Abstract Jervis Bay contains a lenticular marine sand body occupying an alluvial valley cut in Permian sandstones and siltstones. The sediment covers an area of 32 sq. miles with an average thickness of 60 feet. The sediments have been characterized by texture and mineralogy (including terrigenous minerals, carbonates and heavy minerals) and grouped into mappable facies by use of a classificatory computer program capable of handling quantitative and qualitative data. A study of foraminifera has been made and used to characterize the environment. The facies are then characterized in terms of the environmental factors operating within the bay. Two facies are evident, a low energy central facies consisting of a sublitharenite with less than 85% quartz and a marginal, high energy facies containing sublitharenites with greater than 85% quartz or quartz arenites. SEDIMENTATION IN JERVIS BAY,

NEW SOUTH WALES

AND

AUSTRALIAN CAPITAL TERRITORY.

by

G. TAYLOR.

JANUARY 1970.

A thesis submitted in fulfilment of the

requirements for the degree of Master of

Science at the University of New South

Wales UNIVERSITY OF N.S.W.

42945 12. OCT. 7 2 LIBRARY The following thesis is the result of twenty-two months of independent research in the School of Applied

Geology at the University of New South Wales and later the

Department of Geology at the Australian National University.

Where the work of others, whether published, unpublished or by personal communication, has been made use of or referred to,the fullest acknowledgement has been given.

No part of this work has ever been presented to any institution for the award of a qualification.

G.M.Taylor, January, 1970. "The most remarkable feature along

the coast are the two rocky head­

lands which project some five miles

beyond the general line of the east

coast, and enclose the wide expanse of

ocean known as Jervis Bay."

Griffith Taylor. ACKNOWLEDGEMENTS

The author wishes to acknowledge the interest shown and both the physical and scholarly assistance given by Dr. A.N. Carter, his supervisor. He also wishes to record his appreciation to the following

Professor J. Frankel (U.N.S.W.) for accepting me as a graduate student; to the Royal Australian Navy for their assistance in providing accommodation, ships and men during the period spent in the field; to Professor D.A. Brown (A.N.U.) for allowing this study after the author1s move to Canberra. For technical assistance and useful discussion given at all stages in the project the author wishes to thank Dr. A.D. Albani (U.N.S.W.), Colin Bembrick (N.S.W. Geol. Survey), Mr. A. Hefford (U.N.S.W.), J. Pennington (A.N.U.), Mr. D. Falvey (U.N.S.W.) and Mrs. Robyn Lawrie (A.N.U.)0 The author also acknowledges the Bureau of Mineral Resources,and in particular Mr. R. Dulski for providing and operating their continuous seismic equipment. A special thanks is recorded by the author to his wife Helen and Mother for invaluable assistance in preparation of the text for submission.

During the first year of the project the author was in receipt of a Commonwealth Post-graduate Scholarship.

G.M. Taylor CONTENTS Page

Chapter 1 (INTRODUCTION) 1

Detailed Contents 2

1.1 General 3

1.2 Physiography 9

1.3 Geology 10

1.4 Bathymetry 15

1.5 Hydrological Features 18

1.6 Meteorological Data 22

Chapter 2 (COASTAL MORPHOLOGY & SEDIMENTATION HISTORY) 27

Detailed Contents 38

2.1 Introduction 39

2.2 Wave Cut Platforms 41

2. 3 Beaches 45

2.4 Beach Ridges 47

2.5 Swamps 49

2.6 Marine Sedimentation 52

2.7 Conclusions 57 Page

Chapter 3 (TEXTURAL ANALYSIS) 59

Detailed Contents 60

3.1 Introduction 62

3.2 Field Procedures 63

3.3 Theoretical Considerations 64

3.4 Summary of Laboratory Procedure for Textural Analysis 95

3.5 Results 95

3.6 Discussion 115

3.7 Environmental Conclusions 130

Chapter ■4 (LIGHT MINERALS) 132

Detailed Contents 133

4. 1 Introduction 134

4.2 Method of Analysis 134

4.3 Mineralogical Composition 135

4. 4 Distribution 138

4.5 Petrographic Provinces and Arenite Classification 147

4. 6 Discussion 155

4.7 Conclusions 157 Page Chapter 5 (HEAVY MINERALS) 159 Detailed Contents 160 5.1 Introduction 162 5.2 Separation 163 5.3 Analysis of Concentratesl66

5.4 Quantitative Results 168 5.5 Microscopic Results 170 5.6 Distribution 177 5.7 Discussion 183 5.8 Conclusions 199

Chapter 6 (CARBONATE MATERIALS) 201

Detailed Contents 202 6.1 Introduction 203 6.2 Laboratory Procedure 203 6.3 Distribution 204 6.4 Durability of Shell Material in the Marine Environment 215

6.5 Carbonate Grain Morphology 217

6.6 Discussion 218

6.7 Effects of Carbonate on the Textural Parameters 226

6.8 Summary Page Chapter 7 (FORAMINIFERAL STUDIES)232

Detailed Contents 233 7.1 Introduction 230

7.2 Laboratory Procedure 235

7.3 Distribution 235

7.4 Discussion 250

7.5 Conclusions 258

Chapter 8 (MUD FRACTION STUDIES) 260

Detailed Contents 261 8.1 Introduction 262 8.2 Laboratory Procedure 262 8.3 X-ray Pretreatment and procedure 263 8.4 Results 265 8.5 Discussion 268

Chapter 9 (CONCLUSIONS) 272

Detailed Contents 273 9.1 General 274

9.2 Method 274

9.3 Data 286

9.4 Results 292

9.5 Discussion 296 Page

REFERENCES 299

APPENDICES 316

Appendix A 317

Appendix B 323

Appendix C 328

Appendix D 332

Appendix E 337

Appendix F. 338

Appendix G 342

Appendix H enclosed

Appendix I 344 LIST OF FIGURES Page

1.1 Locality Map 4

1.2 Local Place Names 5

1.3 Sample Locality Map 7

1.4 Geology and Structure Map 11

1.5 Coastal Morphology Map 14

1.6 Bathymetric Map 16

1.7 Chlorinity Vfs Temperature 19

1.8 Depth V's Temperature 21

1.9 Wind Direction, 9 a.m. 1960-64 24

1. 10 Wind Direction, 3 p.m. 1960-64 25

1.11 State of the Sea, 9 a. m. 1960-64 27

1.12 State of the Sea, 3 p. m. 1960-64 28

1.13 Swell Direction, 9 a.m 1960-64 30

1.14 Swell Direction, 3 p.m 1960-64 31

1.15 State of the Swell, 9 a.m. 1960-64 32

1.16 Wave Diffraction pattern from SSE Swell 33 Page 2. 1 Coastal Morphology 42 2.2 Seismic Traverses 51 2.3 Photographs - example of Seismic Record 52 2.4 Basement Contour Map 54

2.5 Sediment Isopach Map 55 3.1 Grab Sampler (inc. small photo) 65 3.2 Size Distribution and Sieving (after van der Plas, 1962) 69 3.3 Folk Helix 89 3.5 Mean Size Distribution, including Carbonates 97

3.6 Mean Size Distribution, excluding Carbonates 99 3.7 Sorting Distribution including Carbonates 100 3.8 Sorting Distribution excluding Carbonates 102 3.9 Skewness Distribution including Carbonates 103

3.10 Skewness Distribution excluding Carbonates 104 3.11 Kurtosis Distribution including Carbonates 105

3.12 Kurtosis Distribution excluding Carbonates 106 Page

3.13 Sand/Mud Ratio Distribution 108

3.14 Sediment Type - Triangular Diagram 110

3. 15 Sediment type distribution 113

3. 16 Mean Size V’s Sorting, including Carbonates 121

3. 17 Mean Size VTs Sorting, excluding Carbonates 123

3.18 Percent Carbonate V’s Sorting 125

3. 19 Mean Size V’s Skewness, excluding Carbonates 126

3.20 Percent Carbonate V’s Skewness 129

4. 1 Coarse Fraction Quartz Distribution 139

4.2 Fine Fraction Quartz Distribution 140

4.3 Coarse Fraction Rock Fragments Distribution 143

4. 4 Fine Fraction Rock Fragments Distribution 144

4.5 Coarse Fraction Feldspar Distribution 145

4.6 Fine Fraction Feldspar Distribution 146

4. 7 Arenite Classification Schemes 151

4.8 Folk Classification and Plot of Petrographic Provinces in Jervis Bay 153 Page

4. 9 Distribution of Petrographic Provinces 154

5.1 Heavy Mineral Separationl64

5.2 Zircon Distribution 178

5.3 Tourmaline Distribution 179

5.4 Epidote Distribution 181

5.5 Leucoxene Distribution 182

5.6 Heavy Mineral Provinces 185

5.7 Zircon/Tourmaline Ratio Distribution 194

5.8 Zircon/Tourmaline Vfs Depth 196

5.9 Zircon/Tourmaline V’s Distance from Shore 198

6.1 Percent Carbonate greater than 63 micron Distribution206

6.2 Percent Carbonate less than 63 micron Distribution 210

6.3 Percent Mud Carbonate Vfs Percent Mud 207

6.4 Percent Sand Carbonate V's Percent Mud Carbonate 208

6.5 Mean Size of Carbonates 211

6, 6 Sorting of Carbonates 212

6.7 Relation between Mean Size of the Sediments and of the Carbonate Fraction 223 Page

6. 8 Mean Carbonate Size V ’ s Percent Carbonate 224

6.9 Sediment Sorting V’s Percent Carbonate 225

6. 10 Percent Carbonate V’s Difference in Grain Size Sediment including and excluding Carbonate 227

6.11 Sediment Skewness V’s Percent Carbonate 229

7.1 Distribution of Sub-order Textulariina 237

7.2 Distribution of Sub-ord^r Miliolina 240(a)

7.3 Distribution of Sub-order Rotaliina 241

7.4 Distribution of Fauna Group A’ 246

7.5 Distribution of Fauna Group A” 247 7.6 Distribution of Fauna Group B 249

7.7 Distribution of Fauna Group C 251

9.1 Dendrogram of Cluster Analysis 281

9.2 Group 178 (Central) 283

9.3 Group 175 (Marginal) 285 | 9.4 Group 176 289 Page

9.5 Group 170 291

9.6 Group 165 293

9.7 Group 169 295 INTRODUCTION

CHAPTER 1 2

INTRODUCTION

1.1 General

1.11 Previous work in the area

1.2 Regional Physiography

1.3 Regional Geology

1.4 Bathymetry

1.5 Hydrological Features

1.6 Meteorological Data

1.61 Wind

1.62 State of the Sea

1.63 Ocean Swell

1.64 Tides 3

1.1 GENERAL

Jervis Bay is situated some 120 miles south of

Sydney, New South Wales. It is a large, almost land-locked marine basin about 32 square sea miles in area (refer Figure

1.1). Figure 1.2 shows local geographical names referred to throughout the text of this thesis*.

This study is aimed at looking at some of the environmental factors operative in the bay and their influence upon one another. The major factors examined are:-

i Coastal geomorphic units and geological

development of the area over the past 20,000 years ii Sediment types and distribution iii Foraminiferal assemblages iv Biogenic carbonates v Heavy minerals

* Some names appear on the R.A.N. chart, others on the Lands

Department maps, but do not necessarily correspond, e.g.

Lambs or Plantation Point. Other locality names used in

the text are unofficial, e.g. Sailor’s Beach and Vincentia

Beach. 4

FIGURE 1.1

NEW SOUTH WALES

SYDNEY \

Canberra ■ JERVIS BAY 5

FIGURE 1.2

Call a lew Hare Bay Callalo£j.v'if*& Callala Pt. Currarong

Beecroft Peninsula

Vincentia \\ Bay Plontalion Pt. V i n c e n t i

Tasman Sea

N; s_w _ ACT. Je

Patch JERVIS BAV

Hare> h h Hare 6

vi Meteorology, hydrology and other minor

environmental agents

This was achieved by a programme of sampling and measuring carried out during three major and numerous short

trips over the past two years. Systematically arranged

sampling/measurement stations are shown in Figure 1.3.

This material has been analysed by methods des­ cribed in the appropriate sections and results collated both

"subjectively" and by computer analysis.

To integrate all aspects of such a study is

difficult and to attempt to interrelate all environmental factors to each other as a cohesive unit is almost impossible due to the diversity and complexity of these factors.

1.11 Previous work in the area

Apart from minor geographical and geological notes about Jervis Bay no comprehensive work, either geological or marine, had been published until 1952.

Perry and Dickins (1952) completed a brief report FIGURE 1.3

SAMPLE LOCALITY MAP

•150 V.';.

95a

•74

61a X/-62

y-5o

25a X

a - BEACH SAMPLE

b - BEACH RIDGE SAMPLE

C - CREEK SAMPLE MISCELLANEOUS SAMPLE

JERVIS BAY 300b N.SW. - ACT 8

on the geology of the Commonwealth Territory, Jervis Bay.

This was concerned mainly with geology and Quaternary deposits, mainly on the ocean side of Bherewerre Peninsula.

In 1966 Rose compiled the Ulladulla geological map (1:250.000) showing geology* structure and areas of Quaternary deposits - the notes to accompany this map are as yet unpublished.

In 1967 Walker completed a thesis "The Coastal Geomorphology of the Jervis Bay Area" in which he discussed the Plio-

Pleistocene and Recent development of Jervis Bay. His wrok is confined to a study of geomorphology and he only considers marine sedimentation in a limited fashion. It is noted here that the author of this thesis has only been aware of Walker’s work during the latter stages of compiling this study.

With the recent interest in Jervis Bay as a centre for a Nuclear Power-house and a steel mill there have been a number of studies in the area. The New South Wales Geologic

Survey is assessing the potential of the sands for glass manu­ facture, Dr.A.D. Albani is at present studying sediment thicknesses in the bay and the Bureau of Mineral Resources is studying the engineering and economic geology of the area. All these studies have been commenced since the author’s work in the area was begun. 9

1.2 REGIONAL PHYSIOGRAPHY

Jervis Bay is a large almost land-locked marine

basin with a surface area of approximately 32 square miles situated on a narrow coastal plain which reaches a maximum

height of 800 feet before rising to 1500 feet on the

Sassafras Tableland eight miles inland. The bay is bounded

to the north by a low range of hills with an average height of 125 feet. This range separates Jervis Bay from the

Shoalhavei River flood plain. The bay is cut off from the ocean by two peninsulas, Bherewerre Peninsula and Beecroft Peninsula, both with an average height of 200 feet. Beecroft

Peninsula is connected to the mainland at its north end by a series of sand ridges which reach a maximum height of 45 feet.

The bay entrance from Bowen Island to Point Perpendicular is 2.3 miles wide and another less than \ mile wide between Bowen Island and the mainland.

There are no large rivers draining into Jervis Bay. The largest is a 12 mile long creek, Currambeen Creek which enters the bay at Huskisson. The total catchment for

the bay is just under 100 square miles. to

A more detailed description of the swamps, beaches and sand ridges is included in Section 1.3 of this Chapter

and in Chapter 2.

1.3 REGIONAL GEOLOGY

Jervis Bay is situated in the southern margin of the Sydney Basin and the majority of outcrop in the area is of Permian age. The rock units outcropping around the bay are the Conjola Formation and the Wandrawandian Siltstone

(Rose, 1966) as well as the Nowra Sandstone and Berry Shale (Brown et. al. , 1968) cover most of the catchment area.

(Refer Figure 1.4). Apart from the Permian rocks the only formations are the late Tertiary and/or Quaternary sands (beach, beach ridge and ae^lian) and marsh deposits which surround much of the bay. Minor outcrops of Tertiary clays and some basic dykes of unknown age occur within the catch­ ment area and along the shoreline.

Jervis Bay is situated on a structural depression,

the Jervis Bay Syncline. This syncline is flanked on the

east and west by anticlines and the dips in the area are of 11

FIGURE 1.4

LEGEND

[*H VOLCANICS ?

□ BERRY SHALE

NOWRA SANDSTONE

WANDRAWANDIAN SILTSTONE

HZ] CONJOLA FORMATION GEOLOGY NO SURFICIAL GEOLOGY

SHOWN

CATCHMENT BOUNDARY

A ANTICLINE

-V-' SYNCLINE

FAULT

DIP

SCALE (MILES)

STUCTURE 12

the order of 5° to 10°. The age of this tectonic activity is unknown,[R. Twist for Smart Oil Exploration Company Ltd. unpublished company report), refer Figure 1.4. It is unlikely that the syncline provides the basin in which the bay is now situated, however, it is probable that it provided structural control for the old Currambeen Creek drainage pattern which eroded the depression now occupied by the bay.

The Permian units outcropping the shores of the bay consist of sandstones, silty sandstones, pebbly siltstones, conglomerates and shales. From the five slides examined of these rocks (excluding shales) they all contain up to 85% quartz with minor amounts of feldspars,rock fragments and micas. These rocks outcrop along 55% of the bay coastline (refer Figure 1.5) and form wave-cut platforms which are up to 100 yards wide at Callala Point, but relatively narrow on the eastern shoreline. In all areas where rock outcrops at sea level there is evidence of active erosion thereof (refer to Section 2.2). At several localities these rock platforms extend underwater to form shallow rock reefs.

These occur notably off Longnose Point, Plantation Point, Green Point, Callala Point and Huskisson. This latter reef 13

extends across the mouth of Currambeen Creek and prevents the

greater part of the sediment transported by Currambeen

Creek from reaching the bay.

Deposits of sand occur round the northern end of

the bay (refer Figure 1.5) as sub-parallel sand ridges behind present beaches. They are up to 25 feet high in places and extend back from the shore for half a mile at Callala Beach. They are well stabilized by vegetation with reasonable soil development in some regions. The more easterly sand ridges are higher, up to 30 feet, particularly behind the Hare Bay beaches. The sand ridges are composed almost entirely of well sorted fine quartz sand with less than 1% rock fragments and feldspar and less than 2% carbonate material. In some localities around the bay these ridges are being eroded while in others they are stable or undergoing accretion, (refer Section 2.4 and Chapter 3).

Both the Permian rocks and Pleistocene deposits are thought to provide the source material for the sediment in the bay, (refer Chapters 3.4 and 5).

The Tertiary deposits of Bherewerre Peninsula 14 FIGURE 1.5

JERVIS BAY COASTAL MORPHOLOG MAP

IFGENO

ICAlf ' I MKII 15

(Rose 1966) are not important in the study of sedimentation in Jervis Bay. However, the three dykes (Piax 1968) of unknown age intruding the Permian rocks of the rock platforms may contribute very minor amounts of material to the sediment.

Similarly the small igneous bodies in the Currambeen Creek drainage area (Rose, 1966; Piax 1968) may also contribute minor amounts to the sediment. Their contribution includes plagioclase, hornblende, rutile, zircon and sphene.

1.4 BATHYMETRY

The bathymetry is largely based on R.A.N. Chart

Aus. 80 and on depths taken while sampling and on continuous seismic reflection profiling, (refer Chapter 2).

Figure 1.6 shows the bathymetry within the bay and for a short distance off-shore. Although the off-shore bathymetry is net shown, it is briefly discussed here.

Figure 1.6 shows the bay shelves gently and uni­ formly towards the centre of the entrance where it reaches a maximum depth of 21 fathoms. Locally the bottom shelves more steeply, particularly in the vicinity of Longnose Point 1G

FIGURE 1.6

JERVIS BAY BATHYMETRY

FROM R.A.N. CHART AUS. 80

CONTOURED IN FATHOMS 17

and Point Perpendicular, and along the eastern shore-line between Montagu Road and Longnose Point. A basement high in the entrance of the bay causes local shallowing. This high is 8.5 fathoms deep and sediment has been sampled from it, however the "seismic reflection survey", (refer Section

2.6) shows it to be outcrop . Hence it is concluded that any sediment present is very thin. Other shallow areas of rock outcrop form shallow reefs which are exposed at low tide. These occur off Green, Callala, Plantation, Longnose and Perpendicular Points as well as off Huskisson. These rock reefs are, for the most part, a continuation of the wave-cut platform, (refer Section 2.2).

The continental shelf off Jervis Bay is 10-11 miles wide. The shelf slopes to 50 fathoms within 2 sea miles of the coastline. Beyond this point the shelf drops only 30 fathoms in 8 miles to 80 fathoms. 80 fathoms is the point of the effective break between continental shelf and slope in this region. Phipps (1963) regards this break as an old shore-line and the plain (i.e. between 50 and 80 fathoms) he regards as an old erosion surface formed during a lower stand of sea-level, (refer Section 2.1). Phipps, in the same paper, also notes a sub-marine canyon on the \6

continental slope 12 miles from Point Perpendicular on

a bearing of 130°. This is regarded by Phipps (pers. comm.) to be further evidence of the same low stand in sea-level since the canyon is no longer active as its walls are sediment

covered.

1.5 HYDROLOGICAL FEATURES

Very little hydrological data is available from

Jervis Bay either from C.S.I.R.O. Division of Fisheries & Oceonography or the R.A.N. Hydrographic Office. During February 1968 the author conducted a limited survey in the southern sector of the bay. This included a definition of water layers and salinity and temperature profiling. In all, 36 stations were included over a period of 4 days. The instru­ ments used were a shallow bathythermograph (no. 190GI) for determination of layers and a C.S.I.R.O. Portable temperature- chlorinity bridge (developed by B. HaTmon for work in estuaries and shallow oceanic work, unpublished C.S.I.R.O. note). No work on dissolved oxygen, nitrogen, carbondioxide, etc. is available, nor was measurement of these parameters undertaken by the author. 19

FIGURE 1.7 TEMPERATURE °C

TEMPERATURE V« CHLORINITY 20

The bathythermograph recordings revealed two general layers, the main upper layer varying between 25 and 50 feet thick and a thermocline between 25 and 50 feet. (See Figure 1,8). There is some indication of a minor surface layer, however this was not recorded at all stations - when present it varied between 6 to 12 feet in thickness.

Also between the top layer (25 - 50 feet) and the bottom layer there is, at some stations, a small intermediate layer up to 14 feet thick but the average thickness'of this is only 8 feet.

Due to the isolated nature of this study no comment on the persistance of these layers or the extent of them to the north can be made.

Chlorinity values all fall between 19.45°/oo and 19.75°/oo and do not appear to be related to temperature or depth. The average surface chlorinity being 19.69°/oo and at 15 meters it is 19.64°/oo. These being similar values to those recorded by Rochford (1951) in other central east coast estuaries and bays. There is no marked geographic variation within the area studied and nor does chlorinity appear to be related to temperature, (refer Figure 1.7), 21

^ a a Z~ '5 ^ 'mj^n 9 S & 9 S g but it is to some extent to depth regardless of temperature.

Temperature studies are also only available for February 1968 and only in the southern portion of the bay. The average surface temperature recorded is 23.10°C and for the bottom temperatures range from 24.84°C to 16.25°C. The highest temperature on the bottom being recorded at 7 meters at

Station 4 and the lowest in the entrance of the bay.

Discussion on water movements, tides, etc. are treated under Meteorology because the only information about these features that is available is derived from routine observations made at Point Perpendicular Lighthouse and for­ warded, with meteorological data to the Bureau of Meteorology.

