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By Richard H. T. Garnett

Diamonds were discovered on the coast of Namibia in 1907 but it was not until 1962 that the first gems were produced from offshore by a barge employing an airlift. Geophysical surveys and a sampling program were initiated and an understanding of the diamond distribution was gained. Several vessels, some with multiple airlifts, were used until the early 1970's. Some spectacular production results were achieved, but generally the systems failed to retrieve the gravels efficiently from beneath the overburden and off the bedrock. Various companies continued working with mixed outcomes until the mid-1980's, when new regulations were enacted by the authorities. The local Southern sea conditions dictate the present mining methods which are now applied over several hundred kilometers of the west coast. In shallow waters divers operate from small vessels, suctioning the diamondiferous gravels to surface with gravel pumps. In water depths of up to 50 m airlifts of various designs continue to be utilized with recovery plants installed on the vessels. Beyond 100 m depths a remote controlled, tracked, vehicle is used, together with a large drill mounted on swell compensator. Each system is deployed from a separate ocean-going vessel. Production of diamonds from the offshore is rising rapidly, with expectations of further increases. The coastline is likely to be the scene of new developments in marine mining techniques.

Jan 1, 1992

By Huaiyang Zhou

It has been long known that manganese nodules occur more or less in some part of marginal seas in West Pacific Ocean. On the other hand, it is difficult to understand their distribution and the genesis as those nodule samples were collected mostly by dredge from the deep basins generally has much higher sedimentation rate than the open ocean. For example, the sedimentation rate in the South China Sea is about three orders of magnitudes than that in region of the Clarion-Clipperton Fracture Zone. In June of 2013, a small seamount (named as Jiaolong Seamount), consisting of southern part and northern part with a distance of about 3 km each other, was visited by DSV Jiaolong/RV XiangYangHong 9. It is discovered that abundant manganese nodules exist only on the surface sediment in the southern part with a water depth of about 3800 m to 3300m, on the platforms nearby an obvious crater where volcanic rocks exposed on the wall. There are no any nodules be observed on the sediment in the northern part of the seamount (about 100 m deeper than the southern part) and surrounding deep basin (approximately 4000 m in water depth). It is speculated that a source of core for manganese nodule and a dynamic sedimentation environment, are two major governors for the growth and distribution of manganese nodule in the marginal seas.

Sep 14, 2011

By Siobhan Quayle

Managing sediment plumes under multiple jurisdictions Management of activities in the New Zealand EEZ can be characterized as a distributed basis of decision-making with each independent and separate decision-maker focused on specific elements of a proposal (environmental, work place safety, wildlife management, fisheries, navigation, oil spill). The New Zealand EEZ Act 2012 was intended as gap-filling legislation to address the lack of an environmental assessment lens for permissions to undertake certain activities in the New Zealand EEZ. These activities relate mostly to marine scientific research, dumping and discharges, oil and gas exploration and development, and seabed mining. The regulatory decision-maker for most EEZ Act marine consents is the New Zealand EPA. Since 2013 when this gap-filling legislation took effect, the EPA and its decision- making committees have processed three seabed mining applications. Two consents were refused, one consent was granted in 2017. A common feature of all consents has been the assessment and consideration of the scale, significance and effects of sediment plumes arising from the activity. One consent is for irons and mining in about 40m of water where the plumes reach the nearby coastal waters and shoreline, the second consent is far offshore but plumes extend far beyond the mining area (850 km2) in to rare coral habitats and in to a significant offshore fishery. A significant consideration for decision-makers is how the assessment and management of plumes under the EEZ Act interact with, and potentially overlap, management of such plumes under other legislation (Resource Management Act, Marine Mammals Protection Act, and Wildlife Act). This is in a statutory context where the EEZ Act requires explicit consideration of the nature and effect of other marine management regimes over the matter under consideration.

