Deep-Sea Sediments

850 Pages·2011·69.389 MB·English

by  Heiko HüNeke and Thierry Mulder (Eds.)

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11 12 13 10 9 8 7 6 5 4 3 2 1
Finally, we are particularly grateful to our families and friends
whose enduring support and forbearance has sustained us over
the years that “the book” has been in preparation
to my parents, my wife Dagny and my children, Ragnar and
Lukas (H. H.)
tomyparents,mywifeClaireandmychildren,Lucy,Clothilde,
Romaric and Lorraine-Marie (T. M.)
C
ONTRIBUTORS
TorstenBickert
Zentrumfu¨rMarineUmweltwissenschaften,Universita¨tBremen,Germany
StevenN.Carey
Graduate School of Oceanography, University of Rhode Island, Narragansett,
RhodeIsland,USA
Jean-ClaudeFauge`res
Universite´ deBordeaux,UMRCNRS5805EPOC,TalenceCedex,France
Ru¨digerHenrich
Department of Sedimentology and Paleoceanography, Faculty of Geosciences,
University of Bremen, klagenfurter Straße, Bremen, and Fachbereich Geowis-
senschaften,Universita¨tBremen,Germany
ReinhardHesse
EarthandPlanetarySciences,McGillUniversity,Montreal,Quebec,Canada
HeikoHu¨neke
Institut fu¨r Geographie und Geologie, Universita¨t Greifswald, Jahn-Strasse 17a,
D–17487Greifswald,Germany
PatriceImbert
Total,CSTJF,AvenueLarribau,64000Pau,France
ThierryMulder
Universite´ de Bordeaux, UMR CNRS 5805 EPOC, Avenue desfaculte´s, 33185
TalenceCedex,France
UlrikeSchacht
Australian School of Petroleum, The University of Adelaide, Adelaide, SA,
Australia
Jean-LucSchneider
Universite´ Bordeaux 1, Observatoire Aquitain des Sciences de l’Univers,
CNRS-UMREPOC,TalenceCedex,France
A.Stadnitskaia
DepartmentofMarineOrganicBiogeochemistry,RoyalNetherlandsInstitutefor
SeaResearch(RoyalNIOZ),Texel,TheNetherlands
xi
xii Contributors
A.Uchman
Institute of Geological Sciences, Jagiellonian University, Krako´w, Oleandry 2a,
Poland
A.J.VanLoon
Geological Institute, Adam Mickiewicz University, Mako´w Polnych 16, 61–606
Poznan,Poland
HelmutWeissert
DepartmentofEarthSciences,ETH-Z,Zu¨rich,Switzerland
A.Wetzel
Geologisch-Pala¨ontologischesInstitutderUniversita¨t,Basel,Switzerland
A.J.Wheeler
School of Biological, Earth & Environmental Sciences and Environmental
ResearchInstitute,UniversityCollegeCork,Cork,Ireland
P
REFACE
Therearemanyreasonsforthefast-growingunderstandingofdeep-marine
sedimentary processes during the past few decades. Research has benefited
greatlyfromanumberofnewlydeveloped,highlysophisticatedexploration
techniques and comprehensive data sets, thanks to the immense industrial
interest in deep-sea sediments. Multidisciplinary research, in addition, has
shed increasingly more light on the complex biogeochemical processes
driving and controlling productivity and, thus, an important part of the
deep-sea sedimentation. Moreover, deep-sea sediments have been recog-
nizedasarchivesofinformationaboutthechangingboundaryconditionsin
the oceans’ histories and in the evolution of life. They also became of
particular interest as keys for unravelling present-day climate changes,
which challenge modern society.