1.6 METEOROLOGICAL DATA

The only data available covers the period from

1960 to 1964 with readings taken at 0900 and 1500 hours (E.A.T.) of the following phenomena: i Wind direction ii State of sea iii State of swell iv Direction of swell 23

This data was summarized by the Bureau of

Meteorology as follows:

(i) Direction of swell by state of sea 1960 to 1964

0900 and 1500 hours.

(ii) Direction of swell by state of swell 1960 to 1964

0900 and 1500 hours

(iii) Wind direction by state of sea 1960 to 1964

0900 and 1500 hours.

(See Appendix B)

From this data Figures 1.9 to 1.16 were compiled and used for interpretation.

1.61 Wind

A study of Figures 1.9 and 1.10 shows that the modal wind direction changes from morning to afternoon, The morning mode is from the north-west with secondary modes from the south and north and in the afternoon the primary mod< is from the east-north-east with a secondary mode from the south by south-south-east. The north-westerly morning winds are most frequent during Autumn and Winter, the northerly and southerly morning winds are most frequent in the Summer 24

FIGURE 1.9

N

WIND DIRECTION 9a.m. I960- 64

54 readings CALM ,'A / / V X —‘-—10 Observation*

\ \

\ / -w L E- y

S 25

FIGURE 1.10

WIND DIRECTION

30 reading* CALM

/ '10 Observations and Spring. The east-north-easterly afternoon wind is most frequent during Summer, Spring and Autumn and the southerly

during Autumn, Winter and Spring. This means all areas of the bay are subject to mass water movement due to wind

(Fleming & Revelle, 1955). Prolonged blowing from the one direction can cause surface currents or cause modification in

existing surface currents.

1.62 The State of the Sea

This includes wind generated waves exclusive of the ocean swell. Such waves are wind generated and hence their height and direction are directly related to wind velocity and direction.

Hence from wind direction it is clear that the areas of the bay most subjected to wave activity are the north-western and southern areas, the eastern shoreline only being affected by refracted waves. Wave action causes turbulence, particularly in the shallower zones of the bay and this is thought to cause sorting and associated removal of finer material from these zones as was found by Harris

(1959) and many other workers. From Figures 1.11 and 1.12 N ° of OBSERVATIONS STATE

of

SEA the

SEA STATE

-

9a.m.

1960-64 FIGURE

1.11 27 26

FIGURE 1.12 STATE of the SEA - 3p.m. 1960-64

SEA STATE 29 it can be seen that the modal wave height is between 2 and 4 feet with a spread from 0 to 20 feet. The exact depth at which sediment will be affected by these waves is unknown, but it is thought to be at least to a depth of 20 feet, or as deep as 60 feet has been suggested.

1.63 Ocean Swell

The swell entering Jervis Bay is primarily from the south-east and varies between east-south-east and south-south-east (refer Figures 1.13 and 1.14) and has a long modal wave length with a low amplitude, but varies through average and short to long heavy swells (refer Figure 1.15).

This swell is consistent and has the greatest effect in the entrance and northern part of the western areas but does affect almost the whole bay as shown in the swell diffraction map (refer Figure 1.16) which was constructed from aerial photographs.

1.64 Tides

Little information is available about tides in 30

FIGURE 1.13 T N

SWELL DIRECTION 9a.m. I960- 64

S 31

FIGURE 1 14

SWELL DIRECTION 3 p.m. 1960

10 Observations 32

FIGURE 1.15

STATE of the SWELL - 9a.m. 1960-64

0 no swell 1 low short wave-length 8-

6-

O O s§ s 4- ot Z

2-

0

SWELL STATE 33

FIGURE 1.16

WAVE DIFFRACTION PATTERN FROM A SSE SWELL ..-iji-s*taken from air— photos.

JERVIS BAY N.SW - ACT 34

Jervis Bay as no information is available on tidal current velocities through the entrance of the bay. Some tidal information can be gained from R.A.N. Chart Aus. 80 on which appears the following Table and other information can be inferred from the sediment in the entrance where a concentration of coarse material suggests the presence of a strong tidal current in this area, however the majority of the bay is not thought to be affected by any strong tidal currents, as the ebb and flow is not res­ tricted to a relatively narrow channel except in this area.

Hjulstrom (1955) presents a table relating water velocity to transportable grain-sizes. From this table the tidal currents necessary to remove particles finer than

0.236 (refer Chapter 3) would be between 10 and 20 cm sec’"1,

-0.23d is the mean grain-size of sediment in the tidal scour in the entrance.

During the last months of this study the R.A.N. installed a tide guage at Jervis Bay. The records from this gauge are too short to attain any reliable tidal information from them. 0 p 1 3- 1 P M H- P 3 O 0 H H* a p H

4^ (f) 2 H- • 13 0 3 ^0 3 p H\ - H* 3 X O 3 0 3 vQ H- 3 if) vO P X > 3J 3- H- < 3- H- VO 0 O 4^ 2 2 3" 3 P 3 • 0 0 P cr O P P s: VO 0 P -• 1 3 p 0 < 3 0 3- 0 a 0 3 a O X p 0 3- P H- 3 3 o C/) 2 vQ 3 3- • 1 0 3^ vO 3 JU rf 0 o «• H* 3 0 3i p 3 r+ vQ 0 3 U) r 0 3 o 3 3 a M 2 £ s: H- * 0 0 p 3 Ul P P rf iQ H* 1 3 0 if) if) 3

In 1 2 s: i 3 1 • H- 0 p H- 0 0 00 vO P 3- VO p H* - 3J 3 0 3* 3 'O 3 0 the ts 3J 3

P C/) 3- O r s £ r o • O 0 P 0 M (/) to < P 3- 3 (/) 11 - 0 3 0 r+ 3 3 3 H- H- 0 3 0 iQ 0 if) On several occasions conversations between the author and ships’ officers suggested that there are no tidal currents which affect the passage of ship, however the currents which affect shipping are of a different order of magnitude to those which affect sediment movement. COASTAL MORPHOLOGY AND SEDIMENTATIONAL HISTORY

CHAPTER 2 3 6

COASTAL MORPHOLOGY AND SEDIMENTATIONAL HISTORY

2.1 Introduction

2.2 Wave cut platform

2.3 Beaches

2.4 Beach ridges

2.5 Swamps

2.6 Marine sedimentation

2.61 General

2.62 Method of study

2.63 Results

2.64 Discussion

2.7 Conclusions 39

2.1 INTRODUCTION

Sea levels over the past 20,000 years are important in a study of coastal morphology. Sea levels

during this period are, however, not well established either spatially or chronologically. During the last glacial, Wiirm lib, approximately 20-12,000 B.P. the sea

level was about 70-80 fathoms lower than at present.

This low stand of the sea is well established, however events since then are not so clear.

Data from Australia has frequently been used to postulate sea-levels during the past 6,000 years higher than that of the present (Fairbridge, 1961; Gill, 1957 and 1964; Sprigg, 1959; Butler, 1964; Ward; 1965; Logan, 1969). The majority of this evidence is geomorphic including raised beaches, peat bogs, pumice beds, rock platforms, infilled lagoons, river terraces and shell beds. The sea-levels postulated by the above works are of the order of 0 to 15 feet above thepresent mean sea-level.

Criticism of the above hypothesis based on evidence from North America and Europe (Jelgersma, 1961; Scholl and

Stuiver, 1967) and more recently from the Central Pacific 4G

and Australia (Shepard et.al., 1967; Wright, 1967; Thom et.al., 1969 and Langford-Smith and Thom, 1969) is so strong that the earlier Australian data must be viewed critically.

Wright (1967) working on the Shoalhaven Barrier system several miles north of Jervis Bay found no evidence for any high in post-glacial sea-levels and similarly no evidence has been found by the author in Jervis Bay.

A discussion of the various geomorphic entities of the coast line are included below (Sections 2.2 to 2.5).

The features discussed herein are based on general ob­ servations made during the field work in the area and from aerial photograph interpretation. The textural data used is discussed in detail in Chapter 3 of this thesis. The geomorphic entities shown include wave-cut platforms, beaches, beach ridges and wet and dry swamp. Their areal relationships are shown in Figure 2.1. This figure is drawn from aerial photographs and also shows some sub-marine features (sand bars and rock reef) which were visible on the photographs.

The wave-cut platforms are backed by cliffs varying in height from 10 feet to 250 feet. These in turn 41

are backed by regions of soil cover and scattered rock outcrop. The beaches for the most part are backed by sand ridges, up to 25 feet high, a series of which may extend landwards for up to § mile as at Callala Beach.

These sand ridges are bounded on the landward side by small or large areas of swamp or marshland. The situation between Warrain Beach and Hare Bay is a special case and is discussed in detail in Section 2.4 of this Chapter.

2.2 WAVE CUT ROCK PLATFORM

Rock outcrops at sea level around 55 percent of the coast line within Jervis Bay. Rock platforms are developed over much of this coast line just above high tide level. They vary in form depending on local structure, lithology and intensity of wave attack (Bird, 1968). However strong wave attack destroys high tide shore platforms and hence they are only well developed in areas protected from the southerly storm waves and from the south-easterly ocean swell.

High tide shore platforms are thought to develop along the level of permanent saturation of the rock. The rock below this level is not eroded or weathered while the FIGURE 2.1

JERVIS BAY COASTAL MORPHOLO MAP

IEGEND 43

rock above, which is subjected to wetting and drying from

sea spray and also subjected to salt crystallization. These

processes cause the rock to weather readily and the detritus

is removed during storms or spring tides from the high tide

shore platform (Bird & Dent, 1966). This process is essentially confined to the areas of coastal outcrop of

shale and siltstone at sea level.

Between Plartfation Point and Jervis Bay where rocks dip at angles of 10 degrees into the bay the cliffs tend to be dip slopes with no significant platform developed.

The cliffs on the east side of the bay have a narrow platform at their base. They are of the order of

100 feet high rising to 250 feet at Point Perpendicular.

Due to the blocky nature of the sandstone along this shore any platforms developed are piled with fallen sandstone blocks.

Along the west facing shore within the bay where the platforms are exposed they are seen to be dip slope, high tide platforms.

The south faceing cliffs of the eastern shore are however footed by flat, narrow high tide platforms (refer to Figure 2.1

Lithological control of rocky coasts may be divided into two:- i. Where coastal outcrop is Wandrawandian Siltstone

the cliffs are low and the platform wide. This

______is due to the relatively higher weatherability 44

and erodability of these silty and shaly rocks, ii. Where the coastal outcrop is Conjola Formation

the majority of cliffs are relatively higher and platforms, if present, narrow. This is a direct

result of the resistant nature of the coarse

sandstone and fine granule conglomerate. (Walker, 1967). An outcrop map of Permian sediments

appears in Figure 1.4.

The energy relationship to the development of wave platform is difficult to assess. It is noted that from Point Perpendicular to Longnose Pointy the highest energy coast in the bay, the platforms are at, or slightly above, high tide level and narrow. They are also covered by fallen blocks of sandstone. This indicates a fast erosion of the cliffs to supply material to this scree deposit, however it would also appear that the platform, although covered is retreating rapidly also, it being comparatively narrow. |

Walker (1967) states that the shore platforms and cliffs have been mainly formed since the most recent marine transgression, however he also produces evidence which suggest that cliffing, at a level similar to that of the present erosion, was in progress during a previous high-stand of sea-level.

2.3 BEACHES

Beaches make up about 45 percent of the total coast line in Jervis Bay. The beaches around the whole bay are similar with respect to both morphology and sedimentology.

Morphologically the beaches all have a low profile above high water and relatively steeper below water level.

All beaches are backed by beach ridges, these however vary in type in different areas of the bay.

All beaches appear to be in a state of equilibrium with the prevailing swell and waves except that certain changes to this were noted by the author after heavy seas in November,

1968. These changes included erosion of many of the beaches exposed to south easterly seas and on Lamb’s and Callala

Beaches small cliffs were developed near the back of the beaches. These cliffs were of the order of 18 inches to 2 feel and their formation required the removal of large volumes of sand. Other features developed during this same period were accumulations of heavy mineral concentrates near the backs of the beaches. These had not been noted on any other field 46

trips to the area over a period of 18 months. Small cuspate

deposits of fine pebbles and granules of quartz also were

formed at the same time. All evidence of these deposits was removed after one month of "normal" events, and the

beaches restored to an equilibrium state.

The beaches are composed of medium sand to vary

fine sands which are well sorted (refer Chapter 3). The

skewness varies from fine to symmetrical, the majority showing

a very slight negative (or coarse skew) within the symmetrical

skewness class. All beaches contain less than 12 percent

carbonate material and more than 90 percent of the terrigenous material is quartz.

The beach sand is very closely packed, in fact it

is packed hard enough to support a motor vehicle. This packing is a direct consequence of the fine grain size of

the beach material (Bird, 1968).

Significant long shore drift of sand on the beaches in Jervis Bay has not been noted. Minor signs of

drifting around beaches in Hare Bay has been noted but this

does not change the state of equilibrium attained by the beaches. 47

2.4 BEACH RIDGES

Beach ridges, sand ridges or dunes are developed behind all beaches in Jervis Bay which are not backed by

"bedrock” cliffs. The beach ridges are developed parallel or sub-parallel to the present beach fronts. The area covered by beach ridges varies directly with the size of the embayment across which they are formed. All dunes are backed by infilled or partially infilled lagoons or esturine swamp.

The ridges are up to 25 feet high and as low as

15 feet in some of the smaller embayments and in protected regions (e.g. Hyams Beach and Montague Road beach respectively]

The higher ridges are formed in areas of higher energy, i.e. those areas subject to the south-easterly swell and southerly storms, which covers the beaches between

Huskisson and west Hare Bay. The frontal beach ridges in these areas are also subject to erosion during periods of storm. Sand ridges in the remainder of the bay are presently accreting.

The sand ridges are thought to be Recent features having formed since the last marine transgression. The ridges have developed across embayments around the bay and prograded seawards. The sand for the ridges being moved

progressively towards the margins of the basin by the trans­ gressive sea.

Beach ridges pre-dating the last transgression have been recorded (Walker, 1967) west of Huskisson along Currambeen Creek at a level slightly higher than that of the presently forming ridges. This evidence correlates with the

evidence quoted by Walker (1967) covering shore platforms.

The Recent sand ridges may be correlated with the outer barrier system discussed by Langford-Smith and Thom (1969). Similarly the older Pleistocene beach ridge remnants may be correlated with the inner barrier system also discussed by Langford-Smith and Thom (1969), (Walker 1967).

Both Pleistocene and Recent beach ridges support a vegetation cover. The older dunes support a richer and more varied type of growth than the Recent ridges which are covered by marram grass and low scrub. Those ridges 49

presently accreting are being rapidly stabilised by

advancing marram grass.

2.5 SWAMPS

These are the areas of embayments cut off by the development of beach ridges to form lagoons which have since become filled with organic peaty material, fluvial sediment

and aeolain sand from the beach ridges. Figure 2.1 shows these swamps to be of two types High level or dry and Low level or wet

The wet swamps represent partially infilled lagoons cut off by Recent beach ridge development. They occur between 0 and 5 feet above sea level and are wet all year. The wet swamp also supports a wide variety of marsh grasses, and where they border on the tidal reaches of Currambeen and Caramma Creeks mangroves flourish.

The dry high leval swamps are older and represent

infilled lagoons cut off by Pleistocene beach ridges (Walker

1967). They are similar in nature to the low level swamp 50

except they are 5 to 8 feet higher and dry for most of the year. They support a low scrub type vegetation with occasional trees.

2.6 MARINE SEDIMENTATION

2.61 General

Cores of the sediment in Jervis Bay were, at the time of study, unattainable due to the nature of the sedi­ ment and the lack of any coring device able to core sandy material. In the absence of cores traverses of continuous seismic reflection profiles were run. The ten traverses run are shown on Figure 2.2.

2.62 Method of Study

The equipment used was a "sparker" seismic profile constructed and operated by the marine section of the Bureau of Mineral Resources, Canberra. It consists essentially of a capicator bank, powered by a portable generator, which provides power pulses to a sparking 5i

FIGURE 2.2

SEISMIC TRAVERSES MAY 1968

JERVIS BAY N.S.W. - ACT sea miles FIGURE 2.3 52i

unit streamed behind the ship. The power output and frequency of impulses is varied depending on conditions of operation. The ’'sparking" unit which consists of three electrodes in contact with the sea, provides an energy source. The reflected energy, as well as direct, is received by a series of geophones incorporated in a polythene tube also streamed behind the ship. The reflected impulses were then recorded on a Gifft Depth

Recorder - Model G.D.R.T. The record is a visual display with millisecond time lines (refer Figure 2.3).

Navigation and location of traverses was attained by using a theodolite to fix points along a traverse made by the ship steering on a compass bearing.

Ship and shore stations were in continuous radio communication.

2.63 Results

The results of the survey are compiled and shown in Figures 2.4 and 2.5. From the data records corrections for time were made at intervals along the traverses and isopaches of unconsolidated sediment and basement contours

(i.e, The Permian is considered here as basement) plotted. 53

FIGURE 2.4

JERVIS BAY- BASEMENT CONTOUR MAP-

CONTOURS IN FEET 54

The time corrections were made on the basis of the following velocities:

sea water at 15°C - 4750 feet see 1 (Clark, 1966)

unconsolidated sediment - 4950 feet see (Clark, 1966)

Some evidence of an intermediate velocity layer between the unconsolidated sediments and the Permian bedrock

(velocity 10,200 feet see""1 to 14,000feet see 1) has been noted. This has a velocity between 6,000 feet see”1 and

9,000 feet see”1. The distribution of this intermediate velocity layer is not evident from data available to the author. A.D. Albani (pers. Comm.), however on more recent and more precise data, in the entrance sector of the bay as well as at other scattered localities, does show the distribution of the intermediate layer.

From Figures 2.4 and 2.5 it is clear that Jervis

Bay is an old drainage basin of Currambeen Creek and

tributaries. The sediment distribution is thickest in

Pleistocene extensions of the Currambeen Creek drainage system and thinner on the ridges and in the heads of valleys. FIGURE 2.5

JERVIS BAY- SEDIMENT ISOPACH MAP-

SCALE : 1 mile

ISOPACHS IN FEET 56

2.64 Discussion

From the seismic data it is clear that J ervis

Bay was, during a past low-stand of sea-level, subjected to subaerial erosion by small streams and creeks. This eroded basement has since been covered by sands of varying thickness, which depends on the basement topography and recent environ­ mental influences on sedimentation.

The sediment in the bay redistributed relic sediment deposited by an extended Currambeen Creek drainage system during several Plio-Pleistocene retreats of the sea from the bay. The sediment was reworked and redistributed during the marine transgressions of the Plio-Pleistocene interglacials. Hence some sediment in the bay has undergone several cycles of marine reworking and probably several cycles before that, at least one fluvial cycle to deposit it in the bay and one to deposit the Permian sequence from which it was derived (refer Chapter 3 for a discussion of sediment maturity). Very little sediment is thought to have entered the bay from the continental shelf during periods of transgression. 57

Also an intermediate velocity (6 - 9,000 feet see" ) layer has been found at several locations in the bay. Similar layers of intermediate velocity have been found and traced by

A.D. Albani (pers. comm.) in the entrance and Darling Road

region of the bay. Albani found this layer to be situated

in areas protected from erosion by a regressive or trans­

gressive sea. The higher velocity is probably due to a

degree of cementation effected during sub-aerial exposure

and erosion. Other workers in the area have attributed this intermediate velocity layer to a weathering zone of the Permian basement rocks. However, in the light of the work

of Albani and the author it is more probable that this layer is a relict deposit, partially cemented, than a weathered zone.

This intermediate layer was noted in the early records made available to the author and is included as part of the unconsolidated sediment, the isopachs of which are shown in Figure 2.5.

2.7 CONCLUSIONS

The beaches, cliffs and shore platforms are, with 5d

minor exceptions, Recent features reflecting an equilibrium condition. The beach ridges of Recent development and

Pleistocene age are present and reflect an active accretion at present and a similar transgression at about

the same level during the Pleistocene. The swamps similarly reflect the present processes and a similar

earlier process.

The bay bedrock is formed of Permian sediments which have been eroded by streams to produce a typical fluvial topography. The basement has been covered in part by recent sediments and in part by sediments relict during previous low-stands in sea-level. TEXTURAL ANALYSIS

CHAPTER 3 60

TEXTURAL ANALYSIS

3.1 Introduction

3.2 Field Procedures

3. 3 Theoretical considerations

3.31 Grain Size Measurement

(a) Sedimentation tube

(b) Direct grain measurement

(c) Sieve analysis

(d) Other methods 3.32 Descriptive Parameters

(a) Historical

(b) Moment Measures

(c) Median Diameter (d) Mean size

(e) Sorting

(f) Skewness

(9) Kurtosis

(h) Calculation of Grain-size Statistics

3.4 Summary of Laboratory procedure Textural Analysis

3.5 Results

3.51 Distribution of Sediment Textural Parameters 6 i

(a) Mean size

(b) Sorting

(c) Skewness

(d) Kurtosis

(e) Sand/Mud Ratio

3.52 Distribution of Sediment Types

(a) Gravel (b) Sand (c) Calcareous Sand

(d) Sandy Calcarenite

(e) Sandy Muddy Calcarenite (f) Muddy Calcareous sand Discussion

3. 61 Mean size

3.62 Sorting

3.63 Skewness

3. 64 Kurtosis

3.65 Sand/mud Ratio

3.7 Environmental conclusions 6 4*

3.1 INTRODUCTION

Source, transport and sink are primary factors in controlling the production of a sedi­ mentary deposit. Each of these stages in a sedi­ ment's history are not clearly separable and hence processes in one overlap into another. In the source area such factors as climate, relief, erodability and type of exposed rock are important as far as a future deposit is concerned. The character of the trans­ porting agent controls the shape, size (to some extent), mineralogy and attitude of the deposit. The typical transport mechanisms considered are water (waves and currents), wind, gravity and ice.

In the basin of deposition factors in­ fluencing the deposition include topography, hydraulic processes, organisms (at least in marine environments), and the tectonic state of the region.

Through mechanical analysis an attempt is made to delineate provenance, method of trans­ port and basin of deposition characteristics. The direct aims of mechanical analysis in this study are to: 63

i. Texturally describe the sediments in

Jervis Bay. ii. Examine the relationship between texture

and environment. iii . Attempt to use the analysis in giving

some indication as to the sedimentary history

of the Bay.

3.2 FIELD PROCEDURES

The Bay was divided up by a half mile gird system, this figure being arbitrary in the absence of any data about the sedimentation pattern, source materials for sediments and hydrology in the Bay. Thirty six samples were collected at the intersection points of the gird.

However,after examination of some of these samples in the laboratory, it was considered unnecessary to sample as closely as this; consequently on later field trips, samples were collected every mile on east-west traverses spaced half a mile apart in a north south direction.

The sample positions were fixed by using a tripod-mounted surveying compass on the western end of each traverse and a theodolite normal to the centre of 64 a traverse where practicable. A three way communication network was maintained by the use of radio, in order to direct the sampling boat on to predetermined stations.

This system was quite successful except at times of poor visibility.

|

The samples were taken using a small grab- sampler, constructed by the author. It has a capacity of about 6 lbs. of wet sediment. This was lowered to the bottom by a hand-operated winch. The grab sampler proved very reliable and seldom returned to the surface empty.

A plan and several photographs of the grab are included in figure 3.1.

