From 1 - 10 / 77
  • The aims of cruise SO197 RISE (Rift Processes in the South China Sea) with RV SONNE from Manila, 28th March 2008 to Singapore, 2nd May 2008 are (1) To gain a better understanding of the processes leading to continental breakup and subsequently formation of oceanic crust. (2) To study the evolution of the South China Sea oceanic basin. The South China Sea is particularly well suited for studying rift processes at the transition from extension of continental lithosphere to the formation of oceanic crust. This relatively young marginal basin is currently in a stadium which is characterised by still preserved differences in subsidence and thermal history resulting from rifting. The initial, complex and hardly quantifiable rift processes, however are long enough ago. The area under study comprises the eastern subbasin of the South China Sea, the West Luzon Basin and the transition area from oceanic crust to extended continental crust between the continental blocks of Reed Bank and the islands of Palawan/Calamian Group. By including existing data of earlier cruises (SO-23, -27, -49) a comparison of conjugated margin transects is intended later within the project. A major goal of the project is to study structures at the transition from continental rifting to oceanic spreading and processes resulting from extension of continental lithosphere to the formation of oceanic crust in time and space. The sequence stratigraphy of the synrift and drift sediments will give insights into the formation and evolution of the individual rift basins. The distribution and thickness of the postrift sediments on the continental fragment of the NW Palawan area define the subsidence history. The depth and topography of the Moho show the location of the stretched and thinned crust. By a joint interpretation of the structural setting, the position, distribution and architecture of the basin bounding faults a reasonable rift model will be derived. In addition, we will investigate the transition of a passive rifted margin (off Palawan) to a convergent margin (off Luzon). The timing of the evolution of the South China Sea basin will be more exactly determined by comparing the magnetic anomalies from the eastern subbasin of the South China Sea with existing data from the central/western basin. Particularly the question of a symmetric/asymmetric opening of the oceanic basin and the timing and location of the individual rift/drift episodes will be investigated. Therefore, we investigated rift structures at the southeastern margin of the South China Sea by means of reflection seismology, gravity, magnetics, bathymetry and sediment echosounder and we performed magnetic measurements to identify seafloor spreading anomalies in the eastern subbasin of the South China Sea.

  • Continuing the systematic work which was started during a previous BGR expedition with RV AURELIA in Sept./Oct. 2003 the late Tertiary and Quaternary development of the German EEZ was further investigated by seismic profiling. The data format is Society of Exploration Geophysicists SEG Y. Again the research vessel AURELIA was chartered for a period of 21 days from 31st of May to 19th of June 2004. During the cruise the grid of seismic profiles which was aquired in 2003 was completed and data gaps were closed. A total of 2618km of high quality MCS lines were surveyed.

  • 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.

  • On the MS Explora (1st September, 1976 - 29th September, 1976) multichannel seismic measurements were carried out on 44 lines The area covered was the Barentssea. The data format is Society of Exploration Geophysicists SEG Y.

  • From 15th September to 26th October 2007 BGR together with the German Alfred-Wegener Institute for Polar and Marine Research (AWI), Bremerhaven, the French Institutes from Brest Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) and Institut Polaire Français Paul-Emile Victor (the French Polar Institute, IPEV) and the Portuguese Institute Laboratório de Tectonofísica e Tectónica Experimental (LATTEX) conducted a marine geophysical research cruise on the French research vessel R/V MARION DUFRESNE. The cruise BGR07 MoBaMaSis consisted of two legs MD163 off Central Mozambique and MD164 off Southern Mozambique. The main research objective was to contribute to a better understanding of the initial breakup and the early opening of the Eastern Gondwana.

  • A geophysical reconnaissance survey across oceanic fracture zones has been carried out by the BGR in the eastern North Atlantic using S.V. PROSPEKTA. The geophysical measurements, including multichannel seismic reflection profiling, magnetics and gravity were concentrated on three oceanic crustal areas of Mesozoic crust which are crossed by the Hayes Fracture Zone, the Atlantis Fracture Zone and the Kane Fracture Zone respectively. 24 geophysical lines with a total length of 5,362 km have been measured during the time period from 25th October to 4th December 1985. Besides intracrustal seismic events a deep coherent seismic event is often recognizable in the monitor records between 10 - 12 s (TWT) along several lines, which probably is a reflection from the crust-mantle boundary.

