2wnw Geomorphology Prelims

7/29/2019 2wnw Geomorphology Prelims

1/24

G E O S C I E N C E A U S T R A L I A

A Spatial Analysis

Christina Baker, Anna Potter, Maggie Tran and Andrew D. Heap

APPLYING GEOSCIENCE TO AUSTR ALIA S MOST IMPORTA NT CHALLENGES

Record

2008/07

Sedimentology andGeomorphology of theNorthwest Marine region


2/24

Geoscience Australia Record 2008/07

Sedimentology and Geomorphology of theNorth West Marine Region of Australia

Christina Baker, Anna Potter, Maggie Tran and Andrew D. Heap

Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia


3/24

ii

Geoscience AustraliaChiefExecutiveOfficer:DrNeilWilliamsPSM

Department of Resources, Energy & TourismMinisterforIndustry,Tourism&Resources:TheHon.MartinFerguson,AMMP

Secretary:Dr

Peter

Boxall

AO

CommonwealthofAustralia2008

This work is copyright. You may download, display, print and reproduce this material in

unalteredformonly(retainingthisnotice)foryourpersonal,noncommercialuseorusewithin

yourorganisation.Apart fromanyuseaspermittedunder theCopyright Act 1968,allother

rightsarereserved.

DISCLAIMER

The views and opinions expressed in this publication are those of the authors and do not

necessarilyreflect

those

of

the

Australian

Government.

While reasonable efforts havebeenmade to ensure that the contents of thispublication are

factually correct, the Commonwealth does not accept responsibility for the accuracy or

completeness of the contents, and shall notbe liable for any loss or damage that maybe

occasioned directly or indirectly through the use of, or reliance on, the contents of this

publication.

ISSN: 14482177

ISBN:978

1921236

85

3(Hardcopy)

9781921236846(WEB)

9781921236860(DVD)

GeoCatNo.65769

Bibliographicreference:Baker,C.,Potter,A.,Tran,M.andHeap,A.D.,2008.Geomorphology

andSedimentologyoftheNorthwestMarineRegionofAustralia.GeoscienceAustralia,Record

2008/07.GeoscienceAustralia,Canberra.220pp.

Correspondenceforfeedback:

AnnaPotterGeoscienceAustralia

GPOBox378

Canberra

ACT2601

[email protected]


4/24

iii

Table of Contents

LIST OF FIGURES.............................................................................................................................................vi

LIST OF TABLES...............................................................................................................................................xi

ACKNOWLEDGEMENTS.......................................................................................................................... ......xiii

EXECUTIVE SUMMARY....................................................................................................................... ..........xiv

1. INTRODUCTION ........................................................................................................................................... 1

1.1.BACKGROUND ....................................................................................................................................... 11.2.SCOPE........................................................................................................................................................ 2

1.2.1.GenerationandSynthesisofSeabedInformationfortheNWMRandtheNNMR ............................ 21.2.2.ExpectedProjectOutcomes ................................................................................................................. 21.2.3.ProductsandOutputs ......................................................................................................................... 3

1.3.DESCRIPTIONOFGEOMORPHOLOGY ............................................................................................ 31.4.MARINEREGIONS ................................................................................................................................. 3

1.4.1.NWMRandNominatedAreaoftheNMR ......................................................................................... 31.5. BIOREGIONS............................................................................................................................... ............. 4

1.5.1.BioregionsoftheNWMR .................................................................................................................... 51.5.2.BioregionsoftheNominatedAreaoftheNMR(NNMR) .................................................................. 6

1.6. REPORTSTRUCTURE......................................................................................................... .................... 72. DATA AND METHODS ................................................................................................................................. 8

2.1.EXISTINGPHYSICALDATAFORTHENWMR................................................................................ 82.1.1.Bathymetry.......................................................................................................................................... 82.1.2.

Geomorphology

.................................................................................................................................... 8

2.1.3.SedimentData ................................................................................................................................... 102.2.PREVIOUSDATACOVERAGEOFTHENWMR............................................................................. 132.3.ASSESSMENTOFSIGNIFICANTGAPSINEXISTINGSAMPLECOVERAGEFORTHENWMR.......................................................................................................................................................................... 14

2.4.SAMPLEIDENTIFICATIONINTHENWMRANDSELECTIONFORANALYSIS...................142.4.1.SampleIdentification......................................................................................................................... 142.4.2.SampleSelection................................................................................................................................ 15

2.5.SAMPLEACQUISITIONANDANALYSIS ....................................................................................... 172.6.ASSESSMENTOFSIGNIFICANTGEOMORPHICFEATURES ..................................................... 172.7.MAPPRODUCTION............................................................................................................................. 18

2.7.1.PercentGravel/Sand/MudandFolkClassificationandPercentCarbonate...................................... 183. REVIEW AND SYNTHESIS OF LITERATURE FOR THE NORTH WEST MARINE REGION .... 19

3.1.THENORTHWESTMARINEREGION ............................................................................................ 193.1.1.Introduction....................................................................................................................................... 193.1.2.TectonicHistory ................................................................................................................................ 203.1.3.Oceanography.................................................................................................................................... 213.1.4.LateQuaternary(Holocene)Evolution ............................................................................................. 243.1.5.Geomorphology.................................................................................................................................. 253.1.6.Sedimentology ................................................................................................................................... 33

3.2.THENOMINATEDAREAOFTHENORTHERNMARINEREGION ......................................... 393.2.1.Introduction....................................................................................................................................... 393.2.2.TectonicHistory ................................................................................................................................ 393.2.3.Oceanography.................................................................................................................................... 40


5/24

iv

3.2.4.LateQuaternaryEvolution................................................................................................................403.2.5.Geomorphology ..................................................................................................................................413.2.6.Sedimentology....................................................................................................................................43

4. QUANTITATIVE DESCRIPTION OF THE NWMR AND NNMR........................................................46

4.1.