3.3 THEORETICAL CONSIDERATIONS

3.31 Grain Size Measurement

Only nine samples contain more than 10 per cent mud (i.e. grain-size less than 64 microns) and hence it was considered unnecessary to carry out size analysis of mud sized fractions.

There are many methods of measurement of the fraction greater than 64 microns in grain-size. Before h p/■e/~ deciding which method to use in the analysis of the

sediment from Jervis Bay,the author gave consideration

to the various methods available in the literature.

Most were discarded because the equipment necessary

was not available or because the method was uneconomically

time-consuming.

(a) Sedimentation tube: (Zeigler et al., 1960;

Plankeel, 1962 and Schlee, 1966).

This method is certainly the most rapid and

also takes into account the "odd" shaped grains by giving

an "hydraulic1’ size for particles. It is also advantageous

in that it allows for density variations in the grains being measured. Most authors (e.g. Folk, 1966) state that

analysis by sedimentation for sand-sized particles does not allow accurate calculation of skewness and kurtosis and

also that the turbulence caused by the settling of the coarse particles distorts the analysis of the finer particles.

Further more, this method,although rapid, requires expensive equipment which was not available. This applies to the

several variations on the sedimentation tube method.

(Bascomb, 1968; Prokopovich, 1958). 67

(b) Direct Grain Measurement: (Hulbe, 1955; Friedman, 1961; Hornsten, I960 and Sahu, 1968)

Whether in thin section or individual grains are being measured there are two obvious drawbacks in this method. Firstly if a statistically valid answer is to be obtained then many hundreds of grains must be measured. This is too time-consuming and secondly it is difficult to be sure of attaining a representative sample of several hundreds of grains from millions. Other disadvantages of this method are that the sizes measured must be converted to weights to make them comparable with other methods. Also when measuring the grain size if the smallest dimension is measured the curve will have a coarse bias or similarly if the largest diameter is measured the curve will be displaced to the right (van der Plas, 1962), since the surface observed will be larger and smaller respectively than the great circle of a sphere with the same volume as the particle measured.

Hence this method was discounted on the 8 basis of its slow and tedious nature,and the theoretical difficulty of converting area measured into weight.

(c) Sieve Analysis:

This is the method most commonly employed by sedimentologists because it is relatively inexpensive and rapid. A complete analysis on half phi intervals from -2phi to 4phi requires 3o- 45 minutes. More importantly, it is generally accepted as the most accurate method of size analysis and the most sensitive to slight changes in the nature of the sediment caused by environment as shown by Mason and Folk in 1958 for beaches versus dunes and Friedman in 1961 for rivers versus beaches versus dunes.

However, the "size" of grains measured by each screen may not have the same diameter in each direction as a sphere which will pass through that mesh, and since sand grains are not spherical the number of grains passing through any one sieve will be greater than the number of grains passing through that mesh, (van der Plas, 1962), refer figure 3.2.

This means the mean size of the sample will 69

FIGURE 3.2

*

S/ei/C - d/Sy>/*7/Z?/<*

Vo/u**te. /y^e^tsSsfGy tzY&Yr/b vfrost 70 be significantly different from that of a sample consisting of spheres with a volume equal to the volume of the grains in the actual sample. Hence not only a volume distribution (i.e. weight, assuming constancy of specific gravity) is measured by sieving but a shape factor is of some importance in determining what will and what will not pass through any given sieve.

Sieving techniques do not take grain density into account. This is important where large volumes of heavy minerals are present in the sample but for almost homogeneous materials, as present in

Jervis Bay,the error so caused is small.

Sieve calibration is necessary before the calculation of skewness and kurtosis can be performed accurately (Folk, 1966). Calibration can be effectively carried out by sieving several sands of similar type (e.g. beach sands) from three different localities and studying their size distribution curves. If there is a "kick" in the same position in each curve then the chances are that there is an inaccurate sieve, at the position of the "kick". This was carried out on three different beach sands from Jervis Bay and no "kick" was found, indicating the sieves were accurately calibrated. 7i

Sample size is important in sieve analysis (McManus, 1965). If the sample is too large i.e.

greater than 65 grams then clogging of sieves occurs, particularly in the finer meshes. As a result sample

splits between 20 and 50 grams were chosen as a good

working weight. Errors increased rapidly with weights less than 20 grams, (McManus, 1965). A half phi set of

sieves was used in the analysis. The sieves were manufact­ ured by Endecott (Filters) Ltd. and the set used was a set of U.S. Standard Sieves (A.S.T.M. ) commencing at -3/

or sieve number 5/16”. However not all sieves were

required for each analysis and only those required were used. An Endecott Test Sieve Shaker (Model A) was used to shake the sieves.

(d) Other Methods:

Many other methods of size analysis exist, they include: -

(a) Pipette analysis: described in Folk (1968) suitable for the fraction finer than 64 microns only, and hence not employed in these analyses. 72

(b) Hydrometer analysis: described in Milner

(1962). This method also only applies to the mud fraction and is hence not employed here, as does,

(c) Centrifugal sedimentation analysis: described in Milner (1962) and Trask (1930).

(d) Falling Drop analysis: Mourn (1965).

This method of analysis also only applies to the mud fraction and hence is not employed in this study. It is based on the calculation of the density of a drop contain­ ing suspended mud and hence the particle concentration in the drop.

3.32 Descriptive Parameters I I

(a) Historical: |

Udden (1898) first applied grain size measurement to sedimentary deposits and after some years of development he claimed in 1914 to be able to distinguish depositional environments from the study of grain sizje distributions which he expressed as percentage weight. He also proposed a scale to describe natural grain size grades which was modified in 1922 by Wentworth, whose scale is now generally accepted. Table 3.1 shows Udden and Wentworth’s scales as well as the divisions in millimeters and phi units.

Krumbein in 1934 proposed the use of cumulative curves in preference to using histograms as they represented the individual characteristics of the sediment better. Later, in 1936 he also proposed the "phi” notation for use in simplifying parameter calculations. This he defined as:

i I <6 = -log a where a = grain diameter in millimeters

He based the "phi” scale on the Udden class limits which can be expressed as powers of two, i.e. 4 millimeters 22, 8 is 23, 1 is 2°, § is 2-1 etc. He therefore proposed the use of a logarithmic scale to the base 2 and to avoid negative numbers in the sand i I I and mud range he multiplied the value by -1. 74

TABLE 3.1

Table showing the relationship between phi units, millimeters and Udden and Wentworth grain size Class limits

Phi size Millimeter Wentworth size Udden Krumbein 1936 size Class (1922) (1914)

-12 4096

-10 1024 Boulder

-8 256 Boulder

-6 64 Cobble

-4 16 Pebble

-2 4 Gravel

-1 2 Granule i 0 1 Very coarse sand Very coarse sand

1 0.5 Coarse sand Coarse sand

2 0.25 Medium sand Fine sand i1 3 0.125 Fine sand Very fine sand

4 0.0625 Very fine sand

5 0.031 Silt i 6 0.0156 Silt

7 0.0078 !

8 0.0039 i 9 0.002 Clay

10 0.00098 Clay l 11 0.00049 •

12 0.00024 75

In 1963 McManus criticised the use of phi on the basis that:

There is a mistaken correlation of phi

with millimeters. This results from taking the logarithm of a dimension rather than a pure number. McManus therefore

redefines phi as: - / _ a mm o - logo^ -----aQ mm where a mm = the grain diameter in milli­ meters and

aQ mm = the standard grain diameter defined as 1.00 mm This formula overcomes the "logarithm of a dimension criticism" but does not afLter Krumbein's scale as his also had its , origin at 1.00 mm As a corollary to i. phi-units are often i misused as a dimension. m. The misuse of phi in the expression of| values of standard deviation. Instead I of dd = 0.56 McManus suggests that

O' <6 = 0.5 ^units be used. 76

Krumbein (1964) also discusses the mathe­ matical meaning of phi in the light of McManus's criticism. I

Other workers have proposed size dis­ tribution scales including Doeglas (1946) who proposed an arithmetic scale, Rogers (1963) who is of the opinion that silt may be arithmetic normally distributed and Brezina (1963) who proposes a size distribution based on settling velocities.

. The results obtained from mechanical analysis were during the period from 1898 when Udden began work in this field, to about 1934, presented as histograms. Histograms are of pictorial value only and are of little or no quantative use. Krumbein

(1934) proposed the use of cumulative curves, a practice i which is for the most part still being followed. In

1939, Otto proposed the use of probability paper for plotting mechanical analysis. This allows normal curves to plot as straight lines and is hence more superior than arithmetical plots as interpolation is cut to a minimum. Other workers, Inman (1952), Mason & Fplk

1958), Rogers (1959) and others also advocate the use of this method of plotting. 77

Sediment parameters were first used in the 1920’s to describe sediments in more or less standardized terms. The statistical properties commonly used include:-

(b) Moment Measurers: This method was first proposed by Van Orstrand (1925) and was modified and used by Hatch & Choate (1929) and Wentworth (1929),

Krumbein (1936) adapted the technique for use with phi notation and since then many workers have used this method for statistical analysis: (Griffiths, 1955, 1958, 1961 and Friedman, 1962).

The method of moments is a computational method (not graphical)of obtaining values in which every grain of sediment affects the measure, hence if all grains of the sediment are taken into account it probably gives a more accurate picture than the graphic method in which only a few centile lines are read.

The following table (3.2) and text are an example of the computation of moment measure cal­ culations taken from Krumbein (1936). < H CQ U o B

iputation of the moments of size distribution of beach if) rtf S id from the southern shore of Lake Michigan •H •H O •rl b r •H ^ O -P b r b -P rtf P — 0 e if) P rtf 0 e V) — 1 1

cm CO co cm

-H -H •H *H b b •p b H b 'H b b b C & a e G QN £ h H|(M 1 \ — ON o l i ON' rH 'f ON — ON — + — + l 1 1 1 1 1 1 • 1 • • • 1 1 h i 00 O CM in o — o o o o O |M 1 i n • i h \ rH 00 co CM NO rH CO O n CO no rH NO CO CO o o O + + + + + O |^ 1 i • • • * \ \ rH 00 t rH NO CO CM O CM 00 CO n rH — o + o + + + + O 1 1 • 1 • • H rH rH •P o o o o C0 i m 1 CO CM + rtf + — + — 0 if) • • • • i 1

• •rl V •rl •rl •rl b M b •rl b b -P -P •p b •p -P II p 0 cr 0 0 0 o >> P if) if) 0 e 0 C O 0 0 0 p 0 0 0 c £ ON h h • h 1 •rl b b •rH •rl b b •H •p b b •P H •P •p n rtf p 0 E X 0 rtf 0 rtf E E ON if) U in 0 0 if) 0 P O rtf P P P O 0 rtf >> N 0 rtf 0 O O h

-rl -P

h

-H •rl b rH b b b b b -P -P b b rH 0 > rtf G p rtf P O o in O 0 rtf 0 0 rtf 0 ON if) rtf O > 0 rtf rtf p 0 C 0 O £ l

-H -rl b -H -H b b rH -P -p o p rtf c E 0 0 if) 0 cr o 0 0 0 ON rtf > 0 rtf 0 0 O if) o 0 O P if) > O > > O 0 0 0 O 0 CO • h h H H •rl b b b H b •H -p b b b b T -P b b b rH 1 --

ii p 0 O 0 P O rtf 0 rtf 0 o O £ o rtf 0 P rtf 0 rtf ON O rtf h h h 1 1 h

I 1 1 1 1 j 1 1 1 | 76 79

The first moment about the origin of the d scale (n-^) is given by

n^ = 2 f d/f

Similarly n3 or the second moment about i the d scale origin is

n3 = fd^/f

Again n3 or the third moment about the d scale origin is given by

n3 = fd~Vf , I i.e. from the above table (3.2) n^ = 0.315

ri2 - 0.417

n3 = 0.327 I The arithmetic mean (M«4) is found by j adding n^ to the mid-point of the d scale, here 1.5<& In the above example = 1.5 + 0.315 = 1.815 The standard deviation

2 — l O <6 = (n3 - (n^) )2 which from the table (3.2) is 0.563 80

Skewness (Sk^) is given by

Ski£> = n3 - 3n2 = 2(n^)^ or in the above example Sk<4 = - 0.004 The Kurtosis (Kg4) is given by 2 4 K6 = n4 - 4n^n3 = 6n^ n2 - 3n^

where n^ is given by

n4 = fd4/f or from the above table (3.2)

K<6 = 0.247 8i

This method does have some shortcomihgs.

Firstly, if sieves are at all inaccurate the third

(skewness) and fourth (kurtosis) moments are inaccurate.

Also if the data is open ended (e.g. the mud faction is unanalysed) then the moment measures are meaningless. i Finally it is assumed that the "centre of gravity" of the class interval is at the half way point which may not be so in natural samples. It also presents slightly

different results to the more conventional measures

(e.g. Inman, 1952) but if used in one study the results are meaningful but make comparison with other studies more difficult as most authors have used some variety of Inman’s statistics. 1 I

(c) Median Diameter (md^ = <6 50) (Trask, 1932): I The median is that diameter which has half the grains finer and half coarser (by weight). It is easy to determine, is frequently similar to the principal modal diameter and is less dependent on skewness than other average grain-size measures but is the least accurate I measure of average grain-size.

In many unimodal sediments it may reflect I the current velocity at the site of deposition (Wrigley, j 1961) but for bimodal sediments this correlation will not hold, nor will it hold for highly skewed unimodal sediments. 82

(d) Mean Size: The method of moments takes into account the whole curve when calculating the mean.

However, due to the difficulties in calculating moments, other methods, based on graphical techniques, to calcu­ late the mean have been devised.

Otto (1939) proposed

H<6 = <616 + <684 2

A similar formula was used by Inman (1952).

These estimates of the mean however neglect the central third of the curve, only considering centiles at each end. Folk and Ward (1957) remedied this by proposing

= g$16 +

Inman M<6 measure. Since 1957 McCammon (1962) surveyed previous measures and compiled the quoted efficiency ratings, he also proposed two more efficient computations:

{<610 + <630 + <670 + <690) (93% efficient)

5 and {<65 + <614 +

These two measures are however almost as

tedious to compute as moment measures, when calculated

manually. They are however more efficient than the

previous computations because they take more cognizance of the "tails" of the distribution.

The above efficiency estimates of various methods of mean size calculation methods are based on

the set of observed percentile measures for the calcu­ lation. From this the variance of these percentile

measures is used as an indicator of the precision of the calculation (McCammon 1962). The mean or an approximation to it reflect the overall size of the sediment as it is influenced by the source material, transporting media and thepiooesses in the basin of de­ position. In bimodal sediments, however, a study of modes will yield more information about provenance (Brezina 1963).

Since 1800 when Sorby recognised the breakage of particles into three dominant modes (sand, coarse silt and clay) other workers have recognised

I natural gaps in natural size distributions. Lifted

are the gaps noted by later workers: 34

Udden (1914) 3-46 sands

Wentworth (1922) at 16, 8*4 and 3.56

Hough (1942) 16 - 1.56 and 46 - 4.56

Pettijohn (1957) 06 - 26 and 36 - 56

and other later workers who found similar gaps.

I

Griffiths (1957) rejects these gaps as being natural and attributes them as being due to changes in analytical technique.

(e) Sorting (Standard Deviation) O': Sorting is an estimate of the square root of the second moment or variance. Variance is another measure of variability, it is the square of the standard deviation (i.e. o^). Many workers have proposed methods of approximations using graphical methods. Udden (1914) used a ratio between successive class intervals on a histogram to give a measure of sorting. Trask (1932) proposed: SQ = (Q25/Q75)i where Q25 or Q1 is the 25th percentile in mm and Q75 or Q3 is the 75th percentile in mm. Krumbein (1936) proposed a 0 analogue of So:

QD^ = (075 - 025)/2 QD^ was proposed because it transformed

So, a geometric measure to an arithmetic measure. Griffiths (1951) when dealing with skewed Carribbean

sediments proposed a more sensitive measure dealing

with the central 80% of the curve:

P.D^ = 690 - 610 2

but later abandoned it and used moment measures.

Inman (1952) proposed another graphic

approximation to the standard deviation i

06 = 684 - 616 2 but on further examination Folk and Ward (1957) found this did not take into account the poorly sorted tails of curves encountered in their study. As a result, they improved the measure to include the tails of curves

O'j = (684 - 6l6)/4 + (695 - 65)/6.6

Other workers including Tanner (1958)

and McCammon (1962) have proposed variants of these measures.

Friedman (1962) shows that Folk and Ward

sorting (0j) correlates closely with the second moment I 8G

I but that (56 (Inman) correlates poorly for poorly I sorted material. That is the Folk and Ward parameter

(graphical) is a closer approximation to the moment value than those previously proposed.

Sorting values may be used as an indication of constancy of energy in an environment and transporting media to that environment. The poorer the sorting the greater the energy fluctuation or the more turbulent the current and vice versa.

Folk (1966) notes an association between size and sorting. He shows that sorting is best in the fine sand range and decreased with coarser and finer grades. This is thought to be due to the rarity in nature of granules and fine silt sizes. Hence when considering continuity of energy, this second factor should also be taken into account. I

(f) Skewness: In a normal curve the mean and median correspond, but if the distribution is skewed the mean departs from the median. Trask (1932) observed 87

this and attempted to qualify this deviation

SK = (MM25) (MM75) (MM50)2 This measure is not geometrically independent of 1 sorting and is hence an invalid index of skewness.

Inman (1952) overcame this by proposing:

Alpha (6 = ^((616 + (684) -MdgS m After Inman 1952 or Alpha <6 =(dl6 + (684)- 2(650 <684 -'(616 After Folk 1966 For the central position of the curve and

Alpha 2(6 = j(<65 + (695)- Md(6 (J(6 After Inman 1952 i or Alpha 2(6 =((65 + (695)- 2(650 (684 - (616 After Folk 1966

For the tails of the curve. These measures, however were not found to be satisfactory when curves were highly skewed as Alpha 2(6 often gave values greater than I ll which is invalid.

Thus Folk and Ward (1957) in dealing with highly skewed river gravels developed a more sensitive skewness measure by combining Inman’s first skewness with an analogue of the second giving SK j which is

SKT = (616 + (684 - 2(650 (65 + (695 - 2(650 2((684 - (616) 2((695 - (65) 86

This has limits -1

The interpretation of skewness values is more difficult than for M^and Cj-. Strongly skewed sediments are often associated with zones of miixing,

Inman (1953) and Inman and Chamberlain (1955). Folk and Ward (1957) plotted Mz versus 0^- versus SK^ and found that an helix resulted (i.e. Mz versus GJ- sinusoidal: G'j versus SK^ circular (refer figure 3.3).

A similar trend has been found by later workers. Plots of skewness versus kurtosis provide a powerful tool for distinguishing environments due to the addition or removal of tails, Mason and Folk (1958) and Friedman (1961).

(g) Kurtosis: Kurtosis is a measure of "peakedness" relative to the normal curve. It is an index of some ration between the spread in the central part of the distribution and the spread in the tails. i

Krumbein and Pettijohn (1938) give a formula 89 FIGURE 3.3 I 90

Kga = ^75 - (625 *(d90 - ^10) but this has been little used. Inman (1952) proposed the following skewness measure

/3 d = {695 - (65) - (g$84 - <616) / (684 - <616 for the normal curve being 0.65

Kg = (695 - <^5 2.44(^75 - (Z$5) I Kg was developed by Folk and Ward (ig57). j So K for normal curves would be 1.0. The geolog- y ical interpretation of Kurtosis has been discussed under section 3.32(f), skewness. 9i

(h) Calculation of Grain Size Statistics: To avoid lengthy manual computation the author with assis­

tance of D.Falvey from the School of Applied Geology University of New South Wales modified a computer pro­

gramme of Kane and Hubert (1963). This programme, University of New South Wales, Department of Oceanography, revised version of Missouri Sed.Pet. is written in Fortran IV Level 1 for use in an I.B.M. 360 Computer.

Although Folk Statistics (Folk and Ward

1957) are used in this study the programme also calcu­ lates moment measures and Inman Statistics (Inman 1952) from raw imput data of weights of material retained on U.S. Standard Sieve Sizes and from pipette analysis.

(i) Method: Moment measures are based on the physical concept of the motion of massive bodies. The application of this to frequency distributions makes the first moment analogous to the centre of gravity or in this case the arithmetic mean. The varienceI or second moment is analogous to the radius of gyration and its square root is called the standard deviation. The third and fourth moments have no direct significance but when combined with the appropriate functions of standard deviations reflect kurtosis and skewness. Their calculation is shown in Appendix H. The

statistics assume an unbiased sampling of the popu­

lation. "Open endedness" due to inaccuracies or uncompleted analysis violates this assumption and although the programme calculates moments, a close

study of the data and methods of analysis is necessary to evaluate the validity of the data, for use in moment

measure calculation.

The Folk and Inman Statistics are calcu­ lated using the formulae described in Section 3.32 of i this chapter. The phi-centile {65, 625 ..... 695) are from 2 x 57 matrix of cumulative percent and associated sieve size. This is achieved by a straight i line interpolation between the closest two cumulative percentages to the required centile (sub-routine Zonk,

refer Appendix H).

(ii) Imput Requirements:

i 1. 57 weights from sieve data to be punched in order of increasing 6

with 8 weights per card, from

-46 to 106 in increments of \6.

2. Sample number, no alphabetic

characters and up to 9 digits. 93

(iii) Imput Form:

1. The 57 weights are to be punched

in order of increasing phi in the format 8F10.4. The decimal point may

be shifted to the right to decrease

the accuracy. 2. Where weights are absent the appro­

priate 10 columns are left blank, it

is not necessary to punch zeros.

3. Card one contains the sample number and is right justified in Columns

1-10. Card two is the start of

the weights, -4(6 in Columns 1 - 10 and all 57 weights whether zero or not must be present, i.e. 8 cards after that containing the sample number must

be present.

(iv) Output Form: An example of this is shown in Appendix H. The output includes:

. Sample number

. List of phi values weights (raw sieve) Percentage weights cumulative percentage weights

. Moment measures . Folk statistics and textural description Inman statistics 94

(v) Accuracy: The internal accurancy of

the programme is to 2 digits.

(vi) Time: The run time is variable de­

pending on the number of data put in.

For 20 samples the run time is 0.27

seconds or 0.014 records per sample.

Note: This programme has only been

used for samples with phi ranges from

-16 to 4(6 and has been found to give satisfactory results. Its performance with samples outside this range is untested. 95

3.4 SUMMARY OF LABORATORY PROCEDURE FOR

TEXTURAL ANALYSIS

(i) Sample washed and less than 64 micron fraction removed, dried and weighed. The remaining coarser than 64 micron fraction

was (ii) Dried, weighed and sieved through a

set of sieves at \ 6 intervals. Each sieve fraction being weighed and

(iii) The acid soluble fraction removed. After removal of calcium carbonate the

samples were dried and weighed. (iv) The percentage of carbonate in the mud was also quantitatively determined. (v) The various size fraction weights (i.e. sediment as a whole, sediment minus carbonate and carbonate weights) were coded for computation in the computer.

3.5 RESULTS I i

3.51 Distribution of Sediment Textural Parameters

To attempt to analyse the sedimentary processes at any locality it is necessary to know not only the distribution of mineral provinces but also of 96

mean size, sorting and perhaps skewness and kurtosis of the sediments. (a) Mean Size:

(i) Including Acid Solubles (Carbonates)

The mean size (Mz) ranges from -0.64(6 to

3.316 with an average grain size of 2.276, i.e. a fine sand. This is excluding the mud fraction which at a maximum forms only 16.1 percent of the sediment.

