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The oceanographic variability along the North Atlantic margins through the last 2000 yrs [Elektronische Ressource] : climatic impacts and forcing mechanisms reconstructed from high-resolution diatom records / vorgelegt von Isabelle Martins Gil

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The oceanographic variability along the North Atlantic margins through the last 2000 yrs: climatic impacts and forcing mechanisms reconstructed from high-resolution diatom records Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften im Fachbereich Geowissenschaften der Universität Bremen Vorgelegt von Isabelle Martins Gil Bremen, Mai 2006 Tag des Kolloquiums: 30.06.06 Gutachter : 1. Herr Prof. Dr. Dierk Hebbeln 2. Frau Dr. Fátima Abrantes Prüfer: 1. Herr Prof. Dr. G. Bohrmann 2. Herr Prof. Dr. K.- U. Hinrichs -Erklärung- Erklärung Hiermit versichere ich, dass ich 1. die Arbeit ohne unerlaubte fremde Hilfe angefertigt habe, 2. keine anderen als die von mir angegebenen Quellen und Hilfsmittel benutz habe und 3. die den benutzten Werken wörtlich oder inhaltlich entnommenen Stellen als solche kenntlich gemacht habe. Bremen, den 15. Mai 2006 Isabelle Martins Gil 5 6-Acknowledgments- Acknowledgments I am deeply grateful to my two supervisors, Priv. Doz. Dr. Dierk Hebbeln (University of Bremen) and Dr. Fatima Abrantes (INETI – Marine Geology Department, Lisbon). Their guidance, support and suggestions have without any doubt contributed to the realization of this thesis.

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Published 01 January 2006
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Language English
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The oceanographic variability along the North
Atlantic margins through the last 2000 yrs:
climatic impacts and forcing mechanisms
reconstructed from high-resolution diatom
records








Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften
im Fachbereich Geowissenschaften der Universität Bremen







Vorgelegt von

Isabelle Martins Gil
Bremen, Mai 2006





























Tag des Kolloquiums:
30.06.06


Gutachter :
1. Herr Prof. Dr. Dierk Hebbeln
2. Frau Dr. Fátima Abrantes


Prüfer:
1. Herr Prof. Dr. G. Bohrmann
2. Herr Prof. Dr. K.- U. Hinrichs


-Erklärung-












Erklärung



Hiermit versichere ich, dass ich

1. die Arbeit ohne unerlaubte fremde Hilfe angefertigt habe,

2. keine anderen als die von mir angegebenen Quellen und Hilfsmittel benutz
habe und

3. die den benutzten Werken wörtlich oder inhaltlich entnommenen Stellen als
solche kenntlich gemacht habe.



Bremen, den 15. Mai 2006



Isabelle Martins Gil














5

6-Acknowledgments-
Acknowledgments

I am deeply grateful to my two supervisors, Priv. Doz. Dr. Dierk Hebbeln (University of
Bremen) and Dr. Fatima Abrantes (INETI – Marine Geology Department, Lisbon). Their
guidance, support and suggestions have without any doubt contributed to the realization of this
thesis. I also thank them for their capacity to find time when deadlines got hot.
I am thankful to Priv. Doz. Dr. Dierk Hebbeln for accepting me as a Ph. D. student and for very
helpful advices that helped me to progress and to conclude this thesis.
I am also deeply thankful to Dr. Fatima Abrantes for all her support, her encouraging
enthusiasm, friendship and her availability. I also thank her to offer me the chance to board on
oceanographic cruises.
I would also like to express my gratitude to Prof. Dr. Gerold Wefer, the head of the Department
of Geosciences at the University of Bremen, for welcoming me at the department as a Ph. D.
student.
Special thank also to Dr. Lloyd Keigwin for offering me the possibility to work with the material
from the Laurentian fan and for his support with quick feedbacks while writing the paper.

I thank Apolónia Inês for all the support in the preparation of the diatom samples at the
laboratory of the Marine Geology Department (Lisbon) and her special care. Special thanks to
Antje Voelker for interesting and important initial conversations about data; and to Margarida
Henriques when solving administrative issue. Thanks are also due to the colleagues of the
Marine Geology Department (Lisbon) and of the University of Bremen for their support.
Special “obrigada” to Emilia Salgueiro for her continuous support and company while being in
Bremen. Also special acknowledgments to Fontes Mil-Homens family to have been such a
reliable and comfortable support during those last years, and especially to Nuno.
“Vielen dank” to Ulrich Alt-Epping for his friendship and also for his practical help while in
Bremen, facilitating my stays and making them fun. I would like also to express my gratitude to
Silvia Hess and Stefan Rothe for the very warm welcoming into their home and their continuous
moral support that helped me to end this thesis with the best conditions.