QUANTITATIVE

DESCRIPTION

OF

THE

NWMR ..........................................................................464.1.1.Geomorphology ..................................................................................................................................464.1.2.Bathymetry.........................................................................................................................................504.1.3.SedimentDataCoverageintheNWMR............................................................................................514.1.3.1QuantitativeTexturalandCompositionalData...........................................................................514.1.4.QuantitativeregionalsedimentdistributionintheNWMR .............................................................57

4.2.QUANTITATIVEDESCRIPTIONOFTHENNMR ...........................................................................814.2.1Geomorphology ...................................................................................................................................814.2.2.Bathymetry.........................................................................................................................................854.2.3.SedimentDataCoverageintheNNMR ............................................................................................864.2.4.QuantitativeregionalsedimentdistributionintheNNMR..............................................................91

5. GEOMORPHOLOGY AND SEDIMENTOLOGY OF BIOREGIONS..................................................1125.1INTRODUCTION ..................................................................................................................................1125.2.CENTRALWESTERNSHELFTRANSITION(CWST) ...................................................................1215.2.1.Geomorphologyandbathymetry ......................................................................................................1215.2.2.SampleCoverage ..............................................................................................................................1215.2.3.SedimentologyoftheCentralWesternShelfTransition..................................................................124

5.3.CENTRALWESTERNSHELFPROVINCE(CWSP)........................................................................1255.3.1Geomorphologyandbathymetry .......................................................................................................1255.3.2.Samplecoverage ...............................................................................................................................1265.3.3.SedimentologyoftheCentralWesternShelfProvince.....................................................................1295.3.4.SedimentologyofSignificantGeomorphicFeatures.........................................................................129

5.4.NORTHWESTSHELFPROVINCE(NWSP).....................................................................................1325.4.1.Geomorphologyandbathymetry ......................................................................................................1325.4.2.SampleCoverage ..............................................................................................................................1335.4.3.SedimentologyoftheNorthwestShelfProvince ..............................................................................1385.4.4.SedimentologyofSignificantGeomorphicFeatures.........................................................................139

5.5.NORTHWESTSHELFTRANSITION(NWST).................................................................................1465.5.1.Geomorphologyandbathymetry ......................................................................................................1465.5.2.SampleCoverage ..............................................................................................................................1475.5.3.SedimentologyoftheNorthWestShelfTransition..........................................................................1525.5.4.SedimentologyofSignificantGeomorphicFeatures.........................................................................153

5.6.TIMORPROVINCE(TP)......................................................................................................................1615.6.1.Geomorphologyandbathymetry ......................................................................................................1615.6.2.SampleCoverage ..............................................................................................................................1625.6.3.SedimentologyoftheTimorProvince ..............................................................................................1675.6.4.SedimentologyofSignificantGeomorphicFeatures.........................................................................167

5.7.NORTHWESTTRANSITION(NWT) ................................................................................................1715.7.1.Geomorphologyandbathymetry ......................................................................................................1715.7.2.SampleCoverage ..............................................................................................................................1725.7.3.SedimentologyoftheNorthwestTransition ....................................................................................1765.7.4.Sedimentologyofsignificantgeomorphicfeatures ...........................................................................177

5.8.NORTHWESTPROVINCE(NWP) ....................................................................................................1825.8.1.Geomorphologyandbathymetry ......................................................................................................1825.8.2.

Sample

Coverage ..............................................................................................................................182

5.8.3.SedimentologyoftheNorthwestProvince .......................................................................................185


6/24

v

5.8.4.Sedimentologyofsignificantgeomorphicfeatures........................................................................... 1865.9.CENTRALWESTERNTRANSITION(CWT) .................................................................................. 1925.9.1.Geomorphologyandbathymetry...................................................................................................... 1925.9.2.SampleCoverage ............................................................................................................................. 1935.9.3.SedimentologyoftheCentralWesternTransition .......................................................................... 196

5.9.4.Sedimentology

of

significant

geomorphic

features........................................................................... 197

6. SUMMARY AND DISCUSSION ............................................................................................................. 200

6.1.SEDIMENTTRENDSOFTHENWMR............................................................................................. 2006.1.1.InnerShelf....................................................................................................................................... 2016.1.2.MiddleShelf..................................................................................................................................... 2016.1.3.OuterShelfandSlope...................................................................................................................... 2026.1.4.AbyssalPlain/DeepOceanFloor..................................................................................................... 202

6.2SEDIMENTTRENDSOFTHENOMINATEDAREAOFTHENNMR........................................ 2036.3.IMPLICATIONSFORMARINEHABITATMAPPING ................................................................. 2036.4.LIMITATIONS...................................................................................................................................... 204

6.5.

RECOMMENDATIONS...................................................................................................................... 2056.6.SUMMARY............................................................................................................................................ 206

7. REFERENCES ............................................................................................................................................. 207

8. APPENDICES ............................................................................................................................................. 216

8.1.APPENDIXA:PROJECTSTAFF........................................................................................................ 2168.2.APPENDIXB:MAPPINGPARAMETERS ....................................................................................... 2168.2.1.Gravel,Sand,MudandCarbonateMaps........................................................................................ 2168.2.2.SeabedSedimentTypeFolkClassification.................................................................................... 2168.2.3.SedimentTextureRed/Green/BlueImage .................................................................................... 217

8.3.APPENDIXC:EXPLANATIONOFTABLEFIELDS ...................................................................... 218

8.3.1.Chapter

4Tables.............................................................................................................................. 2188.3.2.Chapter5Tables.............................................................................................................................. 219

8.4.APPENDIXD:METADATA............................................................................................................... 2208.5.APPENDIXE:DATAGENERATED ................................................................................................. 2208.6.APPENDIXF:LASERGRAINSIZEDISTRIBUTIONS.................................................................... 2208.7.APPENDIXG:WEBACESSIBLEDIGITALMAPSFORDATACOVERAGEANDSEDIMENT

PROPERTIES................................................................................................................................................ 220


7/24

vi

List of FiguresFigure1.1.LocationandextentoftheNorthWestMarineRegion(NWMR)andnominatedarea

oftheNorthMarineRegion(NNMR)relativetootherMarineRegionsintheAustralian

EEZ................................................................................................................................................. 4

Figure1.2.

Bioregions

of

the

North

West

Marine

Region

and

nominated

area

of

the

Northern

MarineRegion. ............................................................................................................................. 5

Figure2.1.Sampleswitheithercarbonateand/orgrainsizedataavailableintheMARSdatabase

priortoandfollowingthetaskinrelationtobioregionsoftheNWMRandNNMR.See

Figure3.6forunobstructedviewofgeomorphicfeatures....................................................11

Figure3.1.PhysiographicdivisionoftheNWMR,includingtheinner,middleoutershelf/slope

andabyssalplain/deepoceanfloor. ........................................................................................ 20

Figure3.2.MajoroceancurrentsthatinfluencetheNWMR(CSIRO,2004). ............................. 22

Figure3.3.Summarydiagramofthemajoroceanographicclimaticfactorsthataffect

sedimentationontherampthatcharacterisestheNorthwestShelf(Jamesetal.,2004). 23

Figure3.4.