Jan 1, 2018

By Richard T. Haworfh

The United Nations Convention on the Law of the Sea (UNCLOS) entered into force, for those nations who had ratified it, on November 16, 1994. The Convention deals with nearly every aspect of ocean affairs, including marine scientific research, fishing zones, freedom of the high seas, protection of the marine environment and deep seabed mining. Article 76 of the Convention defines edge of the continental shelf in a way that many earth scientists find bizarre. Out to this limit, a coastal state has sovereignty over the seabed and sub-seafloor resources. Beyond that limit, the key principle of UNCLOS, that "the resources of the deep seabed represent the common heritage of mankind and should be developed to benefit all nations" is invoked. Establishing that limit and managing development in the different areas of jurisdiction is no small task. Canada's continental shelf as defined by UNCLOS covers an area approximately equal to half the area of the Canadian land mass. Interpretation and application of the convention is therefore highly significant for Canada. For example, the sedimentary basin in which the offshore Hibernia oil field is found, extends beyond the 200 mile limit but lies predominantly within the limits of the (UNCLOS) continental shelf. Responsibility for development of inshore placer deposits rests firmly with the coastal state. However, development of deep sea mining, in which the international community plays a management role under UNCLOS, has raised many concerns. Of particular interest to Canada will be the application of the provisions of the convention to interest in the polymetallic sulfides sampled on the mid-ocean ridges such as the Juan da Fuca Ridge. A further complicating factor for Canada is management of fishing stocks. Canada has sought to resolve this "problem" through multilateral negotiations under the UN. Under its "Oceans Act," currently being debated by Parliament, Canada intends to become a world leader in oceans and marine resource management. Similar activity in most maritime nations is setting the stage for a revolution in the way in which use of the world's oceans is managed. Much of this revolution will be guided by UNCLOS. Coastal states that have ratified the convention have ten years in which to define the limits of their continental shelves the clock is already ticking for them! We have yet to see how their actions will guide, or be guided by, those who have not yet ratified. We also have yet to see how national legislation and aspirations will mesh with international conventions that were drawn up in a previous era of environmental standards. This is a time in which many questions have been raised and few firm answers received. However, we must ensure that everyone is aware of what is happening, with what potential consequences, in order that rational decisions can be made. Canada has taken a few small steps that it is happy to share with the world community.

Jan 1, 1996

By Freddy Pøhner

The paper describes recent advances in the technology for mapping of the seabed with acoustic instrumentation. These instruments are typically single beam echo sounders, multibeam echo sounders and high resolution sub bottom profiler. For the single beam echo sounders, new features for deep water mapping are described, as well as the possibility for combining investigation of shallow areas with side scan sonar and vertical echo sounding in the same instrument. Multibeam echo sounding technology for deep and shallow water is reviewed, and some new high resolution instruments using dynamic beam focusing is presented. The sediment profiling technology deals with a novel design for high resolution sub bottom profiling, based upon a Mills Cross transducer with resolution as good as 3 degree in its largest configuration and a frequency range of 2,5 ? 7 kHz. Remarkable features of the system are a very high ping rate even for deep water, and the capability to map buried objects or structures by several simultaneous beams. Some results obtained with the first installation on the French research vessel ?Beatemps Beaupré? are presented.

