Organic Matter Accumulation: The Organic Cyclicities of the Kimmeridge Clay Formation (Yorkshire, GB) and the Recent Maar Sediments (Lac du Bouchet, France)

189 Pages·1995·5.667 MB·English

by  Elisabeth Lallier-Vergès, Nicolas-Pierre Tribovillard, Philippe Bertrand (auth.)

Lecture Notes in Earth Sciences 57
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The Organic Cyclicities of the
Kimmeridge Clay Formation (Yorkshire, )BG
and the Recent Maar Sediments
(Lac du Bouchet, France)
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Authors
Dr. Elisabeth Lallier-Verg~s
U.R.EO., Laboratoire de Grologie de la Mati~re Organique
Universit6 d'Odrans
BP 6759, F-45067 Odrans Cedex 2, France
Dr. Nicolas-Pierre Tribovillard
Universit6 Pads Sud, Sciences de la Terre
B~timent 504, F-91405 Orsay Cedex, France
Dr. Philippe Bertrand
Universit6 Bordeaux I, Grologie et Ocranologie
Avenue des Facultrs, F-33405 Talence Cedex, France
"For all Lecture Notes in Earth Sciences published till now please see final pages of
the book"
ISBN 3-540-59170-2 Springer-Verlag Berlin Heidelberg New York
Library of Congress Cataloging-in-Publication Data.
Organic matter accumulation: the organic cyclities of the Kimmeridge Clay For-
mation (Yorkshire, GB) and the recent maar sediments (Lac du Bouchet, France) /
edited by Elisabeth Lallier-Verg~s, Nicolas-Pierre Tribovillard, Philippe Bertrand.
p.cm. - Lecture notes in earth sciences: 57)
ISBN 0-387-59170-2. - ISBN 3-540-59170-2
.1 Sedimentation and deposition- England - Yorkshire. 2. Organic geochemistry -
England - Yorkshire. 3. Sedimentation and deposition - France - Bouchet Lake.
5. Kimmeridge Clay (England and Scotland) I. Lallier-Verg~s, Elisabeth. II.
Triboviltard, Nicolas-Pierre, 1962- HI. Bertrand, Philippe, 1954- . IV. Series
QE571.0736 1995 552'.5'094281-dc20 95-12984
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(cid:14)9 Spfinger-Verlag Berlin Heidelberg 1995
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SPIN: 10492885 32/3142-543210 - Printed on acid-free paper
Preface
The four-year period of activity of the Groupement de Recherche 942 (GDR) of the
Centre National de la Recherche Scientifique (CNRS) came to an end in December
1993. This GDR was a scientific association grouping research teams from the
academic sphere -- i.e. the Unit(s de Recherches Associ(es 723 & 724 of the CNRS as
well as the Universities of Orl6ans and Paris-Sud -- and from the industrial world: Elf-
Aquitaine Production, TOTAL and the Institut Fran~ais du P&role (IFP).
The aim of the GDR.was to understand the processes and the causes of organic carbon
fossilization in sediments, especially when they can be modified by environmental
conditions such as climate, eustatism, productivity etc., factors which can alko interact.
This goal implies the simultaneous study of ancient geological formations
(hydrocarbon source rocks from the famous Kimmeridge Clay Formation) and recent
Quaternary sediments (the Lac du Bouchet or lake Bouchet maar, Massif Central,
France). In the latter case, we benefit from a fine-scale stratigraphical framework as
well as a reliable reconstruction of the local and regional environment.
This volume is a collection of papers representing oral presentations given on
December 7, 1993, at the Soci6t6 G6ologique de France in Paris, during the final
meeting of the GDR. These articles thus report the latest developments of the studies
carried out under the GDR. However, this is not the first publication of our results,
which can be found in the papers referred to in each article.
The Kimmeridge Clay Formation was previously studied in 1987, by the Yorkim
Group from IFP, Elf-Aquitaine and the British Geological Survey, on the basis of a
series of wells drilled across the Cleveland Basin of Yorkshire. In each well, the
distribution with depth of the total organic content is cyclic. We have compared some
of the organic cycles from two wells (Matron and Ebberston) based on mineralogy,
organic and inorganic geochemistry and petrography, at a high resolution scale
(centimetric). The main conclusion of this work is that the driving force for organic
matter accumulation in the studied cycles was organic phytoplankton productivity.
Oxygenation conditions seem to have played a secondary role as a positive feedback
action enhancing organic matter storage.
