Marine Geology

Upcoming events:

� 5^th International Symposium on Deep-Sea Corals

2-7 April 2012, Amsterdam, The Netherlands

Recent events:

� The national marine-geosciences group has been initiated (web pages)

� Read more about the recent XRF workshop here

Latest news:

� Geochimica et Cosmochimica Acta paper: �Contrasting variability in foraminiferal and organic Paleotemperature proxies in sedimenting particles of the Mozambique Channel (SW Indian Ocean)� by Ulrike Fallet, Jenny E. Ullgren, Isla S. Casta�eda, Hendrik van Aken, Stefan Schouten, Herman Ridderinkhof & Geert-Jan Brummer is accepted! Click here for the online-early version.

� Pages Newsletter: �2010 international workshop on XRF core scanning� by Rik Tjallingii and workshop participants. Click here for the online version.

� GEO members at Sea: Juliane Steinhardt on her way in the Mozambique Channel onboard the RV Algoa.

Click on image for

actual position of Pelagia

The Department of Marine Geology

Research in the Marine Geology department (GEO) focuses on seabed systems, where the geo-, bio- and hydrosphere interact. GEO has three main objectives for which it uses advanced sea-going techniques and NIOZ-based analytical facilities in a multidisciplinary approach that all address the general topic of Seafloor dynamics, theme 2 of the NIOZ Science Plan:

� Study present day sedimentological processes and environmental conditions to better understand the geological record and calibrate proxies for SST, rainfall and dust emissions

� Learn about paleo climate / environmental conditions by investigating sediment and coral records

� Use paleo and present-day studies to make predictions about future climate / environmental changes e.g. increased methane release in the Arctic

In addition GEO is contributing to other NIOZ science themes, as:

� Climate variability and the Sea: ocean-climate reconstruction by proxy development

� Biodiversity and Ecosystem functioning: cold-water coral reef functioning (seasonality in pelagic export productivity

All topics are essential parts of NIOZ-wide research that rely on solid marine geological knowledge as well as field and lab expertise. GEO has operated almost world-wide over the last six years. Today GEO is still very much open-ocean oriented but the current and future focus will be on the Atlantic and the Arctic Oceans and possibly the Caribbean (Netherlands Antilles). GEO, developed and continues to employ benthic landers, versatile instrumented moorings as well as sediment-coring and analytical techniques. Reconnaissance prior to sediment sampling with multibeam and seismic techniques is commonly used throughout all sea-going departments in the institute. Hydroacoustic techniques are currently further developed with respect to free-gas flux mapping and quantification. GEO has a strong commitment to multidisciplinary sea-going research and therefore, we collaborate with all departments within NIOZ as well as abroad through international projects like:

� COST ACTION PERGAMON: PERmafrost and GAs hydrate related methane release in the Arctic and impact on climate change: European cooperation for long-term MONitoring. Coordinated by NIOZ (ESF, 2010-2013) Contact: Jens Greinert

� GATEWAYS: (Ocean variability and impact of water column properties on proxy formation (EU-FP7 Marie Curie International Training Network, 2009-2013). Contact Geert-Jan Brummer

� HERMIONE: Hotspot Ecosystem Research and Man's Impact on European Seas (EU-FP7, 2009-2012). Contact: Henko de Stigter

� EMSO PP: European Multidisciplinary Seafloor Observatory (EU FP-7, 2008-2012). Contact Jens Greinert

Scientific Topics

1) Influence of meso-scale eddies on the sediment record temperature signal of planktonic foraminifera in the Mozambique Channel

Meso-scale eddies are a principal feature of ocean boundary currents with a potentially significant impact on continental margin sedimentation. Sediment-trap and ADCP equipped moorings across the Mozambique Channel show periodic off-shelf sedimentation of lithogenic and biogenic organic matter by fast-rotating, meso-scale eddies feeding the Agulhas Current. These eddies modulate seasonal fluxes of temperature-specific pelagic foraminifera and organic compounds. This has to be considered in paleo SST calibrations and organic-compound based proxies of past seasonal ocean-climate and land-sea interaction from sediment cores. (Fallet et al., 2010; Jonkers et al., 2010)

2) Long-term lander deployments reveal earthquake-related sediment transport along canyons

Submarine canyons are an important conduit for sediment dispersal on continental margins. Off central Portugal, canyons act as depocenters for metals like Pb, Zn, and Cr from industrialised metropolitan areas. Year-long lander deployments revealed that internal tides force sediment re-suspension and transport in the upper-middle canyon, while sediment gravity flows predominate below. Turbidity-current transport occurs on centennial or longer timescales, while gravitational sediment transport appears restricted to earthquake-tsunami events. (de Stigter et al., 2007; Richter et al., 2009)

