Prof. Dr. Tilo von Dobeneck

Stratigraphic studies of ocean margin environments based on shipboard physical properties and laboratory paleo- and rock magnetic measurements (RCOM C1)
Our group puts particular emphasis on iron minerals, which can be assessed in great detail by rock magnetic, geochemical, mineralogical and optical methods. Iron-based proxies are used as source, weathering, and transport indices and help to establish correlation networks and sediment budgets. The ultimate signatures entering the geological record undergo (bio)geochemical overprinting. Iron mineral reduction and relocation in sulfidic and methanogenic environments are indicative of the state and timing of diagenetic processes. A range of other specific element (Ti, Al, Si, Ca, C, S, Ba) and physical-property logs give insight into ocean-margin sedimentary compositions and their controls.

Using non-negative matrix factorization in the unmixing of diffuse reflectance spectra
Records of millennial-scale NW African climate change from off-shore Senegal

• Bleil, U. and T. von Dobeneck (1999). Geomagnetic events and relative paleointensity records - clues to high-resolution paleomagnetic chronostratigraphies of Late Quaternary marine sediments? In: G. Fischer & G. Wefer (eds), Use of Proxies in Paleoceanography: Examples from the South Atlantic, Springer, Berlin, 635-654.
• Bleil, U. and T. von Dobeneck (2004). Late Quaternary Terrigenous Sedimentation in the Western Equatorial Atlantic South American versus African Provenance Discriminated by Magnetic Mineral Analysis; In: The South Atlantic in the Late Quaternary: Reconstruction of Material Budgets and Current Systems, Edited by G. Wefer, S. Mulitza, and V. Ratmeyer; Springer-Verlag, pp 213-236
• Fabian, K. & T. von Dobeneck (1997). Isothermal magnetization of samples with stable Preisach function: A survey of hysteresis, remanence, and rock magnetic parameters, J. Geophys. Res., 102, 17659-17677.
• Franke, C., D. Hofmann and T. von Dobeneck (2004). Does lithology influence paleointensity records? A statistical analysis on South Atlantic pelagic sediments. Phys. Earth Planet. Inter., 147, 285-296.; doi:10.1016/j.pepi.2004.07.004
• Franke, C., Fu, Y., Heslop, D., von Dobeneck, T. (2009): Data report: Natural remanent magnetization of IODP Holes U1319A, U1320A, U1322B, and U1324B and magnetic carrier identification by scanning electron microscopy. Proceedings of the IODP, 308, 209; doi: 10.2204/iodp.proc.308.209.2009
• Franke, C., Pennock, G.M., Drury, M.R, Engelmann, R., Lattard, D., Garming, J.F.L., Von Dobeneck, T. and Dekkers, M.J. (2007). Identification of magnetic Fe-Ti oxides in marine sediments by electron backscatter diffraction in scanning electron microscopy, Geophys. J. Int., 170 (2), 545-555 (RCOM0501);doi: 10.1111/j.1365-246X.2007.03410.x
• Franke, C., von Dobeneck, T., Drury, M.R., Meeldijk, J.D., and Dekkers, M.J. (2007). Magnetic Petrology of Equatorial Atlantic Sediments: Electron Microscopic Results and their Environmental Magnetic Implications, Paleoceanography, 22, PA4207, doi: 10.1029 / 2007PA001442 (RCOM0536)
• Frederichs, T., T. von Dobeneck, U. Bleil and M.J. Dekkers (2003). Towards the identification of siderite, rhodochrosite, and vivianite in sediments by their low-temperature magnetic properties. Physics and Chemistry of the Earth, 28, pp 669-679.
• Frederichs, T., U. Bleil, K. Däumler, T. von Dobeneck and A. Schmidt (1999). The magnetic view on the marine paleoenvironment: parameters, techniques and potentials of rock magnetic studies as a key to paleoclimatic and paleoceanographic changes. In: G. Fischer & G. 'Wefer (eds), Use of Proxies in Paleoceanography: Examples from the South Atlantic, Springer-Verlag Berlin Heidelberg, pp 575-599.
• Fu, Y., von Dobeneck, T., Franke, Ch., Heslop, D., Kasten, S. (2008). Rock magnetic identification and geochemical process models of greigite formation in Quaternary marine sediments from the Gulf of Mexico (IODP Hole U1319A). Earth and Planetary Science Letters, 275, 233-245; doi: 10.1016/j.epsl.2008.07.034
• Funk, J.A., T. von Dobeneck, and A. Reitz (2004). Integrated Rock Magnetic and Geochemical Quantification of Redoxomorphic Iron Mineral Diagenesis in Late Quaternary Sediments from the Equatorial Atlantic, In: The South Atlantic in the Late Quaternary: Reconstruction of Material Budgets and Current Systems, Edited by G. Wefer, S. Mulitza, and V. Ratmeyer; Springer-Verlag, pp 237-260
• Funk, J.A., T. von Dobeneck, T. Wagner, and S. Kasten (2004). Late Quaternary Sedimentation and Early Diagenesis in the Equatorial Atlantic Ocean: Patterns, Trends and Processes Deduced from Rock Magnetic and Geochemical Records, In: The South Atlantic in the Late Quaternary: Reconstruction of Material Budgets and Current Systems, Edited by G. Wefer, S. Mulitza, and V. Ratmeyer; Springer-Verlag, pp 461-497
• Futschik, K., H. Pfützner, A. Doblander, P. Schönhuber, T. von Dobeneck & N. Petersen (1989). Why not use magnetotactic bacteria for domain analysis? Physica Scripta, 40, 518-521.
• Garming, J.F.L., Bleil, U., Franke, C. and von Dobeneck, T. (2007). Low-temperature partial magnetic self-reversal in marine sediments by magnetostatic interaction of titanomagnetite and titanohematite intergrowths, Geophys. J. Int., 170 (3), 1067-1075 (RCOM0508)); doi: 10.1111/j.1365-246X.2007.03504.x
• Gingele, F.X., F. Schmieder, T. von Dobeneck, R. Petschik & C. Rühlemann (1999). Terrigenous flux in the Rio Grande Rise area during the past 1500 ka: evidence of deepwater advection or rapid response to continental rainfall patterns? Paleoceanography, 14, 84-95.