  • The expedition PS155/1 started on August 5th, 2018 in Tromsø (Norway) and ended in Longyearbyen (Spitsbergen) on September 3rd, 2018. In the course of BGR’s GREENMATE project the geological development of the European North Atlantic and the northern and north eastern Greenland shelf was analyzed using various marine geophysical methods (seismics, magnetics, gravity, heatflow measurements) and geological sampling (gravity corer, box corer, multi-corer, dredge). Sampling of marine Shelf sediments was undertaken in close correspondence with co-users from Geomar (add-on project ECHONEG), aiming to reconstruct Holocene paleo environmental and climatic evolution. Using the ship’s helicopters, marine sampling was complemented by onshore sampling operations to extract geological material at selected near coastal locations. Other scientific project groups used the cruise PS115.1 as an opportunity to quantify marine mammals and sea birds and their statistical distribution in our research area as part of the long-term project (add-on project Birds& Mammals) and to gather additional meteorological data via radiosondes (add-on Project YOPP). Against all expectations, outstanding ice conditions along the northern coast of Greenland enabled us to carry out reflection seismic surveys north of 84°N at the southern tip of Morris Jesup Rise with a 3 km long streamer. Structural data of this particular region of North Greenland is of special importance for BGR’s project GREENMATE for reconstructing the continental margin evolution. A 100 km long refraction seismic profile was measured to complement the reflection seismic data. After completing this, scientific work was concentrated on the northeastern Greenland shelf area between 76°N and 82.5°N. Over the time of the cruise a total of 2500 km of reflection seismic profiles (2250 km measured with 3km streamer length) and 100 km of refraction seismic profile (using nine ocean bottom seismometers) were measured, accompanied by gravity and magnetic surveys and seven heat flow measurement stations. Along the shelf and deep-sea area 21 geological sampling sites were chosen, with all together one dredge (around 200 kg of sample), 16 gravity cores (total core length 65 m), 12 box corers and 6 multi-corer stations. Onshore sediment sampling was done at 11 sampling sites. Beside sediment sampling hard rock from near coastal outcrops was collected in a total amount of 250 kg that will be used for age dating. The entire science program was carried out under consideration of the highest ecological standards to protect marine mammals and to meet all environmental requirements of the permitting authorities. In addition to external marine mammal observers (MMO) various acoustic monitoring systems and AWI’s on board infrared detection system AIMMS monitored any activity of marine mammals in the ships perimeter, especially during seismic operations.

  • In the period from February 13th to March 2nd 1980 4,037 km of magnetic, gravity and bathymetric lines and 1,195 km of digital reflection seismic lines were recovered on the 2nd leg of METEOR cruise no. 53. Heat flow measurements have been performed on 13 stations; on two stations sonobuoy refraction measurements and dredging have been carried out. From a preliminary interpretation of the seismic monitor records the Mazagan Plateau is part of the Moroccan Meseta. Seawards of this stable swell lies the 75 km wide, downfaulted rift graben characterized by salt diapirs. A submarine body, 150 square kilometres large, lying at the foot of the Mazagan Escarpment in water depths of 3000 m - 3800 m beneath sea level, from which western flank few granitic fragments were retrieved, is interpreted as a subsided and tilted block of the Mazagan Plateau. The north-trending magnetic anomalies, discovered during METEOR cruise no. 46 within the Essaouira continental margin segment have also been recognized within the Tafelney Plateau segment, situated between latitudes 30°45'N and 31°30'N off Morocco. Two neo-volcanic zones were found west of the Conception Bank and west of the Betancuria Massif/Fuerteventura Is. The Mesozoic and Tertiary depositional sequences are highly deformed by small piercement structures interpreted as dykes within these zones.