3) Changing environmental conditions revealed by desert dust and river runoff in marine sediments

Fluvial and wind-blown sediments end up as complex mixtures in marine deposits. These can be un-mixed by end-member modelling of grain-size distributions to reveal changing environmental conditions on land. Sedimentary records with varying temporal resolutions off NW Africa and SE America show a linear relationship between desert-dust fluxes and the Atlantic Meridional Overturning Circulation, abrupt and persistent droughts in the Sahel throughout the past 57kyrs, and the disruption of this natural variability since the start of colonial land use. (Stuut et al., 2007; Mulitza et al., 2010)

4) High-resolution XRF-core scanning identify monsoonal river discharge in tropical currents

Giant corals fill the data gap in Indian-Ocean climate history on human time scales. Coral carbonates record seasonal surface temperature, hinterland erosion, and sediment discharge over centuries. Ultra Violet Spectral Luminescence discriminates between soil-derived humic acids and detritic sediments delivered by monsoonal river discharge. Regional responses in precipitation appear linked to accelerated Indian Ocean warming and natural multi-decadal variability. (Grove et al., 2010)

5) Spatial quantification of methane fluxes and their possible influence on atmospheric methane concentrations

Methane is a strong greenhouse gas that escapes from seabed sediments in unknown quantities into the atmosphere. Ship-based hydroacoustic systems are used to improve spatial coverage and to determine free-gas fluxes remotely. Integrated approaches of direct observations, geophysical mapping, geochemical analysis, and bubble-dissolution modelling in the Black Sea enabled the first complete budget of methane fluxes from the seafloor into the atmosphere. The results show that only small CH₄ amounts reach the atmosphere under present day conditions. (Greinert et al., 2010; Greinert & Mc Ginnis, 2009).

Seafloor images recorded during the submersible dives with JAGO in 2004. (a and b) The flat seafloor around seep sites is typically covered with white Beggiatoa mats. Bubbles are released from within the mats or very close to their outer edge. (c) Three bubble streams only a few tens of cm apart. The claw of the submersible holds a little metal sphere (6 mm in diameter) as scale for the bubble size. (d) The inverted funnel over a bubble stream during one of the flux measurements (from Greinert et al., 2010).

Cited references

Fallet, U., Brummer, G.J., Zinke, J., Vogels, S., Ridderinkhof, H. (2010): Contrasting seasonal fluxes of planktonic foraminifera and impacts on paleothermometry in the Mozambique Channel upstream of the Agulhas Current. Paleoceanography 25, PA4223.

Greinert, J., McGinnis, D.F. (2009) Single bubble dissolution model - The graphical user interface SiBu-GUI. Environmental Modelling and Software 24, 1012-1013.

Greinert, J., McGinnis, D.F., Naudts, L., Linke, P., De Batist, M. (2010): Spatial methane-bubble flux quantification from seeps into the atmosphere on the Black Sea shelf. Journal of Geophysical Research 115, C01002.

Grove, C.A., Nagtegaal, R., Zinke, J., Scheufen, T., Koster, B., Kasper, S., McCulloch, M., Van den Bergh, G.D., Brummer, G.-J.A. (2010) River runoff reconstructions from novel spectral luminescence scanning of massive coral skeletons. Coral Reefs 29, 579-591.

Jonkers, L., Brummer, G.‐J.A., Peeters, F.J.C., Van Aken, H.M., De Jong. M.F. (2010): Correction to Seasonal stratification, shell flux, and oxygen isotope dynamics of leftcoiling N. pachyderma and T. quinqueloba in the western subpolar North Atlantic, Paleoceanography 25, PA3209.

Mulitza, S., Heslop, D., Pittauerova, D., Fischer, H.W., Meyer, I., Stuut, J.-B.W., Zabel, M., Mollenhauer, G., Collins, J.A., Kuhnert, H., Schulz, M. Increase in African dust flux at the onset of commercial agriculture in the Sahel region. Nature 466, 226-228.

Richter, T.O., De Stigter, H.C., Boer, W., Jesus, C.C., Van Weering, T.C.E. (2009): Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin. Deep Sea Research Part I: Oceanographic Research Papers 56, 267-282.

de Stigter, H.C., Boer, W., De Jesus Mendes, P.A., Jesus, C.C., Thomsen, L., Van den Bergh, G.D., Van Weering Tj.C.E. (2007): Recent sediment transport and deposition in the Nazar� Canyon, Portuguese continental margin. Marine Geology 246: 144-165.

Stuut, J.-B. W., Kasten, S., Lamy, F., Hebbeln, D. (2007), Sources and modes of terrigenous sediment input to the Chilean continental slope, Quaternary International 161, 67-76.