Thisbookgrewoutofourdesiretokeepupwiththisrapidlyexpanding
area of knowledge and to integrate the main process-based aspects of
siliciclastic,biogenicandvolcaniclasticdepositsofbothmodernandancient
deep-marine sedimentation into one single, unified and comprehensive
text. The volume is structured to follow the various sedimentary deposi-
tional processes in the deep sea, from sediment gravity flows and contour
currentstopelagicsettlingandhemipelagicadvection,periplatformsettling,
plankticandbenthicbioproductivity,andvolcanicactivity.Inaddition,the
relationships between depositional environment and endobenthic organ-
isms, as well as early-diagenetic processes at and within the deep-sea floor
are dealt with. The book, finally, includes an introduction to the climatic
interpretation of the various proxies that reveal global changes during the
Mesozoic greenhouse and Neogene icehouse conditions, and it addresses
the specific interest of the hydrocarbons industry in deep-water sediments.
While each chapter is self-contained, they are interrelated, thus reflecting
thecomplexityofthesubject,spanningflowtransformationofsedimentary
density flows and currents, bentho-pelagic coupling, changes in sea-water
chemistry, major innovations in organism evolution, and changes in
external controls on sedimentation and productivity.
The book is an attempt to bring together the knowledge both of
scientists working in the present-day deep oceans and geologists studying
ancient deposits of deep-marine environments now exposed on land. The
main advantage of the actualistic point of view is, of course, that the
processesdrivingtheproduction,thesupplyandthedepositionofsedimen-
tary particles accumulating in the deep sea can be qualified and quantified
xiii
xiv Preface
more or less precisely. The fossil record, on the other hand, if successfully
deciphered holds valuable clues about the changing boundary conditions,
controlling the sedimentation in deep-marine environments. This is
important in particular where evolutionary processes are involved in the
formation of deep-sea sediments.
Wehaveendeavouredtoproduceawell-balancedbookwithoutimpor-
tantomissions.Weattempttosummarizethecurrentfactualknowledgein
thefieldofdeep-seasedimentationandtheapplicationofthisknowledgeto
a variety of scientific and applied problems. We invited authors from both
academiaandindustrytocontributetothisbook,thusstrivingfordifferent
viewpoints on the various aspects of deep-marine sedimentation. Consid-
eringtheratherbroadtopicofthebook,however,wecannotexcludethat
some gaps may be found. We hope there are not too many.
This book will be of interest to undergraduates taking specialist courses
or simply orientating themselves with respect to the largest depositional
setting on Earth: the deep sea. Postgraduates and professional geologists
concerned with deep-sea research will find it useful for understanding
specificaspectsofdeep-seasedimentology,orasanintroductiontoregional
considerations. Oceanographers, geochemists, biologists, palaeontologists,
geophysicists,palaeoclimatologistsandstructuralgeologistswillalsofindthe
bookusefulasareferenceforunderstandingthesedimentologicalaspectsof
the deep sea.
First of all, we thank our authors, who not only kept up a very high
standard of contribution, but also stuck (fairly closely) to the guidelines
imposed by us. This also concerns our reviewers, chosen from various
countries, who deserve considerable praise for their efforts in providing
quick and fair critical comments on the contributions.
The editors gratefully express their thanks also to Tom van Loon, the
series editor who encouraged the publication of a volume on this rather
broad topic and gave us longstanding valuable support during the prepara-
tion.Itwasapleasuretoworkwithyou.WealsothankthestaffofElsevier
for their help in organizing this book, in particular Anita Koch, develop-
ment editor, Derek Coleman, senior developmental editor, Mageswaran
BabuSivakumar, project manager, and Karishma Rathore, rights adminis-
trator.Furthermore,wewouldliketo thankHeikeSengpiehl andDagmar
LaufromtheGeologicalDepartmentattheUniversityofGreifswald,who
did a large part of the high-quality figure drawing for many chapters.