The geographic distribution (figure 3.5) shows that in general the sediment becomes coarser towards the centre of the bay except that two areas of very fine sand occur in the central region of the north end. Also areas of coarser sand occur in Darling Road, Hare Bay and in the entrance region.

The sediments of the greater part of the bay fall into the fine sand range with areas of very fine sand off Green Point, in Vincentia Bay and in the central northern end of the bay. The southern portion of Darling Road is composed of medium sand while areas of coarse and very coarse sand occur in the centre of the entrance and off Longnose Point. FIGURE 3.5

MEAN GRAIN SIZE (including carbonate)

CONTOURS IN ♦ UNITS

JERVIS BAY N.SW - ACT sea miles (ii) Excluding acid solubles (terrig­

enous material)

The average grain size is 2.34<6 with a range from 3.54(2$ to 0.17

In general the grain size is fairly uniform with localised areas of finer and coarser sediment and a general increase in grain size sea­ wards .

(b) Standard Deviation (Sorting):

(i) Including acid solubles

Sorting values range from 1.90 phi units to 0.33 phi units and have an average of 0.59 phi units. The geographic distribution of sediment in­ cluding carbonate is shown in figure 3.7. This shows the central region and western and northern areas less 99

FIGURE 3.6

MEAN GRAIN SIZE (excluding carbonates).

Jij /.)

CONTOURS IN ♦ UNITS

JERVIS BAY N.SW. - ACT FIGURE 3.7

SORTING (including carbonates)

CONTOURS IN +

UNITS

JERVIS BAY N.SW. - ACT seamiles than 2 fathoms to be well sorted. The remainder

with the exception of three small regions is moder

ately sorted.

(ii) Excluding acid soluble

The average sorting value without carbonates in the sediment is lower (0.51 phi units)

with a range of 1.47 phi units to 0.26 phi units. The distribution is much the same as that discussed above except a large area is covered by well sorted material with a reduction in the amount of poorly sorted material (figure 3.8). Most marginal areas, as well as most of the central and northern areas, are well sorted. Only a small area of poor sorting exists in the bay entrance, the remainder of the area is moderately well sorted.

(c) Skewness•

The skewness distributions with and with­ out carbonates are shown in figures 3.9 and 3.10 respectively. As is shown the distributions are complex. With carbonates present the majority of the bay, particularly the eastern and central areas are coarse skewed. Without carbonates present the areas of skewed sediment are reduced but are in similar 10 2

FIGURE 3.8

SORTING (excluding carbonates)

CONTOURS IN UNITS

JERVIS BAY N.SW. - ACT 103

FIGURE 3.9

SKEWNESS (including carbonate)

CONTOURS IN ♦

UNITS

JERVIS BAY N.SW. - ACT 104

FIGURE 3.10

SKEWNESS (excluding carbonate)

CONTOURS IN UNITS

JERVIS BAY N.S.W. - ACT 105

FIGURE 3.11

KURTOSIS (including carbonates)

CONTOURS IN

UNITS JERVIS BAY N.S.W. - ACT sea miles 106

FIGURE 3.12

KURTOSIS (excluding carbonates)

CONTOURS IN

UNITS

JERVIS BAY N.SW. - ACT positions to those with the same skew in the presence of carbonates.

(d) Kurtosis:

Kurtosis values vary from 0.74 to 2.20 for the bay sediment with carbonates and without carbonates from 0.55 to 2.27. With and without carbonates present the central region of the bay is leptokurtic with platykurtic zones in the north and southwest. However when carbonates are removed the leptokurtic character of the sediment extends further south. Both distributions are complex and are shown in figures 3.11 and 3.12.

( e) Sand/Mud Ratio:

The sand/mud ratio varies from infinity (i.e. no mud) to 1.75. The greater part of the bay is covered by sediment containing less than 1% mud.

Areas of greater than 5% mud occur off Sailors Beach,

Vincentia Bay and southern Hare Bay. The areal distribution is shown in figure 3.13.

3.52 Distribution of Sediment Types 106

FIGURE 3.13

SAND / MUD RATIO

JERVIS BAY N.S.W. - ACT 1G 9

The sediment types are based on percent­ ages of sand, mud and calcium carbonate and these are also used as the three end members on a triangular diagram (figure 3.14).

A tabulation of percentages of each end member and a descriptive classification based thereon is presented in Appendix C. Also areal plot of the sediment-type distribution is given in figure 3.15. These are plotted to give an added indication to environments of deposition.

The triangular plot to show sediment type is an attempt to represent the three major components on one diagram. The sand and mud end-members are essentially textural terms, representing the grain sizes -1 6 to 46 and less than 46 respectively. The end-member labelled Carbonate on the diagram is however a compositional term. Hence although the end-members, sand and mud do have a compositional connotation they are incompatible with the end-member carbonate as used in this case, as the carbonate has no size limits implied. Hence it must be considered that in the general concept of triangular diagrams, this one is 110

FIGURE 3.14

SAND

SEDIMENT TYPES in °/c MUD CARBONATE CONTOUR JERVIS BAY (marine samples only)

.-"-Calcareous Sand

Muddy Calcareous Sand

-'Sandy Calcareni*e

Sandy Muddy Calcaremt-

MUD SAND CARBONATE ill

invalid. It does however have some use in describing the sediments forming in the bay at the present. Some attempt has also been made to contour this diagram to represent percent mud carbonate. The results however show that the percentage of mud carbonate is related directly to the percentage of mud and/or carbonate present. A sketch of these contours appears in figure 3.14.

(a) Gravel;

This is not shown in figure 3.14 but it does occur at stations 34, 46, 58 and 59. Most of the pebbles are sandstone, quartz or biogenic (broken and abraded, as opposed to complete organisms as found at other stations). No sediments have a mean size in the gravel range but are noted to emphasise the fact that gravels do occur in some of the sediments in the study area. They only occur however in the entrance to the bay where tidal currents are strongest.

(b) Sand:

These are sediments containing greater 112

than 90% of sand sized material, excluding sand sized carbonates. They consist of mainly quartz with minor amounts of rock fragments and feldspar. These sedi­ ments occur almost wholly in the northern half of the bay and are broken up only by small areas of muddy and calcareous material in Vincentia Bay, eastern Hare Bay and Montagu Road. A small area of sand also occurs in western Darling Road.

(c) Calcareous Sand:

This includes greater than 50% terrigenous sand sized material with less than 10% mud and less than 50% carbonate material. The carbonates range from 63 microns complete to shells up to 1 cm in maximum size. However the average carbonate size is in the fine sand range (i.e. 2.0 to 3.0^).

This material covers most of the study area except that area described above which is covered by sandy material. The calcareous sand type covers the greatest part of the bay. 113

FIGURE 3.15

SEDIMENT TYPE DISTRIBUTION .

SAND

CALCAREOUS SAND

SANDY CALC-ARENITE

SANDY MUDDY CALC- ARENITE MUDDY CALCAREOUS SAND JERVIS BAY N.SW. - ACT 114

( d) Sandy Calc-arenite

This sediment contains greater than 50% calcareous material and less than 50% sand and less than 10% terrigenous mud. It is restricted to three areas in the bay. These areas (i.e. sample locality

125, in east Darling Road) derive their carbonate from an abundant infauna. The region of sandy calc-arenite off Longnose Point contains primarily coarse fragmented material of biogenic origin.

(e) Sandy muddy calc-arenite

The composition of this can be seen from the triangular diagram (figure 3.14). This sediment is restricted to a small area north of the R.A.N.C. Jervis i Bay. It is a muddy sand containing numerous complete molluscan shells and a lesser amount of calcerous fragments.

It is a relatively unimportant sediment type but does have some value in environmental interpretation. 115

(f) Muddy Calcereous Sand

The composition of this is shown by the

triangular diagram (figure 3.14). This type of sediment

is restricted to a small area in the south east of the bay. It is a sand containing greater than 10% terrigenous mud and abundant broken biogenic fragments.

3.6 DISCUSSION

3.61 Mean Size

The mean size is generally accepted to reflect to some degree the strength and direction of the current which moved the sediment to its present position.

It also reflects many other features,the most obvious being the original particle size before transportation.

Excluding sediments east of Longnose Point and Bowen Island the general trend is for grain size to become coarser towards the centre and north and south ends of the bay (refer figures 3.5 and 3.6). However for the most part the grain size range is only over 1.units in the fine to very fine sand range whether carbonates are present or absent. ii8

Such a distribution may reflect a uniform size of material being contributed from the source.

This excludes the Permian rocks around the bay as a prominent source rock, however some contribution is

evidenced by the rock fragments present (refer Chapter 4) and by the heavy minerals (refer Chapter 5). However

a reworked relic Plio-Pleistocene sand deposit formed in

the bay during the last interglacial, could provide such a source.

The contribution of the Permian sediments to the sediments is however noted in the two extremes of grain size. If the majority of sand is from relict j deposits,similar to the parallel beach ridges at Callala Beach,then they were devoid of muds, coarse sand and fine gravel,all of which are present in the sediments of the bay. Hence it is suggested much of the mud has been con­ tributed from Permian siltstones along the western and northern shores of the bay,and that the coarse sand and gravel is derived from the sandstones along the eastern and southern shore lines.

The influence of currents is strong in the 117

entrance region of the bay where tidal currents have removed fine materials leaving gravel and medium to coarse sand resting in a scour 20 fathoms deep (refer figures 3.5 and 3.6). Other than the above no clear evidence of tidal current action is apparent from the study of grain-size distributions within the bay. However a similar effect to the above but to a less marked extent occurs in the tidal reaches of Currambeen

Creek. Most of the coarse material in the creek consists of broken shell fragments, terrigenous gravel being rare.

Wave action has a winnowing effect, removing fine material and concentrating coarser. This effect is most noticeable off Longnose Point and Point Perpendicular, where the continual action of waves has concentrated calcereous gravel (refer figure 3.5) mixed with medium sand. The medium sand in east Darling Road is also due to a concentration of coarser material by wave activity.

The various small patches of coarser sediment in the bay are difficult to explain without having detailed current information, however they are probably due to small areas of higher energy. The large areas of very fine sand (refer figures 3.5 and 3.6) are shallow areas with less wave activity and probably less current activity and hence the retention and concentration of finer materials in these areas is possible.

The differences in grain size distribution with carbonates included and excluded, is negligible, if the size grade decreases effected by the removal of carbonate is neglected. The only exception being off

Longnose Point where the percentage of carbonate in the sediment is high.

3.62 Sorting

The sorting co-efficient exhibited by any sediment is an indication of two factors

i. The sorting in the original sediment,

and, ii. The consistancy of energy, the velocity, turbulence in the transporting media.

A minor factor is that grain size influences the degree of sorting attained in a sediment (Folk 1966). it 9

When considering degrees of sorting within any given environment it is more meaningful to discuss relative degrees of sorting (Emery, 1964) rather than using absolute terms as proposed by Trask (1932).

Figures 3.7 and 3.8 show the surface dis­

tribution of sorting in phi units with carbonate present

and absent respectively. Both figures 3.7 and 3.8 reveal areas of relatively well sorted material in marginal areas of the bay, as well as in the central areas. The relatively high degrees of sorting in marginal areas (i.e. beaches, breaker zones and shallow off-shore) is due to continual winnowing caused by wave action (Miller, 1956; Eaton, 1951; Grant, 1943; Ingle, 1966).

The area of well sorted sediment in the central deeper region of the bay is also the result of sustained turbulent current activity. This turbulence is possibly the result of a seiche or a periodic oscillation of the water mass within the bay (Clarke, 1968). This phenomenon is common in enclosed basins, however literature on their effects on sediments is unknown to the writer. It is suggested however that the seiche recorded in Jervis Bay is responsible 120

for the relatively good sorting in the central areas of the bay. This results from the higher turbulence caused by the seiche in the central area compared to the extremities at least for its primary mode of oscillation.

The area of poorer sorting in the central entrance (figures 3.7 and 3.8) at 20 fathoms is in a deep tidal channel. This area is subject to strong tidal currents which result in strongly bimodal sediments containing a coarse sand or gravel mode and a medium sand mode. This bimodality results in a poorer sorting than that exhibited by the unimodal sediments which occur over the greater part of the area.

Figure 3.7 shows two other areas of relatively poorly sorted sediment, off Longnose Point and in eastern

Darling Road. The poor sorting here is due essentially to bimodality. In the case of the latter it is due to a coarse mode produced by the growth of a large number of small gastropods. This area is not noted in figure 3.8 where the carbonate is removed. Sorting (<$ units Jo

o

64 0-5 10 Mean MEAN

15 Size i nc

SIZE

lud

(4> ing

A 0 ) 0

V Creek Average Beach Marine Beach carb s

.

SORTING

a Ridge Sample onate T

Sample

' " '

2

Sample 5

s . a* •

, -F

• o 30 FIGURE *{• 121

3.16 122

The area off Longnose Point is also poorly

sorted because of the presence of a coarse carbonate mode. This carbonate material is concentrated in this locality because of intense wave activity. There is however no terrigenous gravel in this locality, hence the waves are selectively concentrating carbonate because of the shape and specific gravity of the particles.

The large areas of relatively moderate sorting (figures 3.7 and 3.8) are caused by relatively less wave action or from the resonant wave and in some areas, Hare Bay and off Callala Beach in particular, by growth of small calcareous organisms, (gastropods and bivalves) to produce a bimodality in the sediment.

The relationships between mean size and sorting with and without carbonate present are shown in figures 3.16 and 3.17. Both show the general re­ lationship that fine sands are better sorted than medium and coarse sands. A comparison between these two figures shows the effects of carbonates on the distributions. The presence of carbonate simply gives a wider dispersion of points, i.e. a wider range of mean sizes and sorting values. The overall effect is to increase grain size and increase standard deviation

(i.e. poorer sorted). This is discussed further in 123

FIGURE 3.17

MEAN SIZE Vs SORTING.

excludinq carbonates.

Marine Sample

i/i -j- Beach "

D ® Beach Ridge Sample -©■

A Cfeek Sample CD C ■ Average O l/) 1

-r

'<4 ’* •• •

' • * -f-

0 0 5 10 15 2 0 2-5 3 0 3 5

Mean Size () 124

Chapter 6.

The relationship between the percentage

of carbonate present in the sediment and sorting is

shown in figure 3.18. The relationship shows that

in general the better sorted sediment contains lower percentages of carbonate and the higher the carbonate

the poorer the sorting. This relationship between carbonate percent and sorting results from the shape of the carbonate grains, and is discussed further in

Chapter 6.

3.63 Skewness

The skewness distribution (figures 3.9 and 3.10 is not apparently related to any observed physical characteristics of the environment and Folk and Ward (1957), Friedman (1961) and others have attributed skewed distributions to hydrologic features causing a mixing of two modes or a preferential winnowing out of a particular size class. There is in Jervis Bay no observable correlation between the skewness and hydrological features, either observed or inferred. 125

FIGURE 3.18

Sorting (including carbonate) V's % Carbonate.

Marin* Sampl*

.j. I*ach

A Cr**k “

a B*ach Ridg* Sampl*

' .2L o U

-I- ■ ■' -i- .

L®_ 0 3 10

Sorting (<1> units) 126

FIGURE 3.19

Mean Size V's Sl

. Marine SampF

Beach

& Creek

0 Beach Ridge Sample

Skewness 4>units 127

Hough (1942 )records grain size and skewness as being directly related, however figure

3.19 makes no such relationship readily apparent in Jervis Bay. The only general remark to be made from figure 3.19 is that finer sediments tend to have a coarse skew, the reverse not being true.

Skewness is not proportional to the

percentage of carbonate present in the sediment of

the bay (refer figure 3.20) whether the skewness is calculated including carbonates or not.

3.64 Kurtosis

No relationship between kurtosis and any physical properties in the bay are observed. Plots of kurtosis against mean size sorting and percent carbonate show no clear or definitive relationship, e.g. kurtosis versus mean size (figure 3.2)

From a comparison of figures 3.11 and

3.12 it is noted that removal of the carbonate tends to remove extremes of kurtosis. Hence, although this is not noted on a kurtosis versus percent carbonate 12d

plot, the presence of carbonate tends to make sedi­ ments more leptokurtic. This is due to the presence of carbonates causing a poorer sorting in the "tails” of the sediment to a greater extent than it does in the bulk of the sediment.

3.65 Sand/mud ratio

This is a calculated value of the ratio between the proportion of sediment above and below

64 microns. These calculations are based on carbonate free samples.

The expected distribution would be one in which the ratio was lowest in areas of low current or wave activity (i.e. least turbulence) or high in areas of deeper (and hence less turbulent) water.

Figure 3.13 shows this to be true in part.

Areas sheltered from wave and current activity (Vincentia Bay and south Hare Bay) have a low sand/mud ratio. However the area off Sailors Beach which is shallow and is subjected to moderate wave activity 129

FIGURE 3.20

SKEWNESS (including carbonate)_Vj_%_£AMQNAJJi

, Marin* Sampl*

.1. Beach >•

$ ■ Ridge Sample

0) o §4 -D D U

-Hi

0 5 Skewness (4» units) 130

the ratio is high. This can only be explained in terms of this area being a relatively low energy zone.

3.7 ENVIRONMENTAL CONCLUSIONS

The influences on sediment type and texture in Jervis Bay are:

i The source of material

ii Carbonate nature and amount

iii Hydrological features

Since the majority of the sand in the bay is a redistributed relict sand (probably beach sands) the resultant range of possibilities or re­ working is limited, excluding the addition of sedi­ ment from another source.

Sediment has been added to relict sands in the bay from the Permian rocks forming cliffs and shore platforms around the bay and also biogenic sediment (i.e. carbonates). These additions have been shown to influence the distribution of sediment type and texture to a marked degree in localized areas 131

(also refer Chapters 5 and 6).

Hydrological features are found to have only minor influence on the sediments except on and near beaches and in the entrance area of the bay. 132

LIGHT MINERALS

CHAPTER 4 133

LIGHT MINERALS 1 4. 1 Introduction

4.2 Method of Analysis

4.3 Mineralogical Composition

4. 31 Quartz

4.32 Rock fragments

4. 33 Feldspar

4.34 Heavy Minerals and Others

4.4 Distribution

4. 41 Quartz

4.42 Rock Fragments

4. 43 Feldspar

4.5 Arenite Classification and Petrographic Provences

4.6 Di scussion

4. 7 Conclusions 134

4.1 INTRODUCTION

Light minerals are those which have a specific gravity less than 2.9 or those which "float" on tetra- bromoethane.

Those fractions remaining after heavy mineral separations (Chapter 5) were used for foraminifera studies

(Chapter 6) and hence separate fresh samples were used in this section of the study and hence include heavy minerals.

Light mineral studies aid in a balanced inter­ pretation of an area. By studying them it avoids over­ emphasis of heavy minerals and provides a means of classifying the sediments forming in Jervis Bay.

4.2 METHOD OF ANALYSIS

The samples chosen for analysis were the residue from sieve and carbonate analysis. Hence light mineral studies were carried out on carbonate-free size graded 135

fractions. Not all stations were studied but only 14 distributed to give adequate coverage of the study area.*

Two size fractions were studied from each station, one coarse (between 16 - 1.56) the other fine (between

2.56 and 36). The grains were mounted in plastic and a thin section cut. No staining was carried out. The grains were then counted using a Swift point counter and Mechanical stage.

Over 200 grains were counted in each slide and the records analysed by comparison of distribution maps of mineral species.

Petrographic provinces were also determined.

4.3 MINERALOGICAL COMPOSITION

The detailed mineralogical composition of each sample for the two size fractions is shown in Appendix G.

4.31 Quartz

Colourless transparent quartz grains constitute the

* The stations from which light mineral studies are available

are: 3, 10, 16, 20, 25, 33, 59, 67, 85, 99, 125, 129,

157, 169. 136

bulk of the material in both size grades. Four "quartz types" are included in the count, single grains and multiple grains, both with straight extinction, and single and multiple grains, showing undulose extinction.

Inclusions are common in most grains and include bubbles, acicular rutile, mica and sericite or clays along fissures and on the margins of some grains. This latter feature is thought to result from cement and matrix of the grains in the source rocks still adhering to some grains. Reworked quartz, present as rounded grains, forms a major part of the detrital material and hence indicates a high degree of maturity for the sediments in Jervis Bay. This suggests a source of older sedimentary rocks or residual sand deposits, or both. It is also clear that both metamorphic and igneous rocks originally contributed much of the detritus due to the presence of both unstrained and strained quartz grains, Folk (i960), Conolly (1965). This latter statement is contested by many workers who believe that extinction character of detrital quartz is no indication of provenance

(Blatt and Christie, 1963 and Hubert, i960).

No detailed study of surface features of the quartz grain has been undertaken. 137

4.32 Rock Fragments

Fragments of sedimentary rocks are most common. I Sandstone rock fragments are more common in the coarser fraction and siltstones and weathered feldspathic rocks in the finer fractions. Igneous rock fragments are rare. Those observed are of a fine grained basic origin. Included in the rock fragment count are highly weathered feldspar grains because, in some cases, it is difficult to separate these from fragments of fine grained rocks.

4.33 Feldspars

Most of the feldspars are highly weathered and of a soda lime type with only minor amounts of potash feldspar. No zoning is evident in any grains. Most feldspar grains are less rounded than quartz but not angular. The feldspars frequently show large inclusions of mica. No count of the percentages of feldspar types has been made. Also, it is noted that feldspar is more common in rock fragments in the sediment than in the sediment as a whole.

4.34 Heavy Minerals and others

These are included here as they have not been 13d

removed from the samples analysed for light minerals (refer Section 4.2). The percentage given is not representative of

the percentage of "heavies" in each sample as they are for the most part finer than the samples examined in this section.

The heavy minerals observed in the bay are discussed in detail in Chapter 5.

Other minerals include, mica, chert, jasper and biogenic silica. Micas are rare. They occur as angular or ragged grains in the fine fractions only. Biotite is more common than colourless species.

4.4 DISTRIBUTION

4. 41 Quartz

The distribution of quartz for both coarse and fine fractions is shown in figures 4.1 and 4.2. From this it is evident that the quartz content is highest in the north and

south ends of the bay (greater than 90%) and generally de­ creases to less than 80% in the entrance. An area of low quartz (less than 80%) occurs in the southern end of Sailor’s

Beach. The remainder of the bay contains between 80% and

90% quartz. 139

FIGURE 4.1

QUARTZ coarse fraction

JERVIS BAY N.S.W - ACT sea miles 140

FIGURE 4.2

QUARTZ - fine fraction.

JERVIS BAY N.S.W. - ACT Expected page number is not in the original print copy. 142

4.42 Rock Fragments

In general, the percentage of rock fragments

increases seawards as shown in figures 4.3 and 4.4. Rock

fragments are more common in the coarse fractions reaching

percentages as high as 21.3% off the south end of Sailor’s

Beach and 20.8% in the entrance. The percentages of rock

fragments for both fractions fall off to less than 5% in

the north end of the bay, showing a general decrease in

percentage away from the entrance. An area in Darling Road

contains less than 5% rock fragments in the coarse fraction.