• Heslop, D., von Dobeneck, T., Höcker, M. (2007). Using non-negative matrix factorization in the “unmixing” of diffuse reflectance spectra. Marine Geology, 241, 63-78 (RCOM0488)); doi: 10.1016/j.margeo.2007.03.004
• Itambi, A. C., von Dobeneck, T., Mulitza, S., Bickert, T., Heslop, D. (2009): Millennial-scale northwest African droughts relatesd to Heinrich events and Dansgaard-Oeschger cycles: Evidence in marine sediments from off-shore Senegal. Paleoceanography, 24, PA1205; doi: 10.1029/2007PA001570
• Itambi, A.C., von Dobeneck, T., Adegbie, A. T. (2010): Millennial-scale precipitation changes over central Africa during the late Quaternary and Holocene: Evidence in sediments from the Gulf of Guinea. Journal of Quaternary Science, 25 (3), 267–279; doi: 10.1002/jqs.1306
• Itambi A. C., von Dobeneck, T., Dekkers, M. J., and Frederichs, T. (2010): Magnetic mineral inventory of equatorial Atlantic Ocean marine sediments off Senegal - glacial and interglacial contrast, Geophysical Journal International, 183: 163–177; doi: 10.1111/j.1365-246X.2010.04736.x
• Köhler, C.M., Heslop, D., Dekkers, M.J., Krijgsman, W., van Hinsbergen, J.J., von Dobeneck, T. (2008): Tracking provenance change during the late Miocene in the Eastern Mediterranean using geochemical and environmental magnetic parameters. Geochemistry, Geophysics, Geosystems; doi: 10.1029/2008GC002127
• Kosterov, A., Th. Frederichs and T. von Dobeneck (2006). Low-temperature properties of rhodochrosite (MnCO3), Phys. Earth Planet. Inter., doi:10.1016/j.pepi.2005.09.011
• Müller, H., von Dobeneck, T., Nehmiz, W., Hamer, K. (2011): Near‐surface electromagnetic, rock magnetic, and geochemical fingerprinting of submarine freshwater seepage at Eckernförde Bay (SW Baltic Sea). Geo‐Marine Letters , 31 (2): 123‐140; doi: 10.1007/s00367-010-0220-0
• Müller, H., von Dobeneck, T., SanFilipo, W., Hilgenfeldt, C., Rey, D. und Rubio, B. (in press): Mapping the magnetic susceptibility and electric conductivity of marine surficial sediments by benthic EM profiling. GEOPHYSICS. VOL. 77, NO. 1; doi: 10.1190/GEO2010-0129.1
• Mulitza, S., Prange, M., Stuut, J.B., Zabel, M., von Dobeneck, T., Itambi, A.C., Nizou, J., Schulz, M. and Wefer, G.(2008): Sahel megadroughts triggered by glacial slowdowns of Atlantic meridional overturning. Paleoceanography, 23, PA4206; doi:10.1029/2008PA001637
• Petersen, N., T. von Dobeneck & H. Vali (1986). Fossil bacterial magnetite in deep-sea sediments from the South Atlantic Ocean. Nature, 320, 611-615.
• Rey, D., Müller, H., Rubio, B., von Dobeneck, T., Vilas, F., Hilgenfeldt, C., Frwederichs, Th., Bernabeu, A. Fernandez, S., Mohamed, K.J., Grupo GEOMA. Using electromagnetic sensors to estimate physical properties and environmental quality of surface sediments in the marine environment. Preliminary results. Geotemas (RCOM0565)
• Schmidt, A., T. von Dobeneck and U. Bleil (1999). Magnetic characterization of Holocene sedimentation in the South Atlantic. Paleoceanography, 14, 465-481.
• Schmieder, F., T. von Dobeneck, and U. Bleil (2000). The Mid-Pleistocene climate transition as documented in the deep South Atlantic Ocean: initiation, interim state and terminal event. Earth Planet. Sci. Lett., 179, 539-549
• Spassov, S., F. Heller, M.E. Evans, L.P. Yue, and T. von Dobeneck (2003). A lock-in model for the complex Matuyama-Brunhes boundary record of the loess/palaeosol sequence at Lingtai (Central Chinese Loess Plateau). Geophys. J. Int., 155, pp 350-366.
• Vali, H., T. von Dobeneck, G. Amarantidis, O. Förster, G. Morteani, L. Bachmann & N. Petersen (1989). Biogenic and lithogenic magnetic minerals in Atlantic and Pacific deep sea sediments and their paleomagnetic significance. Geol. Rundschau, 78, 753-764.
• von Dobeneck, T., N. Petersen & H. Vali (1987). Bakterielle Magnetofossilien - Paläomagnetische und paläontologische Spuren einer ungewöhnlichen Bakteriengruppe. Geowiss. in unserer Zeit, 5, 27-35.
• von Dobeneck, T., Th. Frederichs, K. Fabian & U. Bleil (1996). Rock Magnetic Micro-Scanning mit. HTSL-SQUID-Gradiometer. In Supraleitung und Tieftemperaturtechnik 1996, VDI-Technologiezentrum (ed), VDI-Verlag Düsseldorf, 51-54.
• von Dobeneck, T. (1993). Neue Ansätze zur Messung und Interpretation der magnetischen Hysterese von Tiefseesedimenten. Dissertation Univ. München, Verlag Marie L. Leidorf, Buch am Erlbach, 190 S.
• von Dobeneck, T. (1996). A systematic analysis of natural magnetic mineral assemblages based on modelling hysteresis loops with coercivity-related hyperbolic basis functions, Geophys. J. Int., 124, 675-694.
• von Dobeneck, T. (1998). Analytical Strategies in Environmental Magnetism - a South Atlantic Perspective. Habilitationsschrift Universität Bremen, 166 S.
• von Dobeneck, T. (1998). The concept of ‘partial susceptibilities’. Geol. Carpath., 49, 228-229.
• von Dobeneck, T. and F. Schmieder (1999). Using rock magnetic proxy records for orbital tuning and extended time series analyses into the super- and sub-Milankovitch bands. In: G. Fischer & G. Wefer (eds) Use of Proxies in Paleoceanography: Examples from the South Atlantic, Springer, Berlin, 601-633.
• von Dobeneck, T. and J.A. Funk (2002), Integrated rock magnetic and geochemical proxies for iron mineral dissolution and precipitation in marine sediments based on single sample and new split core scanning techniques, Quad. di Geofisica 26: 183-185.

