Depth of late Cenozoic sediments in the German North Sea — Top seismic unity SU1

The map shows the top of the seismic unit SU1 in meters below NN. The unit is the oldest of seven mapping units identified above the Midmiocene discordance using seismic and borehole geophysical data. In the publication “Late Cenozoic evolution of the German North Sea — Sedimentation in a Subsiding Basin” a detailed description of these units is documented. Sedimentation in the southern North Sea was dominated by a delta system moving eastward to the west, the so-called Eridanos Delta (sensu Overeem et al., 2001). The dimensions of this fossil delta are comparable to those of Earth’s largest delta systems today (Black, 1996). The development of this deposit system has been the subject of numerous scientific studies in recent decades (e.g. Sörensen et al., 1997; Overeem et al., 2001; Kuhlmann, 2004), which, however, concentrated mainly on the neighbouring North Sea sectors and relatively little was known about the German part. However, for the overall understanding of the delta sedimentation prevailing during this period and its development, the German part is essential, since from the Uppermiocene to the late Pliocene, the main deposit area of the giant delta was predominantly in today’s German North Sea sector. On the basis of extensive seismic data and geophysical well information, a detailed mapping of the late-Cenozoic delta deposits in the German North Sea sector has been carried out for the first time. The sedimentary sequence, which was previously only coarse or not subdivided, was structured according to seismostratigraphic and sequence stratigraphic concepts (e.g. Mitchum et al., 1977; Catuneanu, 2006). After that, seven regionally significant seismic horizons above the Midmiocene discordance were identified and time-calibrated with the help of new biostratigraphic dating. They divide the late-Cenozoic sediment sequence into seven main deposit units, namely SU1 to SU7. The units, each at their base and top of prominent discordance areas, reflect successive phases of delta development. Literature: Mitchum, R.M.J., Vail, P.R., Sangree, J.B. (1977). Seismic stratigraphy and global changes of sea-level, part 6: stratigraphic interpretation of seismic reflection patterns in depositional sequences. In: Payton, C. (Ed.), Seismic Stratigraphy Applications to Hydrocarbon Exploration. American Association of Petroleum Geologist Memoir, vol. 26. AAPG, Tulsa, pp. 117-133. Black, C. (1996). Holes 89/3, 89/4 and 89/9 on the German North Sea Shelf — sedimentological and magnetostratigraphic findings as well as lithostratigraphic connectivity. In: Streif, H. (Editor), German Contributions to Quaternary Research in the Southern North Sea. Geological Yearbook, 146/Serie A. Schweiserbart: 33-137. Sørensen, J.C., Gregersen U., Breiner M. and Michelsen O. (1997). High-frequency sequence stratigraphy of Upper Cenozoic deposits in the central and southeastern North Sea areas, Marine and Petroleum Geology, 14 (2), 99-123. Overeem, I., G. J. Weltje, C. Bishop-Kay, and S. B. Kroonenberg (2001). The Late Cenozoic Eridanos delta system in the Southern North Sea Basin: a climate signal in sediment supply?Basin Research, 13 (3), 293-312. Kuhlmann, G. (2004). High resolution stratigraphy and paleoenvironmental changes in the southern North Sea during the Neogenes. An integrated study of Late Cenozoic marine deposits from the northern part of the Dutch offshore area, cummulativ thesis, 209 pp, Utrecht University, Utrecht. Catuneanu, O., 2006. Principles of Sequence Stratigraphy: New York, Elsevier, 386 p