In the fine fraction less than 5% rock fragments occur in

the north between Vincentia and Green Point, whilst they

reach a maximum of 18.4% off Target Beach, Beecroft Peninsula

near the entrance.

4.43 F eldspar

The feldspar distribution is shown in figures

4.5 and 4.6. The feldspar content increases towards the central part of the bay between Longnose Point and Plantation

Point. 143

FIGURE 4.3

ROCK FRAGMENTS - coarse fraction

JERVIS BAY N.S.W. - ACT 144

FIGURE 4.4

ROCK FRAGMENTS fine fraction

JERVIS BAY N.S.W. - ACT 145

FIGURE 4.5

FELDSPAR coarse fraction.

JERVIS BAY NSW. - ACT FIGURE 4.6

FELDSPAR fraction.

JERVIS BAY N.S.W. - ACT sea miles 147

TABLE 4.1

Average Abundances of Quartz Feldspar and Rock Fragments in Jervis Bay

Quartz Rock Fragments Feldspar Fine fraction 85.83 9.85 3.57

Coarse fraction 83.45 11.55 4.73

4.5 ARENITE CLASSIFICATION AND PETROGRAPHIC PROVINCES

Classification of sandstones is necessary to provide a summary of descriptive parameters and/or genetic features of the rock/sediment.

i | Many classifications with different emphasis have been evolved by various workers and included here is a short review of some of the more important schemes (refer figure 4.7) .

The first attempt at quantatitive classification was made by Krynine (1948). His classification is based essentially on mineralogy. The three end members being, quartz, feldspar and mica, rock fragments are ignored. This scheme was influenced by Krynine's theory that sandstone mineralogy is an indicator of tectonics. Other schemes based 146 Reference Attributes on which classi­ fication is based______— END % Folk (1954) Quartz and chert Feldspar~^''''> volcanic and rock fragments

Fuchtbauer < co Quartz Feldspar (1959) U W

3S Hubert(1960) < Ph Quartz, Chert Feldspar and Pi H and meta-quarzite feldspathic crystalline r0cl H s fragments

Krynine(1948) Quartz Feldspar kaolin

Van Andel Quartz Feldspar (1958)

Bokman (1955) d Quartz Feldspar and < rock fragments u H o Dapples, Quartz and chert K and Na Krumbein and s feldspar pi (0 Sloss (1953) w w Hp P£ S CQ Gilbert H Quartz, chert Feldspar Q Ph (1954) P H and quartzite

Krumbein £.nd Sloss (1953) s Quartz Feldspar £P Feldspar Pettijohn HW Quartz and chert (1957) ______■

Tallman Quartz Feldspar (1949)

i Crook (1960) D i Quartz and chert Unstable mineraJ Pi O and rock frag^ S 3 CO P < W 8 Pi H Packham , g P Quartz and chert Unstable m^r]e^Lt (1954) < H H and rockJ^P H Q H use P < , Pi P H P < CO < O n 1 4 OF CLASSIFIATION Comments v

Metamorphic rock frag­ Graywacke based solely on "metaphor- ments, micas, meta­ phic constituents. Sedimentary rock morphic quartz fragments ignored.

Rock fragments and Recognises clay rich and clay poor chert sandstone types. Terminology cumber same

Micas and micaceous Non-micaceous rock fragments are not rock fragments treated as a major constituent. Classification designed originally for feldspathic rocks.

Micas and chlorite Ignores rock fragments, Graywacke based solely on mica and chlorite.

Rock fragments and Graywacke based solely on rock chert fragments and chert.

Clay Graywacke based solely on clay contmt Feldspar & rock fragments not diff­ erentiated.

Rock fragments and Graywacke based on some of rock matrix fragments and matrix. Ca feldspar ignored Recognises 2 suites on basis of 10% Unstable fine grained Matrix matrix. Graywacke used as special rock rock fragments type & not part of classification.

\ Clay, sericite and Ignores rock fragments. Graywacke chlorite based on clay, sericite, chlorite and feldspar content.

Rock fragments Matrix Clay matrix is most important property of graywacke Matrix Graywacke based solely on matrix content. Rock fragments ignored.

Recognises 3 suites. Graywacke Matrix based on deposition by turbidity current

Matrix Recognises 2 suites. Graywacke based on deposition by turbidity current. 150

LEGEND FOR FIGURE 4.7

Krynine (1948) Hubert (I960) 0 ortho-quartzite 0 - orthoquartzite

lrg - low rank graywacke mq - micaceous quartzite hrg - high rank graywacke fq - feldspathic quartzite la - lithic arkose qg - quartzose graywacke a arkose qa - quartzose arkose

McBride (1963) g - graywacke q-ar quartz arenite fg - feldspathic graywacke s-ar subarenite ma - micaceous arkose s-lar sublithic arenite a - arkose

Isa lithic subarkose Crook (1960) a arkose qar quartz arenite la lithic arkose sub lfar - sublithic f elsarenite f lar feldspar lithic- arenite sub lar - sub litharenite lar lithic arenite f ar - felsarenite

Folk (1968) If ar lithic felsarenite qar quartz arenite lar litharenite sub a sub arkose sub lar - sublitharenite a arkose SRF — sedimentary rock fragments la lithic arkose MRF _ Metamorphic rock f lar fledspathic fragments 1itharenite IRF Igenous rock lar litharenite fragments 151

FIGURE 4.7

ARENITE CLASSIFICATION

KRYNINE (1948) HUBERT ( I960)

Q Q

Me BRIDE (1963) CROOK ( 1960)

Q

FOLK (1968 )

MRF 152

on mineralogy composition with various end members have also been proposed by Folk (1954), van Andel (1958) and

Hubert (1960). Most of these schemes use end members of quartz, feldspar (and feldspathic rock fragments) and rock fragments (including metamorphic rock fragments).

Perhaps the most common classification scheme is one based on both mineralogy and texture. The addition of textural information is achieved in two ways. Either by the inclusion of matrix as one end member as done by Tallman

(1949), Krumbein and Sloss (1963) and Pettijohn (1957) or by applying a ’’clan name" to a mineralogical classification.

This clan name indicates a "grain size clan", hence a sand sized rock composed of essentially quartz, feldspar and rock fragments would be respectively designated as quartz- arenite, arkose and litharenite depending on the author of the classification. Such schemes have been proposed by

Gilbert (1954), McBride (1963) and Folk (1968).

The third type of classification uses composition, texture and structure. This is an attempt to determine more closely the conditions of sedimentation. Such a scheme was proposed by Packham (1954) and Crook (I960). This 153

Quartz Arenite PETROGRAPHIC PROVINCES in JERVIS BAY

Sublithic Arenit#

FELDSPAR ROCK FRAGMENTS 154

FIGURE 4.9

PETROGRAPHIC PROVINCES

QUARTZ ARENITE

SUB LITHIC ARENITE

JERVIS BAY N.S.W. - ACT 155

classification is dependent on whether the sediment is

deposited by traction or turbidity currents.

Triangular diagrams representative of each

classification are shown in figure 4.7. The classification

adopted for this study is that of Folk (1968). This scheme

is used in this thesis because it incorporates textural, mineralogical and provenancial data in a direct and indirect way. The inclusion of the first two (texture and mineralogy)

in the scheme is clear, the third feature, provenance is

infused by a subsidiary triangle in the rock fragment corner

denoting the types of rock fragments present, (refer figure

4.7). Hence it is a comprehensive classification.

4.6 DISCUSSION

The variation of quartz percentage with size is the reverse to that which would be normally expected. This reversal is due to the breakup of sandstone rock fragments, consequently they are not present in the finer fractions and hence their constituents are counted as individual grains rather than occurring as rock fragments. This corresponds to an overall decrease in the percentage of rock fragments in the fine fraction. 156

There is also a slight decrease in feldspar content with grain size in the bay as a whole, particularly in regions of high concentration. This is due to faster physical break­ up of smaller particles and also their increased surface area and hence faster chemical attack. These processes are also responsible for the decrease in feldspar seawards where a rapid increase in water movement would be expected.

The scarcity of feldspar in Hare Bay and Darling

Road is as follows: In Darling Road it is probably due to the high wave activity causing the destruction of the feldspar by abrasion during periods of north-easterly wind. The scarcity of feldspar in Hare Bay could be due to the high maturity of the parallel beach ridges which act as the source material.

Neglecting the counts of the coarse and fine fractions and taking the total average composition at each station, only two fields of Folk’s (1968) triangular diagram are occupied (figure 4.8). The greater part of the sediment is in the sub-quartzarenite-arenite* (sub-litharenite)

* Sub-quartzarenite-arenite: This is a sediment in the

sublitharenite family of Folk (1968) with rock fragments

of mainly quartz sandstone composition. 157

province with a small area of quartzarenite (refer figure

4.9) in Hare Bay and Darling Road*

This distribution of petrographic provinces follows for similar reasons as the above discussion on mineralogical distribution, i.e. the lithic fragments are more abundant in coarser, deeper deposited sediments due to the presence of sandstone fragments which have not been broken down to form individual quartz grains as has occurred in the finer sediments.

The abundance of sedimentary rock fragments in the total rock fragments indicates a sedimentary provenance, this almost certainly being the Permian sediments in the catchment and around the shores of the bay.

4.7 CONCLUSIONS

1. The percentage of quartz decreases seawards and to a limited extent increases with decreasing grain size, which in turn may be correlated with depth of water. The same is true for feldspar except, as well as decreasing in abundance seawards, it increases towards the centre of the bay. Rock fragments follow the opposite trend to quartz. 158

2. The majority of the sediments may be classified as sub-quartzarenite-arenite using the classification of

Folk (1968). Minor areas of quartzarenite occur in Hare

Bay and Darling Road. These areas of more mineralogically mature sediments are due to increased wave activity causing breakup of rock fragments and feldspar.

3. The light minerals reflect energy regimes but not to the same extent as heavy minerals or textural parameters of the sediments. HEAVY MINERALS

CHAPTER 5 160

HEAVY MINERALS

5.1 Introduction

5.2 Separation

5.3 Analysis of Concentrates

5.4 Quantitative Results

5.5 Microscopic Results

5.51 Zircon

5.52 Tourmaline

5.53 Epidote

5.54 Opaque (a) Magnetite

(b) Ilmenite (c) Haematite (d) Cassiterite (e) Pyrite

(f) Tourmaline

5.55 Leucoxene

5.56 Minor Minerals (a) Garnet

(b) Andalusite

(c) Hornblende

(d) "Green Spinel" 161

(e) Biotite

(f) Corundum

5.57 Monazite

5.58 Rutile

5.6 Distribution

5.61 Zircon

5.62 Tourmaline

5.63 Epidote

5.64 Leucoxene

5.7 Discussion

5.71 Heavy Mineral Provinces

5.72 Heavy Mineral Provenance

(a) Zircon

(b) Tourmaline

(c) Epidote

(d) Opaque Minerals

(e) Other Heavy Minerals -

5.73 Provenance Summary

5.74 Discussion of Distribution Pattern

5.8 Conclusions 162

5.1 INTRODUCTION

The gravity concentrate of minerals in tetrabromoethane (S.G. , 2.9) are known as heavy minerals.

They are generally considered to be of importance in pro­ venance (source rock) studies. They usually occur as

accessory minerals (less than 5.0%) in the source rocks and hence only occur as accessory minerals in the sediment under study. Heavy minerals include such minerals as garnet,

zircon, leucoxene, tourmaline, magnetite.

Heavy Minerals have been used for many purposes: stratigraphic correlations (McElroy, 1961), the determination of provenance of sediment, (van Andel, 1964), the location of economic heavy mineral deposits, (Whitworth, 1956), and the tracing of sediment movement e.g. along beaches (Baker, 1963). These uses of heavy mineral studies depend on the concept of the similarity or consanguinity of deposits

in the same basin and also of the same age.

The majority of heavy minerals are in the size range of 0.12 m.m. to 0.06 m.m. but in this study all minerals with a specific gravity greater than 2.8 and of 163

greater size than 0.06 m.m. are called "heavy”.

5.2 SEPARATION

Before attempting a separation the author

studied the literature in an attempt to evaluate the methods on separation. Milner (1962, p. 113 - 122) contains a good summary of some of the methods put forward.

The first method, panning, used by McElroy (1961) is carried

out using a prospectors pan, however it is inaccurate and has the disadvantage of not separating at a defined specific gravity. Another method proposed by Woodford (1925) is a bromoform (SG 2.85) separation using a separating funnel. This is accurate but time wasting due to the time needed to clean the apparatus between separations. Fraser (1928) suggested the use of a U tube and by suitable manipulations effect a separation. This technique requires a fairly large

amount of practice and only allows the separator to make one separation at a time.

A more refined method and more accurate is to centrifuge the crush or sediment in a liquid with an S.G.

at 2.96. To do this however special hard glass centrifuge

tubes with special fittings are required due to the high pressures incurred by centrifuging heavy liquids and the 164

FIGURE 5.7

HEAVY MINERAL SEPARATION

RESIDUE

CONCENTRATE 185 fittings to enable separation of the heavy and light fractions. The method is however rapid and has an accuracy of about 98%. Various tubes have been designed to enable good separation - e.g. (Brown, 1929; Link, 1966).

The method adopted in this study is that of

Milner (1962; p. 113) using a bank of six funnels enabling six separations to be made simultaneously.

The apparatus was set up as shown in figure 5.1.

This method proved 90% efficient for samples of average heavy mineral content. The efficiency was estimated by comparing results obtained with those obtained from a centrifuging separation of the same sample. However samples with a low heavy mineral content could only be separated to about 80% of the total heavy mineral content. The time to effectively separate six samples was found to be about one hour.

The top funnel was filled with tetrabromoethane and the sediment added. The sediment was then stirred three times at 10 minute intervals. After 30 minutes the clamp was released and the heavy fraction filtered off, washed 188

and dried. The light fraction was also washed and dried and used in studies of foraminifera.

5.3 ANALYSIS OF CONCENTRATES

The concentrates of heavy minerals were examined by conventional techniques. The concentrates were split

and mounted in balsam on a slide on which a grid had previously beoi ruled. The remainder of the grains the minerals were identified in oil and their approximate refractive indices noted. The balsam mounted grains were then identified by using the optical properties of extinction colour, pleochroism, relief and shape. After identification the grains were counted using the grid on the slide. All grains falling within the grid were counted,this being an average of 161 grains. During counting the roundness of species was also noted.

The error in counting 161 grains is given by

(Krumbein and Pettijohn, 1938, p. 472) as +5.1% at 20% or “f- 8.0% at 10%. Although this error is high it is a theoretical error and is based on the assumption of a knowledge of the actual percentages present. As the object of counting is to determine the percentages present 167

these errors can only be taken as a guide and are in fact

probably less, (Krumbein and Pettijohn, 1938, p. 473).

Before attempting to count the opaque

minerals, two polished sections of concentrate from

station 61A were studied. One section contained

magnetic species, the other non magnetic. The species found and percentages of each are listed below.

TABLE 5.1

Percentages of Magnetic and Non Magnetic Mineral Species in the Opaque Minerals Group from Jervis Bay

Magnetic Minerals 55% of total opaques

i. Magnetite 50% of total magnetic sp.

ii. Tourmaline 50% of total magnetic sp.

Non-Maqnetic Minerals - 45% of total opaques

Leucoxene - 40% of total non-magnetic sp. ±- ii. IImenite - 35% of total non-magnetic sp.

iii. Haematite & Limonite - 20% of total non-magnetic sp.

iv. Cassiterite - Tr of total non-magnetic sp.

v. Pyrite _ Tr of total non-magnetic sp. These opaque species are counted in grain mounts as one group, with the exception of leucoxene, which is listed separately, as it is easily counted separately in thin section using reflected light.

Minerals with small abundances with respect to the others have been included under the heading "Minor

Minerals". These include garnet, andalusite, hornblende, biotite and others. The percentage by number for each mineral group is shown in Appendix F. This form of expression is felt to be more accurate than the method devised by (Milner, 1962) which proposes a 9 point scale, 1 representing very rare and 9 a flood.

5.4 QUANTITATIVE RESULTS

The percentage of heavy minerals was not calculated due to the specific gravity difference between them and the light mineral fraction, which tends to make the results of such an investigation meaningless.

The relative abundances of all minerals at 58 stations is given in Appendix F. A Summary of these showing the average abundances and limits of the heavy minerals in the surface sediments are given in table 169

5.2. From this table it can be seen that zircon, tourmaline,

leucoxene, epidote and opaques are quantitatively more important than the remainder. Also the percentage by number of zircon grains with certain degrees of roundness

are shown in Table 5.3.

The most abundant minerals on the average are

the opaques comprising 53.69% of which 26.30% is made up of leucoxene, the remainder are other opaque minerals,

(individual species are described in Section 5.4).

TABLE 5.2

The average abundances and limits for the 8 mineral groups counted (This represents a summary of Appendix F)

Mineral Av. % by Number Limits Zircon 2.24 0 - 14.6

Tourmaline 18.26 6.4 - 42.6 Epidote 15.93 1.4 - 40.5 Opaques 27.39 8.1 - 54.8

Leucoxene 26.30 11.0 - 42.8

Minor Minerals 2.53 0 - 9.5

Monozite 0.10 0 - 2.1

Rutile 0.26 0 - 3.4 170

5.5 MICROSCOPIC DESCRIPTIONS

A total of fourteen mineral species have been identified from grain mounts and classified into eight

groups, See table 5.2. The descriptions are based

entirely on the observation in grain mounts. The minerals

are described in the groups in which they were included for counting purposes.

5.51 Zircon

Most of the zircon present is elongate showing varying degrees of euhedrality and also rounding - see table 5.3.

TABLE 5.3

Shape and Roundness description of Zircon grains in Jervis Bay.

EuhedralX 12%

Subhedral- 41% Anhedral+ 47% ( 34% angular ( 51% subangular - sub rounded ( 15% rounded - well rounded

X shows a slight or no abrasion, good crystal faces. abraded, elongate with one or more crystal faces still recognisable, +either broken crystals or too abraded to recognise any faces. 171

All the grains observed were colourless or cloudy due to abundant inclusions. Inclusions are

common, the most common type being small unidentifiable

rod like crystals parallel to the long axis of the crystal. Also common are small bubbles with or

without a liquid filling. Some grains exhibit zoning but this is rare.

5.52 Tourmaline

Tourmaline occurs with varying degrees of

abundance throughout the bay. It exhibits a variety of colours and differing degrees of rounding.

The most abundant colours are dark to light brown and black pleochroic variety with tinges of olive in some. Less abundant are grey - buff, grey - colourless and dark grey - light olive brown and combinations. The least common is a dark - light blue combination. It

should be noted that these are only visual estimates noted during counting.

Many grains contain inclusions, the most common being a flakey mineral, however some contain bubbles 172

and about 5% leave long black needles which are probably rutile.

Most of the grains are well rounded (80%) with 10% rounded, 5% sub rounded and 5% angular. Most grains are spherical in the coarser sizes with only a few prismatic grains, however, the finer grains are mainly prismatic and more angular.

5.53 Epidote

Most grains of epidote show pleochroism from light green to a yellow green however some colourless grains do occur. The grains are "rough” or poorly rounded for the most part, however some coarse grains are rounded. Most grains are equidimensional, however an occasional grain is slightly elongate. Cleavage is evident in some grains and a large proportion have greater degrees of inclusions.

5.54 Opaques

These are described on grain characteristics after species had been identified in polished section. (a) Magnetite: Occur as small metallic grains with metallic lustre.

These grains are \6 to 1<6 unit smaller than most of the other heavy minerals. It is often in part altered to haematite but this was only noticed in the polished section. Magnetite is well rounded with the exception of rare euhedral octahedral grains.

(b) Ilmenite: Anhedral,well rounded, bluish - black,lustrous, grains. Occasionally ilmenite shows partial alteration to leucoxene.

(c) Haematite: This is similar to magnetite in appearance but often larger and coated with a red-brown oxide of haematite.

(d) Cassiterite: This mineral was identified by chemical means only.

The concentrate was tested by washing it with 5N hydrochloric acid in a zinc bath. This test causes the cassiterite to become shiny due to a surface film of metallic tin. It is an extremely rare constituent of the heavy mineral fraction. 174

(e) Pyrite: Present in one sample only,

(JB 3).

(f) Tourmaline: Black iron-rich tourmaline occurs in the heavy mineral magnetic separate. The grains have similar characteristics to those previously described and are included as far as possible in the earlier group. Counting of such grains is difficult when in both reflected and transmitted light examin­ ation of the mounts no transparency is noted. Hence in some cases some tourmaline is included in the "opaque count". Although no chemical data on these magnetic tourmaline grains was compiled both powder photograph data and diffractometer X-ray analysis results are given for this mineral, refer Appendix E.

These analyses fit with the standards for an iron- rich tourmaline, schorlite (Na,Ca) (Fe,Mn)3(A1,Fe)^

((OH),+3/(603)3/Si^018). Because no chemical analysis has been attempted it can only be assumed that iron is responsible for its magnetic properties.

5.55 Leucoxene

This occurs in small white to brownish 175

microcrystalline aggregates. Many grains contain an ilmenite throughout the grain. Most grains are well rounded and equidimensional. Leucoxene is ubiquitous throughout the study area.

5.56 Minor Minerals

(a) Garnet: Garnet is common but not abundant in separates. All grains noted were colourless and angular or sub-angular. The angular outline, isotropic nature and conchoidal fracture serve to identify these grains. Inclusions are rare, but grains often exhibit a surface pitting thought to result from percussion.

(b) Andalusite: Andalusite, like garnet occurs commonly but not abundantly in concentrates.

It is easily identified by its distinctive colourless to rose pink pleochroic colours. Most grains are fresh, though some show slight alteration. Most grains are rounded to well rounded except where grains have cleaved, this is however rare.

(c) Hornblende: Hornblende is only present 176

in very minor amounts. It is characterised by brown and green pleochroic colours and also a good

cleavage.

(d) "Green Spinel": This mineral is

bluish green in colour and isotropic. Most grains

exhibit no cleavage and some still show what appears

to be remnants of an euhedral form. It is an ex­

tremely rare mineral throughout the study area and

only occurs in a few samples. Most grains are well rounded.

(e) Biotite: This is also extremely rare but is easily identified - its rarity may be only apparent, due to its platy nature and relectance to sink in the "heavy liquid" during the laboratory spearations.

(f) Corundum: Occurs both as rounded,

short hexagonal crystals, and angular grains. It is zoned in sapphire blue to colourless bands and

light brown in colour. Ill

5.57 Monazite

Grains are small, well rounded, frosted and bronze-coloured.

5.58 Rutile

This is only recognised where it is transparent or translucent. It has a characteristic deep red-brown colour and is often pleochroic. It is always rounded to well rounded.

5.6 DISTRIBUTION

The distribution is a plot of the number of a given species from the surface sediment in the area of study. Only species which may show an interpretable pattern have been plotted and are shown in figures 5.2 to 5.5. Hence those excluded from the discussion here are opaques, excluding leuccxene, other minerals and rutile. i

FIGURE 5.2

% ZIRCON

( X BY NUMBER)

JERVIS BAY N.SW. - ACT 179

FIGURE 5.3

% TOURMALINE

(% BY NUMBER)

JERVIS BAY N.S.W. - ACT sea miles 5.61 Zircon (Figure 5.2)

Zircon is almost ubiquitous but less

abundant than tourmaline. Areas of relatively high

zircon concentration are off Plantation Point and

Sailor’s Beach in the eastern-most part of the

southern sector of the bay and off-shore from Callala

Beach. Areas of intermediate concentration occur round the remaining area of the bay with a zone of low concentration in the centre and entrance.

