SeaCause cruise SO186-2, aboard the RV Sonne, was carried out off northern Sumatra between 21st January and 24th February 2006, with mobilisation and demobilisation in Singapore and Penang, Malaysia, respectively. The geophysical survey acquired multichannel seismic data (MCS) using a 240 channel, 3 km Sercel streamer, and a tuned airgun array comprising 16 airguns with a total capacity of 50.8 litres. Bathymetry data, using the 12 kHz Simrad swath system, subseabed data using the hull mounted high resolution Parasound profiler together with gravity and magnetic data were also acquired. The main scientific objective of the survey was to investigate the southern part of the rupture zone of the 26th December 2004 9.3 magnitude earthquake, that caused the catastrophic tsunami of that date, and the rupture zone of the 8.7 magnitude earthquake of March 28th 2005. Specifically, to identify the segment boundary between the two earthquakes, as recognised by the distribution of their aftershocks. This was to be achieved by mapping the structure of the subduction zone including the dip angle of the subducted plate, the architecture of the accretionary prism and the structure of the forearc basins, particularly their strike-slip fault systems. Also to be investigated was whether there was a contribution to the 2004 tsunami from major submarine failures. During the survey a total of 5358 line kilometres of MCS data were acquired, mainly on lines oriented orthogonal to the subduction zone and extending from the ocean basin across the trench and accretionary prism to the forearc basins offshore Sumatra. The orthogonal survey lines were located on average approximately 40 km apart. The survey was planned using the bathymetry from the HMS Scott, RV Natsushima and RV Sonne cruises carried out in 2004. The morphology of the trench and sediment thickness varies from north to south. In the north the trench is poorly defined with shallow seabed dip but with sediment thickness of ~3.5 secs (TWT). The seafloor dips increase southwards, but sediment thickness decreases to ~2.5 secs (TWT) off Nias. Both the ocean basin and trench sediments are dissected by numerous normal faults, oriented subparallel to the plate boundary, with many that penetrate the oceanic crust. In the south Fracture Zones were identified. The structure of the deformation front on the seaward margin of the accretionary prism is highly variable. While the younges main thrust are predominantly landward vergent there are examples for seaward verging thrusts. The frontal fold develops in some cases already in the french while in most cases the frontal fold is at the beginning of the accretionary wedge. At some locations there are large sediment slumps on the frontal thrusts, the slope angle of the prism varies between 6 to 15 degrees, an angle that explains the large scale slumping. The width of the accretionary prism is widest in the north of the area at 140 km and narrows southwards until in the vicinity of the islands it is 40 km. In the north and central parts of the survey area the passage from the deformation front landwards into the older prism is rapid and the seabed gradients steep. The dip of the oceanic crust remains low and there is an obvious twofold increase (6-7 seconds TWT) in the sediment thickness. The basal decollement of the thrusts at the deformation front is in the lower sediment layer overlying oceanic basement. This is traced northeastward. A possible explanation for the increase in thickness of the prism is therefore considered to be the formation of a thrust duplex. Perhaps this is due to the subducted sediment thickness. In this region the prism forms a plateau and the internal pattern of the uppermost sediments shows striking similarities to the trench fill. Offshore of Simeulue Island the prism structure changes and it forms the more usually seen taper. The offscraped sediment forms a thinner section, the thrusts are more steeply dipping. The dip of the subducted plate here is greater than in the north. Three forearc basins were surveyed. In the north the western margin of the Aceh Basin lies along the West Andaman Fault. Within the main basin the sediments are internally undeformed. Farther south in the Simeulue Basin the northern and central parts there are numerous, active steeply dipping faults. In southern part of the basin there is a transpressional fault similarly to the Mentawi Fault off southern Sumatra. There are notable ‘bright spots’ in the upper section that may indicate the presence of hydrocarbon gas. There are also widespread Bottom Simulating Reflectors indication the presence of gashydrates and there may be also one double BSR. At the southern end of the surveyed area the Nias Basin may be subdivided along its length into two parts by a northnorthwest to southsoutheast trending carbonate platform development. The basin has had a varying subsidence history, in the south the subsidence was completed before the northern part started.