HEIKO HU¨NEKE AND THIERRY MULDER
C H A P T E R 1
Progress in Deep-Sea Sedimentology
Thierry Mulder,* Heiko Hu¨neke,† and A.J. Van Loon‡
Contents
1. Introduction 1
1.1. Scopeofthebook 2
2. WhatareDeep-SeaSediments? 3
3. ToolsUsedforDeep-SeaSedimentInvestigations 5
3.1. Geophysics 5
3.2. Geotechnictools 11
3.3. Sedimentsampling 12
3.4. Submersiblesystems 14
3.5. Currentmetersandparticletraps 14
3.6. Laboratoryanalyses 14
4. StructureoftheBook 16
References 22
1. Introduction
Inthisbook,allmarinedomainsextendingseawardoftheshelfbreak
are considered as deep-sea. This domain represents 63.6 % of the Earth’s
surface (the ocean in its entirety covers 361(cid:1)106 km2 or 70.8% of the
Earth’s surface, including continental shelves). From a stricter geological
point of view, the oceanic domain would begin at the boundary between
the high-density (3.25 on average), usually thin (5 km in average) oceanic
crust and the thick (30 km on average) low-density (2.7 in average)
continental crust. A transitional crust may exist in between.
Thestudyofdeep-seasedimentsbenefitedgreatlyfromrecentimprove-
mentsintechnologies.Theseimprovementshavebeendrivenbyacademic
needs (most of the sea floor remains unexplored in detail and most of the
topography of abyssal plains has not been mapped with accurate tools) and
* Universite´deBordeaux,UMRCNRS5805EPOC,AvenuedesFaculte´s,33185TalenceCedex,France
{ Institutfu¨rGeographieundGeologie,Universita¨tGreifswald,Jahn-Strasse17a,D–17487Greifswald
{ GeologicalInstitute,AdamMickiewiczUniversity,Mako´wPolnych16,61–606Poznan,Poland
DevelopmentsinSedimentology,Volume63 #2011ElsevierB.V.
ISSN0070-4571,DOI:10.1016/S0070-4571(11)63001-X Allrightsreserved.
1
2 ThierryMulderetal.
byeconomicneeds,suchasthedemandformineraldeposits(metal-bearing
nodules, exploration of ultra-deep offshore oil). These newly-developed
technologiesbenefitedfrombothinsitudatacollectionanddatainterpreta-
tion in laboratory.
In terms of data collection, this includes:
– Sea-floor morphology (multibeam bathymetry),
– subsurface investigation (seismic tools),
– high-resolution echosounders,
– 3-D tools,
– sampling gear (interface corer).
In terms of data interpretation in the laboratory, this includes:
– core scanners for measurement of geotechnical and physical properties,
X-ray, geochemistry,
– thedevelopmentofbiologicaltracersandbiomarkersforpalaeoenviron-
mental reconstruction,
– the improvement and development of stratigraphic tools and dating
methods based on radiogenic and non-radiogenic elements (especially
for the Quaternary), the development of micro-lithostratigraphy (IRD,
tephra recognition) and magnetostratigraphy.
1.1. Scope of the book
The chapters of this book have the following objectives:
– to explain the formation and supply of sedimentary particles by conti-
nentalerosion(riverload,iceorwindtransport),coastalerosion,current-
induced winnowing, through volcanic and authigenic processes, and by
means of biogenic productivity;
– to describe the way the sediments are transported from the source area
(continental edge, slope, surface water) to the accumulation zone in the
deep-sea;
– topresenttheearlygeochemicaltransformationsaffectingtheparticlesin
the water column or the sediments as soon as they are produced and
accumulate on the sea floor;
– toshowhowsedimentsarepreservedontheseafloordespiteerosionand
dissolution;
– to present the characteristic features and main changes in worldwide
ocean sedimentation with focus on “modern” oceans that have been
formed since the disintegration of Pangaea (Mesozoic-Cenozoic);
– to discuss major changes in biogenic productivity, sea-water chemistry,
and external controls of deep-sea sedimentary processes, depending on
long-term trends in ocean history;
ProgressinDeep-SeaSedimentology 3
– topresenttheacademic(e.g.,palaeoclimaticstudies),societal(e.g.,natu-
ral hazards) and industrial interests (e.g., the exploration for mineral
resources) in the study of deep-sea sediments.
