The thermal history of the western Lower Saxony Basin, Germany [Elektronische Ressource] / vorgelegt von Yvonne Adriasola Muñoz

Yvonne

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• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2006
• Nombre de lectures: 47
• Langue: Deutsch
• Poids de l'ouvrage: 3 Mo

Extrait

The thermal history of the western Lower Saxony
Basin, Germany
Von der Fakultät für Georessourcen und Materialtechnik der
Rheinisch-Westfälischen Technischen Hochschule Aachen
zur Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften
genehmigte Dissertation
vorgelegt von
Diplom-Geologin Yvonne Adriasola Muñoz
aus Räckelwitz
Berichter: Univ.-Prof. Dr.rer.nat. Ralf Littke
PD Dr.rer.nat. Ulrich Glasmacher
Tag der mündlichen Prüfung: 22.12.2006
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar Adriasola Yvonne Munoz
The themal history of the western Lower Saxony Basin. Germany
ISBN: 3-86130-884-3
1. Auflage 2007
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tung in elektronischen Systemen.
Vertrieb:
1. Auflage 2007
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printed in GermanyAcknowledgements
First of all I wish to thank Prof. Dr. Ralf Littke and Dr. Manfred Brix for their
supervision and the useful and extensive discussions about theoretical aspects of
the geochemical investigations, basin modelling and fission track dating in
general, and for the possibility to use the experimental devices used for taking
detailed measurements. I am grateful to Prof. Littke and Priv.-Doz. Dr. Ulrich
Glasmacher for acting as examiners of this thesis.
The implementation was supported by many persons. Lots of knowledge about
the geology of the study area came from the very excited Dr. Horst Klassen,
who organized a field trip to show Dr. Manfred Brix and me all the outcrops in
the study area. Thus, we were able to obtain a really good collection of samples
for fission track dating and maturity measurements.
During my visits to the Geologischer Dienst NRW, Dr. Günther Drozdzewski,
Dr. Dirk Juch and Dr. Volker Wrede always supported me with lots of tectonic
information about the Ibbenbüren area and the Osning lineament.
From industry I received lots of assistance with very interesting ideas and had
informative discussions with Dr. Heinz–Jürgen Brink and Dr. Martin Jentsch
(both former BEB), Dr. Georg Bresser (former Preussag/Gaz de France) and Dr.
Ingrid Winter (DGMK).
Furthermore, I was provided with lots of useful details about the Lower Saxony
Basin by Dr. Franz Kockel, Dr. Peter Gerling and Dr. Peer Hoth from the BGR
Hannover as well as Dr. Volker Lüders of the GFZ Potsdam.
Proof reading by Dr. Rolando di Primio, and PD Dr. Ulrich Glasmacher helped
to improve chapters 2 and 3 respectively.
I express my gratitude to all the people who helped with sample preparation and
experimental problems: Rolf Mildenberger, Frank Hansen, Dr. Bernd Krooss,
Ina Blumenstein and Jens Köster.
I gratefully acknowledge the financial support received from the Deutsche
Forschungsgemeinschaft (DFG; Li 618/12). The study was performed under the
SPP 1135 Project “Dynamics of synsedimentary systems under varying stress
regimes: The example of the Central European Basin” under the aegis of the
DFG and DGMK in conjunction with the RWTH Aachen. Sample material was
provided by various German oil companies (BEB, Mobil, Preussag, RWE-Dea
and Wintershall) and quarries (DSK Anthrazit Ibbenbüren, Piesberger
Steinindustrie GmbH & Co. KG).
II saved lots of time because I received administrative support from Dorit
Kanellis and Renate Wuropulos. Of course, I will always remember the fruitful
and scientific atmosphere which I got to know at the institute. I will especially
always keep in mind the nice lunch breaks with my work colleagues Danny,
Sabine, Susanne, Marta, Andreas Beha, Andreas Busch, Yves, Dirk and Sandra.
Thanks to all my friends who indulged me, when I was unbalanced and
unintimate. Beyond doubt some of the persons were my housemates in the
Monheimsallee (Silke, Michael, Jochen, Elmar, Jerôme, and Anika), and my
new housemates in the UK (Matt, Neil, AJ and Olaia).
Finally, I want to thank my husband, my family and my sister for all the support