Regionalisation

of

the

Australian

continental

shelf

for

fine

sand

(0.1mm)

distribution

calculatedfromwaveandtideexceedenceestimates(PorterSmithetal.,2004)............. 24

Figure3.5.ThegeomorphicfeaturesoftheNWMRasidentifiedbyHeapandHarris(inpress).

Numbers1to19refertokeyplacenameswhichareprovidedinTable3.1..................... 27

Figure3.6.Bathymetryof,a)CarnarvonTerrace;b)RowleyTerrace......................................... 30

Figure3.7.BathymetryandlocationoftheWallaby,ExmouthandScottPlateaus.................. 31

Figure3.8.BathymetryandlocationoftheRowleyShoals,Scott,Seringapatam,andAshmore

Reefs............................................................................................................................................. 32

Figure3.9.LocationandbathymetryoftheCuvierandArgoAbyssalPlains. ......................... 33

Figure3.10.Sedimentaryfaciesmodelofthenorthwestshelf(CarrigyandFairbridge,1954).34

Figure3.11.

Sedimentary

facies

model

of

the

Dirk

Hartog

Shelf

(James

et

al.,

1999). .............. 35

Figure3.12.Sedimentfaciesofthenorthwestmargin,facies1)shellfragments,pteropods,

benthicandplanktonicforaminifera;facies2)pteropods,planktonicforaminfera;3)

planktonicforaminifera;facies4)radiolarian,diatoms,partlydissolvedplanktonic

foraminifera(ColwellandVonStackelberg,1981). .............................................................. 36

Figure3.13.SeabedsedimentsoftheNorthwestShelf(Jamesetal.,2004). ............................... 37

Figure3.14.ThegeologicalsettingoftheArafuraShelf,includingtheArafuraBasinand

GoulburnGraben(fromMoore,1995). ................................................................................... 40

Figure3.15.ThegeomorphicfeaturesoftheNNMRasidentifiedbyHeapandHarris(inpress).

ForkeyplacenamesseeTable3.2. .......................................................................................... 42

Figure3.16.

The

distribution

of

calcium

carbonate

concentrations

on

the

Arafura

Shelf

(redrawn

fromJongsma,1974). ................................................................................................................. 45

Figure3.17.ThedistributionofsurfacesedimentsontheArafuraShelf(redrawnfromJongsma,

1974). ............................................................................................................................................ 45

Figure4.1.a)GeomorphologyoftheNWMRandb)percentageareaofeachgeomorphic

provincewithintheNWMRandEEZ..................................................................................... 48

Figure4.2.a)GeomorphologyoftheNWMRandb)percentageareaofeachgeomorphicfeature

withintheNWMRandEEZ. .................................................................................................... 50

Figure4.3.DistributionofwaterdepthsfortheNWMR(greybars)andEEZ(greybars)

expressedaspercentages. ......................................................................................................... 51

Figure4.4.

Location

of

all

quantitative

textural

and

compositional

sample

points

for

the

NWMR

inrelationtobathymetry. ......................................................................................................... 53


8/24

vii

Figure4.5.a)SampledensitydistributionacrosstheNWMR,andb)Frequencydistributionof

sampledensity. .......................................................................................................................... 54

Figure4.6.SampledensityofgeomorphicprovincesandfeaturesintheNWMR(yaxisshows

averagedensitymeasuredassamplesper1,000km).......................................................... 55

Figure4.7.Sampledensityforwaterdepthsfora)depths


9/24

viii

Figure4.25.SampledensitiesofgeomorphicprovincesandfeaturesfortheNNMR(yaxis

showsaveragedensitymeasuredassamplesper1,000km).............................................. 90

Figure4.26.SampledensitiesforwaterdepthsfortheNNMR(yaxisshowsaveragedensity

measuredassamplesper1,000km)....................................................................................... 91

Figure4.27.Texture(mud:sand:gravelratio)ofsedimentintheNNMR. ................................. 93

Figure4.28.

Carbonate

content

of

NNMR

sediment:

a)

bulk;

b)

mud;

c)

sand;

and

d)

gravel.94

Figure4.29.a)Muddistributionwithb)theareacoveredbyeachclassexpressedas%ofthe

interpolatedareaoftheNNMR. .............................................................................................. 95

Figure4.30.a)Sanddistributionwithb)theareacoveredbyeachclassexpressedas%ofthe


Figure4.31.a)Graveldistributionwithb)theareacoveredbyeachclassexpressedas%ofthe


Figure4.32.a)Bulkcarbonatedistributionwithb)theareacoveredbyeachclassexpressedas%

oftheinterpolatedareaoftheNNMR. ................................................................................... 98

Figure4.33.InterpolatedgrainsizedatadisplayedasFolkClasseswithb)theareacoveredby

eachclass

expressed

as

%

of

the

interpolated

area

of

the

NNMR. ................................... 100

Figure4.34.Textureofsedimentingeomorphicprovinces:a)shelf&b)slopeoftheNNMR.105

Figure4.35.Bulkcarbonatecontentofgeomorphicprovinces:a)shelf&b)slopeoftheNNMR.

.................................................................................................................................................... 106

Figure4.36.Texturalcomposition(mud:sand:gravelratio)ofgeomorphicfeaturesinthe

NNMR:a)bank/shoal;b)deep/hole/valley;c)basin;d)canyon;e)ridge;f)apron/fan;and

g)terrace.................................................................................................................................... 109

Figure4.37.CompositionofbulkcarbonatecontentingeomorphicfeaturesoftheNNMR:a)

bank/shoal;b)deep/hole/valley;c)basin;d)canyon;e)ridge;f)apron/fan;andg)terrace.

