Climate development and its effect on the North Sea environment during the Late Holocene [Elektronische Ressource] / vorgelegt von Carolyn Scheurle

Climate development and its effect
on the North Sea environment
during the Late Holocene




Dissertation
zur Erlangung des Doktorgrades der Naturwissenschaften
am Fachbereich Geowissenschaften
der Universit t Bremen




vorgelegt von
Carolyn Scheurle
Bremen 2004



Tag des Kolloquiums:
24. M rz 2004



Gutachter:
1. Prof. Dr. Gerold Wefer
2. Prof. Dr. Gerhard Bohrmann



Pr fer:
1. Priv. Doz. Dr. Dierk Hebbeln
2. Prof. Dr. Tilo von Dobeneck
Table of contents ! I
Table of contents


Abstract..............................................................................................................................................1
Zusammenfassung.............................................................................................................................3
1 Introduction ..........................................................................................................................5
1.1 Motivation and main objectives..............................................................................................5
1.2 European climate development of the Late Holocene ............................................................6
1.3 Climate reconstructions unique possibilities in Europe.......................................................8
1.4 Geographic and oceanographic setting of the North Sea area ................................................9
1.4.1 Skagerrak ..............................................................................................................................11
1.4.2 Helgoland mud area ..............................................................................................................13
1.4.3 Elbe catchment area ..............................................................................................................14
2 Material and methods.........................................................................................................16
2.1 Core locations and sampling.................................................................................................16
2.2 Methods ................................................................................................................................17
2.2.1 Age determination.................................................................................................................17
2.2.2 Gamma-ray attenuation18
2.2.3 X-ray fluorescence core scanner...........................................................................................18
2.2.4 Stable isotopes ......................................................................................................................19
2.2.5 Organic carbon......................................................................................................................19
2.2.6 Foraminiferal analyses..........................................................................................................20
3 List of publications..............................................................................................................21
4 Depositional history of the Helgoland mud area, German Bight, North Sea ................23
4.1 Introduction...........................................................................................................................24
4.2 Material and methods.25
4.3 Results...................................................................................................................................27
4.4 Discussion.............................................................................................................................30
4.4.1 Correlation of the cores.........................................................................................................30
4.4.2 Age model.............................................................................................................................31 Table of contents ! II
4.4.3 A major resedimentation event at the beginning of the record (~1300 years BP) ............... 34
4.4.4 The high sedimentation period at AD ~700 to ~1250.......................................................... 34
4.4.5 The low sedimentation period from AD ~1250 to the present............................................. 37
5 Stable oxygen isotopes as recorders of salinity and river discharge in the German
Bight, North Sea ................................................................................................................. 41
5.1 Introduction.......................................................................................................................... 42
5.2 Regional setting.... 43
5.3 Material and methods........................................................................................................... 44
5.4 Results.................................................................................................................................. 45
5.5 Discussion ............................................................................................................................ 46
5.5.1 Proxy evaluation .................................................................................................................. 46
5.5.2 Proxy calibration.................................................................................................................. 47
5.5.3 Proxy discussion... 51
5.5.4 Proxy application... 52
5.6 Conclusions.......................................................................................................................... 52
6 An 800 year reconstruction of Elbe river discharge and German Bight sea-surface
salinity ................................................................................................................................. 55
6.1 Introduction.......................................................................................................................... 56
6.2 Regional setting ................................................................................................................... 57
6.3 Material, methods and stratigraphy...................................................................................... 60
6.4 Proxy application and interpretation .................................................................................... 61
6.5 Reconstruction of paleosalinity and paleodischarge ............................................................ 62
6.6 Paleoclimatic implication..................................................................................................... 63
6.7 Conclusion ........................................................................................................................... 65
7 Late Holocene environmental changes in the Skagerrak, eastern North Sea -
foraminiferal indication 67
7.1 Introduction.......................................................................................................................... 68
7.2 Geographic and oceanographic setting ................................................................................ 69
7.3 Material and methods........................................................................................................... 71 Table of contents ! III
7.4 Chronology ...........................................................................................................................73
7.5 Foraminiferal analyses and faunal interpretation..................................................................75
7.5.1 Benthic foraminifera .............................................................................................................75
7.5.2 Planktonic foraminifera ........................................................................................................82
7.6 Environmental changes and historical epochs ......................................................................83
7.7 Summary and conclusion......................................................................................................87
8 Stable isotopes recording environmental conditions in the Skagerrak (North Sea)
during the Late Holocene ...................................................................................................89
8.1 Introduction...........................................................................................................................90
8.2 Regional setting ....................................................................................................................91
8.3 Material and methods............................................................................................................93
8.4 Results...................................................................................................................................94
8.4.1 Stable oxygen isotopes..........................................................................................................94
8.4.2 Stable carbon isotopes.94
8.5 Discussion.............................................................................................................................95
8.5.1 Stable oxygen isotopes.95
8.5.2 Stable carbon isotopes.97
8.6 The atmospheric circulation system and marine environments in the Skagerrak...............10