2. What are Deep-Sea Sediments?
The sea-water environment can be subdivided into shallow (epicon-
tinental) seas and deep seas. The morphology of modern oceans and mar-
ginal seas is based on the water depth and on changes in the slope gradient
(Fig. 1.1). Using a classical cross-section through a passive continental
margin, the shallowest environment is the continental shelf (or platform),
which extends in the continental domain from the shoreline to the shelf
break.Itrepresents26(cid:1)106km2(7.2%ofthemarinearea).Inthisarea,the
sea-floor gradient is < 0.5(cid:3). In offshore direction, the water depth extends
downto100–110msuchasonthenorth-westernAfricanmargin(Seibold
andHinz,1974)or200monmostofthecontinentalmargins,includingthe
northern European and the North-American Atlantic margins. Its extent
canbefromseveralhundredsofkilometres(1500kmfortheSiberianshelf,
>600kmforthesouthernArgentina–PatagonianShelf)toafewkilometres
(off Nice in the Mediterranean). Active continental margins, such as the
South-American Pacific margin, are usually only a few kilometres wide.
The continental shelf is exposed to numerous oceanographic processes
that are absent in deep seas. Most of them are related to atmospheric
processes. They include swell and storm waves that generate oscillatory
motions in the water column (producing specific sedimentary structures
such as hummocky cross-stratifications), tides, shallow contour currents, as
well as shelf and coastal currents, including littoral drift. The continental
shelf is separated from the continental slope by the shelf break, which is
defined by a change in the slope gradient. The slope steepens from a
gradient<1(cid:3) ontheshelfto3–5(cid:3) inaveragealongtheslope,tosometimes
(cid:3)
more than 20 in areas where canyons are incised the slope and the shelf.
Further downslope, it passes into the continental rise at a water depth of
about 2500 m. The continental slope corresponds approximately to
the bathyal zone (200–3000 m). On the rise, the slope gradient decreases
(cid:3)
to 1–2 and the relief becomes smoother. Because of this change, the
continental rise is the preferential area for final deposition of terrigenous
sediment that bypassed the shelf and slope area. Together, the continental
shelf,slopeandriseformthecontinentalmargin.Themargincanbepassive
andtectonicallyquiescent(NorthAtlanticmargin)oractiveandtectonically
dynamic (circum-Pacific margins).
At about 5000 m water depth, the rise passes into the abyssal plain.
Abyssal plains represent the largest oceanic domains with a mean water
4 ThierryMulderetal.
deep sea
littoral zone bathyal zone abyssal zone hadal zone
coastline shelf
0m
slope
2000m
average ocean depth
rise
ridge 4000m
abyssal plain 6000m
8000m
10,000m
trench
active margin
passive margin
ocean
continent
continent
LITHOSPHERE
oceanic crust continental crust mantle
Figure 1.1 Cross-section through an ocean, showing the various deep-sea environ-
mentsanddomains.Lithosphere includesupperpartofuppermantleplusoceanicor
continentalcrust.(Amulti-colourversionofthisfigureisontheincludedCD-ROM.)
depth of (cid:4) 3800 m. Abyssal plains are “flat” at a large scale. A closer look
reveals, however, that their “flatness” is disrupted by tectonic and volcanic
features: transform faults at different scales and strike-like faults with hang-
ingwallsofseveralhundredsofmetresorevenseveralkilometresinheight
andrelatedlocalsedimentarybasins.Thereare,inaddition,hot-spot-related
volcanic mounds and islands, volcano alignments forming the oceanic
ridges, channels and thick and extensive accumulations of sediments form-
ing drifts, and levees, gypsum diapirs; there are also dissolution structures.
Thecontinentalriseandabyssalplainsconstitutetheabyssaldomain(3000–
6000 m). Only 2% of the total ocean surface is deeper than 6000 m (hadal
domain).Insubductionareas,thepresenceofasubductiontrenchgenerates
the deepest oceanic environments, down to 11,020 m (Mariana Trench).
There,thepresenceofanaccretionaryprismcangenerateimportantrelief-
formingprocesses,suchasmuddiapirsandvolcanoes(whichmayberelated
to the upward motion of deep fluids) and pockmarks, which are due to
liquefaction related to fluid escape.
Thesedimentsinthedeep-seaconsistof(1)clasticparticlesderivedfrom
erodedrocks andsediments outcroppingeither on the emerged continents
or previously deposited in a marine environment, (2) particles formed by