Lac du Bouchet is located on the Dev~s volcanic plateau, 51 km SW of Le Puy en
Velay, at an altitude of 1205 m. The depth of the water column is 28 m. The lake has a
subcircular shape 1( km in diameter) and a very restricted watershed. This site is
exceptionally suitable for research on climate variations and palaeomagnetic field
IV
modifications (Euromaars EC Program). The GDR focused on sedimentary organic
matter and its relationship to inorganic phases. An important result is that organic
matter appears to be a good indicator of palaeoenvironmental reconstructions for over
350 000 years. In addition, the study of early diagenetic reactions in surficial sediments
(porewater and solid phase) allows the specification of the processes of organic matter
degradation and storage in such an oligothrophic lake.
Acknowledgements Elf-Aquitaine Production, TOTAL and the Insfitut Fran~ais du
P6trole (IFP), as well as the Centre National de la Recherche Scientifique and the
Universities of Ofl6ans and Paris Sud, are thanked for their scientific contributions and
financial support. Eugene Bonifay and Nicolas Thouveny from the eriotarobaL ed
eigolo~G ud erianretauQ (CNRS, Marseille, France) and the European Program
EUROMAARS are greatly thanked for their help during fieldwork, sample processing
and scientific discussions. We are also indebted to Elizabeth Jolivet, Andrew J.
Patience and Simo Boussafir (University of Orl6ans) for improving the final
manuscript.
Table of contents-
The Organic Cyclicities of the Kimmeridge Clay Formation (Yorkshire, UK)
E. Lallier-Verg~s, P. Bertrand, N.-P. Tribovillard and A. Desprairies
Short-Term Organic Cyclicities from the Kimmeridge Clay Formation
of Yorkshire (UK): Combined Accumulation and Degradation of
Organic Carbon under the Control of Primary Production Variations ............... 3
M. Boussafir, E. Lallier-Verg~s, P. Bertrand and D. Badaut-Trauth
SEM and TEM Studies on Isolated Organic Matter and Rock
Microfacies from a Short-Term Organic Cycle of the Kimmeridge Clay
Formation (Yorkshire, UK) ............................................................ 51
F. Gelin, M. Boussafir, S. Derenne, C. Largeau and P. Bertrand
Study of Qualitative and Quantitative Variations in Kerogen Chemical
Structure Along a Microcycle: Correlation with Ultrastructural
Features
................................................................................... 31
J.-R. Disnar and L. Ramanampisoa
Palaeoproduction Control on Anoxia and Organic Matter Preservation
and Accumulation in the Kimmeridge Clay Formation of Yorkshire
(UK): Molecular Assessment ........................................................... 49
A. Desprairies, M. Bachaoui, A. Ramdani and N.-P. Tribovillard
Clay Diagenesis in Organic-Rich Cycles from the Kimmeridge Clay
Formation of Yorkshire (UK): Implication for Palaeoclimate
interpretations ............................................................................. 63
The Recent Maar Sediments (Lac du Bouchet, France)
E. Viollier, P. Alb6fic, M. Evrard, D. J6z&luel, D. Lavergne,
G. Michard, M. ,ep~LP G. Sarazin and P. Zuddas
Geochemical Study of the Lac du Bouchet, Haute-Loire, France.
Part I: Water Balance and Biogeochemical Implications ............................ 95
D. J6zfquel, P. Alb6ric, A. Desprairies, M. Evrard, D. Lavergne, G.
Michard, A.J. Patience, M. Pepe, G. Sarazin, N.-P. Tribovillard and
E. VioUier
Geochemical Study of the Lac du Bouchet, Haute-Loire, France. Part
:I1 Water-Sediment-Organic Matter Interactions during the Last 2 500
Years ...................................................................................... 911
A. J. Patience, E. Lallier-VergEs, A. Sifeddine, P. Alb6ric and
B. Guillet
Organic Fluxes and Early Diagenesis in the Lacustrine Environment:
the Superficial Sediments of thge Lac du Bouchet (Haute-Loire,
France) ................................................................................... 541
A. Sifeddine, P. Bertrand, E. Lallier-Verg~s and A.J. Patience
Organic Sedimentation and its Relationship with Palaeoenvironmental
Changes over the last 30 000 Years (Lac du Bouchet, Haute Loire,
France). Comparison with Other Palaeoclimatic Lacustrine Examples ........... 157
IIIV
B. GuilIet and Ousmane Maman
Sulphur Speciation in the Late Glacial and Holocene Sediments of the
Lac du Bouchet (Haute Loire, France) ............................................... 169
List of Contributors .............................................................................. 183
Subject Index ..................................................................................... 185
Short-term organic cyclicities
from the Kimmeridge Clay Formation of Yorkshire (G.B.):
combined accumulation and degradation of organic carbon
under the control of primary production variations
Elisabeth Lallier-Vergks I Philippe Bertrand, I Nicolas Tribovillard 2 and Alain Desprairies .2
)1 6tisrevinU d'Ofldans, ARU 427 ud ,SRNC .tpdD sed secneicS ed la ,erreT F45067 snadlrO xedec
)2 dtisrevinU Paris Sud, ARU 327 ud ,SRNC tnemit~,b 504, 50419-F Orsay xedec
Key words- Kimmeridge Clay Formation, organic carbon cyclicity, primary
production, microbial degradation, modelisatian.
