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  • 1
    Publication Date: 2016-12-11
    Description: The Arctic changes rapidly in response to global warming and is expected to change even faster in the future (IPCC 2001, 2007, 2013). Large areas of the shelves and continental slopes bordering the Arctic Ocean are characterized by permafrost and the presence of gas hydrates. Future global warming and potential hydrate dissociation in the Arctic Ocean challenge the slope stability of these areas. This may lead to slope failures. The first, and so far only reported, largescale slope failure in the Arctic Ocean is the Hinlopen/Yermak Megaslide (HYM). Following our previous studies, we wanted to investigate this giant slope failure and the deeper structure of the Sophia Basin in detail to elucidate the potential causes of the main and following failure events as well as to test existing hypotheses on the generation of this giant submarine landslide. Our investigations focused on (1) pre-site survey of proposed IODP drill sites, (2) deep tectonic structure and seismicity of the Sophia Basin and (3) future failure potential north of Svalbard. Furthermore, we extended measurements along the Spitsbergen Fracture Zone in the Fram Strait, where a new deep-sea slide was discovered in 2012 during cruise MSM 21/4. Also, we tied existing ODP drill holes on top of the southern Yermak Plateau to our new and existing seismic networks. We applied a combination of hydro-acoustic mapping, deep and high-resolution multichannel seismic reflection profiling and a wide-angle seismic survey with broad-band oceanbottom seismometers (BB-OBS). We mapped two headwall and sidewall areas of the HYM for indication of gas seepage including sampling. In addition, we sampled sediments to characterize the young sedimentation record, for dating and for geo-technical analysis.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Miscellaneous , notRev
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  • 2
    Publication Date: 2016-12-11
    Description: According to classical plume theory, the Tristan da Cunha hotspot is thought to have played a major role in the rifting of the South Atlantic margins and the creation of the aseismic Walvis Ridge by impinging at the base of the continental lithosphere shortly before or during the breakup of the South Atlantic margins. However, Tristan da Cunha is enigmatic as it cannot be clearly identified as a hot spot but may also be classified as a more shallow type of anomaly that may actually have been caused by the opening of the South Atlantic. The equivocal character of Tristan is largely due to a lack of geophysical data in this region. It is of central importance to characterize the region around Tristan da Cunha with geophysical data in a more coherent way to understand the tectonic processes of the opening of the South Atlantic and the formation of the Walvis Ridge, i.e. to understand whether Tristan da Cunha is the cause or the consequence of the rifting. We therefore staged a multi-disciplinary geophysical study of the region by acquiring passive marine electromagnetic and seismic data, bathymetric data as well as gravity data from which we will derive an electrical resistivity, seismic velocity and density model down to a depth of several hundred kilometres. These models will be interpreted in the context of geochemical data and tectonic models developed within the SPP1375 South Atlantic Margin Processes and Links with onshore Evolution (SAMPLE). On the cruise MSM24 we acquired bathymetric data within the Tristan da Cunha region and recovered 26 out of 26 ocean-bottom magnetotelluric stations (OBEM), 22 out of 24 broadband ocean-bottom seismometers (BBOBS) as well as two seismic and one magnetotelluric (MT) land stations from the uninhabited Nightingale Island. These stations were deployed one year ago during cruise MSM20/2. The cruise also offered the opportunity for a colleague from the University Heidelberg to conduct geological sampling on Tristan da Cunha.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Miscellaneous , notRev
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  • 3
    Publication Date: 2016-12-11
    Description: According to classical plume theory, the Tristan da Cunha hotspot is thought to have played a major role in the rifting of the South Atlantic margins and the creation of the aseismic Walvis Ridge by impinging at the base of the continental lithosphere shortly before or during the breakup of the South Atlantic margins. But Tristan da Cunha is enigmatic, as it cannot be clearly identified as a hot-spot but classifies also highly as a more shallow type of anomaly that may actually have been caused by the opening of the South Atlantic. The equivocal character of Tristan is largely due to lack of geophysical data in this region. To understand the tectonic processes of the opening of the South Atlantic, the formation of the Walvis ridge and to understand whether Tristan da Cunha is the cause or the consequence of rifting, it is of central importance to characterize the region around Tristan da Cunha in a more coherent way. Within this research cruise we deployed 26 ocean bottom electromagnetic stations (OEBM) and 24 ocean bottom seismometer (OBS) for a long term acquisition (1 year) of magnetotelluric and seismological data, acquired bathymetry and gravity data and performed geological sampling on Tristan da Cunha. The data will be interpreted in the context of geochemical data and tectonic models developed within the SPP1375 South Atlantic Margin Processes and Links with onshore Evolution (SAMPLE).
    Repository Name: EPIC Alfred Wegener Institut
    Type: Miscellaneous , notRev
    Location Call Number Expected Availability
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