Jan 1, 2003

By Alexander Malahoff

The new ship-submersible system with R/V Ka'imikai-o-Kanaloa as a mothership and the PISCES V as the submersible completed its first season of dives. The dives involved deployment of the PISCES V in the Hawaiian Islands between the months of July and October 1996. Submersible deployments up to depths of 2,000 meters in sea states up to a high three were made. The new hook and clasp deployment and retrieval connection for PISCES V to the telearm was shown to be an effective system for handling the PISCES V with the A-frame. The shipboard multibeam survey and seawater sampling capability proved to be especially effective in re-mapping the summit of the submarine volcano Loihi following a major volcano-tectonic event and for following the source and configuration of the new hydrothermal plume. Following the earthquake swarm of July 17 to August 18,1996, major changes in the geological setting of Loihi submarine volcano took place. Prior to the seismic event, the geology and structure of the summit of Loihi was represented by a platform-like area 8,100 meters long and 5,400 meters wide enclosed by the 1,200-meter depth contour. The summit was characterized by the presence of two prominent pit craters and eastern and western crater located at water depths of 1,100 and 1,370 meters, respectively. A hydrothermally active volcanic cone, named Pele's Vents, was located at a depth of 960 at the southern edge of the summit. The floor of the summit of Loihi was largely covered by prismatic talus, with interstitial hydrothermal clays. Pillow and tube lavas with volcanic cones 5 to 50 meters high were exposed along the axes of the southern and northern rift zones. The inner margin of the summit displayed fissures and normal faults with the downthrown component towards the center of the summit. The pre-earthquake structural data suggest a pre-caldera structural stage for Loihi. Maximum sustained hydrothermal activity observed on Loihi over the past 10 years existed at Pele's Vents with other sporadic venting occurs along the summit platform and along the south rift. Following the earthquake swarm, the hydrothermally saturated Pele's Vents cone gave way and slid into the inner pit crater. Subsequently, the observed above- bottom hydrothermal plume source deepened from 960 to 1,160 meters, possibly emanating from the same intrusive heat source as Pele's Vents. The observed inward collapse of the summit structures and subsequent opening of fissures gave rise to diffuse venting from the newly formed caldera-like depression with the bottom-hugging hydrothermal pool located at depth between 1,250 and 1,220 meters at the sites of the pit craters.

Jan 1, 1996

By B. J. Bluck

Diamond mega-placers, in order to rank amongst the primary diamond deposits, are defined as => 70 m carats at =>95% gem quality. There is only one mega-placer known and that is found along the coast of southwestern Africa fringing the Kaapvaal craton. Placers are classified as residual when they are left on the craton, transient when being eroded into the exit drainage and terminal. Terminal placers, in being the final depositories of diamonds off the craton, have the greatest probability of being a mega-placer and such is the case in the placer deposits near the Orange River mouth, southwestern Africa. There are four main groups of conditions leading to the development of a mega-placer: the craton, the drainage, the nature of the environment at the terminus and the timing. The craton, in its role as the producer of diamonds is significant in respect to its size, diamond-fertility, the degree to which diamonds from successive kimberlite intrusions have been retained there and their availability to the final drainage yielding the mega-placer. Cratons in being buoyant have a tendency to leak diamonds into surrounding basins but in being incompressible often have orogens converge onto them resulting in lost sediment being returned as foreland basin fills. In order to concentrate a bulk of diamonds the drainage basin has to be large with a high proportion of it on the craton. The drainage yielding the mega-placer should ideally not have been preceded by older drainage and other systems that may have robbed the craton of earlier diamonds. The exits of diamonds from the craton need to be few in order to focus on their supply and the drainage network needs to be efficient in order to remove the maximum volume of diamonds off the craton. This efficiency and the focused termination is best achieved by the rejuvenation of a pre-existing drainage network. The drainage should be young enough to yield host sediments friable enough to allow brittle diamonds to be recovered from them.

Jan 1, 2004

By Robert Ditchburn

Within New Zealand?s extended EEZ there exists a vast submarine hydrothermal mineral resource associated with the Kermadec intra-oceanic arc. Along this arc more than thirty submarine volcanoes have been explored by GNS-lead researchers and, of these, c. 60% are known to be hydrothermally active and a site of active seafloor mineralisation. Assessment of whether this mineralisation is economically viable in terms of grade and tonnage is now underway. A key aspect of these investigations is determining the age of the mineralization which will have a direct bearing on its mode of formation, the time elapsed to amass an economic deposit and, ultimately, its capacity for sustainable extraction. Intact barite-rich ?black-smoker? chimneys similar to that depicted here (86 cm long) have been recovered from Brothers volcano in the southern part of the arc. These and other hydrothermal deposits provide evidence of active volcanic massive sulphide (VMS) mineralisation along the arc, the age of which can be determined from the disequilibrium between isotopes within the thorium or uranium decay chains. A chimney from Mariana arc has also been dated using these radiometric methods. The principle dating technique for chimneys up to 15,000 years old uses the decrease in 226Ra/Ba due to radioactive decay after the VMS was deposited. An initial ratio is obtained from chimneys that are proven to be less than 100 years old and this involves dating with 210Pb, 228Ra and 228Th that have short half-lives compared with 226Ra.