• Recent Research Activities
• Publications
• Curriculum vitae, positions, memberships and awards

Deep-towed electromagnetic sounding of the seafloor in combination with magnetometry and sediment acoustics (RCOM C1)
Electromagnetic (EM) sounding with controlled sources is turning into the leading non-seismic technique to characterize hydrocarbon reservoirs. The physical principles of the method allow to map magnetic susceptibility as well as electric conductivity with high lateral resolution. For the tasks of several projects in RCOM Research Areas C, D, E and F, this new technique seems to offer very promising perspectives.
We plan to start operations with scientific divers and the light Research Boat Neridis (equipped with DGPS, PC & WLAN access point, echosounder and a deep towed option for our Magnetometers and an intended electromagnetic sensor) at a test site in the Eckernförde Bay in the summer of 2006. From 2007, the system will be step-wise adapted for deep-water applications with MOVE, ROV and AUV platforms.

Environmental magnetism at the seafloor: cold seeps in the Eckernförde Bay

Mineral and rock magnetic properties at low temperatures, high fields and variable frequencies (RCOM C1, EUROPROX)
Several redox sensitive iron and manganese minerals like siderite, rhodochrosite and vivianite are paramagnetic at room temperature, but develop a magnetic order at low temperatures, which enables their identification and quantification in sediments. Important magnetic minerals like magnetite, hemoilmenite and pyrrhotite show characteristic phase changes at low temperatures. The climate sensitive terrestrial minerals hematite and Goethite can be quantified by high temperature and high field measurements. With our Quantum Design Magnetic Properties Measurement System we can perform highly sensitive magnetic measurments at 2-800 K and 0-7 T. This analytical tool is used to investigate diagenesis processes in marine sediments and to develop proxy methods for paleoclimatology.

Magneto-mineralogical identification of Fe Ti oxides and their environmental implications

Physical principles of sedimentary paleomagnetic recording - field, laboratory, and numerical investigations (DFG Priority Program ‘Geomagnetic Variations’)
Sea floor spreading and sedimentation continuously record and archive the changing geomagnetic field at global scale. Sedimentary records attain superior temporal and spatial coverage, but climate-controlled factors such as sediment accumulation and composition, bioturbation and compaction influence the mobility, alignment and fixation of magnetic particles in the sedimentary matrix. These factors modulate and filter the remanence acquisition process leaving imprints on the resulting paleomagnetic record. Reversal sections and relative paleointensity records with their typically low field intensity lows are particularly affected. Using a wide range of approaches from in-situ experiments in maar lakes to laboratory compaction experiments and numerical discrete element models, we investigate mechanisms of lithological and climatic overprint in magnetostratiphy.