5.62 Tourmaline (Figure 5.3)

The distribution of tourmaline is almost the reverse of that of zircon. There is an area of relatively high concentration of tourmaline in the centre of the bay with areas of lower concentration around the margins. Unlike zircon its concentration increases seawards.

5.63 Epidote (Figure 5.4)

Epidote shows an irregular distribution.

The concentration is relatively low in Hare Bay and 181

FIGURE 5.4

% EPIDOTE

( % BY NUMBER )

JERVIS BAY N.S.W. - ACT 182

FIGURE 5.5

% LEUCOXENE

( % BY NUMBER)

JERVIS BAY N.S.W. - ACT sea miles 183

Darling Road with a region of high concentration in the central and eastern sector of the bay. The remainder of the area has an intermediate concentration.

5.64 Leucoxene (Figure 5.5)

Leucoxene has a complex distribution with an area of high concentration in the north and south of the bay grading to a low concentration in the centre of the bay. These trends are, however not as definite as those for the previous mineral distribution but the evidence is sufficient to arrive at the above generalised trends.

6.7 DISCUSSION

The distribution of heavy minerals in the marine environment depends on many factors.

These factors include source, transport., species, size, depositional environment hydrology and chemical conditions in the environment. In this section the author attempts to elucidate the effect.of these factors on the heavy mineral distribution of Jervis

Bay. 184

5.71 Heavy Mineral Provinces

A sedimentary province is an area unified by its possession of one or more common features. Such provinces may overlap or intermix but recognition of them may aid in understanding the history of an area.

Three such provinces may be defined for heavy mineral groups in Jervis Bay. They are:-

1 Zircon province - above 8% zircon

ii Tourmaline province - about 20% tourmaline iii Epidote province - above 15% epidote.

A plot of these provinces is shown in

Figure 5.6. It is clear that the tourmaline and zircon provinces are fairly separate although there is a considerable overlap of both with the epidote province. 185

FIGURE 5.6

HEAVY MINERAL PROVINCES

ZIRCON

TOURMALINE

R 1 M EPIDOTE

JERVIS BAY N.S.W. - ACT sea mWes 186

5.72 Heavy Mineral Provenance

(a) Zircon: Two physically different types

of zircon exist in the sediments of Jervis Bay, a well rounded barrel shaped variety and an angular or euhedral variety (table 5.3). It is generally

accepted that euhedral grains have only undergone one cycle of sedimentation and well rounded grains are polycyclic. Hence at least two separate sources must be invoked, (refer Table 5.4). They are:

i An acid igneous source for the euhdral grains (Milner, 1962) and (Baker, 1962) or an authigenic origin in the Permian sediments (Saxena, 1966) around the bay, or no rounding is visible after only 2

or 3 recycling events

and

ii A reworking of older sedimentary form­

ations to provide the well rounded grains.

The zircon types present in the Permian rocks surrounding the bay were studied by examination of slides and heavy mineral concentrates. Sand samples from Warrain Beach and Mary Bay have also been examined 187

TABLE 5.4

Characteristic assemblages of the more common detrital heavy minerals from different source rocks (modified after Baker 1962)

Source Rock Characteristic Heavy Mineral Assemblages

Acid Igneous Apatite, biotite, hornblende, magnetite rocks moncfzite, sphene, tourmaline, zircon

Basic Igneous Anatase, angite, biotite, chromite, rocks hypersthene, ilmenite, leucoxene, magnetite, olivine, rutile, spinel, zircon

Pegmatites Flourite, garnet, moncfzite, topaz, tourmaline, zircon

Low r ank Biotite, chlorite (if clastic), metamorphic leucoxene, tourmaline rocks

Reworked Garnet, leucoxene, rutile, tourmaline, sediments zircon

Chemical Haematite, limonite, pyite Preciptates

Authigenic Dolomite, chlorite, (occasionally Preciptates tourmaline (occasionally) anatase, flourite, brookite, pyite, zircon (overgrowths) i So

in an attempt to isolate the sources of the different types of zircon present in the bay.

The Permian sandstones contain up to 40% zircon of the total heavy mineral assemblage. They

are, for the most part, colourless but a few yellow

grains have been observed. They commonly contain

inclusions of rod like minerals, bubbles and are rarely zoned. The majority of the grains (95%) show some signs of abrasion with only 5% showing undamaged crystal faces.

The Permian siltstones, on the other hand, contain only 30% zircon in the total heavy mineral assemblage. These grains are finer than the average size of zircon in the bay and there is a higher percentage (20%) of euhedral grains. Zoning is com­ paratively common as are yellow zircons.

The zircon from Warrain Beach (north of

Currarong) makes up only 2.0% of the total heavy mineral population. It is well rounded and larger than the average size of zircon grains in the sediments 189

of the bay.

The beach sands from Mary Bay (south

side of Bherewerre Peninsula) contains less than 10%

zircon which is well rounded and large compared to

the zircon in the sediment in Jervis Bay. Euhedral

grains are rare but do occur, although not as

frequently as in the bay, also the euhedral grains

are slightly larger than those found in the sediments

of the bay.

Hence no clear evidence of source of

the zircon is available, however from the above the most probable source is the Permian sediment and relict sand deposits around the bay. This provides a source which will supply polycyclic zircon grains to the sediment. The evidence for authigenic zircon is scanty at best, and is emphatically denied by

Marshall (1967) and K.A.W.Crook (pers.com.). The comparative lack of euhedra of zircon outside the bay and their abundance in the relict sand deposits and the Permian sediments around the bay leads to the conclusion that the zircons originate from the older sediments in the region. The euhedral grains must also be polycyclic (i.e. undergone at least 2 or

3 cycles of erosion). However this will not damage the grains sufficiently for such damage to be noted by microscopic study, K.A.W.Crook (Pers.com) .

Hence it is concluded that, due to the relative abundance of euhedral and rounded zircon in the Permian and beach ridge deposits, compared to that on the beaches north and south of Jervis Bay, the zircons originate from within the area of the bay and very little influence from outside is apparent.

(b) Tourmaline: Most of the tourmaline in the bay is the brown and greenish variety which tends to indicate a low rank metamorphic source according to Krumbein and Pettijohn (1938) or acid igneous source according to Krynine (1946). However, due to the very high percentage of well rounded tourmaline present, the author suggests most of the tourmaline in the bay is polycyclic and originates from the Permian sediment and parallel beach ridges around the bay.

The polycyclic origin is supported by the abundance and variety of tourmaline found in the

Permian sediments around the bay. The Permian con­ tain approximately 15% of tourmaline by number of the total heavy mineral fraction. They vary in colour from black to colourless to grey pleocroic browns, greens and blues, the greenish brown varieties being most common.

Although such varieties of tourmaline also occur on beaches outside the bay the suggested origin for the zircon supports the above and tends to discount any influence from external sources.

(d) Epidote: Most of this is also thought to originate from the Permian rocks around the bay. However this mineral is considerably less stable than zircon, tourmaline and rutile and would tend to be altered in such sediments before reaching the Recent sediments. The other alternative is that it has been introduced from metamorphic rocks to the north or south of Jervis Bay, although this is unlikely in view of the foregoing discussion.

(d) Opaque Minerals: The opaque minerals are common in the sedimentary rocks around the bay and in the Currambeen Creek catchment (65.3%) of total heavy minerals (found in Currambeen Creek at 192

its crossing with the Princes Highway). Hence it is probable that the majority of the opaques were derived from Permian and younger marginal sediments.

Only minor amounts may have been introduced from out­ side the bay. The leucoxene present is thought to be an alteration product of ilmenite. If Appendix F is examined an antithetic relationship is found between leucoxene and opaques which suggest that the former is a secondary derivitive. Smithson (9141) found a similar situation in the Triassic and Jurassic rocks of Yorkshire.

(e) Other Heavy Minerals: Andalusite, garnet and hornblende are probably from a metamorphic source, and the spinel, monazite and rutile from igneous rocks (table 5.4) and also from the surrounding sediments. This latter origin is the most probable since examination of the Permian rocks show traces of all these minerals in the heavy mineral concentrates. They are more common in the more silty rocks on the western shoreline of the bay but no correlation between these and the minerals distribution being biased to that side of the bay was noted. 193

7.73 Provenance Summary

There is no direct evidence as to the primary source of the heavy minerals in Jervis Bay.

The majority of species present, exceet authigenic, forms can be traced with fair certainty to the Permian sediments and parallel beach ridges around the shore line of the bay. To examine provenance beyond this is outside the scope of this thesis.

5.74 Discussion of Distribution Pattern

From examination of the Province Figure 5.6 and figures 5.7, 5.8 and 5.9 which zircon/tourma­ line ratios plotted geographically, against depth and against distance from the shore, it is clear that at least some "species" show a systematic variation. This results from a concentration of heavy minerals by wave action. Species not shown in the above figures are ubiquitous or occur scattered erratically over the area of the bay. No attempt is made in this study to explain the distribution of those species with an erratic distribution. i 9 4

FIGURE 5.7

ZIRCON / TOURMALINE | RATIO

JERVIS BAY N.SW. - ACT 195

From studying the distribution of zircon and tourmaline and relationships between these minerals the author attempts to isolate the source of the factors affecting sediment distribution and in particular those affecting the heavy mineral components. The zircon province is almost completely separate from the tourmaline province, the former occuring in more shallow water (less than 9 fathoms). Although this is not a clear cut relationship it is present and results from the inherent specific gravity difference between these two minerals (zircon

SG between 4.2 - 4.86), (tourmaline 2.98 - 3.2).

Because of this difference they will tend to concen­ trate in different energy zones. The differences in energies are due to differences in wave activity, more intense wave activity producing higher energy zones.

The sorting of heavy minerals according to specific gravity will also be influenced by the shape of the two minerals concerned, i.e. zircon and troumaline. The influence of shape is, however, unknown as quantitative studies on heavy mineral shapes have not been carried out. It can be stated 196

\ \ \ \\ \

\\x \

\. ' Y \

u I > » TOURMALINE

/

ZIRCON that there is a shape difference, usually having an elongated barrel shape, while tourmaline is generally platy or equidimensional. The significance of this difference would require more detailed study.

Although the zircon province exists in the bay down to a depth of nine fathoms, examination of a plot of zircon/tourmaline against depth shows this ratio to be independent of depth until 5 fathoms is reached (figure 5.8). The area less than 5 fathoms is within 500 yards of the shoreline for most of the bay and if the source of the heavy minerals is from the rocks and dunes surrounding the bay then this region of zircon/tourmaline independence from depth could be due to a mixing of a new material population with that of the bay. Only below 5 fathoms does the new population become sorted to conform with that exhibited by the bay as a whole. Another possible explanation is that figure 5.8 shows one curve of zircon/tourmaline ratio to be depth dependent, another depth independent. This depth independent curve occurs in the depth range of an intermediate water mass in the bay between 4 and 7 fathoms, (refer 196

ZIRCON/TOURMAIINE V's DISTANCE TROM SHORE

• • • # «

76

ZIRCON / TOURMALINE 199

Chapter 1, section 1.5). Hence it is possible that this water mass does not possess the properties necessary to sort the minerals as the ones above and below it do.

To explain the distribution of other minerals in terms of the above, is difficult. Epidote (S.G. 3.36) is close to tourmaline with respect to specific gravity and is more abundant in the central region of the bay but occurs in zones of high and low energy. Leucoxene (S.G. 3.2 - 4.5) is concen­ trated in the south-east corner of the bay and in Hare Bay. The former being an intermediate energy zone on the basis of zircon/tourmaline ratios and the latter being low to high. This non-conformity of leucoxene to the distribution with respect to specific gravity is probably due to a disequilibrium caused by its authigenic formation at different rates in different localities.

5.8 CONCLUSIONS

The distribution of heavy minerals in Jervis Bay reveals nothing about their source, but is controlled by the hydrological behaviour of

"species”. This behaviour is dependent on this specific gravity of the species and to an unknown extent on their shape.

Some minerals show no clear provinces within the bay and others do not conform to an expected distribution based on specific gravity.

This is possibly due to lack of sensitivity in counting procedures and broad grouping of species.

The provenance of the heavy minerals is confined to relict deposits in the bay and to the Permian sediments surrounding the bay. No introduction of sediment from outside the bay or its catchment is evidenced in the present sediment. 201

CARBONATE MATERIALS

CHAPTER 6 202

CARBONATE MATERIALS

6.1 Introduction

6.2 Laboratory Procedure

6.3 Distribution

6.31 Bulk Carbonate greater than 63 microns

6.32 Bulk Carbonate less than 63 microns

6.33 Mean Size of Carbonate Sand 6.34 Sorting of Carbonate Sand 6.35 Biogenic constituents 6.4 Durability of shell material in the marine environment

6.5 Carbonate Grain morphology

6.6 Discussion 6.61 Variation with depth 6.62 Geographic Distribution 6.63 Faunal influences 6.64 Mean size and sorting of Carbonates

6.7 Effect of Carbonate on the Textural Parameters

6.71 Mean size

6.72 Sorting values

6.73 Skewness and Kurtosis

6. 8 Summary 2G3

6.1 INTRODUCTION

Calcium carbonate in the marine environment occurs in two forms, calcite (hexagonal system) and aragonite

(orthorhomibic system). The former being the more common variety in Jervis Bay. The carbonate is an important factor in the sedimentary processes of the bay and effects the resultant sediment distribution.

6.2 LABORATORY PROCEDURE

The carbonate content of the sediments is examined from three aspects i. Bulk acid-soluble fraction ii. Size distributed acid soluble fractions iii. Descriptive carbonate count

Many methods of carbonate determination have been proposed,most employing the technique of measuring the volume of carbon dioxide evolved during the acid dissolution of the carbonate (Bien, 1952). Others are based on the titration of dissolved carbonate against a base (Link, 1966).

These methods were not followed because of the time and equipment involved. / - 204

The method adopted was simply to dissolve the carbonate from each tared size fraction in approximately

2N hydrochloric acid and decant the acid after one hour.

The samples were then washed, dried and weighed. The percentage of carbonate was calculated and tabulated.

The accuracy of this method was checked against the titration method and results were found to be within

+ 1%.

The mud fraction was treated as above except that before decantation the samples ;yere centrifuged to minimise loss.

6.3 DISTRIBUTION

6.31 Bulk Carbonate greater than 63 microns

The percentage of carbonate materials in the bay varies between 1.4% and 78.6%, in Currambeen Creek it is lower at 0.1% and is less than 12% on all beaches and absent from parallel beach ridges. The greater part of SOS

the bay is covered by sediment containing between 5% and

20% carbonate with areas of high concentration in high

energy zones (north and central entrance, off Murrays Beach)

and in areas of abundant faunal growth (east Darling Road,

off Captains Point, off Green Point and Vincentia Bay

and to a lesser extent at station 125). The percentage

of sand sized carbonate at each station in the bay is shown

in Appendix D, and the geographic distribution in Figure A 6.1.

6.32 Bulk Carbonate less than 63 microns

The percentage of the mud fraction consisting

of carbonate material varies between 12% and 90%. Figure

6.2 shows the percentage of carbonate mud to be lowest around

the margins of the bay and in the centre with regions of high concentration between. Areas which are comparatively rich in mud do not have the highest percentage of carbonate mud

(refer figure 6.3), however no correlation between percent

sand carbonate and percent mud carbonate is noted (refer figure 6.4) £06

FIGURE 6.1

% CARBONATE > 63 microns

JERVIS BAY N.S.W. - ACT 207

F ICiURI. 0.3

O v

'H

6 v..;

60 70

Mud 206

FIGURE 6.4

100

SAND CARBONATE Vs % MUD CARBONATE 7/o

Q Z < 50- to

0 50 100 MUD £09

6.33 Mean Size of Carbonate Sand

The average size of carbonates within the bay is 1.95(6. The geographic distribution is shown in figure 6.5. Areas of coarse carbonate occur in east Hare Bay, east Darling Road and in the entrance region. Areas of fine carbonate (i.e. less than 3.0(6) occur in Vincentia Bay and at station 125.

6.34 Sorting of the Carbonate Sand

The distribution of carbonate sorting is shown in figure 6.6. The carbonates are essentially moderately sorted around the margin of the bay and poorly in the central regions.

Areas of marked poor sorting are shown (i.e. standard deviation greater than 1.3(6 units) in figure 6.6.

Three of these correspond to areas of faunal growth, the other two, at Longnose Point and Bowen Island, to areas of high energy.

6.35 Biogenic Carbonate

The carbonate in Jervis Bay is made up entirely 210

FIGURE 6.2

% MUD CARBONATE

JERVIS BAY N.S.W. - ACT sea Miles 211

FIGURE 6.5

MEAN SIZE of the CARBONATE FRACTION

CONTOURS IN ♦

UNITS

JERVIS BAY N.S.W. - ACT FIGURE 6.6

CARBONATE SORTING

CONTOURS IN

UNITS

JERVIS BAY N.SW. - ACT 213

of biogenic debris. It consists of broken fragments of molluscs and echinoids with minor amounts contributed by other organisms.

The samples listed below* have been examined in detail and the relative contribution of each organism group to the biogenic carbonate mass noted. The results are shown in table 6.1 A and B. 6.1A shows the abundant and moderately abundant faunal remains and 6.IB the rare faunal remains.

Pelecypod remains are abundant throughout the bay, as are echinoid spines. Foraminifera are rare, but occur throughout the bay, and gastropods and worm tubes occur in moderate abundance throughout the bay.

Bryozoans, ostrocods and echinoid plates are more common in the regions closer to the bay entrance.

* Stations examined include: 6, 26, 33, 59, 64, 115, 125, 133, 163, 165. 214

TABLE 6.1 Table showing the variations of faunal remains between stations arranged successively further from the open-sea

Table 6.1A for abundant and moderately abundant remains

Stations Faunal Remains 33 59 6 64 115 26 125 163 165 133 Pelecypods A A AAA A AAAA Gastropods A M A AAM A Echinoid Spines M MM M MM A Worm Tubes M A M Bryozoa MM M M Echinoid Plates M M Foraminifera M M M Ostrocoda M

Table 6.IB for rare remains

Stations Faunal Remains 33 59 6 64 115 26 125 163 165 133 Foraminifera R R R R R R R Ostrocoda R R R Crustacea R R R R R Bryozoa R R Worm Tubes R R Echinoid Plates R R Gastropods R R Echinoid Spines R R Pelecypods R 215

Small living gastropods (Diala sp.)were found living

in abundance off the north end of Callala Beach and in east

Hare Bay. A variety of species are also found in Darling Road with some larger pelecypods, including Brachyodontes sp The most abundant form found living in the bay are small irregular echinoids which are more abundant in the central

portion, but present in most areas.

Many large undamaged forms are found on beaches after periods of more intense wave activity. They include the genera Ostrea, Pecten, Chlamys, Haliotis, Turbo, Brachyodontes, Polinices, Anadara, Glycymeris and others. It must therefore be assumed that these forms also live in the bay. Their distribution is however unknown as only Brachyodontes has been collected in grab samples.

6.4 DURABILITY OF SHELL MATERIAL IN THE MARINE ENVIRONMENT

The durability of shells under marine conditions depends on many interrelated factors. Besides the obvious mechanical abrasion and breakage of shells there are many other physical and chemical effects which influence the persistence of carbonate fragments. The physical characteristics of the organism and shell effects the durability. The relative rates of growth and destruction effect the rate of accretion or destruction. The actual structure of the hard parts of the animal control the shape and size of fragments derived from those organisms. Similarly the structure controls the length of transport which a shell etc. can undergo before its breakdown (Chave 1964) eg: bryozoans and echinoids will breakdown before massive pelecypods and gastropods. Again the relative thickness of the periostracum, prismatic layer and lamellar layer of pelecypods will control the shell’s resistance to breakdown.

Other effects which influence the rate of des­ truction and disintegration of carbonate include: the effects of boring organisms, the porosity of the interring sediment, the amount of decayed organic matter in the sediment and many others. Corrosion and solution of carbonates may occur where oxidation of organic remains produces carbon dioxide. This dissolved in water then attacks the carbonate. Similarly under reducing conditions shells may be bleached,etched and ultimately dissolved.

These effects have been noted in several areas in Jervis Bay, particularly where sea-weed grows in abundance (i.e. east Hare Bay and Vincentia Bay). A* 17

Hence the eventual amount and distribution of carbonate in Jervis Bay depends on the physico-chemical environment within the bay.

6.5 CARBONATE GRAIN MORPHOLOGY

The morphology of carbonate grains will depend on the organism from which it is derived. Also the sedimentary behaviour of these grains will also depend on their morphology. There is a significant difference between the morphology of carbonate grains and terrigenous grains.

The carbonate grains are either platy or elongate, the pelecypod, echinoid plates, some bryozoans, worm tubes and gastropods yield platy grains, each with different surface textures. The echinoid spines, gastropods, worm tubes and some bryozoans produce elongate grains, also with varying surface textures.

Complete organisms also behave differently to terrigenous sediment in the environment. hi to

The grains in carbonate mud are finely divided forms of the above, however many grains are more equant than above. A large proportion of the mud carbonate (up to approximately 20%) is made up of small (less than 0.05mm long) calcite rods, some with a small central capillary tube. They are often pitted on the surface and tapered.

Their origin is doubtful but are thought to be protozoan remains and not part of another organism (K.S.W. Campbell, pers. comm.)

6.6 DISCUSSION

The distribution, size and relationship between carbonate and terrigenous sediment will result from the interaction of various environment factors including depth, currents and waves, fauna, chemical activity and terrigenous material. An attempt to illucidate the effects of each factor independently is difficult.

6.61 Variation with Depth

No systematic relationship between percent carbonate and depth exist, except that beaches contain a low percentage 219

of carbonate material. The lack of carbonate is due mainly to the shape difference between the predominant quartzose beach sands and the carbonate grains. The rejection of carbonate grains by beaches results from the depositional processes operative on beaches (Moss, 1962). This results essentially from the different shape between quartzose grains and carbonate grains.

6.62 Geographic Distribution

Apart from faunal influences detrital carbonate (i.e. broken shall material) is distributed throughout the bay with local concentration and deficiencies. These local anomolies are related to local energy conditions and the deposition of carbonate depends on their stability under varying energy situations.

In high energy situations, i.e. strong wave and current activity, abundant carbonate material is collected.

This indicates that carbonate deposits (of a relatively large size,greater than 1$) are stable under these conditions. These areas contain relatively low percentages of terrigenous material (refer Chapter 3). 220

Areas of moderate energy (i.e. areas of shoaling waves) are relatively depleted of carbonate. These areas are on and near beaches which are subjected to frequent wave activity (Lambs Beach, Green Patch and Callala Beach and West Hare Bay). Similarly the majority of the northern end of the bay is depleted. This is probably due to wave activity or the winnowing activity of a seiche (refer Chapter 3).

In areas of low energy (i.e. deeper areas and areas protected from waves and currents) the amount of carbonates in the sediment is moderately high. This is due to the lack of current and wave activity, strong enough to concentrate or remove the carbonates.

The parameter responsible for this separation of carbonates into three zones is shape. The different shape of carbonate grains causes them to be unstable in the zone of moderate energy and they are rejected. The concentration in higher energy zones is the result of size and shape.