.................................................................................................................................................... 112

Figure5.1.

a)

Sample

coverage

of

bioregions

within

the

NWMR;

and

b)

sample

density

of

each

bioregionbeforeandafterthetask........................................................................................ 115

Figure5.2.Texturalcomposition(mud:sand:gravelratio)ofsedimentsintheshelfbioregionsof

theNWMR;a)NorthwestShelfTransition,b)NorthwestShelfProvince,c)Central

WesternShelfTransition,d)CentralWesternShelfProvince,ande)Carbonatecontentof

alltheaboveshelfbioregionsedimentsintheNWMR. ..................................................... 118

Figure5.3.a)Texturalcomposition(mud:sand:gravelratio)ofsedimentsintheoffshore

bioregionsoftheNWMR;a)CentralWesternTransition,b)TimorProvince,c)Northwest

Transition,d)NorthwestProvince,ande)Carbonatecontentofalltheaboveoffshore

bioregionsedimentsintheNWMR....................................................................................... 120

Figure5.4.

a)

Geomorphology

of

the

Central

Western

Shelf

Transition

(CWST)

with

location

of

samples;andb)PercentageareaofeachgeomorphicfeaturewithintheCWSTwith

numberofcorrespondingsedimentsamples....................................................................... 122

Figure5.5.a)BathymetryoftheCentralWesternShelfTransition(CWST)withlocationof

samples;andb)PercentageareaofbathymetryclasswithintheCWSTwithnumberof

correspondingsedimentsamples. ......................................................................................... 123

Figure5.6.Texturalcomposition(mud:sand:gravelratio)ofslopesedimentswithintheCWST.

.................................................................................................................................................... 125

Figure5.7.CarbonatecontentofslopesedimentswithintheCWST. ....................................... 125

Figure5.8.a)GeomorphologyoftheCentralWesternShelfProvince(CWSP)withlocationof

sedimentsamples;

and

b)

Percentage

area

of

each

geomorphic

feature

within

the

CWSP

withnumberofcorrespondingsedimentsamples. ............................................................ 127


10/24

ix

Figure5.9.a)BathymetryoftheCentralWesternShelfProvince(CWSP)withlocationof

sedimentsamples;andb)PercentageareaofeachbathymetryclasswithintheCWSPwith

numberofcorrespondingsedimentsamples. ..................................................................... 128

Figure5.10.Texturalcomposition(mud:sand:gravelratio)ofa)shelfandb)slopesediments

withintheCWSP...................................................................................................................... 131

Figure5.11.

Carbonate

content

of

sediments

within

the

CWSP

on

a)

shelf

and

b)

slope. .... 132

Figure5.12.a)GeomorphologyoftheNorthwestShelfProvincewithlocationofsediment

samples;andb)PercentageareaofeachgeomorphicfeaturewithintheNWSPwith

numberofcorrespondingsedimentsamples. ..................................................................... 136

Figure5.13.a)BathymetryoftheNorthwestShelfProvincewithlocationofsedimentsamples;

andb)PercentageareaofeachbathymetrywithintheNWSPwithnumberof

correspondingsedimentsamples.......................................................................................... 137

Figure5.14.Texturalcomposition(mud:sand:gravelratio)ofa)bank/shoal;b)deep/hole/valley;

c)plateau;d)ridge;e)shallowwaterterrace;andf)shelf/slopesedimentswithinthe

NWSP. ....................................................................................................................................... 144

Figure5.15.

Carbonate

content

of

a)

bank/shoal;

b)

deep/hole/valley;

c)

plateau;

d)

ridge;

e)

shallowwaterterrace;andf)shelf/slopesedimentswithintheNWSP........................... 146

Figure5.16.a)GeomorphologyoftheNorthwestShelfTransition(NWST)withlocationof

sedimentsamples;andb)PercentageareaofeachgeomorphicfeaturewithintheNWST


Figure5.17.a)BathymetryoftheNorthwestShelfTransition(NWST)withlocationofsediment

samples;andb)PercentageareaofeachbathymetryclasswithintheNWSTwithnumber

ofcorrespondingsedimentsamples. .................................................................................... 151

Figure5.18.Texturalcomposition(mud:sand:gravelratio)ofa)bank/shoal;b)basin;c)

deep/hole/valley;d)plateau;e)terrace;f)shelfsedimentswithintheNWST................ 158

Figure5.19.

Carbonate

content

of

a)

bank/shoal;

b)

basin;

c)

deep/hole/valley;

d)

plateau;

e)

terrace;andf)shelfsedimentswithintheNWST. .............................................................. 160

Figure5.20.a)GeomorphologyoftheTimorProvince(TP)withlocationofsedimentsamples;

andb)PercentageareaofeachgeomorphicfeaturewithintheTPwithnumberof


Figure5.21.a)TimorProvinceshowingbathymetrywithlocationofsedimentsamples;andb)

PercentageareaofeachbathymetryclasswithintheTPwithnumberofcorresponding

sedimentsamples..................................................................................................................... 165

Figure5.22.Texturalcomposition(mud:sand:gravelratio)ofa)deep/hole/valley;b)terrace;and

c)slopesedimentswithintheTP........................................................................................... 169

Figure5.23.

Carbonate

content

of

a)

deep/hole/valley;

b)

terrace;

and

c)

slope

sediments

within

theTP......................................................................................................................................... 170

Figure5.24.a)GeomorphologyoftheNorthwestTransition(NWT)withlocationofsediment

samples;andb)PercentageareaofeachgeomorphicfeaturewithintheNWTwithnumber


Figure5.25.a)BathymetryoftheNorthwestTransition(NWT)withlocationofsediment

samples;andb)PercentageareaofeachbathymetryclasswithintheNWTwithnumberof


Figure5.26.Texturalcomposition(mud:sand:gravelratio)ofa)upperslopeterraceandb)slope

sedimentsc)ArgoAbyssalPlainwithintheNWT. ............................................................ 180

Figure5.27.