Jan 1, 2005

By Campbell McKenzie

Substantial consideration has been given to the implications that the morphology of the Chatham Rise deposit will have on mining operations. The glacio-tectonic processes involved in the distribution of nodules on the rise has in several areas been quite significant. The recent cruises by Chatham Rock Phosphate Limited (CRPL) have collected data which has affirmed the assumptions previously made and catered for in historic resource estimations. The deformation and displacement of the phosphorite during glacial periods and the redistribution of the mobile sand during interglacial periods is interpreted to have produced a highly variable pattern of phosphorite concentration (kg phosphorite/m2) and coverage (% phosphorite/sample weight). The phosphorite resource probably has a significant spatial variability at a scale of tens of metres. Results of recent surveys show phosphorite-rich patches alternating with phosphorite-poor areas at distances of less than 20 m. The high spatial variability of the deposit has had a bearing on how historical information for the project has been regarded and integrated with the recent exploration approach and data collection process. This coupled with the proposed extraction tool has influenced the size, nature, extent and siting of the proposed mining blocks

Sep 14, 2011

By Sang Bum Chi

In order to better predict and manage benthic disturbance by deep seabed manganese nodules mining, we needed to conduct a benthic disturbance experiment at the selected area, which has a similar environmental condition as the preservation reference area. Therefore, we have performed environmental baseline studies from 2003--not only to select the benthic environmental impact testing site but, also to detect any environmental changes before and after mining activity. Since then, a large dataset of various parameters ranging from physical (e.g. temperature, salinity, current, weather), chemical (e.g. dissolved oxygen, nutrients, dissolved and particulate organic carbon), biological (e.g. bacteria, plankton, benthos), geological (e.g. Mn-nodule abundance, sediment shear strength) and others (e.g. bathymetric profile and slope, mass flux) have been accumulated. Using this dataset, descriptive statistics and cross-correlations were performed to select the benthic environmental impact testing site. Outcome of this analysis suggests that the potential benthic impact testing site would be a rectangular-shape area (10 km × 10 km) and located at 10°27'~10°33'N, 131°53'~131°58'W, which is latitudinally the same as the preservation reference area.

Jan 1, 2011

By Brian D?Olier

Much of the aggregate that is being exploited at present from these areas is a ?relic? deposit. It was originally eroded from primary source rocks and transported to a depositional centre by processes that are now either greatly reduced in effectiveness or are largely absent at the present time. Following the retreat of the Devensian ice sheet, the subsequent rise of sealevel and the drowning of large areas of the continental shelf along with the lower reaches of many rivers, a fresh sequence of sediment sources, pathways and sinks now exist. Sediment is being eroded from several, pre-existing source areas and transported along different, well - defined pathways to a number of new depositional sinks. Some of the present, licenced, aggregate dredging areas lie close to these sources, pathways and sinks with the consequent dredging activity being perceived by some as interfering with the ?natural process? that links the offshore and the coastal / littoral zones. With this perception in mind, the principal, sources, pathways and sinks between Flamborough Head and Beachy Head will be highlighted and the relationship of dredging activity upon them, evaluated. It will be demonstrated that offshore dredging activity has no effect upon supplies of sediment to coastal beaches.

