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Processed seismic data of Cruise VA16 1977

The northwestern Australian continental margin can be considered as a passive continental margin of the rifted atlantic type (Whitworth 1969; Powell 1973, 1976; Falvey 1974; Veevers 1974; Willcox 1974, 1976; Exon et al. 1975) which are usually associated with heavy accumulation of sediments (Beck et al. 1974) and are therefore of interest for hydrocarbon exploration in the longer term. The Federal Institute for Geosciences and Natural Resources (BGR, Hannover, Germany) has conducted geoscientific surveys at various continental margins of the Atlantic Ocean in the past years (Seibold 1972; Hinz et al. 1973; Seibold, Hinz 1974/1976; Seibold et al. 1975; Roeser et al. 1971) and the marine research programme of the Bureau of Mineral Resources, Geology & Geophysics (BMR, Canberra, Australia) is putting the focal point as well on the survey of the continental margins. Hence in the frame of the Australian-German contract of scientific and technical cooperation, BGR has proposed joint geoscientific surveys of the continental margins with the German research vessel VALDIVIA. The Scott-Plateau (NW-Australia) has been chosen as investigation area because BMR has carried out geophysical overview measurements previously in that region. The survey has been planned with the main focus on the geological processes at the early rift stadium and the set of problems about the "transition of oceanic to continental crust". The following regional geological units are known: the archaic-proterozoic Kimberley shield is followed by the Browse Basin - a NE striking epicontinental basin filled with mesozoic and tertiary sediments showing a thickness of up to 10 km (Powell 1976). It is presumed that the Browse Basin is delimitated by the Scott Plateau. Presumably, the Scott Plateau consists of continental crust which thins out to the north in direction to the Argo Abyssal Plain. The development of the Browse Basin is ascribed to a series of rift processes in the late paleozoic and triassic age where gas condensates have been detected at the drill hole Scott Reef 1. The contemporary configuration of the NW-Australian basins and the NW-Australian continental margin has been formed by an important middle jurassic rift phase and a subsequent drift phase. The cruises VA16-2A from 6th to the 25th of February 1977 with geophysical measurements and VA16-2B from 25th of February to 9th of March 1977 with geological sample recovery should clarify these processes. The working area of cruise VA16-2C from 11th to 23rd of March 1977 has been the Timor Trough and the Savu Sea which separate the islands Timor, Roti, Savu and Sumba from the volcanic islands of the inner Banda island arc. The crustal structure of Sumba, of the Savu Sea and of the inner Banda island arc near Flores should be investigated with seismic methods (small explosive charges fired from the research vessel VALDIVIA in the Savu Sea and intended recording units of the Flinders University on the islands Savu, Sumba and Flores) as well as with sonobuoy stations of BGR. Newer investigations (Audley Charles 1975, Chamalaun 1974) suggest that the islands of the Banda island arc (Sumba, Savu, Roti, Timor etc.) represent the northern border of the Australian continent being underlain by the crust of the Australian continent as opposed to the assumption of other investigators (e.g. Beck and Lehner 1974) who presume the northern border of the Australian continent at the Timor Trough south of the Timor island and postulate a subduction zone between the outer Banda island arc and Australia. BMR has provided 9 tons of explosives (Nitramon) with accessories for refraction seismics. The Flinders University has prepared 7 on-shore recording units and sent to Indonesia together with operating staff. BGR conducted the marine seismic work with explosive charges and off-shore recordings with sonobuoys for refraction seismic as well as reflection seismic, gravimetric and magnetic measurements.

Tiefsee der Antarktis wird kälter

Das Forschungsschiff Polarstern des Alfred-Wegener-Instituts für Polar- und Meeresforschung hat die erste Antarktissaison im Internationalen Polarjahr erfolgreich abgeschlossen. 58 Wissenschaftlerinnen und Wissenschaftler aus zehn Ländern waren vom 6. Februar bis 16. April 2008 an Bord des Forschungsschiffs im Südlichen Ozean unterwegs. Das erste Ergebnis dieser Expedition: Die Tiefsee der Antarktis wird nach jahrelanger Erwärmung wieder kälter. Dadurch könnten die Umwälzbewegungen der ozeanischen Wassermassen in Schwung gebracht werden. Gleichzeitig haben Satellitenaufnahmen die höchste Ausdehnung von Meereis im antarktischen Sommer seit Beginn der Aufzeichnungen gezeigt. Ob der kalte antarktische Sommer einen neuen Trend einleitet oder nur ein Ausrutscher war, wird mittels autonomer Messbojen in den nächsten Jahren weiter untersucht.