Within the frame of the comprehensive SPOC project (Subduction Processes off Chile) the SONNE cruises SO161 Leg 2 and 3 have been conducted between October 16th and November 29th, 2001, off central Chile between 28° and 44° S. In that period some 5,300 km were surveyed with multichannel seismic (MCS) reflection, magnetic, gravity, high-resolution bathymetric and echographic methods. In addition, approximately 3,900 km were surveyed with the same spectrum of methods but without MCS. The total number of 2D profiles was 48. Target was the variation of the subduction properties between the convergent oceanic Nazca and continental Southamerica plates and the different conditions that might influence the subduction process as there are: (1) age of the oceanic crust, (2) its structure and composition, (3) its sedimentary cover, (4) its thermal state, (5) the subduction angle and obliquity, and (6) the terrigenous sediment afflux from the continent. Furthermore, special focus was given to the subduction front, the subduction interface, the structure of the slope as well as to the forearc basin structure and history, and the general distribution of gas hydrate indicating bottom simulating reflectors (BSR's). The results are to be compared with previous studies of the Chilean active margin, e.g. CONDOR (SO 101 and 103) and CINCA (SO 104). The SPOC target area was subdivided into three sub-areas A,B and C. One area was chosen for a detailed survey by aid of a narrowly spaced grid and for a close link with a lot of partners. This area is characterized by a distinctly different margin type south of it is assumed. Moreover, the subducting portion of the aseismic Juan Fernandez Ridge is located in that area representing another important target of the survey. Advantageous conditions enabled the survey of an east-west profile south of Chiloé Island, providing a section through the submerged coastal Cordillera into the flooded longitudinal valley. Some results of Leg 2 and 3 are: In all areas A, B and C no subduction bulge (outer high) in the oceanic crust was visible perhaps due to the shortness of the profiles. The sedimentary cover of the oceanic crust is exceptionally thin, and the crustal thickness is generally quite "normal" with around 7 km derived from relatively weak Moho reflections. In area B a so far magnetically unmapped region was filled providing reliable ages of the oceanic crust, and suggesting that the Challenger Fracture Zone abruptly terminates west of the area of investigation. The survey in area C yielded valuable information on the trench morphology. The so far unique MCS profile south of Chiloé island shows a very wide trench and allows to extrapolate the general conditions encountered an area A southward to approximately 44° S. It can be stated that the situation is in sharp contrast to the basin structures detected by industry profiles further north in the Golfo de Corcovado.
Main target of the project GIGICS (Cooperative German-Indonesian Geoscientific Investigations in the Celebes Sea) is the investigation of the internal crustal structure and the plate tectonic evolution of the Celebes Sea and its active continental margins off Mindanao and Northern Sulawesi. These investigations were carried out during the cruise SO98 of RV SONNE by the Federal Institute for Geosciences and Natural Resources (BGR), Hannover; the German Research Centre for Geosciences (GFZ), Potsdam; the GEOMAR, Kiel; the Institute of Oceanography (IfM), Hamburg; the Mines and Geoscience Bureau, Manila; the Agency for the Assessment and Application of Technology, Jakarta, and the Institute of Oceanography, Wormley. The cruise SO98 consisted of three legs of two weeks duration and one leg of four weeks duration. The total amount of data acquired during the cruise were: - 3,300 km of multichannel reflection seismics, - over 6,800 km of gravimetric and magnetic data and approximately 10.000 km of swath bathymetric and sediment echosounder data, - 3 wideangle-/refractionseismic profiles, each of 120 - 150 km length, - geological, geochemical sampling and oceanographical measurements at a total of 37 stations. During the cruise SO98 a widespaced but regular grid of magnetic and gravimetric profiles were acquired in the eastern part of the Celebes Sea from which up to then reliable data were very sparse. WEISSEL (1980) recognized in the western Celebes Sea WSW-ENE striking magnetic lineations, which he interpreted as chrons 18 - 20 (39 - 43 Ma according to the timescale of HARLAND et al. (1990)). The