Jan 1, 2004

By Harald Brekke

On 13 July 2000, the ISA adopted the Regulations on Prospecting and Exploration for Polymetallic Nodules in the Area. The first contracts for such exploration were issued by the ISA the same year. The duration of exploration contracts is 15 years, after which the contractors are expected to go into exploitation. In 2013, ISA with the LTC initiated the process for developing the regulations for exploitation, and are currently working on the first draft to put forward for the Council. In the meantime, the first seven exploration contracts have expired, and been given five years extensions in order for the contractors to get ready to apply for exploitation contracts. According to the current draft of the exploitation regulations, an application for an exploitation contract shall be accompanied by all data acquired during the exploration phase, a mining plan, a financing plan, and a set of environmental plans (i.e. an environmental impact statement, an emergency response and contingency plan, environmental management and monitoring plan, and a closure plan). All of these plans have to be based on substantial scientific and technical data and information. The mining plan requires geoscientific data regarding the mineralogy and grade of the nodules, and the physiography of the mining site as a basis for the consideration of critical aspects, inter alia for making reliable resource estimations, design the mining operations, and forecast revenues. The environmental plans require the input of a substantial set of bioscientific data and information on the exploitation technology in order to establish base-lines, and monitor and evaluate the effects of the mining operations. Under the exploration contracts, such scientific data have been acquired and reported on an annual basis to the ISA. Some testing of mining equipment and experiments on the extraction of metals have also been performed by some contractors. These scientific and technical data from the exploration phase will be the basis for the for the preparation of the studies, plans and documents required for the applications for exploitation. No time frame is specified for the preparations of an application but it must be assumed to take place before the expiration of the exploration contract.

Jan 1, 2018

By Mikhail D. Ageev

The paper concerns with some questions of Autonomous Underwater Vehicle (AUV) control system design, which allows a motion at rough undersea terrain. The AUV advantages reveal itself completely during exploration of such objects as seamounts and reefs area. These objects are characterized by steep slopes (30 degrees and above) and chaotic situated obstacles (rock debris, pinnacles, escarpments). Uses of other technical facilities for operating in such formations are difficult, dangerous or impossible. These regions take an interest due to the presence of iron-manganese crusts. Modern AUV can estimate density of mineral by means of still camera or video recorder. For this reason the vehicle has to move with the distance of 3-5 meters from seabed. Under such conditions micro- and mesorelief presents a considerable danger for AUV. The AUV can bypass underwater obstacles in the various ways. However, in any case AUV motion will be characterized by intensive maneuvering on various speed (from 0 up to 1.5 m/s), circular change of tractive force vector and, hence, a circular flow about the hull. So, AUV is equipped with the propulsion system, which provides free modes of motion. AUV control system (CS) has tri-level structure to allow a motion in a rugged seabed terrain. According to the generally accepted categorizations, CS includes execution, coordination and strategic levels. The strategic level contains the goals of AUV mission. Obstacles avoiding and route choice are realized by means of simultaneous maneuver in vertical and horizontal planes. Sonar system is used for data acquisition about obstacles. It consists of a few echo-sounders with fixed directivity pattern. The route choice algorithm operates at two lower levels of CS. Basic (?reflex?) functions of spatial motion are realized within the execution level and considered in the paper. The choice of motion modes is carried out at the coordination level of system. All accessible navigating information (the data from flight sensors and from multichannel echo-sounder systems) is used for this purpose. In addition the bypass of characteristic types of obstacles is carried out with the help of basic motion modes combination. The modeling results of bypass of various typical obstacles, and also their combinations are described in the paper.

Jan 1, 2011

By Hjalmar Thiel

Since industry is progressing into the deep sea, marine scientists have expressed their concern about environmental disturbances which will be introduced by using the deep seafloor for mining metalliferous resources or as a repository for wastes. Environmental studies have been conducted on national levels and in bilateral or multilateral cooperation in the development of manganese nodule mining, as this is generally achieved in marine research. These investigations were partly large-scale and experimental approaches aiming at the assessment of the impacts expected to occur in commercial mining. The results elaborated till today and expected to be acquired in the foreseeable future may remain limited. Reliable impact evaluation will result from monitoring a Pilot Mining Operation (PMO). The lecture will present the broad outlines of a possible program and a preliminary calculation of approximate costs for such a combined industrial test and environmental monitoring event. Although the extent of necessary efforts for the environmental risks evaluation can only be estimated rather vaguely, it will become evident that the required human, technical, logistical, and financial resources to be mobilized will exceed industrial capacities and go beyond national funds. Therefore, such assessment of environmental risks is calling for broad international cooperation. While industrial developments for mining the deep sea will be ruled by competition or probably by restricted joint ventures, environmental care ranges outside competition and falls within the interest of all parties involved. Environmental studies, unlike technologies for the same function, do not primarily need duplication. International cooperation in PMO monitoring would equally well support all mining companies or consortia, it would minimize the efforts for all engaged in this challenging venture of deep-sea mining and it would maximize the precautionary discussion on and the care for the deep-sea environment.

