TY - BOOK

T1 - Aspects of the Quaternary evolution of the Southern Kattegat and the central North Sea based on interpretation of 2D and 3D marine reflection seismic profiles

AU - Bendixen, Carina

N1 - Ph.d.-grad opnået ved mundtligt forsvar 30. september 2016

PY - 2016/6

Y1 - 2016/6

N2 - In this PhD study interpretation of 2D shallow seismic data in the Kattegat region (Pinger, Sparker and Innomar parametric sub-bottom profiler), 3D conventional seismic data in the central North Sea, combined with sediment core interpretation and radiocarbon dating has been carried out in order to outline the geological development of the southwestern part of the Kattegat region, from the Late Weichselian to Early Holocene and to investigate the potential of using 3D seismic in Quaternary geology.Within the study area of the Kattegat region Late Weichselian (Lateglacial - LG) sediments are widespread and seen as semi-transparent reflections. The LG deposits drape the surface of the underlying till and were deposited during a period of relative high sea level (highstand system tract). The followingpostglacial (PG - Holocene) sediments represent a full depositional sequence including lowstand system tract (PG I), transgressive system tract (PG II) and highstand system tract (PG III). During early Holocene, the southwestern part of Kattegat was characterized by multiple funnel-shaped estuaries withspits and bars (10.8–9.2 cal. ka BP), connected to the freshwater palaeo-Great Belt channel knows as the Dana River. This took place simultaneously with the occurrence and drainage of the Ancylus Lake through the Great Belt. The drainage of the Ancylus Lake was interpreted as non-catastrophic water flowas seismic data shows no evidence of major erosion or delta deposition, which would indicate a catastrophic drainage event. With a continuous Holocene sea-level rise back-stepping (landwards retreat) of the coastal systems occurred, followed by flooding of the northern Great Belt threshold and major erosion took place. Rapid sea-level rise preserved the sea floor morphology which is reflected in the present-day bathymetry seen as spits and bars systems. Based on interpretation of the entire dataset, a reconstruction the palaeoenvironment illustrates the Kattegat region around 9 cal. ka BP, including a complete estuary system with back barrier basin, sand bars and spits.Within the study area of the central North Sea, interpretation of 3D-seismic data has led to the identification of an unknown well-preserved glaciotectonic complex. It is suggested that the glacial thrust complex is evidence for an extensive Pre-Elsterian glaciation. The interpreted thrusts blocks plot wellwithin the range of the thrusts associated with the Weichselian glaciation. Combining this information ith the oxygen isotope record, the presence of stratigraphy above the thrust complex and related iterature it is estimated that the identified thrust complex occurred during MIS 16 with the origin fromScandinavia.

AB - In this PhD study interpretation of 2D shallow seismic data in the Kattegat region (Pinger, Sparker and Innomar parametric sub-bottom profiler), 3D conventional seismic data in the central North Sea, combined with sediment core interpretation and radiocarbon dating has been carried out in order to outline the geological development of the southwestern part of the Kattegat region, from the Late Weichselian to Early Holocene and to investigate the potential of using 3D seismic in Quaternary geology.Within the study area of the Kattegat region Late Weichselian (Lateglacial - LG) sediments are widespread and seen as semi-transparent reflections. The LG deposits drape the surface of the underlying till and were deposited during a period of relative high sea level (highstand system tract). The followingpostglacial (PG - Holocene) sediments represent a full depositional sequence including lowstand system tract (PG I), transgressive system tract (PG II) and highstand system tract (PG III). During early Holocene, the southwestern part of Kattegat was characterized by multiple funnel-shaped estuaries withspits and bars (10.8–9.2 cal. ka BP), connected to the freshwater palaeo-Great Belt channel knows as the Dana River. This took place simultaneously with the occurrence and drainage of the Ancylus Lake through the Great Belt. The drainage of the Ancylus Lake was interpreted as non-catastrophic water flowas seismic data shows no evidence of major erosion or delta deposition, which would indicate a catastrophic drainage event. With a continuous Holocene sea-level rise back-stepping (landwards retreat) of the coastal systems occurred, followed by flooding of the northern Great Belt threshold and major erosion took place. Rapid sea-level rise preserved the sea floor morphology which is reflected in the present-day bathymetry seen as spits and bars systems. Based on interpretation of the entire dataset, a reconstruction the palaeoenvironment illustrates the Kattegat region around 9 cal. ka BP, including a complete estuary system with back barrier basin, sand bars and spits.Within the study area of the central North Sea, interpretation of 3D-seismic data has led to the identification of an unknown well-preserved glaciotectonic complex. It is suggested that the glacial thrust complex is evidence for an extensive Pre-Elsterian glaciation. The interpreted thrusts blocks plot wellwithin the range of the thrusts associated with the Weichselian glaciation. Combining this information ith the oxygen isotope record, the presence of stratigraphy above the thrust complex and related iterature it is estimated that the identified thrust complex occurred during MIS 16 with the origin fromScandinavia.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122886277905763

M3 - Ph.D. thesis

BT - Aspects of the Quaternary evolution of the Southern Kattegat and the central North Sea based on interpretation of 2D and 3D marine reflection seismic profiles

PB - Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen

ER -