data from cruise SO98 show that there is no continuation of these anomalies to the east. In the eastern part the magnetic field of the Celebes Sea is less clear and much more disturbed. Nevertheless, E-W-striking anomalies are recognizable. Because amplitudes of local magnetic anomalies are higher than the lineations, the correlation of these lineations with the magnetic reversal scale is still somewhat ambiguous. The gravity map compiled from the measured gravimetric data shows elongated positive anomalies in the eastern part of the Celebes Sea. Exceptions occur at the deep sea trenches off North Sulawesi (North Sulawesi Trench) and Mindanao (Cotabatu Trench) and at the Sulu Archipelago where strong negative gravity anomalies were found. A remarkable NW-striking gravity high of up to 60 mgal was found in the central eastern part of the Celebes Sea. Gravimetric modelling suggests that this high can be correlated with the gravimetric effect of the Molucca Sea Plate subducting from the east under the Sangihe Arc. The reflection seismic data from the northern part of the Celebes Sea show indications for a juvenile subduction of oceanic Celebes Sea crust under the Sulu Archipelago. The oceanic crust bends down towards the Sulu Arc with angles between 2° and 5° and the sedimentary sequence above is deformed indicating a compressional stress regime. With the exception of two linear arranged seamount-like basement highs the Celebes Sea is dominated by two different oceanic crustal types showing distinct differences in the topography. The first one is showing a very similar reflection seismic pattern as it is found for oceanic crust of the Atlantic (HINZ et al., 1994). This type is characterized by a small-scale block-faulted relief of the top basement and a low reflectivity in lower crustal levels typically related as to be accreted at slow to intermediate spreading ridges. This type is found in the western, northern and southern part of the investigated area. In the eastern and especially in the southeastern part the igneous crust shows a very different image. The reflection of the top of the basement is less distinct and of lower frequency. The relief is very much smoother than in the previous type. This reflection seismic image indicates a volcanic/magmatic overprinting of the oceanic crust in this part of the Celebes Sea. Another target of cruise SO98 was the area of the active continental margin off North Sulawesi and its accretionary complex. The internal structure of the accretionary complex should be investigated to decide whether this active margin is also of the 'splinter-type' or not. During former geophysical cruises with RV SONNE oceanic crustal splinters were discovered in the accretionary wedges of the Sulu Sea and off Costa Rica (e.g. HINZ et al., 1991). From our reflection seismic measurements this active continental margin is morphologically subdivided into three units and consists of two accretionary complexes of different internal structural style: the lower and middle continental slope is underlain by an intensively thrusted, sedimentary accretionary wedge. This wedge was most probably formed during the last 5 Ma. Landward of this wedge an older and seismically very complex accretionary unit is present which is overlain at its landward termination by a sedimentary fore-arc basin. Within this older accretionary complex, units with a strong, low frequency reflection pattern were found which are interpreted to represent crustal splinters of igneous oceanic or ophiolitic nature. This interpretation is supported by our gravity and magnetic data. The magnetic profiles show an increase of the magnetic field towards the north arm of Sulawesi across the continental margin. This increase of the magnetic field suggests an increase of magnetized material within the older accretionary wedge towards the northern arm of Sulawesi where ophiolites are emplaced. During the interpretation of the reflection seismic data of the project GIGICS BSR's (bottom simulating reflectors) were discovered for the first time along the active continental margin of North-Sulawesi. BSR's are the seismic expression of a velocity decrease at the bottom of a gas hydrate zone. The distribution and depth of the BSR's correlates with the geochemical and geothermal results. Radiometric age dating and geochemical analyses from pillow basalts of a seamount from the southeastern Celebes Sea indicate hot-spot activity in this part of the Celebes Sea during or shortly after the formation of the