Special “obrigada” and “merci” to the ones that always accompanied and encouraged the
major steps of my life, my family and the “old” friends from Paris, and especially Elodie Cassan
for her availability to support me during all those years.

Finally, I would like to dedicate this work to my parents for their continuous support and to have
always encouraged all my choices throughout my life. Their strength, optimism and unusual
experiences in life have been always an example that incited me to progress. I also thank my
sister Stéphanie for her support.

This work has been supported by the European Union through funding of the project
HOLSMEER - Late Holocene Shallow Marine Environments of Europe (EVK2-CT-2000-00060)
and Ph D. grant (SFRH/BD/18317/2004) awarded by the Portuguese Foundation for Science
and Technology (FCT-MCES).

To the ones that will read more than this page, I wish a pleasant reading.
7
-Contents-
Contents

Summary…………………………………………………………………………...………..11

Chapter 1: General introduction…………………………………………………...……...15
1. Motivation and main objectives………………………………………………...…17
2. Study areas……………………………………………………………………..…18
3. Diatoms, a proxy for paleoenvironmental changes of the last 2000 yrs………......19
3.1. Diatoms……………………………………………………………...…..19
3.2. The main climatic changes of the last 2000 yrs……………………........20
3.3.Main climatic forcings…………………………………………...………20
4. Material and methods………………………………………………………...…....21
4.1. Material……………………………………………………………….…21
4.2. Methods…………………………………………………….…………....22
• Diatoms: sample preparation and analysis procedure
• Phytoliths
• Fe XRF measurements
• Organic carbon content
• Spectral analyses
• Age models
5. Main results……………………………………………………………….…….…25

Chapter 2: Quantitative diatom analyses—a faster cleaning procedure
Abrantes, F., Gil, I., Lopes, C., Castro, M., 2005
Deep-Sea Research I, 52: 189-198………………………………………………..…33

Chapter 3: Diatom as upwelling and river discharge indicators at the Portuguese margin:
instrumental data liked to proxy information
Gil, I. M., Abrantes, F., Hebbeln, D.,
Will be submitted………………………………………………………...……...……53

Chapter 4: Shallow-marine sediment cores record climate variability and earthquake activity
off Lisbon (Portugal) for the last 2000 years
Abrantes, F., Lebreiro, S., Rodrigues, T., Gil, I., Bartels-Jónsdóttir, H., Oliveira, P.,
Kissel, C, Grimalt, J.O., 2005
Quaternary Science Reviews , 24: 2477-2494…………………………………….…75

Chapter 5: Last two millennia coastal hydrographic and climate changes in the Atlantic
Iberian margin (Tagus Prodelta and Muros Ria)
Lebreiro, S., Frances, G., Abrantes, F., Diz, P., Bartels-Jónsdóttir, H., Stroynowski,
Z., Gil, I., Pena, L., Rodrigues, T., Nombela, Alejo, Briffa, K., Jones, P., Harris, 2005
The Holocene (in press)………………………………………………………….....111

Chapter 6: The North Atlantic Oscillation forcing through the last 2000 years: spatial
variability as revealed by high-resolution marine diatom records from N and SW Europe
Gil, I. M., Abrantes, F., Hebbeln, D.,
Marine Micropaleontology (in press)…………………………………………........141

9-Contents-
Chapter 7: Late Holocene coastal hydrographic and climate changes in the eastern North
Sea
Hebbeln, D., Knudsen, K. L., Gyllencreutz, R., Kristensen, Klitgaard-Kristensen, Backman,
J., Scheurle, C., Jiang, H., Gil, I., Smelror, Jones, P., Sejrup, H., 2005
The Holocene (in press)…………………………………………………………….171

Chapter 8: 1750 yrs of rapid oceanographic changes over the Laurentian Fan (South of
Newfoundland) as revealed by high resolution diatom record
Gil, I. M., Keigwin, L. D., Abrantes, F., Hebbeln, D.,
Submitted to Paleoceanography…………………………………………...….........203

Chapter 9: Conclusions………………………………………………………………...….225

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