Benthos, Dichte

Beschreibung: Räumliche Verbreitung ausgewählter makrozoobenthischer Arten in der deutschen Bucht. Datenquelle: Daten aus Umweltverträglichkeitsstudien (UVS) im Rahmen von Genehmigungsverfahren des Bundesamtes für Seeschifffahrt und Hydrographie in der AWZ der Nordsee und Forschungsdaten des Alfred-Wegener-Instituts (AWI), Helmholtz-Zentrum für Polar- und Meeresforschung; Erfassungszeitraum: 1997 bis 2011, hauptsächlich Frühjahrs- und Herbstdaten (UVS-Daten), aber auch Sommer- und Winterdaten (AWI-Daten) Beprobungsstandards: Die Daten aus UVSn folgen dem Standarduntersuchungskonzept StUK 1-3 (BSH 2007); AWI-Daten dem ICES Standard (Rumohr 1999) Beprobungsgerät: hauptsächlich van-Veen-Greifer (0,1 qm, 30-95 kg je nach Sediment), wenige Stationen Kastengreifer (0,1 qm, 160 kg), für Nephrops norvegicus und Goneplax rhomboides Baumkurre und Dredge (1-3 m Breite) Probennahme: 1-3 Parallelproben pro Station, Siebung über 1 mm, Fixierung in Seewasser-gepuffertem Formalin, Daten aus Kurre/Dredge an Bord erfasst oder Unterproben eingefroren, Abundanz und Biomasse (g Nassgewicht) pro Art Datenauswertung: Fachinformationssystem für benthische Invertebraten; Prüfung der Qualität, Datenharmonisierung, Produkterstellung durch das AWI Produktbeschreibung: Grid: 5x5 qkm für Greiferdaten, 10x10 km² für Daten zu N. norvegicus und G. rhomboides aus Baumkurrendaten; Vorhandene auswählbare Parameter: Anzahl der Stationen, Minimum, Maximum, Mittelwert, Median und Standardabweichung der Dichte (m-2) je Art; Klassifizierungsmethode: Natürliche Unterbrechungen (Jenks-Caspall-Algorithmus); Die Produkte enthalten eine unterschiedliche Klassifizierung der Dichten je Art! Hinweis: Bitte beachten Sie die unterschiedlichen Wertebereiche! Rumohr, H. (1999). "Soft bottom macrofauna: Collection, treatment, and quality assurance of samples." ICES Techniques in Environmental Sciences, No. 27: 1-19. BSH (2007): Standard "Untersuchung der Auswirkungen von Offshore-Windenergieanlagen auf die Meeresumwelt (StUK 3)", Hamburg. Weitere Informationen finden Sie unter: https://gdi.bsh.de/de/data/Benthos-Density_Information_Benthos_Dichte_DE.pdf