they gave me throughout the time of this work.
IIAbstract
For the last 30 years the maturity and geophysical anomalies within the Lower
Saxony Basin (LSB) have been interpreted as the result of a deep lying igneous
intrusion called “Bramsche Massif”. Based on the lignite/subbituminous coal
stage of Upper Campanian rocks overlying the Lower Cretaceous units, a late
Early Cretaceous or early Late Cretaceous age was concluded for the time of
intrusion.
To improve the understanding of the structural evolution of the basin the aim of
this work was to provide a better coverage with maturity and palaeotemperature
data in order to discriminate structural domains and to constrain time-
temperature paths by the application of fission track thermochronology.
The combined analysis of different thermal indicators (e.g. vitrinite reflectance
and fission track data) should help to reconstruct the temperature history of the
basin.
Chapter 2 presents the results of vitrinite reflectance measurements for different
wells and pseudo-wells in the basin performed to obtain calibration data for 1D
basin modelling. In this context the influence of temperature on organic matter
was evaluated. Based on the rank gradient first assumptions could be obtained
about the temperature and burial history sediments must have experienced.
The ascertained maturity data for the central and southern part of the LSB
confirm a low reflectance increase with depth which is more likely caused by
deep burial than by an igneous intrusion.
Maturity data also allowed calculating palaeo-temperatures for the time of
maximum burial or maximum temperatures. Thus, a first guess about the
amount of erosion could be achieved.
The implementation of the maturity values as calibration data in the 1D
modelling led to a cumulative thickness of eroded sedimentary rocks between
1300m (northern margin) and 7300m (Piesberg area). Slightly, elevated heat
flows were assumed for the inversion time.
To obtain a more detailed temperature and cooling history of the basin, zircon
and apatite fission tracks covering stratigraphic levels from Upper
Carboniferous to Lower Cretaceous were analyzed.
Investigations on zircon and apatite fission tracks indicate a complex thermal
history of the basin. The data imply that the Lower Saxony Basin has
experienced three thermal heating events after the deposition of the
Carboniferous. The regional pattern of the fission track ages is dominated by a
decrease in zircon FT ages towards the basin centre. Mixed zircon FT ages of
IIIthe basin margins are at about 300Ma. A young age of 130Ma in the basin centre
indicates that highest temperatures were already reached in or before the Lower
Cretaceous. These findings would ask for much higher sedimentation rates
during Upper Jurassic and earliest Cretaceous times than previously assumed.
Moreover, fission track ages imply that the high thermal maturity of the organic
matter in the centre of the Lower Saxony Basin was already obtained in the
Upper Jurassic/Early Cretaceous.
An explanation for the differences of eroded thicknesses as well as for the
regional pattern of zircon fission track ages might be variable synsedimentary
subsidence within the LSB during late Jurassic and early Cretaceous times based
on rift and wrench tectonics. Due to the extension graben and secondary half-
graben systems were formed. In the course of the compressional phase during
the inversion period these areas became those with strongest uplift.
Apatite fission track ages show a south to north decrease within the basin.
Oldest ages of Late Cretaceous age indicate a cooling after the inversion and
occur in the southern part of the basin. In contrast, apatite fission track ages of
the northern margin indicate a renewed temperature increase during the last
10Ma.
Based on these findings a new heat flow history has to be assumed with high
heat flows occurring during Upper Jurassic/Lower Cretaceous times in
conjunction with the rifting taking place at this time.
These results have a major influence on the hydrocarbon generation of the
Mesozoic source rocks within this basin. The expulsion of hydrocarbons started
during Jurassic and Lower Cretaceous times and not as previously assumed in <