Carbonate

content

of

a)

terrace

and

b)

slope

sediments

within

the

NWT.......... 181


11/24

x

Figure5.28.a)GeomorphologyoftheNorthwestProvince(NWP)withlocationofsediment

samples;andb)PercentageareaofeachgeomorphicfeaturewithintheNWPwithnumber


Figure5.29.a)BathymetryoftheNorthwestProvince(NWP)withlocationofsediment

samples;andb)PercentageareaofeachbathymetryclasswithintheNWPwithnumberof

correspondingsediment

samples. ......................................................................................... 184

Figure5.30.Texturalcomposition(mud:sand:gravelratio)ofa)deep/hole/valley;andb)slope

c)Trench/troughs d)DeepwaterplateaussedimentswithintheNWP. .......................... 189

Figure5.31.Carbonatecontentofa)slopeb)Trench/troughsandc)Deepwaterplateaus

sedimentswithintheNWP..................................................................................................... 191

Figure5.32.a)GeomorphologyoftheCentralWesternTransition(CWT)withlocationof

sedimentsamples;andb)PercentageareaofeachgeomorphicfeaturewithintheCWT


Figure5.33.a)BathymetryoftheCentralWesternTransition(CWT)withlocationofsediment

samples;andb)PercentageareaofeachbathymetryclasswithintheCWTwithnumberof

correspondingsediment

samples. ......................................................................................... 195

Figure5.34.Texturalcomposition(mud:sand:gravelratio)ofa)abyssalplain/deepoceanfloor;

andb)slopesedimentswithintheCWT. ............................................................................. 198

Figure5.35.CarbonatecontentofslopesedimentswithintheCWT. ....................................... 199


12/24

xi

List of TablesTable1.2.SummarydetailsoftheprovincialbioregionscontainedintheNWMR.................... 6

Table1.3.Summarydetailsoftheprovincialbioregionscontainedinthenominatedareaofthe

NMR. ............................................................................................................................................. 6

Table2.1.

List

of

geomorphic

provinces

and

features

represented

in

the

NWMR

and

NNMR

(HeapandHarris,inpressa).OriginaldefinitionsareadaptedfromIHO(2001),exceptfor

sandwavesandsandbanks,whicharefromAshleyetal.(1990)........................................ 8

Table2.2.MetadataforsedimentsampleswitheithercarbonateorgrainsizedatainMARSfor

theNWMRpriortotheMemorandumOfUnderstanding(MOU).................................... 12

Table2.3.MetadataforsedimentsampleswitheithercarbonateorgrainsizedatainMARSfor

theNNMR................................................................................................................................... 13

Table2.4.Metadataforsedimentsamplesanalysedforthisstudy............................................. 15

Table2.5.CriteriaforassessingsignificanceofgeomorphicfeaturesintheNWMRorProvincial

Bioregion..................................................................................................................................... 18

Table3.1.

Place

names

and

associated

references

for

geomorphic

features

displayed

in

Figure

3.1. ................................................................................................................................................ 27

Table3.2.PlacenamesandassociatedreferencesforgeomorphicfeaturesdisplayedinFigure

3.2. ................................................................................................................................................ 42

Table4.1.StatisticsofgeomorphicprovincesandfeaturesoftheNWMR. ............................... 46

Table4.2.Descriptionofaveragedensityofsamplespergeomorphicprovinceorfeature.... 52

Table4.3.StatisticsofgeomorphicprovincesandfeaturesoftheNNMR................................. 81

Table4.4.Descriptionofaveragedensityofsamplesineachgeomorphicprovinceandfeature.

...................................................................................................................................................... 87

Table5.1.DescriptionofchangeinsamplecoverageoftheNWMRareaofbioregionswithtask

.................................................................................................................................................... 121

*ThetaskthatwassetbytheMOUbetweenDEWHAandGA................................................ 121

Table5.2.DetailsofthegeomorphologyoftheCentralWesternShelfTransition................. 124

Table5.3.DistributionofwaterdepthscoveredbythegeomorphologyintheCentralWestern

ShelfTransition. ....................................................................................................................... 124

Table5.4.DetailsofthegeomorphologyoftheCentralWesternShelfProvince. .................. 129


ShelfProvince. .......................................................................................................................... 129

Table5.6.DetailsofthegeomorphologyoftheNorthwestShelfProvince. ............................ 138

Table5.7.DistributionofwaterdepthscoveredbythegeomorphologyintheNorthwestShelf

Province..................................................................................................................................... 138

Table5.8:DetailsofthegeomorphologyoftheNorthwestShelfTransition........................... 151

Table5.9:DistributionofwaterdepthscoveredbythegeomorphologyintheNorthwestShelf

Transition.................................................................................................................................. 152

Table5.10.DetailsofthegeomorphologyoftheTimorProvince. ............................................ 166

Table5.11.DistributionofwaterdepthscoveredbythegeomorphologyintheTimorProvince.

.................................................................................................................................................... 166

Table5.12.DetailsofthegeomorphologyoftheNorthwestTransition................................... 176

Table5.13.DistributionofwaterdepthscoveredbythegeomorphologyintheNorthwest

Transition.................................................................................................................................. 176

Table5.14.

Details

of

the

geomorphology

of

the

Northwest

Province. .................................... 185


13/24

xii

Table5.15.DistributionofwaterdepthscoveredbythegeomorphologyintheNorthwest

Province..................................................................................................................................... 185

Table5.16.DetailsofthegeomorphologyoftheCentralWesternTransition......................... 196


Transition. ................................................................................................................................. 196


14/24

xiii

Acknowledgements

Thankstothosewhoprovidedtechnicalandscientificsupportfortheproductionofthis

report. Many thanks to David Arnold, Silvio Mezzomo and the Graphics and

Visualisation

Team

for

their

outstanding

reproduction

of

the

figures,

the

Seabed

MappingandCharacterisationProjectforinformationandadviceonvariousaspectsof

thereviewandthePalentonologyandSedimentologyLabsforanalyzingsamples.We

thank external institutions including: Federal Institute for Geosciences and Natural

Resources (BGR) Germany, Lamont Doherty Earth Observatory, The Universiy of

Adelaide, OregonState University, Intergrated Ocean Drilling ProgramTexas A & M

University, Research Centre for Marine Geosciences (GEOMAR) Germany, Scripps

Institute of Oceanography and LamontDoherty Earth Observatory for providing

sedimentsamples.WethanktheDepartmentofEnvironment,Water,Heritageandthe

Artsfor

their

guidance

and

support

for

this

project.

The

original

text

benefited

from

the

thorough reviews of Dr Rachel Przeslawski and Shoaib Burq of Geoscience Australia

andChrisMarshallof theDepartmentofEnvironment,Water,Heritageand theArts.

This record is published with permission of the Chief Executive Officer, Geoscience

Australia.

Figure3.2: Reprinted from theCSIROwebsite copyright (2004), with permission from CSIRO.