Abstract- This paper summarises different results acquired on the short-term
organic cycles (about 30 000 years for one metre thick) from the Kimmeridge Clay
Formation (Yorkshire, G.B.). The results, as a whole, support the fundamental
interpretation that considers primary production as the main factor influencing
organic cyclicity. Other developments specify that in addition to the high organic
primary production, the consecutive microbial sulphate reduction, the intensity of
which strictly depends on the organic-walled phytoplanktonic production,
emphasises the accumulation of the produced hydrocarbon-rich organic matter.
This specific accumulation is possible through the selective preservation of bio-
resistant macro-molecules already present in living organisms and/or through early
vulcanisation of lipidic molecules (Boussaf'lr et al.; Gelin et al., this volume). The
latter is favoured by the low availibility of reduced iron species compared to the
massively produced HS- and consequently by the incorporation of HS- in excess
within the organic matter..Here, this interpretation is presented as a mathematical
model whose results are compared to measured data (for microcycles having
organic carbon contents ranging from about 2 to 9 %) and which account for the
cyclic variation in both quantity and geochemical quality of organic matter.
Introduction-
The Kimrneridge Clay Formation is a marine deposit composed of alternating organic-rich
shales and marls that is considered as the lateral equivalent of the main source-rocks of
the North Sea. These immature formations outcrop on the south coast of England (i.e.
Dorset) whereas others were drilled in the Cleveland basin (Yorkshire) by the YORKIM
Group (Herbin and Geyssant, 1993). These deposits present cyclicities of several orders
(Herbin et al., 1993; Desprairies et al.; Disnar and Ramanampisoa, this volume) which
concern their organic content in terms of amount (total organic carbon content expressed
as %TOC) and HC-potential (hydrogen index expressed as HI in mg HC/g C org)
The main objective of the GdR 942 research program was to answer the question: what is
the nature and the origin of this organic carbon cyclicity? For this, short-term organic
cycles representing about 30 000 years for one meter in thickness, have been sampled.
One ELCYC( )1 is located at the base of a second-term organic cycle in the Eudoxus Zone
(Hole Marton 87) and records variations in TOC from about 2 to 9 %, the second ELCYC(
2) is situated at the peak of the same second-term organic cycle and exhibits TOC
variations from about 4 to 30%. A high resolution study of these organic-rich rocks has
been completed on both the mineral and the organic fractions of the rocks. The organic
matter has been investigated by both petrographical and geochemical methods.
The aim of this paper is to propose a general interpretation based on some of the results of
our research group and also from the litterature. Most of these studies (including their
respective analytical techniques) are either presented in this volume or already published.
They concern the characterisation of the mineral content of the organic cycles, the
identification of the organic content and of its preservation state. Here, we specifically
develop the importance of the microbial sulphate reduction in the close variation of both
the quantity and the chemical quality of organic matter and we propose a mathematical
model which accounts, at best, for the organic carbon cyclicity. The main idea is to
propose a new highlight concerning the processes of accumulation of HC-enriched
organic shales and to infer it to the source-rock deposition.
Result summary-
Composition of the sediment and nature of the organic matter-
The mineralogical and geochemical study of the bulk samples first indicates that the
organic cyclicity is really due to the variation of organic matter content. No dilution due to
the mineral phases occurs and no variation in the mineral composition has been found
throughout the cycles (Tribovillard et al., 1992). A study of the trace element behaviour
shows that environmental depositional conditions were always anoxic, even if some
differences in the 02 depletion intensity may exist between the two cycles studied
(TriboviUard et al., 1994).
Petrographical studies have been completed on the organic matter isolated from the
mineral matrix by acidic treatments and on the organic matter analysed in situ in the
microtexture of the rock. These studies were performed by the means of optical studies
(Ramanampisoa et al., 1992; Pradier and Bertrand, 1992) and electron microscopy
studies (cf. Boussafir et al. 1994; this volume). The sediment is always laminated and no
bioturbation has been found, whatever the TOC, attesting the anoxic depositional
conditions.
The composition of the organic matter varies with the TOC content. This variation mainly
concerns the "orange amorphous organic matter" proportion (as described in palynofacies
preparation by Ramanampisoa et al., 1992) corresponding to the bituminite maceral