DANCORE-Day Master s Thesis Interpretation of Shallow Seismic and Sediment Cores from the Area stretching from the Southern Part of Kattegat to the Great Belt in the Period Late-Weichselian to Early Holocene. Carina Bendixen Dias 1
Content - Aim of project - Regional geology - Results - Processing of seismic data - Vibrocores - Late Glacial sediments - Channel infill - Barrier islands - Discussion - Late Glacial sediments - Channel infill and faulting - Bathymetric map - Conclusion Dias 2
AIM OF THE PROJECT Aim of the project Outline the development of the study area from Late-Weichselian to Early Holocene - Interpreting shallow seismic 5 Boomer profiles 71 Sparker profiles - 10 Sediment cores Dias 3
REGIONAL GEOLOGY Regional Geology Jensen et al. 2002 18.000 BP to 13.000 BP Deglaciation of the southwestern Kattegat High sea level 60 m Younger Dryas 11.700 AD to 12.900 AD Lowest sea level 30-40 m (b.s.l) Fjord-like estuary Lowstand Holocene Rising sea level (transgression) Coastal barrier islands are flodded Dias 4
RESULTS PROCESSING OF DATA Results Processing of data using ProMAX Boomer profiles - Navigation errors. Removal of traces - Frequency filtering - Bandpass filter Sparker profiles - Migration using the velocity 1480 m/s (Kirchhoff time migration with RMS Velocity) - Extended migration (three profiles) (Kirchhoff time migration with varying velocities) - Water: 1480 m/s - Sediment: 1600 m/s Dias 5
RESULTS PROCESSING OF DATA Boomer profile 572017 Dias 6
RESULTS PROCESSING OF DATA Sparker profile R3_019a Sted og dato Dias 7
RESULTS - VIBROCORES Sediment core - Vibrocores 4.14m 8.65m 3.82m 5.18m Dias 8
Results Results Late Glacial Dias 9 YLG Youngest Late Glacial OLD Oldest Late Glacial
Late Glacial Distribution of the Late Glacial sediments OLG YLG Sted og dato
Results Results Sted og dato Dias 11
Results Results infill Dias 12
Results/Discussion Results/Discussion Barrier Islands Dias 13
Discussion Discussion Late Glacial sediments - Sediments deposited during a high sea level (highstand) - The faulting that limits the distribution of the sediments occured before 15 cal. ka BP (Jensen et al., 2002A) Profil R3_006 Sted og dato Dias 14
CHANNEL INFILL Discussion Channel infill and faulting - Two types of sediment infill Different infill directions Change in environment Boundary between the two units represent a hiatus - Strike-slip faulting Possible event which caused gas migration Sted og dato Dias 15
Discussion Regression, Lowstand and Transgression Discussion Unit 2 r2 - Two erosional surfaces identified Lower boundary of unit 2 and unit 3 Possible tectonic offset causing a local transgression (deposition of unit 2) Limited distribution of unit 2 due to erosion - Reflector r2 is at a lowstand level Limited distribution of the reflector - Can be due to erosion during the transgression Unit 3 r3 - Both units have a connection with the interpreted palaeo-great Belt channel Dias 16
DISCUSSION Discussion - Palaeo coastline - Palaeo-Great Belts canals - Sediment progradation - Back-stepping of barrier islands with rise in sea level Dias 17
CONCLUSION Conclusion - The processing of the seismic data have resulted in better data quality hence better interpretation - Interpretation of the bathymetric map has resulted in the identification of a former coastline. This has resulted in the construction of a palaeogeographical map - The Late Glacial sediments were deposited during high sea level (highstand) - The fualts that bounds the Late Glacial sediments occured before 15 cal. ka BP Dias 18
CONCLUSION Conclusion - During the regression a local transgression occurred where unit 2 were deposited - The Lowstand occurred before 9 cal. ka. BP - Two types of canal infill Change in infill direction Change in environment - Barrier islands are back-stepper with rising sea level and eventually drowned Dias 19
DANCORE-DAY Article Bendixen, C., Jensen, J.B., Bennike, O., & Boldreel, L.O. 2013: Late Glacial to Early Holocene development of southern Kattegat, Geological Survey of Denmark and Greenland Bulletin, accepted for publication Thanks My supervisors Lars Ole Boldreel (IGN) and Jørn Bo Jensen (GEUS) GEUS and Danish Nature Agency for providing the data Dias 20
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