Figure3.3and3.13: ModifiedfromSedimentology,51,James,N.P.,Bone,Y.,Kyser,T.K.,Dix,G.R. andCollins,L.B.,The importance of changing oceanography in controlling

late Quaternary carbonate sedimentation on a highenergy, tropical, oceanic ramp:

northwesternAustralia, copyright (2004), with permission from WileyBlackwell

Publishing.

Figure 3.10: Modified from the Journal of the Royal Society of Western Australia, 38, Carrigy, M.H. and Fairbridge, R.W., Recent Sedimentation, physiography and

structure

of

the

continental

shelves

of

Western

Australia,

copyright

(1954),

with

permissionoftheRoyalSocietyofWesternAustralia.

Figure3.11:ModifiedfromJournalofSedimentaryResearch,69,James,N.P.,Bone,Y.andHallock,P.,Subtropicalcarbonatesinatemperaterealm:Modernsedimentsonthe

SouthwestAustralianshelf,copyright(1999),withpermissionfromSocietyfor

SedimentaryGeology.


15/24

xiv

Executive Summary

Thisreportcontainsareviewofliteratureandtheresultsofastudyofthesedimentologyand

geomorphologyof theNorthWestMarineRegion(NWMR)andnominatedareaoftheNorth

Marine

Region

(NNMR).

The

study

is

a

collaborationbetween

Geoscience

Australia

and

the

Departmentof theEnvironment,Water,Heritageand theArts (DEWHA).Datageneratedby

this study expands the national fundamental marine samples dataset for Australias marine

jurisdiction, with analyses consistent with those completed on samples from the rest of the

margin.InformationcontainedinthisreportwillcontributetoGeoscienceAustraliasnational

workprogramthroughthecreationofseascapes(surrogatesforseabedhabitats)fortheNWMR

and will be used by the Department of the Environment, Water, Heritage and the Arts

(DEWHA)aspartoftheMarineBioregionalPlanningworkprogram.

Geoscience Australia is the national repository and custodian of marine sediment data

includinganational

marine

samples

database

(MARS;

http://www.ga.gov.au/oracle/mars)

that

is a fundamental marine dataset for the Australian margin. This study has significantly

improvedthedistributionofquantitativetexturalandcompositiondatastoredinMARSforthe

NWMR and NNMR. To realise the principal aim of the study, the following three objectives

weredevised:

1. Analyseseabedsedimentsamples(nominally200)forquantitativegrainsizedistribution

andcarbonatecontent;

2. IdentifysourcesofmarinesedimentsamplesandpopulateMARSwiththedata;and

3. Produceareportsynthesizingandsummarizingtheoceanography,tectonichistory,late

Quaternary evolution, geomorphology and sedimentology of the NWMR and the

NNMRbased

on

this

data

and

previous

literature.

Results of the analyses are presented as a regional synthesis within the framework of the

Integrated Marine and Coastal Regionalisation of Australia (IMCRA) and National

BioregionalisationofAustralia2005andwherepossiblewithin theconstraintsofgeomorphic

features identified inarecentstudyof thegeomorphologyof theAustralianmarginbyHeap

and Harris (in press). Reporting the results in this way provides both an updated and

quantitativeanalysisoftheregionalsedimentologyfrompreviousworksandcharacterisesthe

broadscale management zones designed to support bioregional marine planning.

Characterising sedimentologyby geomorphic feature allows the resolution of relationships

betweenfeature

and

sediment

type.

TheNWMRisatropicalcarbonatemarginthatcomprisesanextensiveareaofshelf,slopeand

abyssalplain/deepoceanfloor.Thenorthernshelf(NorthwestandSahulShelves)isbroadand

gentlewithanindiscernibleshelfbreak,andthesouthernshelf(DirkHartogShelf)isnarrow.

ThenorthwestmarginiscontrolledbytectonicactivityoftheTriassic(250Ma)toJurassic(145

Ma)thatoccurredasaresultofcontinentalbreakup.ThemarginisinfluencedbytheLeeuwin

CurrentandIndonesianThroughflow,aswellasseasonalupwellingevents,internaltidesand

cycloneinducedstorms.Aseriesofreefsarelocatedontheoutershelf/slope.Eightbioregions

occurwithintheNWMR,andtheseincludefouroffshore(~65%oftotalNWMRarea)andfour

shelf(~35%

of

total

NWMR

area)

bioregions.


16/24

xv

The regional sedimentology is dominated by marine carbonates. Sediments show abroad

zoningandfiningwithwaterdepth.Oceanography,tectonichistory,lateQuaternaryevolution

andgeomorphologyhaveestablishedthesedimentarysettingforthemargin.Mainsedimentary

trendsoftheNWMRinclude:

Atropicalcarbonateshelfthatisdominatedbysandandgravelto latitudesofaround

15.

Anoutershelf/slopezonethatisdominatedbymud;and

Arelativelyhomogenousriseandabyssalplain/deepoceanfloorthat isdominatedby

noncarbonatemudbecauseitoccursbelowthecarbonatecompensationdepth.

Significantoutcomesofthisstudyinclude:

Production of the most uptodate and comprehensive representation of the seabed

sedimentology for the northwest and the northern Australian margin, building on

existingregionalsedimentmodels;

Production of a detailed synthesis and review of literature for the NWMR and the

NNMR;

Quantification of regional seabed sediment characteristics and distribution in the

NWMRandNNMRandassessmentofthesedimentvariabilityataNWMR,bioregion

andgeomorphicfeaturelevel;

Production of a robust, consistent quantitative dataset that permits defensible

quantitative comparisons of the seabed sedimentology to be made between the

northwestmarginandthewholeAustralianmargin;and

Recognition and quantification of the spatial heterogeneity of seabed sedimentology

within the NWMR and the NNMR that canbe linked to seabed habitat complexity.

Capturing the spatial heterogeneity of the seabed sedimentology will allow more

accurateand

precise

mapping

of

seabed

habitats

(seascapes)

and

aid

in

more

effective

futuresamplingstrategies.

A principal application of the study is to support research into the associations between

physical seabed properties such as sediment texture and composition and the distribution of

benthicmarinehabitatsandbiota.ThisresearchcontributestoGeoscienceAustraliasworkon

the spatial representation ofbenthic marine habitats andbiota for Australias vast marine

jurisdiction.Thisworkiscrucialfordevelopingrobust,defensiblemethodsofmappinghabitats

over thousands of kilometres using spatially abundant physical data combined with site

specificbiologicaldata.