Processed seismic data of Cruise BGR95 1995

The cruise BGR95 from 19th November to 28th December 1995 with M.S. AKADEMIK NEMCHINOV was designed to acquire new marine geophysical data for a better understanding of the geological processes and structural variations of the Cretaceous-aged oceanic crust of the Angola Basin in the South Atlantic regarding its reflectivity pattern, its shape of the basement surfaces and its crustal thickness. These evaluations were extended onshore to the ‘Damara Igneous Province’. The aim of this study was the investigation of the rift-related volcanic-magmatic processes accompanying the initial stage of the opening of the South Atlantic Ocean. The survey was a co-operation of BGR, Alfred Wegener Institute for Polar and Marine Research (AWI), GeoForschungsZentrum Potsdam, University of Göttingen and Johann Wolfgang Goethe-University Frankfurt/Main. The M.S. AKADEMIK NEMCHINOV generated the seismic signals by a tuned airgun array of 3260 cu.in. (= 53.4 l) together with two AWI owned large volume guns of 2 x 2000 cu.in. (= 65.6 l), recorded the MCS signals with a 3000 m streamer and controlled the shot releases for the ocean bottom hydrophones (OBH’s) and the onshore seismic stations (PEDAS). A total of 5,114 km of multichannel seismic reflection data in parallel with magnetic and gravity measurements have been collected onboard the M.S. AKADEMIK NEMCHINOV. 1069.4 km of the seismic work was done on 3 combined refraction/wide angle offshore and onshore traverses. The offshore part was recorded by 7 ocean bottom hydrophones (OBH) operated by the M.V. POLAR QUEEN (Reichert et al., 1996). The registration onshore Namibia was performed by 25 mobile seismic landstations (PEDAS) on each profile (Schulze et al., 1996). First results are described in the offshore and onshore reports of these investigations (Reichert et al., 1996, and Schulze et al., 1996). The data clearly show distinct series of the seaward dipping reflector sequences (SRDS) and isochronous variations in the accretion of the oceanic crust. The onshore and offshore registrations show deep arrivals from diving and refracted waves in a range up to 200 to 400 km.

Processed seismic data of Cruise MSM9/3

The cruise leg MSM09/3 was conducted as a cooperative project between the Alfred Wegener Institute for Polar and Marine Research (AWI), the Federal Institute for Geosciences and Resources (BGR), the Geological Survey of Denmark and Greenland (GEUS) and Dalhousie University. The data format is Society of Exploration Geophysicists SEG Y. A geophysical survey covered areas of Baffin Bay and Davis Strait between Greenland and the Canadian Baffin Island. A component of the IPY 2007/08 Lead Project Plate Tectonics and Polar Gateways in the Earth System (PLATES & GATES), this project DAVIS GATE is aimed to develop a tectonic and sedimentary reconstruction of the opening process of this oceanic gateway. Baffin Bay and Davis Strait play an important role in the shallow water exchange from the Arctic to the Atlantic Ocean. The plate-tectonic evolution as well as the magmatic history of this region has been sparsely known and required a careful geophysical investigation in order to construct a set of gridded detailed paleotopographic maps for a complete geodynamic reconstruction of this gateway. With a set of three seismic refraction/wide-angle reflection profiles, using ocean-bottom seismometers on 62 stations, as well as multi-channel reflection seismic recordings with a 3000-m long streamer, data were acquired from the sedimentary cover to the deep crust and even from parts of the uppermost mantle. Additional seismic data supplement these profiles and provide insights into the structures of the basement and dominant fault zones such as the Ungava fault system. A parallel running magnetic survey aimed to resolve the temporal evolution of the oceanic crust of Baffin Bay. The extension and subsidence of the continental and transitional crust in the Davis Strait and the evolution of oceanic crust in the Labrador Sea and Baffin Bay could be investigated with dataset to which continuously recorded gravity anomaly data and sub-bottom profiler data also contribute. This dataset provides the basis of geometrical and physical properties of the crust required for a realistic geodynamic model which will describe the break-up and the ocean basin evolution between Greenland and Canada in terms of detailed paleo-topography.

Processed seismic data of Cruise ARK25/3

The multidisciplinary marine geoscientific expedition ARK-25/3 was focused on the Greenland part of northern Baffin Bay and was aimed to acquire new geoscientific data to be used for modelling the evolution of the Greenland continental margin and its hydrocarbon prospective. The data format is Society of Exploration Geophysicists SEG Y. The cruise was performed under the direction of the Federal Institute for Geosciences and Natural Resources Hannover in cooperation with the Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven. Using 70 days of ship time onboard the research icebreaker R/V POLARSTERN a comprehensive data set was acquired along profiles extending from the deep oceanic basin in the central part of North Baffin Bay onto the Greenland continental margin in an area which was bordered by the Kane Basin in the North and Disko Island in the South. By means of multi-channel seismic, wide angle seismic, gravimetric and magnetic methods the structural inventory of the crust in the NW Baffin Bay was investigated. Additionally, heat flow data and sediment cores were collected along lines crossing the Greenland continental margin. The cores were extracted for geochemical and geomicrobiological analysis to be used for basin modelling, studying the hydrocarbon potential, and the hydrocarbon degradation by microorganisms under polar conditions. Geological sampling in the coastal area was done between Melville Bay and Washington Land. The collected rock material will be used to derive constraints on the erosion history of the coastal area. Aeromagnetic data was acquired covering a substantial part of the marine survey area to investigate magnetic signatures of the oceanic crust and the continental margin. This report summarizes the working programme and contains the documentation of acquired data and first results of the expedition.