oceanic crust approximately at 43 Ma ago. Three NW-striking ridges or seamount-chains in the northeastern Celebes Sea were mapped and investigated in detail. They are thought to represent a wrench fault system extending through the northeastern Celebes Sea. At the flank of one of these ridges a strongly alterated plagioclase-olivine basalt sample was dredged which was overlain by non-fossiliferous clay stone. A similar lithostratigraphic sequence was drilled during ODP leg 124 (RANGIN et al., 1990). The geochemical composition of these basalts is different from typical MORB. The existence of a large crustal splinter within the accretionary wedge off southwestern Mindanao obviously is responsible for a high thermal conductivity which in turn could have enhanced heat flow (108.1 mW/m2) and methanogenesis (405 ppb). The heat flow of 103.0 mW/m2 at the deformation front of the Mindanao wedge and the high methane concentration of 5.555 ppb suggests tectonically induced fluid transport within the wedge. High methane concentrations between 8.044 and 49.006 ppb at the lower slope off Sulawesi and in the North Sulawesi Trench are accompanied by high heat flow values of up to 100.5 mW/m2. Heat flow is significantly lower upslope (31.3 mW/m2). This general heat flow distribution pattern is seen over a large portion of the accretionary wedge. The elevated heat flow values and high methane concentrations near the deformation front most likely result from heat transport by fluids squeezed out from vertically and laterally compacting sediments. The reduced heat flow towards the coast is compatible either with a cooling effect of slow subduction of the oceanic crust, or stacking of cool slabs of compacted sediments. A subduction of oceanic crust with a heat flow around 60 mW/m2 over a period of more than 3 million years would have produced the low heat flow values of the upper slope if the wedge consists of claystone with a low thermal conductivity (1.2 - 1.7 W/mK). Even in the low-heat flow area isolated fluid venting is possible. Lateral variations in the heat flow pattern (e.g. broadening of the anomalies in the west) may be due to different thermal regimes within the subducted crust.
During RV SONNE cruise 137 from 21st November to 28th December 1998 Geoscientific Investigations on the active Convergence Zone between the east Eurasian and Indo-Australian Plate (GINCO I) were carried out along the Sunda Arc, off Sumatra, Java and the Sunda Strait. The studies were headed by the BGR in close cooperation with German and Indonesian research institutions. A total amount of 5,500 km of magnetic, gravity and swath bathymetric profiles were recorded of which multi-channel seismic data exceeded 4,100 km. The scientific objectives were: (1) investigation of the structure and age of the accretionary wedges, outer arc highs and fore-arc basins off Sumatra and Java with special emphasis on the evolution of the Sunda Strait and the Krakatau area (2) differences in tectonic deformation between oblique (Sumatra) versus frontal (Java) subduction (3) search for oceanic crustal splinters in the accretionary wedges (4) definition of seismic sequences, thicknesses and ages of the fore-arc basin sediments as a pre-requisite for later on hydrocarbon assessments (5) identification and regional occurrence of bottom simulating reflectors (BSR) indicating gas hydrates. From the GINCO I project there is evidence for the existence of two accretionary wedges along the Sunda Arc: wedge I is of assumed Paleogene age and wedge II of Neogene to Recent age. The first inner wedge I is composed of tectonic flakes which are correlated from SE Sumatra across the southern Sunda Strait to NW Java. This implies a very similar plate tectonic regime at the time of the flake development during the Upper Oligocene to Lower Miocene and without marked differences in plate convergence direction from Java to Sumatra. Wedge I shows backthrusting along the northern transition toward the fore-arc basin. Today, wedge I forms the outer arc high and the backstop for the younger, outer wedge II. Magnetic, gravity and seismic results show, that within both wedges, there are no indications for an oceanic crustal splinter as hitherto postulated. Both wedges are underlain by oceanic crust of the subducting Indo-Australian slab which could be correlated from the trench off Sumatra up to 135 km to the northeast and up to 65 km from the trench off Java. Since the top of the oceanic crust differs considerably in reflectivity and surface relief