Size because only large particles are stable in high energy zones and only carbonates form particles large enough to be deposited. The influence of shape is not clear but 221

occasional pebbles of a similar size to the carbonate occur in the bay but are not concentrated in the highest energy zone. This is interpreted as being due to the shape difference between the carbonates and the pebbles.

6.63 Faunal Influences

Abundant faunal growth in certain areas increases the percentage of carbonate in the sediment.

The organisms present in these areas and in the bay in general are given in Section 6.34 of this Chapter.

The effect of complete organism in sedimentation is unknown except that burrowing forms will cause a sub­ stantial amount of bioturbation. However the effects of infaunal and epifaunal (Thorson, 1957) influences on sedimentation and carbonate distribution would require a detailed ecological study of the bay; this is outside the scope of this study.

6.64 Mean Size and Sorting of Carbonates

The mean size and sorting distributions of carbonates are shown in figure 6.5 and figure 6.6 respectively. 222

The mean size of the carbonates, as would be expected, follows that of the terrigenous material closely over the greater part of the bay, (refer figure 6.7)..This distribution results from the same energy distribution and hence although the percentage of carbonates present may vary with energy the size for the most part does not.

In areas of high concentration the mean size is slightly coarser than the terrigenous material in that area (refer figure 6.8).

The sorting co-efficientsof the carbonate sediments vary from 2.26 to 0.4^ units for the marine environment to 0.08^ on the beaches. This is a wider range than for the sediments and results primarily from faunal influences. The average sorting of carbonates in the bay is 0.89^ units which is also significantly larger than that for the terrigenous sediments (refer

Appendices A and D).

The poor sorting of carbonates results from their widely varying shape compared to terrigenous sediments. The areas of high carbonate content are also areas of poorest sorting, (refer figure 6.9). 23

FIGURE 6.7

RELATION BETWEEN MEAN SIZE

3- OF THE SEDIMENT & OF THE -L

CARBONATE FRACTION ' •

CD N

% o c T o _n oV— U c a i a;

Mean Sediment Size (4>) 2e* 2^ 4

FIGURE 6.8

MEAN CARBONATE SIZE V's % CARBONATE

JD

o\° 20

.-I- ' -;1 If) • t -j* ______r______i___ £.. 1 2 Mean Carbonate Size f•*>) 225

FIGURE 6.9

Sortingjinclading cnrbonate)_Vs %,jCarbonate.

Marin# Sampl*

••ach ••

A ••

$ B«ach Ridg« Sample

i uO as

. K

•♦uJ 0 3

Sorting (

The areas of moderate sorting are areas of continual wave activity and hence a continual winnowing and sorting.

6.7 EFFECTS OF CARBONATE ON THE TEXTURAL PARAMETERS

These effects are discussed in Chapter 3 and are here discussed only briefly.

6.71 Mean Size

The dilution of terrigenous material by carbonates in general causes an increase in grain size. This increase over all stations sampled is 0.076, however some stations show a much greater increase than this,and others less.

Figure 6.10 shows that as the percentage of carbonate in the sediment increases the difference in grain size between the sediment including carbonate and excluding carbonate increases. Hence the addition of carbonates for the most part causes an increase in grain size. Some points on the plot however represent decreases in grain size even although such sediments contain up to 39% carbonate. FIGURE 6.10

CARBONATE V'. DIFFERENCE IN GRAIN SI Zh OF SEDIMENT

INCLUDING 4 EXCLUDING CARBONAIE NEGATIVE DIFFERENCE * INCREASE IN GRAIN SIZE ON REMOVAL CARBONATE

T DIFFERENCE ♦ UNITS 226

6.72 Sorting Values

The poorer sorting exhibited by sediments including carbonates results from the bimodality caused by the addition of large percentages of carbonate to the sediment. This is most common in areas of high energy (i.e. central and northern entrance and Bowen Island Channel) and in areas of abundant faunal growth. The carbonate fraction which is present at any one station is on the average coarser than the terrigenous fraction (refer figure 6.7).

At all but two stations in the bay the presence of carbonate produces a relatively poorer sorting or produces no difference in sorting.

6.73 Skewness and Kurtosis

The presence of carbonates causes a slight increase in the area of the bay covered by sediments with a coarse skew. This is expected since the carbonates provide a mode slightly coarser than that of the terrigenous sediments in most cases (refer figure 6.7). Figure 6.11 shows that the higher the percentage of carbonate the more coarsely skewed the sediments. 229

FIGURE 6.11

SKEWNESS (including carbonate) Vs % CARBONATE

. Marin# Sample

.{. Beach ■■

* " Ridge Sample

H:

-0 5 Skewness (4> units) 230

The variability of kurtosis with the addition of carbonate is less clear than for other parameters. From examination of Appendix A and figures 3.11 it is suggested that the presence of carbonates causes more variability of kurtosis. However no systematic variation of kurtosis with the addition or removal of carbonates is apparent.

6.8 SUMMARY

The origin of carbonates in the bay is wholly biogenic and the types of carbonate present may be divided into two types; broken shelly material which forms the majority of the carbonate and faunal remains (i.e. whole shells, tests etc.).

The brokeishelly material is distributed and concentrated in differing concentration by currents and waves. Intense wave and current activity produces large concentrations of coarse material, moderate energy conditions reject shelly material and low energy conditions enable the concentration of moderate amounts of medium to fine carbonates. These differences in concentration are 231

attributed to the shape of the carbonates compared to the shape of the bulk of the sediment.

Faunal growth is abundant in certain regions and its presence causes changes in the textural parameters by its addition of a coarse mode to the sediments.

The effects of carbonates on sedimentation are, that by addition of a coarser mode to the sediment the sediments tend to be coarser, more poorly sorted and more coarsely skewed than they would be if no carbonates were present. 232

FORAMINIFERAL STUDIES

CHAPTER 7 233

FORAMINIFERAL STUDIES

7.1 Introduction

7.2 Laboratory Procedure

7.3 Distribution

7.31 Distribution, General

7.32 Sub-Order Distribution (a) Textulariina

(b) Miliolina

(c) Rotaliina

7.33 Species Distribution (a) Group A (b) Group B (c) Group C

7.4 Di scussion

7.5 Conclusions 7.1 INTRODUCTION

The study of foraminifera in Jervis Bay was

attempted with the purpose of establishing a reliable

indicator of sub-environments within the bay. To establish faunal groups restricted to a given area of the bay would provide a strong factor for definition of environments.

The study was restricted to examining foraminifera from 32 stations* spread such that the bay was adequately covered. The study of foraminifera from adjacent sample localities showed little variation and the 32 stations were widely enough separated to show some variation. Approx­ imately one in three samples were studied.

The foraminifera distributions were compared to distributions of other features of the environment (sediment, texture, depth, mud content, etc.) and any correlations observed noted.

* The stations from which foraminifera were studied are:

3, Ml, 6, 9, 12, 21, 26, 31, 33, 47, 52, 56, 59, 62, 65, 67, 73, 80, 89, 103, 107, 127, 130, 137, 144, 155, 159, 163, 165, 169, 207, 211; chosen to provide an even coverage of the bay. 235

7.2 LABORATORY PROCEDURE

Twenty grammes of sediment were wet-sieved on a 63 micron sieve to remove silt and clay. After sieving, it was boiled in a sodium carbonate solution for one hour or placed in an ultrasonic bath for 10 minutes to clean the foraminifera - the samples were then washed and dried.

The foraminifera were then concentrated by floatation, using carbon tetrachloride, the residue being dried and refloated to separate any remaining foraminifera.

Each sample was then examined and at least one specimen of each species from each sample was mounted and identified. The identification was made using Albani’s papers (1968, a and b). This was possible as all species found were described by him.

7.3 DISTRIBUTION

The distribution of species at stations is given in Table 7.1. From this table the species were grouped into their respective Sub-Orders and the distributions of the numbers of species in each Sub-Order is shown in Table 7.2. The distribution of total number of different species

from a 20 gramme sample is also shown in Table 7.2 The distribution of species in the bay showing their cut-off points with increasing distance from the sea is shown in

Table 7.3

7.31 Distribution - General

The total number of different species noted at any one station decreases slightly away from open sea conditions (refer Table 7.2). Hence other distributions noted in Section 7.32 will also tend to reflect this trend. A discussion of these distributions follows in Section 7.4 of this chapter.

7.32 Sub-Order Distribution

(a) Textulariina: The textulariinids are generally more abundant near the open sea and in areas directly affected by open sea conditions. (i.e. stations 12, 26,

56; refer figure 7.1).

(b) Miliolina: The miliolids are distributed uniformly throughout the bay with local concentrations at stations 2 37

FIGURE 7.1

% TEXTULARIINIDS

JERVIS BAY N.S.W - ACT 23o

TABLE 7.2

Showing the distribution of foraminifera sub­ orders in increasing distance from the sea. The percent­ age abundance is also shown, as well as number of species at each station.

1. Station numbers arranged in increasing distance from the sea

2. Number of species in Sub-Order Textulariina

3. Percentage of species in Sub-Order Textulariina

4. Number of species in Sub-Order Miliolina

5. Percentage of species in Sub-Order Miliolina

6. Number of species in Sub-Order Rotaliina

7. Percentage of species in Sub-Order Rotaliina

8. Total number of species at each locality

1 2 3 4 5 6 7 8

47 4 6.9 16 27.6 38 65.5 58

33 5 12.5 9 22.5 26 65.0 40

59 2 20.0 3 30.0 5 50.0 10

21 4 6.6 8 13.3 42 70.0 60

56 4 14. 8 3 11.1 20 74. 1 27

Ml 2 9.1 5 22.7 15 68.2 22

31 5 16.1 6 19.4 20 64.5 31

80 4 10.3 9 23.1 26 66.6 39

67 2 5.6 7 19.4 27 75.0 36

12 4 10.3 7 17.9 28 71.8 39 239

1 2 3 4 5 6 7 8

6 2 13.3 3 20.0 10 66.6 15

3 5 8.5 15 25.4 39 66.1 59

65 3 9.1 7 21.2 23 69.7 33

103 1 5.0 4 20.0 15 75.0 20

52 2 6.9 7 24. 1 20 69.0 29

89 2 4.5 9 20.5 33 75.0 44

9 2 6.6 5 16.6 23 76.6 30

130 3 6. 6 15 33.3 27 60.0 45

26 5 13.2 6 15.8 27 71.0 38

127 1 4.8 5 23.8 15 71.4 21

62 0 0.0 2 22.2 7 77.7 9

73 2 9.1 7 31.8 13 59.1 22

137 1 3. 4 7 24. 1 21 72.4 29

159 0 0.0 0 0.0 1 100.0 1

107 2 6.5 9 29.0 20 64.5 31

163 1 7.7 3 23.1 9 69.2 13

155 2 5.4 13 35.1 22 59.5 37

165 1 6.6 6 40.0 8 53.3 15

144 1 3.4 6 20.7 22 57.9 29

169 0 0.0 2 33.3 4 66.6 6

207 0 0.0 8 33.3 16 66.4 24

211 0 0.0 1 50.0 1 50.0 2 z 4 o

FIGURE 7.2

% MILIOLINIDS

JERVIS BAY N.S.W. - ACT sea miles 240

3, 47, 130 and 155. (refer Figure 7.2).

(c) Rotaliina: The rotaliinids decrease slightly

in abundance away from the open sea, however they are

relatively abundant throughout the whole bay. (refer Figure 7.3).

These distributions, as well as being affected by the distribution discussed in Section 7.31 will also

reflect the absolute abundance of foraminifera in the bay.

To avoid this the proportions of species in each Sub-Order (expressed as a percentage) are also shown in Table 7.2. The above distributions are based on proportional abundances at each statation.

7.33 Species Distribution

Table 7.3 shows the distribution of species with increasing distance from the sea. This table shows little variation throughout the bay and comparatively few species are restricted to isolated areas. The only species which occur in areas remote from "open sea effects” are Vertebralina

striata (Station 73), Peneroplis planatus and Massilina 241

FIGURE 7.3

°/ ROTALIINIDS 'O

JERVIS BAY N.S.W. - ACT o 42

secans tropicalis (Stations 130 and 144). Other species noted in Table 7.3 show a ’’first occurrence’’ at distances up to four miles from the entrance. Although their first occurrences are at such distances some localities at which they occur are subject to direct open-sea influences. (A fuller discussion of Table 7.3 follows in Section 7.4 of this Chapter).

The distributions of each species have been geographically plotted and these distributions grouped where distributions are similar. The distributions of these groups are shown on Figures 7.4, 7.5, 7.6 and 7.7, and their distribution compared to all other foraminifera occurrences is shown in Tables 7.1 and 7.3. Certain species show scattered distributions or distributions not common to any groups and are hence not included in any groups. Because some species are not included in these groups a comparison of the distribution maps of the groups will show an apparent absence of foraminifera from some regions of the bay. This is not so, foraminifera occur throughout the bay.

(a) Group A contains the following species ; 243 TABLE 7,1

Slat Ion No. 9 12 21 26 31 33 47 52 56 59 62 65 67 73 80 89 103 10’ 127 |30 137 155 15° 163 165 169 *07 <11 Haplophragwoldee canarlenele

T. porrecta T. paeudogramen T. aaggltula unti T~. s i phonl fera Caudryina quadrangular1a Splrolocul lna c.nil IcuUti S. COCTnunla S. antlllarum S. 1ucIda Qulnquelocul lna lamarcklana Q- «ng^tn« «r«Mt« Q. h»r«gvin»thf Q. coatacT 5"! paeudoretleulata 0. «trlata 0, aubpo'ygona Q. aetalnula aewlnula" jugoaa Vertebrallna atr lTta Haaalllna aacana troplcalla Ml 1lolInal 1 a labtoaa SI gaol 1lna auatralla Trllocullna oblonga T. atrlatotrlgonula T, alllnil T. tricarlnata T. trlgonula Fllntlna craaaatlna Pyrgo depreaaa Peneroplla planatua Cut tullna pact f lea C. lac tea

C. aeguemana Sigmoidal la elegantlaalaa Clobullna glbba globoaa Lentlcullna orblcularla L. renlforala L. llaboaa Amphlcoryna acalarla Vaglnullna vertebralla Lagana acuttcoata 1. gracllllaa l. flatulcnta" 1.. Implicate L. perluclda

L. eulcata pecullarla Oollna globoea

0. strltopunctata geaaa Planularla patens Flaaurlna faaclata carlnata F. lacunata Bollvlna alata

Splrllllna vlvlpara Bullmlnella elegantleelaa B. gracilis B. baelcostata Bullalnoldee wl11laaaonlanua Builmlna glbba B. marglnata ^atlnella lnconeplcua X X Reuaaella splnuloea Uvlgerlna baaacnala X X Chrysalldlnella dlaorpha Angulodlacorbla quadrangularle Clabratella pate 11 Iforate C. auetralensla Bagglna phi 11pp1nena1e Roaallna angllca XXX R. australis XXX R. berthelotl R. bradyl D1atorblnella olanoconcava Rota 1 la perluclda Dlacorbla dlmldlatue Armonla beccarll Pyoclblcldcs blaerlalla Clblcldea rofulgcns

Clblcldcl la varlabllle Cymbaloporctta bradyl Cloblaerlna bulloldea Cloblgcr1 no Idea conglobatua C. quadrllobatua sacclllfer C. ruber Clobquadrlna duteitrel Cloborotalla truncanoldea C. 1nf lat a C. hlreuta Orbullna unlvcrsa Sphaerold 1 no 1 la dehlecene Pullenlatlna ob1lqullocu lata Anoaallna nonlonoldca Elphldlua advenua E. cratlculatum E. dcpreaaulua

E. lmperatrlx

E. mlUettl E- lenseni E. poevanum F. , d 1 s c o 1 d a 1 c mu 1111 oc u 1 um E. maccllurn E. pap 11losum Nonlonc1 la aur la 244 7.3

2 3

5

8 9 10 11

13

13 16 17 18 19

21 22 23

25 26 27 28 29 n 32 33 34 35 36

38 39 40

42 43

45

•£47 48 49 50 31

53 54 55 36 57 58 59 60 61

63 64 65

67 68 69 70

72

74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

91 92 93 94 95 96 97 98 99 00 01 02 03

05

08 09 245

Guttulina regina ) ) Triloculina affinis ) ) A' Textularia candeiana ) ) Quinqueloculina seminula )

Ammonia beccarii ) ) Cibicides refulgens ) ) Glabratella australensis ) ) A" Triloculina oblonga ) ) Quinqueloculina striata ) ) Q. anguina arenata ) ) Cibicidella variabilis )

This group has been subdivided into groups A* and A” on the basis of marginal differences in this distribution. Both groups occupy the whole bay except for group A’, being absent close to the western shore line and group A" being absent around the northern shore line

(refer Figures 7.4 and 7.5).

(b) Group B contains the following species: FIGURE 7.4

GROUP A

JERVIS BAY NS.W. - ACT 247

FIGURE 7.5

GROUP A

JERVIS BAY N.S.W. - ACT sea miles 246

Elphidium peoyanum

Spiroloculina antillarum

Discorbis dimidiatus

Dyocibicides biseralis

This group is restricted to the northern half of the bay and a restricted zone close to the shore line in

Darling Road. Discorbis dimidiatus also occurs in a small area containing three samples to the south east of Plantation Point. (Refer Figure 7.6).

(c) Group C contains the following species:

Amphicoryna scalaris Gaudrydna quadrangularis Uvigerina bassensis Textularia pseudogramen T. porrecta

Bulimina marginata

This group is restricted to the southern half of the bay, except around the shore line from Sailors Beach south to Bowen Island. (Refer Figure 7.7.). 249

FIGURE 7.6

GROUP B

JERVIS BAY N.S.W. - ACT sea miles 250

7.4 DISCUSSION

The features of the physical environment that may influence the distribution of foraminifera in Jervis Bay are known to a limited extent. The sediment characteristics, bathymetry and meteorology affecting the sea conditions are known in detail. (Refer Chapters 3 and 1 respectively).

However, and perhaps more importantly no detailed hydrology and geochemistry is available. Thus the distribution of foraminifera can be only related to those parameters available which are, at best, of limited use. Phleger (1964) states that the only reliable approach to the problem is to con­ tinuously record hydrological environment parameters (including temperature, pH, salinity, dissolved oxygen). Phleger discusses depth as being significant as well as turbulence, however sediment type has, except in a very broad way, been shown not to greatly influence foraminifera distributions, (Phleger, 1964).

The total number of species present decreases with increasing distance from open sea. This trend is due in part to a relative decrease in turbulence from tidal currents and waves and changes in the salinity and 251

FIGURE 7.7

GROUP C

lr ’-5

JERVIS BAY N.SW. - ACT 252

dissolved gasses in the more restricted areas of the bay.

It may also be due to a decrease in food supply. These restricted areas are the north eastern quarter of the bay,

in the south easterly lee of Plantation Point and in

Currambeen Creek (Sample Nos. 73, 74, 85, 209, 210, 159, 167 and 169) and to a lesser extent Darling Road and

southern Sailor’s Beach (Sample Nos. 9, 26, 4, 3, 6, 7 and

10).

Local anomolies do occur, for example only 10

species are recorded from station 59 close to Point Per­ pendicular. This is exposed to open sea conditions and yet the number of species found is relatively lower than at stations further away from the entrance. In this case the lack of variety is attributed to the relatively coarse sedi­ ment (mean size including carbonates is 1.44?$), and to the continuous vigorous wave activity. Tidal currents are not as important here as in the central entrance region.

The distribution of Sub-Orders shows the text- ulariinids to be most abundant in the area of the bay sub­ jected to open-sea conditions, i.e. increased turbulence, wave and current activity and geochemical conditions (t>y 253

inference only). The other Sub-Orders are distributed evenly throughout the bay when considered as a percentage of the total number of species present. Any trends present in the absolute abundance of members of the three Sub-Orders are attributable to the variation in total number of species.

(See Table 7.2).

Table 7.3 shows the species distribution with increasing distance from the sea. All species except

Massilina secans tropicalis, Peneroplis planatus and Vertebralina striata have their first occurrence within four miles radius of the entrance to the bay. This corre­ sponds approximately to the 10 fathom bathymetric contour (Figure 1.6), hence most species have their first occurrence in at least 10 fathoms of water, however Group B (refer Section 7.33b of this Chapter) is mainly restricted to areas shallower than this. The remainder of points of first occurrence remain uncorrelated with any observed physical change in the environment.

The groups of species defined in Section 7.33 of this Chapter are not mutually exclusive, nor does each species included in these groups occur throughout the whole 254 area of the group. However, some generalized correlations between the groups and physical environments can be made.

Some reference is also made to occurrences of some species in other localities.

Groups A’ and A” occur in both deep water (20 fathoms) with high velocity tidal currents to relatively shallow water with negligible current and wave activity. Neither depth nor turbulence appear to affect this group.

Group A” occurs predominently in an area containing less than 1% mud as does Group A’. (Compare Figures 7.4 and 7.5 with 3.13. Both groups are absent from zones of shoaling waves in certain areas of the bay, namely between Sailors Beach and Huskisson for Group A1 and Callala Beach and Hare Bay beaches for Group A".

Albani (1968) found some of the species in Group

A' to exist in 3 of his 6 faunal groups in Port Hacking

(N.S.W.). These three faunal groups inhabit regions of deep (17 fathoms) and shallower water with both strong and weak tidal influence. All members of Group A are present in Port Hacking and all the species have also been recorded from the open sea along the east coast of Australia by various workers, (Collins 1958; Parr 1943, 1945; Cushman and Ozawa 1930). 255

Group B is restricted to an area of less than 10 fathoms in depth and further removed (3 miles) from the open sea than Group C and parts of Groups A’ and A". Phleger (1964) notes a distinct faunal break at between

7 and 10 fathoms which corresponds to the lower limit of intense wave-generated turbulence. Hence it is suggested that Group B is one which requires turbid water

and is restricted to such areas.

It is also noted here that Discorbis dimidiatus occurs in a more restricted environment in Jervis Bay and Port Hacking (Albani, 1968b) than it does off Victoria and South Australia. A.N. Carter (pers. comm.) states that this species in the latter occurrences is an open-sea form as opposed to its more restricted environment in N.S.W. waters.

Albani (1968b) recorded one species from Group B in his Faunal Group D. The species was Spiroloculina antillarum. It was found in water from 100 feet to 18 feet deep, the shallower areas being subjected to moderately strong tidal currents, however water movement in the deeper area was probably restricted. All other species in Group

B were also recorded by Albani but are not used to define 256 any of his Faunal Groups. Other workers (Chapman 1941; Parr 1943 and 1950) have recorded species in this group from shallow water off New South Wales, Victoria and South Australia.

Group C, unlike B, is restricted to an area which is for the most part deeper than 10 fathoms and subject to the direct effect of ocean swells, strong tidal currents in part and strong turbulence from waves along the western margin and in the area of Dart and Longnose Points. (These features of the environment are inferred from meteorological and sedimentological observations). No correlation between sediment character and the distribution of Group C is observed. It occurs on bottoms with up to 15% mud as well as in areas of very coarse sand and gravel.