Processed seismic data of Cruise BGR 2007 MoBaMaSis

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.

Müllmenge in der arktischen Tiefsee steigt stark an

Innerhalb von zehn Jahren ist die Verschmutzung an einem Messpunkt in der arktischen Tiefsee um mehr als das 20-fache gestiegen. Dies ergab eine Studie des Alfred-Wegener-Instituts, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), die im Februar 2017 in der Fachzeitschrift Deep-Sea Research I veröffentlicht wurde. Seit 2002 dokumentieren AWI-Wissenschaftler den Müll an zwei Messpunkten im sogenannten AWI-Hausgarten. Dabei handelt es sich um ein Tiefsee-Observatorium, das aus 21 Messstationen in der Framstraße zwischen Grönland und Spitzbergen besteht. Die Wissenschaftler haben an den beiden Messpunkten den Meeresgrund in einer Tiefe von 2500 Metern beobachtet. Dafür nutzten sie das ferngesteuerte Kamera-System OFOS (Ocean Floor Observation System). Seit Beginn der Messung haben sie auf insgesamt 7058 Fotos 89 Müllteile entdeckt. Da sie mit den Kameras nur ein relativ kleines Gebiet beobachten können, haben die Wissenschaftler die Mülldichte auf eine größere Fläche hochgerechnet. So kommen sie in dem Untersuchungszeitraum von 2002 bis 2014 auf einen Durchschnittswert von 3485 Müllteilen pro Quadratkilometer. Unter den fotografierten Müllteilen konnten vor allem Plastik und Glas ausmacht werden. Glas driftet nicht über größere Distanzen, sondern sinkt sofort an Ort und Stelle auf den Meeresgrund. Die Messreihe zeigt entsprechend, dass die Mülldichte in der arktischen Tiefsee mit der Intensivität der Schifffahrt in der Region zunimmt. Über die genaue Herkunft des Plastikmülls lässt sich dagegen kaum etwas sagen. Denn meist hat das Plastik schon eine weite Reise hinter sich, bevor es den tiefen Meeresgrund erreicht.

Fixed-wing Magnetics NOGRAM I + II

In 1998, as part of the expedition NOGRAM I (Northern Gravity, Radio Echo Sounding and Magnetics), a flight campaign was carried out over the Lincoln Sea north of Greenland with the Polar 2 aircraft (Dornier 228-100) in cooperation with the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research. A second flight campaign NOGRAM II took place in 2011 with the Polar 5 (Basler BT-67) over the Wandel Sea north of Greenland. The aim of the research was the structure and architecture of the upper Earth’s crust underneath the ice-covered offshore areas of the Morris Jesup Plateau and coastal waters north of Greenland. The airborne magnetic surveys were carried out with a flight line spacing of 3 km, and control profiles were flown every 30 km. During the two expeditions, 33000 km of line data were collected (16000 km in 1998, and 17000 km in 2011).

Arktisches Meereis auf dem Rückzug

Am 14. September 2016 wurde in einer gemeinsamen Pressemitteilung der Universität Hamburg, CEN – Centrum für Erdsystemforschung und Nachhaltigkeit, und dem Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung Bilanz der Sommerschmelzperiode 2016 gezogen. Im September 2016 ist die Fläche des Arktischen Meereises auf eine Größe von knapp 4,1 Millionen Quadratkilometern abgeschmolzen. Dies ist die zweitkleinste Fläche seit Beginn der Satellitenmessungen. Weniger Meereis gab es nur im Negativ-Rekord-Jahr 2012 mit 3,4 Mio km2. Seit Ende August 2016 sind die Nordost- und die Nordwestpassage in der Arktis wieder offen. Die südliche Route der Nordwestpassage wurde in diesen Wochen von Yachten und einem Kreuzfahrtschiff durchfahren.

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