we distinguished two types in the seismic records. One type is characterized by strong top reflections and a smooth surface and underlies accretionary wedge II and the southwest part of the wedge I (outer arc high) off Sumatra and Java. The second type has a low reflectivity and a rougher relief and underlies the tectonic flakes of accretionary wedge I (outer arc high) between the southwestern tip of Sumatra, the SundaStrait and NW Java. The missing outer arc high off the southern entrance of the Sunda Strait is explained by Neogene transtension in combination with arc-parallel strike-slip movements. The NW-SE running, transpressional Mentawai strike-slip fault zone (MFZ) was correlated from the SE Sumatra fore-arc basin to the NW Java fore-arc basin. Off the Sunda Strait northward bending branches of the MFZ are connected with the Sumatra Fault zone (SFZ). It is speculated that the SFZ originally was attached to the Cimandiri-Pelabuhan-Ratu strike-slip faults and shifted from the volcanic arc position into the fore-arc basin area due to clockwise rotation of Sumatra with respect to Java as well as due to increasingly oblique plate convergence since the late Lower Miocene. We explain the transtension of the western Sunda Strait (Semangka graben) and the transpression with inversion of the eastern Sunda Strait, along the newly detected Krakatau Basin, by this rotation. Seismostratigraphic interpretation revealed 5 main sequences (A - E), tentatively dated as Paleogene to Recent in age. The oldest seismic sequence A of assumed Eocene to Oligocene age is bounded at the top by a major erosional unconformity that was identified on all GINCO seismic profiles. The seaward diverging seismic pattern of sequence A is interpreted as a correlative sequence to the prograding Paleogene deltaic sediments encountered by wells offshore central and northern Sumatra. This is opposed to previous interpretation which assumed seaward dipping reflector sequences of basaltic origin erupted along the former Mesozoic passive margin of Sumatra. According to constructed time structure maps, the main NW-SE running depocentres of the post-Paleogene sediments are arc-parallel off Sumatra and Java with thicknesses of 3 s (TWT) and 5 s (TWT), respectively. The main depocentres of the Semangka graben and of the Krakatau Basin of the Sunda Strait strike north-south and have infills of 2 s - 5 s (TWT). Bottom simulating reflectors (BSR) occur within the upper sequences C - D along the flanks of the fore-arc basins and along doming structures but could not be detected in basin centres. Empiric relations of heat flow values and depths of BSR were determined indicating that with increasing waterdepth and decreasing heat flow the depths of the BSR increase.
Between 08.11.1999 and 02.12.1999 the active convergent margin off Costa Rica was investigated using the S/V Professor Polshkov. The cruise had three scientific targets. Several seismic profiles in the dip-direction of the subduction zone were acquired to map the general variability of the accretionary wedge. Near the Jaco Scarp, a dense net of seismic profiles using a smaller seismic source should deliver information about the amount of gas hydrates within the shallow sub-surface. In an area of this wedge south of the Quepos Plateau densely spaced seismic lines were measured to prepare an ODP campaign (which was finished in 2011 as IODP Expedition 334).
From 19th November to 19th December 2004 BGR conducted a marine geophysical cruise between 34°S and 36°S off Uruguay and between 46°S and 50°S off Argentine. The main research objective was to contribute to a better understanding of the initial breakup and the early opening of the South Atlantic. In continuation of our former work on the South Atlantic continental margins off Argentina, Brazil, Uruguay, Namibia and South Africa marine geophysical research (multi-channel seismics, refraction-/wide-angle reflection seismics, magnetics and gravity) was performed in close cooperation with the Argentine and Uruguayan authorities Comisión Nacional del Límite Exterior de la Plataforma Continental (COPLA) of Argentina and Servicio de Oceanograficia, Hidrograficia y Meteorologia de la Armada (SOHMA) of Uruguay. Multi-channel seismic lines with a total length of 3,754 km and additional 3540 km with the other geophysical methods were acquired . Along two lines refraction-/wide-angle reflection seismic work was carried out. The preliminary analyses of the new seismic data show different images of the crustal structures