17/24

xvi


18/24

1

1. Introduction

1.1.BACKGROUNDThis

report

presents

the

geomorphology

and

sedimentology

of

the

North

West

Marine

Region

(NWMR)andasectionoftheNorthernMarineRegion(NMR)termedthenominatedareaofthe

(NNMR). The three main outputs of the report include: 1) a review of previous geological

researchundertakenintheNWMRandNNMR;2)theresultsofaquantitativestudyofseabed

sediment texture and composition for these regions; and 3) a synthesis of this information

characterisingregionaltrendsinsedimentology,geomorphologyandbathymetry.Thestudyis

acollaborationbetweenGeoscienceAustraliaandtheDepartmentoftheEnvironment,Water,

HeritageandtheArts(DEWHA)andisacontinuationofsimilarworkconductedfortheSouth

WestMarineRegion(Potteretal.,2006;Richardsonetal.,2005).

Previoussediment

studies

in

the

NWMR

have

predominantly

produced

qualitative

results

at

localscales.Existingquantitativetexturalandcompositionaldataavailablefortheregionprior

tothistaskwasrelativelysparse.Thestudyhasimprovedthecoverageofquantitativedatafor

the NWMRby procuring and generating quantitative texture and composition data for 200

nominal seabed samples. This data expands the national marine sediment dataset for

Australiasmarinejurisdiction,withanalysesconsistentwiththosecompletedonsamplesfrom

the rest of the margin. By combining results of previous qualitative work and quantitative

information generated from existing and new data, this report provides an improved

understandingofsedimentologyfortheNWMRandtheNNMR.Informationcontainedwithin

thisreportwillcontributetotheDepartmentoftheEnvironment,Water,HeritageandtheArts

Marine

Bioregional

Planning

work

program

and

willbe

one

information

input

used

for

the

selection of candidate marine protected areas for the North West and nominated area of the

NorthernMarineRegion.

Geomorphic,sedimentaryandbiologicalinformationhaspreviouslybeenutilisedtodevelopa

NationalBioregionalisationofAustraliasExclusiveEconomicZone (EEZ)(Departmentofthe

Environment and Heritage (National Oceans Office), 2005; now the Department of the

Environment,Water,HeritageandtheArts)andsubstantivegeomorphicfeaturesofthewest,

northwestandnortherncontinentalmarginshavealreadybeenidentifiedandmapped(Heap

andHarris,inpress).Thisreportaddssignificantlytothesepreviousstudiesbyincorporating

theinformation

in

asedimentological

synthesis

that

includes

adiscussion

of

the

implications

formarineconservationintheNWMRandnominatedareaoftheNMR.

The physical characteristics of the seabed, as describedby sediment texture and composition

data, can assist in determining the diversity ofbenthic marine habitats. These data represent

enduring features which are elements of the physical environment that do not change

considerably(inhumanlifespans),andtheyareknowntoinfluencethediversityofbiological

systems. This is important for marine conservation due to the better definition and

characterisation ofbenthic habitats. Seabed texture and composition are easily measurable

parametersthat,whencombinedwithotherphysicalfeaturescanbeusedtocreateseascapes

thatserve

as

broad

surrogates

for

benthic

habitats

and

biota

(Whiteway

et

al.,

2007).

Seascapes

have the potential tobe used in informing the marinebioregional planning process and the


19/24

2

design of a national system of representative Marine Protected Areas (MPA). This data

increases the sediment coverage of the NWMR and NNMR tobe used in the generation of

seascapes.

1.2.SCOPE1.2.1.GenerationandSynthesisofSeabed Information for theNWMRandtheNNMRIn April 2007, Geoscience Australia and the DEWHA agreed to undertake a collaborative

projectto identify,analyseandcollateexisting informationonthetextureandcompositionof

theseabedintheNWMRandtheNNMR.Themainobjectivesofthisprojectwereto:

Identifyandsummariseallpreviousgeological information for theNWMRand

theNNMR;

Procure and analyse sediment samples (nominally 200) from the NWMR,

currentlyheldbyGeoscienceAustraliaandothermarinescienceinstitutions,for

grainsizeandcarbonateconcentrations;

Provide data on the texture and composition of the seabed for the NWMR to

populate Geoscience Australias national marine samples database (MARS;

www.ga.gov.au/oracle/mars)withthedata;and

Produce a report synthesising and summarising the sedimentology and

geomorphology of the seabed for the NWMR and the NNMR in support of

marinebioregionalplanningandcreationofanationalsystemof representative

marineprotected

areas.

1.2.2.ExpectedProjectOutcomesTheexpectedoutcomesofthisprojectare:

To obtain a better understanding of the nature of the seabed for the west,

northwestandnorthernmarginsofAustralia;

ToimprovetheavailableinformationonthesedimentologyoftheNWMRforthe

scientific and planning communities, leading to the development of Marine

BioregionalPlans;

To

improve

access

to

data

on

the

nature

of

the

seabed

through

continued

populationoftheMARSdatabaseasanationalfundamentalmarinedatasetand

Toprovidetextureandcompositiondataforfutureprojects;forexample,thedata

may be combined with other physical data on the seabed (i.e. depth,

geomorphology,sedimentmobilityetc)tocreateseascapesthatrepresentmajor

ecological unitsbased on measurable, recurrent and predictable features of the

marineenvironment.


20/24

3

1.2.3.ProductsandOutputsKeyoutputsofthisprojectwillbe:

200 quantitative textural and compositional data points for the NWMR and

associatedmetadataavailableintheMARSdatabase;

A review and synthesis of previous geological information for the NWMR and

nominatedareaoftheNMR(Chapter3);

Quantitative analyses of the sedimentology and geomorphology of the NWMR

andnominatedareaoftheNMR(Chapters4,5and6);

A synthesis of all previous and new sediment information for the NWMR and

nominatedareaoftheNMRatplanningregionandbioregionscales(asdefined

byDEWHA)(Chapters4,5and6);

An

interpretation

of

sediment

information

and

discussion

of

the

significant

findingsandtheirimplicationsforMarineBioregionalPlanning(Chapter6);and

A series of webaccessible digital maps to standards appropriate for data

coverageandsedimentpropertiesintheNWMRandnominatedareaoftheNMR

(AppendixG).