  • As recommended by the Joint CCOP-IOC Working Group on Post-IDOE Studies on East Asia Tectonics and Resources and the proposal of the Bureau of Mines and Geosciences of the Philippines to extend the research of the previous R/V SONNE survey SO-23, the Federal Institute of Geosciences and Natural Resources (BGR) carried out a geophysical survey in the southeastern part of the South China Sea (Dangerous Grounds) and in the northwestern part of the Sulu Sea in two legs from 29th April to 29th June 1983 on SONNE cruise SO-27. Multichannel reflection seismic measurements were carried out in parallel with magnetic, gravimetric, Sea-Beam, and 3.5 kHz subbottom profiler measurements on 34 lines with a total length of 7,204 km. In addition, 26 lines with a total length of 2,800 km were surveyed with only the last four named methods. SONNE cruise SO-27 was financed by the Federal Ministry of Research and Technology (BMFT). Six seismic sequences (DG-1 to DG-6) (DG = Dangerous Grounds) could be distinguished in the surveyed part of the South China Sea. The oldest recognizable sequence is the sequence DG-6, an equivalent of the Pre-Nido Formation of the northwest shelf of Palawan. Seismic unconformity Violet marks the top of the DG-6 sequence, which consists of a complex system of tilted horsts and half-grabens. The half-grabens are presumably filled with clastic sediments of Eocene age (seismic sequence DG-5). The top of seismic sequence DG-5 is bounded by unconformity Blue, which is interpreted as representing the end of the rift phase and the onset of seafloor spreading in the South China Sea about 32 m.y. ago. The overlying seismic sequence DG-4 is characterized by an internal reflection pattern with low frequencies. Lithologically, this sequence consists of shallow-water carbonates with reef complexes of Oligocene to Early Miocene age and has to be regarded as equivalent to the oil-containing Nido Formation of the Palawan shelf. A rapid subsidence of large parts of the survey area during the late (?) Early Miocene ended the growth of the shallow water carbonate platform, indicated by the unconformity Blue. The overlying seismic sequence DG-3 is interpreted as consisting of a transitional facies between a shallow water and a bathyal depositional environment. The top of this sequence is marked by unconformity Red, which most probably represents the end of the drifting phase (seafloor spreading) in the South China Sea during the Middle Miocene. The most prominent structural feature of the shelf and slope of central and southern Palawan is a thick sedimentary wedge originally interpreted as a melange. Our data show that the Oligocene to Early Miocene carbonate platform of the Dangerous Grounds extends beneath the Palawan Trough, as well as beneath the central and southern Palawan shelf, underlying the melange. Based on the finding that i) Rhaeto-Liassic rocks are present in the Dangerous Grounds, ii) the Oligocene to Early Miocene carbonate platform continues from the Dangerous Grounds through the Palawan Trough to the central and southern Palawan shelf, and iii) there is thinned continental crust 20 km thick below the continental slope of southern Palawan, we believe the Dangerous Grounds, together with Palawan and the Caiman Islands belong to a uniform continental fragment which separated from the proto-chinese continental margin when the South China Sea opened during the Oligocene. Previously, the melange of central and southern Palawan, which contains ophiolites, was interpreted as being autochthonous. In our opinion, the melange is an allochthonous mass which has been overthrusted onto the eastern margin of the Dangerous Grounds-Palawan-Caiman microcontinent from the Northwest Sulu Basin. The Ulugan Bay fault is interpreted as the northeastern front of this allochthonous mass. The area of prospective carbonate plays is considerably enlarged by the discovery that the Oligocene to Early Miocene carbonate platform with Nido-type reef structures extends below the allochthonous sediments of central and southern Palawan. We expect that hydrocarbon-bearing structures of the Sabah-type, i. e. thick, folded Neogene sediments, will be found in the western part of the northwestern Sulu basin. If our interpretation is correct, a new chapter of hydrocarbon exploration may be about to begin around Palawan in the Philippines.

  • In the time from 13th August to 13th September, 1989 a geophysical survey was carried out with S.V. PROSPEKTA in the Southeastern Newfoundland Basin and in the Sohm Abyssal Plain. Sixteen multichannel seismic lines with a total length of 3,568 km were surveyed. The general aim of the survey was to study the structure of the oceanic crust formed during the period from 150 to 80 m.y.B.P.. The results we found that the magmatic-volcanic activity at the Mesozoic Atlantic spreading center was episodic, and there was some form of magmatic-tectonic cycling in the Mid-Atlantic Ridge processes. Drastic changes of the oceanic crustal structure have been observed, and a volcanic basement unit characterized by an internally divergent pattern of reflection horizons having an eastward dip was found coinciding with magnetic anomalies M-4 to M-0. This body consists probably of basaltic flows and volcanic clastic rocks extruded near or above sea level, and it appears that this unit is continuous from the Eastern Newfoundland Basin to the New England Seamount Chain. A doubling of the oceanic crustal thickness occurs around M-10 and is present in the area of the young end of the series of magnetic M-anomalies. Doubling of the thickness of the oceanic crust is also present in the conjugate eastern central North Atlantic segment in the area of magnetic anomalies M-10 to about M-0.

Barrierefreiheit | Datenschutz | Impressum