between Uruguay and southern Argentine with regard to the distribution and volume of offshore volcanic rocks (seaward dipping reflector sequences, SDRS) along the South American Atlantic margin. On the northern profiles between 34°S and 36°S one single well developed wedge of SDRS is present. Although the landward termination (‘feather edge’) on most of the lines is masked by multiples the average total width of the wedge across the margin seems to be 90 – 100 km and is very constant for this margin segment. This is strong contrast to the results from former cruises (BGR87, SO85 and BGR98) which covered the area between 38°S and 45°S. There, the SDRS showed distinct multiple wedges which in some places extend over 120 km across the continental slope. The investigation of the sedimentary section yielded that in the area off Uruguay widespread bottom simulating reflectors (BSR) are present. This indications for stable gas hydrates cover a total area of 7000 km2. One major aim of the cruise was to cover the transition between a volcanic passive margin and a non-volcanic passive resp. sheared margin. This was accomplished in the southern part of the investigated area. Two EW-trending profiles across the Argentine shelf into the Argentine Basin still show indications for SDRS but these structures are only 25 – 30 km wide. The profiles which extend from the NE to the SW crossing the Agulhas-Falkland Fracture Zone (AFFZ) onto the Falkland Plateau show the typical trend of a sheared margin. At the northern rim of the Falkland Plateau a set of small pre-rift half grabens were found indicating pre-rift extensional tectonic phases. The magnetic data in the area off Uruguay show lineations which are preliminary interpreted as chrons M0 to M3. This might indicate that the first (oldest) oceanic crust was created at a time around the magnetic polarity reversal between the normal interval M4 and the reversed interval M3 (126-127 Ma). Together with existing data from previous cruises this indicates that the breakup of the South Atlantic started further South because there magnetic chrons back to M9 (130 Ma) were identified. In the southernmost part of the margin at 47°S only the magnetic lineations M0 to M4 were identified in the oceanic domain Nevertheless, it is likely that between M4 and the assumed position of the continent ocean boundary/transition (COB/COT) older oceanic crust exists that for some reasons does not show correlatable lineations. The the free-air gravity map is dominated by the main topographic and structural features in the survey area. Rifted continental margins are characterized by prominent free-air gravity anomalies elongated parallel to the ocean-continent transition. The continental slope is considerably steeper in the North off Uruguay than in the South and thus the gravity high is much more pronounced in the North than in the South. The simple Bouguer anomaly map also shows the difference between the more gentle and wider continental slope in the South and the steeper slope in the North. The lowest Bouguer gravity values are found in the area of the basins on the continental shelf. Especially the Salado Basin in the prolongation of the Rio de la Plata and the Colorado Basin at about 40°S are indicated by Bouguer gravity anomaly highs. The interpretation by forward density modelling shows, however, the presence of SDRS units in the North of relative high density in the area of the continental slope. Whereas the modelling shows no indications for such volcanic bodies in the South. Although the MCS data indicate a small SDRS wedge but this body may be too small to cause an anomaly.From 17th April to 6th June 2003 BGR conducted a marine geophysical cruise between 30°S and 38°S off the Atlantic coast of South Africa. The main research objective was to contribute to a better understanding of the initial breakup and the early opening of the South Atlantic. In continuation of our former work on the South Atlantic continental margins off Argentina, Brazil, Uruguay and Namibia marine geophysical research (multi-channel seismics, wide-angle refraction seismics, magnetics and gravity) was performed in cooperation with the Petroleum Agency South Africa (PASA). Multi-channel lines with a total lenght of 3,260 km, and additional 1,365km, with the other geophysical methods were acquired. Combined onshore/offshore refraction seismic work in cooperation with GeoForschungsZentrum Potsdam (Germany) and the Council for Geoscience (South Africa) was also part of the program.