1.3.DESCRIPTIONOFGEOMORPHOLOGYIn 2004, a collaborative agreement between Geoscience Australia, CSIRO Marine and

AtmosphericResearch,andtheformerDepartmentoftheEnvironmentandHeritage(National

Oceans

Office)

created

a

National

Marine

Bioregionalisation

(NMB

2005)

of

Australia

(DepartmentofEnvironment,Water,HeritageandtheArts,2005).TheNMB2005providesan

overarchingmanagementframeworkforalargepartofAustraliasmarinejurisdictionandis

based on the most uptodate knowledge of thebiophysical properties of Australias marine

environment,includingseabedgeomorphologyandsedimentology.Definitionsofgeomorphic

provincesandfeaturesincludedintheNMB2005andusedinthespatialanalysesinthisstudy

arelistedinTable2.1.

1.4.MARINEREGIONSThefivemarineregionsofAustraliasExclusiveEconomicZone(EEZ)includetheEastMarine

Region, NorthernMarine Region,North WestMarine Region andSouthEast MarineRegion.Marinebioregional plans willbe developed for each of these marine regions including the

NWMRoutlinedinthisreport.

1.4.1.NWMRandNominatedAreaoftheNMRTheNWMRencompassesCommonwealthWatersbetweenKalbarriinWesternAustraliatothe

WesternAustraliaandNorthernTerritoryborderintheBonaparteGulf(Fig.1.1;Fig.1.2).This

regioncomprises1.1millionkm2ofoceanandseabedandisboundedinshorebytheouterlimit

of state waters of northern Western Australia (which generally extends out to three nautical

miles

from

the

territorial

sea

baseline),

and

bounded

offshore

by

the

edge

of

the

Australian

EEZ

(200 nautical miles from the low water mark) except between Cape Leveque and Cape

Londonderry,wheretheNWMRdoesnotextendtotheEEZboundary.


21/24

4

Changestothelocationofthemarineplanningregionboundarieshaveresultedinaportionof

the Northern Marine Region (NMR) being excluded from previous geomorphology and

sedimentologyassessmentsbyGeoscienceAustralia(HeapandHarris,inpress).Thisarea,the

nominated area of the Northern Marine Region herein referred to as the NNMR, hasbeen

includedin

the

present

study.

The

NNMR

covers

an

area

of

nearly

200,000

km2

and

includes

the

seabedandwatercolumnfromtheboundaryoftheNWMRinthewesttotheAurariBayinthe

east(Fig1.1).

Figure 1.1. Location and extent of the North West Marine Region (NWMR) and nominated area of the North MarineRegion (NNMR) relative to other Marine Regions in the Australian EEZ.

1.5. BIOREGIONSThebenthiccomponentoftheNMB2005managementframeworkconsistsofahierarchicalset

of geographic management units. Below the scale of the major oceanbasins that comprise

Australiasmarinejurisdiction (i.e., the Indian,SouthernandPacificOceans), theshelf,slope,

rise and abyssal plain/deep ocean floor are designated as Primary Bathymetric Units that

representthe

broadest

scale

planning

unit

and

have

areas

of

several

million

km2.


22/24

5

Within each of the Primary Bathymetric Units are Provincial Bioregions, which havebeen

definedmainlybythedistributionofdemersalfish,bathymetry,andgeomorphology,andhave

areas of hundreds of thousands of km2 (IMCRA 4.0 2005). The Provincial Bioregions are the

principal planning unit for Marine Bioregional Planning. Marinebioregional plans willbe

developedforeachofthesemarineregionsincludingtheNWMR.

1.5.1.BioregionsoftheNWMRTheNWMRcompriseseightbioregions.(Fig,1.2&Table1.2).Onlythreeofthesebioregionsare

containedentirelywithintheNNMRboundary.Theremaindereitheroccupyareaswithwater

depths


23/24

6

Table 1.2. Summary details of the provincial bioregions contained in the NWMR.

Bioregion% of bioregion

included in NWMRWater type % of total NWMR area

Northwest Shelf Transition 44 Transitional Waters 13

Northwest Shelf Province 88 Tropical Waters 20

Central Western Shelf Transition 76 Transitional Waters 1

Central Western Shelf Province 65 Subtropical Waters 3

Central Western Transition 100 Transitional Waters 15

Timor Province 72 Tropical Waters 15

Northwest Transition 100 Transitional Waters 17

Northwest Province 100 Tropical Waters 17

TheNWMR

contains

the

Northwest

Shelf

Province,

Central

Western

Shelf

Transition,

Central

WesternShelfProvince,andpartoftheNorthwestShelfTransition(Table1.2). Theseprovinces

andtransitionsarelocatedontheshelf.Waterdepthsintheshelfbioregionsarebetween10m

and350mbutaregenerally


24/24

Chapter5.AsfortheNWMR,resultsofthisstudyarediscussedinthecontextoftheProvincial

Bioregions,anddataarepresentedforindividualbioregions.

Theentirearea(179,200km2)ofthetwoshelfprovincesandtransitionsarelocatedontheshelf.

AsmallareaofslopeispresentintheTimorTransitioninthenortheastofthenominatedarea

ofthe

NMR.

Waterdepths in thenominatedareaof theNMRvarybetween10and350m. Deepestareas

occurontheslopealongtheouterboundaryoftheEEZ.Samplecoverageinthenominatedarea

oftheNMR isrelativelyeven,withminordatagapsexistinglocallyatseveral locationonthe

innershelfandonelocationonthemid outershelfinthewestoftheregion.

1.6. REPORTSTRUCTUREThe report provides a regional assessment of the sedimentology and geomorphology of the

NWMR

and

NNMR.

The

report

provides

a

synthesis

of

the

existing

sedimentology

and

geomorphologyoftheNWMRandNNMR(Chapter3)whichprovidesaframeworkinwhich

the new data canbe understood. This is followedby a regional scale spatial analysis of the

sedimentology and geomorphology for the NWMR and NNMR (Chapter 4) and for each

provincialbioregionoccurringintheNWMR(Chapter5),puttingthenewdataintothecontext

oftheplanningzonesusedbyDEWHA.Lastly,resultsofthisstudyandpreviousworkinthe

NWMR and NNMR are summarised and discussed in terms of their implications for marine

planning(Chapter6).

2wnw Geomorphology Prelims

Documents

Transcript of 2wnw Geomorphology Prelims