Jan 1, 1994

By P. C. Hollick

Two marine diamond deposits on concession 2b off Namaqualand along the South African Coast, have been systematically mined over the past year by the mv Moonstar. The two deposits, Smith?s Ulcer and Wedge Point Basin, are comparable in morphology, straddled the same water depths and have similar geology yet have given very different recoveries when compared to their respective grade models. These differences are best ascribed to the different style of mineralisation observed within the two deposits which has been directly controlled by the bedrock morphology. The smith?s Ulcer deposit has been formed in a metagreywacke bedrock displaying a strong north-south trending foliation which dips steeply to the west. Consequently the mineralisation is confined to narrow north-south linear trends with limited lateral extent (less than 5m) making extraction extremely difficult and somewhat variable. RE factors (recovered grade versus estimated grade) for this deposit range from 0.5 to 1.1. The Wedge Point Basin deposit is formed in a micaceous metaquartzite with a conjugate southwest northwest joint set, the southwest lineation being the more prominent, and structural foliation dipping gently to the west. The resultant style of mineralisation is confined to basinal features defined by topographical lows and is fairly lateral in extent (in order of 50m). Extraction of the mineralisation from this deposit is less arduous with recoveries more uniform, RE factors are frequently in the range 2 - 3. This style of mineralisation is more in line with what is to be expected from marine alluvial deposits, the nugget effect of diamond concentration being responsible for the high RE factor. The long narrow linear trends observed in Smith?s Ulcer demonstrably require a specialised approach in successfully sampling, modeling and ultimately mining.

Jan 1, 1998

By Robert Goodden

It is well known that diamonds are found in Kimberlite pipes within the earth’s crust and are also discovered where erosion has released them to be concentrated by rivers in trap sites within alluvial gravels. Few people are aware however, that diamonds are now being found in significant quantities at sea. And that the rugged marine environment has ensured that the quality of diamonds in the sea is predominantly gem quality. Shortly after intrusion of Kimberlites into the host rocks of the karoo in the Cretaceous period massive erosion occurred when torrential rivers carried diamonds from their Kimberlitic source rocks down the rivers and into the sea. In the sea they have been subject to a transporting and concentrating dynamic, which has deposited them in trap sites along the West Coast of Africa for hundreds of kilometers. In the last 60 million years the sea level along the West Coast has varied in steps from the current sea level to – 300m. With time at each beach level the sea has reconcentrated the diamonds previously carried down. These old beach levels exist at roughly 10 meter intervals. Each previous sea level now provides a target for marine miners. Marine diamond mining was started 46 years ago by the first pioneer, a Texan, Sammy Collins. Collins brought the potential of marine diamonds to the attention of major mining companies. With now outmoded technology Collins had days when he recovered pockets of high grade gems worth several million dollars; an excitement hard to equal in any walk of life. Amongst marine miners there is still a strong pioneering spirit but the industry has matured and now aims to consistently produce over two million carats of gems a year. The potential resource is huge stretching up to 30 kilometers offshore along the West Coast of Africa from South Africa to Angola.