The main objectives of the BGR cruise BGR01 POPSCOMS (Properties of a Gas Hydrate Province on a Subduction-Collision Related Margin off Sabah) off Sabah/Malaysia with M/V AKADEMIK NEMCHINOV from 4th November to 3rd December 2001 in co-operation with PETRONAS Malaysia are the research on (1) Marine Methane Gas Hydrates: Detection, distribution and formation; relation to the adjacent highly productive "conventional" gas province in the specific tectonic setting of the collisional belt off Sabah. (2) Tectonic development of the (accretionary) margin off Sabah: Improve the tectonic stratigraphic hypothesis of the subducted Proto-South-China-Sea and continental crust under the accretionary wedge, respectively in the subducted plate. Open questions and targets of the survey: Within the help of the already existing magnetic data and other seismic measurement methods (e.g. special refraction seismic with ocean-bottom hydrophones [OBH], which presumably is an exellent and adequate method) we try to discern between oceanic and continental crust in the subducted plate, to investigate the nature of the transition and get information on the subduction angle. This is important in relation to the Cagayan Ridge (Sulu Sea) that is interpreted as an island arc that is related to the subduction of the proto-South China Sea. Another aim was to enable the determination of seismic anisotropy, distribution of BSR's and hydrates in the area and their v(p) to v(s) ratios. Are the gas hydrates related to the adjacent highly productive "conventional" gas province? What is the structural character of the transition zone between the hydrate province and the adjacent conventional gas bearing province further up-slope? Conversely, are there indication for a possible deepwater source? Can initial conclusions be drawn regarding their biogenic or thermogenic origin? Is there an impact of sedimentation conditions, compressional behaviour (e.g. at active margins) and/or structural properties on the genesis and stability of gas hydrates and BSRs (Bottom Simulating Reflectors)? How do the findings under different conditions compare in that regard? Which are the favorable conditions for the genesis of gas hydrates, and can they be detected by geophysical methods even if there are no BSR's? The findings are expected to provide a contribution to the assessment of the deepwater hydrocarbon potential along the continental margin off Sabah. Results: In the study area the BSRs were identified on the base of their polarity reversal with respect to the seafloor and when they transect reflectors from the strata. The widely distributed BSRs along the seismic lines of the survey deliver an indirect indicator for the presence of gas hydrates in the study area (BSR's in post Miocene sediments). The BSR depths below seafloor vary between 250 and 350 m. Differences in the reflection coefficient of the BSRs are mainly related to the amount of free gas beneath the Gas Hydrate Stability Zone.
Unter dem Motto „Rohstoffe aus dem Meer – Chancen und Risiken“ wurde am 20. Februar 2014, der dritte „World Ocean Review“ (WOR) der Öffentlichkeit präsentiert. Der WOR 3, herausgegeben von der gemeinnützigen Organisation maribus gGmbH und mit Unterstützung der Zeitschrift »mare«, des International Ocean Instituts (IOI) und des Exzellenzclusters »Ozean der Zukunft«, beschreibt ausführlich die bekannten metallischen und energetischen Rohstoffe in den Ozeanen und beleuchtet die Chancen und Risiken des Abbaus und der Nutzung von Rohstoffen. Der neue Report liefert Fakten über die Menge an bekannten Öl- und Gasvorkommen und der festen Gashydratvorkommen unterhalb des Meeresbodens. Ferner geht es um das Potenzial von mineralischen Rohstoffen wie Manganknollen, Kobaltkrusten und Massivsulfiden. Darüber hinaus thematisiert der WOR 3 die Verantwortung der internationalen Staatengemeinschaft für einen umweltverträglichen Abbau und die völkerrechtliche Herausforderung, für eine sozial gerechte Verteilung der Ressourcen in internationalen Gewässern zu sorgen.
| Origin | Count |
|---|---|
| Bund | 139 |
| Land | 7 |
| Wissenschaft | 5 |
| Type | Count |
|---|---|
| Ereignis | 1 |
| Förderprogramm | 131 |
| unbekannt | 12 |
| License | Count |
|---|---|
| geschlossen | 7 |
| offen | 137 |
| Language | Count |
|---|---|
| Deutsch | 132 |
| Englisch | 32 |
| unbekannt | 5 |
| Resource type | Count |
|---|---|
| Archiv | 7 |
| Datei | 1 |
| Dokument | 1 |
| Keine | 28 |
| Webseite | 116 |
| Topic | Count |
|---|---|
| Boden | 144 |
| Lebewesen & Lebensräume | 122 |
| Luft | 100 |
| Mensch & Umwelt | 144 |
| Wasser | 125 |
| Weitere | 143 |