning industries, which demonstrates the leading role of our consortium. The project is funded through the EU Martera program and started in June this year.

Jan 1, 2018

By Sebastian Ernst Volkmann, Felix Lehnen

"INTRODUCTIONWhile today’s mine planning of land-based ore deposits follows methods, which are well established, mining standards for the deep-sea have not established. Having gained a basic understanding of geological settings, there is still a lack of tools and methods to assess and plan future mining projects in the deep-sea. In the framework of the “Blue Mining” research project (2014-2018) technologies and methods for the exploration and exploitation of deep-sea minerals are developed that will bring deep-sea mining a step closer. The “Blue Mining” project receives funding from the European Commission (EC; Framework Programme 7; GA No. 604500) and addresses all aspects of the value chain in the field of deep-sea mining. The project philosophy is that deep-sea mining is planned and executed in the most responsible manner: Ensuring societal benefits and profitability at acceptable resource utilization and lowest possible environmental footprint (Volkmann 2014).Inspired by the high-tech farming industry, a concept to mine seafloor manganese nodules (SMnN) was developed. Mining is considered to be similar to the potato harvest on land (Figure 1), which involves mining a field partitioned into long, narrow strips (Volkmann and Lehnen 2017). The proposed mining system composes of one mining support vessel (MSV), one or two self-propelled, crawler-type seafloor mining tools SMT(s) and different types of underwater vehicles. The MSV follows the mining route of the SMT(s), picking up the about potato-sized nodules from the seafloor. The ore is pre-processed in situ and is lifted on board of the MSV, where the ore is dewatered and loaded onto bulk carriers for transport to the purchaser. Processing and refining of ore is not subject of “Blue Mining” research."

Jan 1, 2017

By Peter Halbach

Within the frame of the German-Indonesian cooperative Bandamin research project two short cruises (7 station days each) were carried out which led to the Flores-Banda basin located north of the active volcanic arc. This basin is part of a large island-arc subduction-collision system resulting from a complex plate tectonic situation in which three major plates collide with each other. The eastern part of the Sunda-Banda convergent margin also includes the transition from subduction of oceanic lithosphere to collision of the Australian continental crust with the arc. This transitional part is cut and displaced by various large obliquely striking fault systems. Thus, the south eastern and eastern arc segments represent geological conditions which are suitable for the development of hydrothermal convection and potential mineral precipitation. Our study area lies north of the transitional section between Flores and Wetar. We started with a high-resolution bathymetric mapping of 240 km2 in a region some 36 km north of the island of Lomblen. A small submarine neovolcanic ridge was discovered striking approximately NW-SE and consisting of several submarine volcanic structures. In the northwest of the study area, the active subaerial Komba Volcano (Batu Tara) marks the youngest continuation of the ridge system examined. From the ridge we collected fresh and hydrothermally altered volcanics with disseminated sulfides (pyrite, pyrrhotite, markasite, and chalcopyrite), together with ferrugenous gossans.

Jan 1, 2004

By Katsuya Tsurusaki

Commercial mining of manganese nodules is expected to begin within the next 20 to 50 years in large areas of abyssal sea floor in the Pacific Ocean. While deep sea mining is expected to realize significant quantities of rare metals that are needed for modern technology, the mining operation will cause extensive resedimentation over large areas of deep sea floor, the effects of which are thought to be harmful to the benthic community. Our present knowledge of deep sea benthic ecology is so limited that we cannot predict the magnitude of the impact. In November 1994, the United Nations Convention on the Law of the Sea was enforced and giving added impetus to improving our understanding of the effects of future mining operations. In order to fully understand the impact of deep sea mining and to mitigate the harmful environmental effects, it is necessary to accumulate more information on the deep sea environment and benthic communities. To achieve these objectives and to understand the relationship between resedimentation and biological reaction, artificial impact experiments are being conducted by the USA and Germany. The former named BIE (Benthic Impact Experiment) began in 1991 and is being performed by NOAA (National Oceanic and Atmospheric Administration of the United State of America) in the North Equatorial Pacific Ocean. The latter named DISCOL (Disturbance and Recolonization Experiment in the Deep South Pacific Ocean) was started in 1989 and is being conducted in the South Equatorial Pacific Ocean by a scientific group from Hamburg University. The Metal Mining Agency of Japan (MMAJ) is also carrying out environmental studies. These studies, commenced in 1989, are being conducted in association with NOAA and include an experiment named the Japan Deep Sea Impact Experiment (JET).

Jan 1, 1996