Sep 24, 2006

By Derek Ellis

There are two environmental issues which have only recently begun to need planning in detail for marine mining. One is the environmental consequences of mine closure; the other is environmental terrorism. In principle it is not difficult to predict the pattern and rate of biodiversity recovery after mine closure on metalliferous depositional seabeds. 1-5 years to a self-sustaining community of organisms is a generalized guideline, depending on depth and particulate composition. The rate and pattern of biodiversity recovery on some metalliferous hard-rock habitats is far less predictable due to the patchiness and rareness of the habitat. Ecoterrorism at mines, whether on-land or marine, is now to be expected. A good example of resource industry ecoterrorism is the fire-bombing of logging and cement trucks in Oregon in 2001. But there have also been bombs at mine sites, as at Asbestos, Quebec. It is also possible to regard some resource-loss lawsuits as frivolous, hence forms of ecoharassment. Marine mining operations should take note of the development of environmental terrorism (and terrorism in general) and its various manifestations and impacts. Potentially these range from minor work stoppage inconveniences, to serious financial risk jeopardizing the economics of a mine, to jail for company executives, managers and environmental staff, and to harassment and killing of mine personnel.

Jan 1, 2005

By Cheng Xiangzhou

The China Ocean Mineral Resources Research and Development Association (COMRA) conducted a topographic survey in its deep seabed claim area with the SeaBeam system in 19475. After analyzing the data, it was determined that there is a group of living things several hundreds of meters in depth that significantly affect the sound waves in the frequency range of interest. We will attempt to investigate more about such influences. Physical model testing is an important means for studying the theory, and for development of the technology for geophysical prospecting. Because the manganese nodules are distributed over the sea floor in irregular patterns, it is hoped that study of the acoustic properties of manganese nodules by means of physical model testing can improve interpretation of the data of the multi-beam system and the SeaBeam system. This will provide a more reliable basis for delimiting the mineral site and evaluating the reserves in the Pioneer area of China.

Jan 1, 1996

By Tina Schneider

Scientists show that polymetallic nodules and massive sulfides from deep sea mining contain valuable metals. These metals have the potential to overcome future shortages of supply. Hence, companies, government agencies and industrial associations increasingly evaluate deep sea mining as a promising supplement of land mining. Technologies to extract, exploit, transport and smelt polymetallic nodules and massive sulfides industrially are still in conceptual stage and not sufficiently advanced for operation. According to the International Seabed Authority, large scale exploitation would require a successful pilot mining test in order to demonstrate e.g. the technological feasibility but also the conservation of environmental systems services. At the same time, NGO´s and a some scientists point out that large scale extraction of polymetallic nodules and massive sulfides could disturb the habitat of benthic organisms, with unknown long-term effects. Aside from the direct impacts of mining, indirect consequences about leakage are likely. In the oral presentation I will show how companies, government agencies, scientists and association/interest groups perceive and assess economical/technological, social and environmental risks and opportunities of deep sea mining. In order to analyze the perspectives of each stakeholder group on deep sea mining, we conducted 15 interviews with four stakeholder groups and a large scale survey (n = 500, return rate = 13 %) in Germany. We used the concept of sustainability with its economical/technological, ecological and social dimensions for the interpretation of the results. The empirical research shows the following core results:

Jan 1, 2018

By A. M. Olivarez

The elucidation of the theory of plate tectonics has provided a conceptual framework for understanding the formation and distribution of different types of ore deposits. For example, we now recognize that certain kinds of mineral deposits are generally associated with a particular type of plate boundary (i.e., massive sulfides often occur along divergent plate boundaries, whereas porphyry copper deposits are typically found along convergent boundaries). During certain geologic time periods, plate reorganization events have changed the relative proportion of different types of plate boundaries. Corresponding changes have been observed in the abundance and distribution of ores deposited during these times. The present study examines the temporal aspects of this relationship; i.e., do plate reorganization events play an active or passive role in ore formation? In other words, do plate reorganizations simply provide a more favorable tectonic setting in which ore formation can occur over significant time periods, or are they directly linked to the mineralization process? We have examined this question by comparing regional tectonic histories with the ages of known massive sulfide and porphyry copper deposits. Because these deposits, in particular massive sulfides, form as a result of hydrothermal activity, we have also compared regional tectonic histories with proxy indicators of this process in the marine sedimentary record. These indicators include increased mass accumulation rates of Ca, Fe, Mn, and opal, characteristic changes in the Sr/Ca and Mg/Ca ratios of biogenous carbonates, and shoaling of the carbonate compenstion

Jan 1, 1988