Albani (1968b) found species from Group C to occur in his Faunal Groups D, E and F. These groups vary in environment from deep (100 feet) quiet waters with muddy sediment through shallow water with high velocity currents and sandy sediment to areas of 50 feet depth with varying turbulence. They are in general the Faunal Groups which are more subject to open sea conditions than those recorded by him higher in the Port Hacking estuary. This correlates closely with the findings in this study. 257

Species from Group C have been recorded from The Great Barrier Reef to Tasmania in relatively, shallow waters by Collins (1958), Parr (1943, 1945 and 1950).

An examination of Table 7.3 shows several members of Group B to occur within one mile of the entrance, but in general most occur over 2\ miles from the entrance. Those within one mile are isolated occurrences and not considered as part of that group on the basis of the dense concentrations

of members of that group in the areas shown in Figure 7.6. Those members of this group near the entrance are in an area of turbulent tidal currents and in this respect, although deeper than the area of major occurrence is similar to the shaded area of Figure 7.6, which is less than 10 fathoms and hence turbid due to wave activity.

Groups Af, A” and C distributions as shown on

Table 7.3 and Figures 7.4, 7.5 and 7.7 agree.

Most other species have a scattered distribution and fit none of the above groups. Their distributions show no correlation with the environment. £5 8

7.5 CONCLUSIONS

The foraminifera groups show little correlation with sediment characteristics, percent carbonate or with other features of the "bottom” (e.g. weed growth, rock outcrop). The only general correlation noted is the absence of Group A from areas devoid of mud.

Group A shows no relationship to depth, however in general Group B is restricted to areas less than 10 fathoms and Group C to areas greater than 10 fathoms.

Correlation with hydrological features of the en­ vironment are difficult as most information about these features is inferred. The correlations discussed with foraminiferal groups and turbulence are valid as the turbulence is reflected in sorting values, percentage carbonates and zircon/tourmaline ratios. The tidal currents in the entrance are also established from sedimentary

evidence. Salinity and temperature are, at least in the

southern half of the bay, normal oceanic in nature. 258

Correlations are evident between foraminifera and the environment, however it should be noted that, on the whole, the distribution is relatively uniform when compared to distributions found in estuaries (e.g. Albani 1968b). The distribution of foraminifera was found to be of little use in delineating sub-environments in the bay when compared with other features examined. 2

MUD FRACTION STUDIES

CHAPTER 8 MUD FRACTION STUDIES

8.1 Introduction

8.2 Laboratory studies

8.3 X-Ray pre-treatment and procedure

8.31 Unoriented samples

8.32 Oriented samples

8.33 X-Ray analysis

8.4 Results

8.41 Unoriented X-ray analysis

8.42 Oriented X-ray analysis

8.44 Microscopic examination

8.5 Discussion 262

8.1 INTORUCTION

The mud fraction of the sediments in Jervis

Bay makes up only a minor fraction of the sediment.

Over the greater part of the bay the percentage of mud

is less than 1% and areas containing a greater proportion than 5% mud occur off Sailors Beach, Vincentia Bay and southern Hare Bay, (refer figure 3.13).

Hence the mud fraction of the sediments, although present, is of relatively small importance. The average composition of the mud in the bay is 61 percent of carbonate material and only 39 percent is terrigenous material of which only 2 percent, or less, is composed of clay minerals.

8.2 LABORATORY PROCEDURE

The mud fraction was separated from the sand by wet sieving through a 63 micron screen. This fraction was then dried and weighed. The carbonate was then removed by dissolution in 2N hydrochloric acid for one hour. The remaining terrigenous mud was washed, dried and weighed, and the percentage of carbonate mud was calculated. 263

Analysis of the terrigenous mud was made by X- raying a randomly oriented mount of the mud. Selected samples were analysed for clay minerals by X-ray diffraction of oriented mounts.* Separate fractions of these same samples were then size analysed by a sedimentation technique to attain the texture of the mud fraction. The method used was the pipette analysis described in Folk (1968). Separate fractions of the above samples were also examined under the microscope and both the carbonate and terrigenous fractions described.

8.3 X-RAY PRE-TREATMENT AND PROCEDURE

8.31 Unoriented samples

Mud fractions of all samples in the bay were prepared for X-ray in unoriented (or random orientation) mounts. The dried mud was crushed to remove any grain

* These were made from samples which had high mud percentages - 9, 125, 137 and 97 264

aggregates present. The sample was then placed in a sample holder and the surface smoothed using a clean glass slide ready for X-raying.

8.32 Oriented samples

These were prepared from selected samples

to enable analysis of any clay-minerals present.

The mud was dispersed in distilled, de-ionised water and allowed to stand for 18 minutes. After this time only material of 15 microns and less remains in suspension. It was necessary to choose a fraction coarser than the normal 2 micron size to get a sufficient concentration of material for X-ray. A small portion of this material was then removed with a pipette and deposited on a clean glass slide which, after it dried, provided a well oriented clay and fine silt aggregate.

8.33 X-ray analysis

This was carried out using a Phillips X-ray diffraction unit coupled to a geiger counter and an electronic

arithmetic recorder. The samples were subjected to nickel 9 65

filtered cobalt radiation (co K - = 1.791) at 40KV and 20 mA. The same equipment was used for both oriented and unoriented samples.

8.4 RESULTS

The percentages of mud of both carbonate and terrigenous origins are given in Appendices A and D respectively. Also a brief discussion of the significance of these results are given in Chapters 3 and 6 respectively.

8.41 Unorientated X-ray analysis (63 microns and less)

All samples examined* contain more than 90% quartz (including sponge spicules and radiolaria). All the other minerals noted are present in minor amounts, mostly less than 1%. These include feldspar, muscovite, hornblende, epidote, tourmaline, zircon, garnet, chlorite aggregates (or weathered hornblende) and opaque minerals.

* Samples examined for terrigenous mud include: Ml, 3,

4, 6, 7, 9, 10, 12, 16, 18, 20, 26, 28, 30, 34, 47, 62,

64, 81, 97, 125, 137. 266

Appendix I contains details of these analyses. The

northern end of the bay contains higher percentages of

muscovite than elsewhere and also a greater amount of

clay minerals which include illite and chlorite. Otherwise the mud content over the bay is remarkably uniform.

8.42 Oriented aggregates

The 15 micron fractions show three major constituents, quartz, kaolinite and muscovite with lesser percentages of feldspar, heavy minerals and chlorite and illite, Little variation in content was noted between the four samples examined.

8•43 The size analysis

Four muds from stations 9, 97, 125 and 137 show a mean size between 4.76

8.44 Microscopic examination

Microscopic examination of the mud enables a notation of mineralogy and shape of the particles to be made. The two most abundant minerals present are biogenic

calcite and terrigenous quartz. Other minerals noted include zircon, tourmaline, garnet, feldspar, hornblende, opaque minerals, chlorite aggregates and biogenic silica.

The biogenic calcite is described in detail in Chapter 6. It consists of very fine shelly debris and

small calcite rods between 10 and 50 microns long of uncertain origin. These made up about 60 percent and 40 percent of the mud size carbonate debris respectively. The broken shelly material forms platy grains and the remainder are small rod shaped grains. The platy forms are moderately to well rounded.

The majority of quartz grains are single grains showing straight extinction and undulatory extinction (70%)

the remainder being composite grains (30%). These composite grains consist of very fine sub-grains with undulose extinction. The quartz grains are equant grains with an angular to sub-angular roundness. The biogenic silica 266

consists of particles up to 50 microns in size derived from sponge spicules.

The feldspar present is only in very minor amounts, less than 3% and is strongly weathered. They form small very well rounded grains. Much of the kaolinite present is probably the result of feldspar weathering, both in the Permian rocks and during transport.

The heavy minerals present (i.e. zircon, tourmaline, garnet, hornblende and opaques) are well rounded,except the garnets and to a lesser extent hornblende. No heavy minerals less than 20 microns have been observed. The chlorite occurs as aggregates between 10 and 15 microns in diameter.

8.5 DISCUSSION

Sedimentological aspects of the distribution of the mud and carbonate mud are discussed in Chapters

3 and 6 earlier in this thesis. This discussion is res­ tricted to the aspects of the provenance of the silt and clay.

The muds are composed essentially of two coarse 269

silt-sized components, quartz and calcium carbonate. The

former is from a detrital source and the carbonate is of

biogenic origin, the remainder of the components are of

detrital and possibly authigenic origin.

The quartz is primarily derived from the Permian siltstones and sandstones forming much of the coastline

of the bay. These Permian sediments contain quartz in the

silt size range (as well as other sizes) while the relict sediments which provide the majority of the sand sized sediment contain very little material in the silt size range,due to its removal by continued reworking of these sediments.

The feldspar present in the muds is also primarily derived from the Permian sediments around the bay, (refer Section 1.3). Feldspar content in relict sediments at Callala is low compared to that of the Permian

sediments. This is due to abrasion of the feldspar during reworking and removal by weathering whilst in the beach ridges.

The heavy minerals are derived from both relict 270

sand deposits and Permian sediments. They are a similar suite to those present in the sand fraction in the bay.

The heavy mineral provinces discussed in Chapter 5 are not reflected in this distribution of heavy minerals. This is due to the limited number of samples examined, however it is expected that a fuller examination would yield results similar to those expressed in Chapter 3.

The chlorite aggregates may originate from the Permian sediments or be formed by diagenesis in the bay.

Grim (1953) states that chlorite material appears to develop from kaolinite in the marine environment. He states it is not known exactly how varying geochemical conditions effect these diagenetic processes. It is presumably related to the oxidizing conditions present and to the ionic composition of the sea-water. Grim also states that this process is most likely to occur near shore, as kaolinite must have a terrigenous source; this latter statement applies in Jervis Bay.

It is concluded that the greater part of the terrigenous mud fraction is derived from the Permian sedi­ ments flanking the bay (and to a lesser extent from those in the catchment) with very little contribution from relict Flio-Pleistocene sand deposits. The carbonate fraction of the muds is derived entirely from a biogenic source. CONCLUSIONS

CHAPTER 9

(ENVIRONMENTAL ANALYSIS,CLUSTER TECHNIQUES) 273

CONCLUSIONS

(ENVIRONMENTAL ANALYSIS, CLUSTER ANALYSIS)

9.1 General

9.2 Method

9.3 Data

9.4 Results

9.5 Discussion 274

9.1 GENERAL

The data in the foregoing chapters was collated by cluster analysis to elucidate significant parameters which delineate environments and sub-environments within the bay. Purdy (1963) successfully used a cluster analysis to represent relationships between the sedimentary con­ stituents on the Great Bahama Banks. Rhodes (1969) also used a similar technique to map granites. Crook et al.,

(in prep.) has applied similar techniques to mixed quantitative and qualitative data to solve stratigraphic problems. Veevers (1968) has used the technique to identify limestone reef facies. It has also been applied successfully to studies of plant ecology and land use

(Williams et al., 1966).

9.2 METHOD

Cluster is a form of cor relation analysis (i.e. searching for relationships in a large symmetrical matrix).

It is a simple, logical, pair by pair comparison of individuals, groups, etc. The results are presented in a two dimensional hierarchial diagram (dendrogram), on which natural breaks between groups are obvious.

Measures of similarity between samples are of two types:-

i. Those that are essentially metric in origin, and ii. Those that are primarily probabilistic. (Sokal

and Sneath, 1963, Williams et al., 1966, Harbaugh and Merriam, 1968).

The programme MULTBET (Lance and Williams, 1967) allows the use of either type of similarity measure. The measure used in this analysis was probabilistic, the inform statistic of Lance and Williams (1967), which is given by:-

A i = Z (ig (2 x.h + xjh)) - ig (z: x.h) - ig (Ujh) - Z (ig (xih + xjh)) ♦ £ (ig(xih) + 2 (ig(xjh)). whereZlI : information gain

q: number of attributes

i and j are groups

Xih and Xjh are the number of individuals in the h th state of an m state attribute, and lgX = x log^x

and is used because the groupings are made on original

data. No averaging or sorting occurs which may distort the results when a metric similarity measure is used. Similarly the plant ecology studies have achieved best results using the information statistic.

Consider the fusion of two groups X and Y. The individuals which have a number of ordered multistate* attributes A, B, ....N. Assume attribute A can occur in any of m states. Then to determine what contribution this attribute makes to the total-A I of the fusion the following procedure is adopted. A 2 times m table is constructed,

* Ordered multistate (Lance and Williams, 1967) - "These characters must be able to exist in more than two states, such that the states are ranked - i.e. the extreme states are considered as being more different than any other pair") 277

TABLE 9.1

An example of fusions strategy ordered for multi states, and the necessity of 3 states to be present to get an ordering effect from the fusion

Three Individuals A, B and C with at least 3 different

states present

12345 states

Then an A - B combination yields 4 2x2 contingency tables

2 to 5 , 1+2 3 to 5 , 1 to 3 4+5 , 1 to 4 5 states

A

B

AB. AB. 276

And similarly B-C yields

And AC

AC, AC. AC, AC

And for each of these tables the AI value is calculated

A IAI2 = 4 log 4-2 log 2 = Ai

A I AB^ = 0 + ai

A T ^ = 0

A I, 4 log 4-4 log 2 = AI BC0 = A ibc. ^e ^e 34

‘^IAC1 = 4 loge4 ' 2 loge2 - 3 loge3 = AIAC 279

A XAC3 = 41oge4 - 41°9e2 = ^XAC4

Since the largest I value is selected as the contribution of an attribute to the fusion

a I = 41og 4 - 21og 2 - 31og 3 AB ^e e e 4>Ibc = 41oge4 - 41oge2

AIac = 41oge4 - 41oge2

And since the smallest a I is chosen from the similarity matrix of AI values to effect a fusion of individuals A and

B are combined.

By similar reasoning the following three fusions of the three individuals X, Y amd Z have the same a I value (21oge2) because only two states are present in any one fusion.

X 1 0 0 0 0

Y 0 1 0 0 0

Z 0 0 0 0 1 280

A IXY 21oge2 ^ IyZ ^ IXZ

It is obvious that to gain maximum use from the ordering at least three states must be present in any fusion. FIGURE 9.1

DENDROGRAM FOR SAMPLES FROM JERVIS BAY

Low-order groups show sample numbers as in figure 1.3. Higher group numbers are assigned by the computer.

178

170 168 169 58,3,7, 34 4,300, 95B 210, 1328,25 1528, 95C, M3 159,Ml, 33 95A,206,14 200,209, 50 165 I67A, I 25 1678, 6I.I52A 35,44,127,123 160 47, 133, 20 99, 89,129, 54 158 130,80, 72,M2 148,115,56 31, 30, 67 169, 113,121,91 153 78,42, 12 59,46,105 J65 153,87, 97 103, 101,139 150, 137 149 52,28,10 64 163,109, 62 141, 93 155, 85 9,18,6 132 A,74 146, 40 157,26 107, 16 144 ■>/sz

showing in row 1 the frequency of occurrence of each of the m states for group X and in row 2 similar frequencies for group Y. This table is then divided into two tables, the first division separating the frequencies in state 1 from those in states 2, 3, ....m. The processes are repeated to separate states 1 and 2 from 3, . ...m and so on until, in the last case, one table has states 1, 2, .... m-1, and the other contains only m. The frequencies over all states in each row of each of these m-1 pairs of tables are summed and m-1 2 times 2 tables result. The A I for each table is calculated (example in Table 9.1) and the largest value selected as the contribution of this attribute to the fusion. These values (i.e. largest A ITs) are made into a matrix of similarity.

Some data may be missing. Thus identical inform­ ation gains may be associated with different amounts of data, i.e. with different degrees of freedom. Lance and Williams (1967) consider the measure:-

i i 0 = 2( AI)i2 - (2v - l)2 (where v is the number of degrees of freedom) to be acceptable for comparing inform­ ation gains with different degrees of freedom. This implies FIGURE 9.2

CENTRAL GROUP

(178) P*

JERVIS BAY N.S.W. - ACT sea miles 284

that, with identical information gains, those individuals

and/or groups with missing data will have a higher 9 and

hence be grouped later.

The intrinsic ordering in an ordered multistate attribute does not influence the fusions until at least

three different states of the attribute are occupied

(example in Table 9.1).

The similarity matrix is searched for the lowest AI value and the two individuals associated with it are fused, subject to the consideration of the number of degrees freedom. The A I is then computed for this new group when compared with all other individuals and/or groups.

The smallest A I is again selected and individuals and/or groups combined. This continues until no more fusions are

possible and a complete dendrogram is provided (refer Figure 9.1).

A diagnostic programme - GROUPER (Lance and Williams et__aT. , 1968) was used to interpret the last 10 groups formed by MULTBET. GROUPER accepts the original data used in MULTBET, the definition of the appropriate MULTBET groups FIGURE 9.3

MARGINAL GROUP (175) JUI

JERVIS BAY N.S.W. - ACT 286

and a statement of the group comparisons required. The output comprises a listing of attributes of the groups in order of decreasing difference between the groups concerned. It also produces attribute-means for each group in the re­

quested comparison, the number of known individuals on which the mean is based, and the numerical contribution of

the whole attribute to the measure selected, in this case

the information statistic (e.g. Table 9.2).

9.3 DATA

Ninety samples from the floor,beaches, beach ridges and creeks of Jervis Bay were considered, each characterised by 20 attributes. A larger number of attributes were available for use. Only those thought to be of environmental significance were chosen. They include:-

mean size ) ) sorting ) of the sediment, ) skewness ) including carbonates ) kurtosis ) 237

TABLE 9.2

Summary of Differences on 20 attributes between the Marginal and Central Environments

Attribute Marginal* Central0

Sorting of Carbonate 0.715(44) + 1.055(43)

Depth 4.086(56) 8.420(44)

Distance from Shore 0.470(46) 1.005(44)

Sorting of Terrigenous Fraction 0.434(46) 0.565(43)

Sorting of Total Sediment 0.486(46) 0.687(44)

Mean Size of Total Sediment 2.440(46) 2.107(44)

% Mud 1.621(46) 6.331(43)

Mean Size of Carbonates 2.187(44) 1.688(43) is Kurtos/of Terrigenous Fraction 1.132(46) 1.130(43)

% Carbonates 9.724(46) 18.527(43)

Mean Size of Terrigenous Fraction 2.453(46) 2.235(43)

Skewness of Terrigenous Fraction -0.010(46) -0.027(43)

Kurtosis of Total Sediment 1.152(46) 1.190(44)

Zircon/Tourmaline Ratio 0.567(30) 0.474(30) 288

* Attribute Marginal “ Central0

Skewness of Total Sediment -0.121(20) -0.103(26)

% Zircon 8.773(30) 7.253(30)

% Tourmaline 19.597(30) 19.467(30)

% Epidote 17.833(30) 15.663(30)

% Opaques 25.690(30) 26.383(30)

% Leucoxene 50.967(30) 53.723(30)

* Marginal group includes 46 samples

o Central group includes 44 samples

+ Represent the mean values for the number of

samples for which this attribute is recorded

in order of decreasing difference. The number

recorded is shown in brackets FIGURE 9.4

GROUP 176

JERVIS BAY N.S.W. - ACT 290

mean size ) ) sorting ) of the terrigenous ) skewness ) fractions only ) kurtosis )

percent mud

percent carbonate

mean size of carbonates

sorting values of carbonates

% zircon

% tourmaline % epidote

% opaques % leucoxene zircon/ tourmaline ratio depth

distance from shore .

These are all numerical. The information statistic is unable to handle such data, hence they were converted to 8-state ordered multistates.

Class divisions or divisions between states were made at natural or equal range points in the data, depending 291

FIGURE 9.5

GROUP 170

JERVIS BAY N.S.W. - ACT 292

on the nature of the data. This tends to normalize the attributes so they are compatible, one with another.

9.4 RESULTS

The cluster analysis (Figure 9.1) shows the last

9 fusions. At least two broad groups (178 and 175) and several sub-groups are apparent.

The two major groups represent deposits of a marginal environment and a central environment whose areal relationships are shown in Figures 9.2 and 9.3. The signif­ icant difference between these environments is in their sorting (Table 9.2), the marginal sediment being moderately sorted and the central poorly sorted. This applies similarly to the total sediment and the terrigenous and carbonate fractions. Depth and distance from shore are important in defining these environments, although they have no direct bearing on the sedimentary character of the environment. The central region contains more mud than the marginal; however the mean size of the total sediment is coarser in the centre as are the carbonates. FIGURE 9.6

GROUP 165

JERVIS BAY N.SW. - ACT 294

A more detailed analysis yields some significant sub-environments. Group 176 (Figure 9.1) is confined to the south west of Callala Point and Vincentia Bay (Figure 9.4).

It is essentially a fine grained sand high in mud. Of secondary importance in defining this sub-environment is the relatively better sorting of all fractions of the sediment and a moderate carbonate content.

Group 170 (Figure 9,1) is essentially marginal (Figure 9.5), although grouped with the central samples. This is due to its poor sorting and high carbonate content. This group is distinctive in its high percentage of coarse poorly sorted carbonate.

Group 165 (Figure 9.1) represents a third distinct sub-environment within the central environment. It is res­ tricted to the central part of the northern end of the bay (Figure 9.6) and is most distinctive of all groups on the dendrogram (Figure 9.1) having better sorted terrigenous and carbonate fractions than most other groups. It is also low in carbonate and both the sediment as a whole and the terrigenous fractions are fine grained.

Within the marginal group (175) only one sub-group FIGURE 9.7

GROUP 169

m marine x beach o dune c creek

JERVIS BAY N.S.W. - ACT 296

(169) is definable, comprising essentially beach, beach ridge, creek and near shore samples (Figure 9.1). This sub-group contains slightly coarser sediment and a coarser better sorted carbonate fraction than other marginal areas. It represents a shallower nearer shore environment than other groups (Figure 9.7).

9.5 DISCUSSION

To achieve a favourable classification the attributes chosen should be mutually independent and this is rarely the case in geological data. Attributes which are dependent cause a "weighting” and hence produce a biased classification. However all the attributes must be used to isolate those of significance in defining en­ vironments. No direct method of assessing a weighting of this nature is available.

The significance of the classification may be assessed by the geological meaningfulness of the results, by comparison with a "subjective" assessment of the data and by its correlation with other criteria external to the analysis. No effective statistical test of significance is available to verify the results (Parks, 1966). 297

The results of the cluster analysis and a subjective analysis by the author are similar and both are geologically meaningful. The groups also conform to the external criteria of areal coherence. Hence the resultant classification is considered valid.

Cluster and subjective analyses of the marginal and central environments show the importance of sorting in defining them. Similarly, both analyses show the centre to be high in mud and carbonate and of finer grain size

(refer Chapters 3 and 6). Only the subjective analysis showed the zircon/tourmaline ratio to be an important distinction. Such differances may result from a weighting of such attributes as sorting and mean size. For example, the total sediment sorting is related to the sorting of the terrigenous and carbonate fractions, hence its inclusion adds weight to sorting in the analysis.

Sub-environments isolated by the cluster analysis

(Section 9.4) are, in general, similar to those identified by subjective analysis (Chapters 3, 5 and 6). These groups in both analyses are based on local variations in attributes

For example, group 176 is rich in mud with a fine grain size o

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SHEPARD, F.P., CURRAY, J.R., NEWMAN, W.A. , BLOOM, A.L., NEWALL, N.D., TRACEY, J.I. andVEEH, H.H., 1967; Holocene changes in sea level: evidence in Micronesia. Science, 157, 542-544

SMITHSON, F., 1941; The alteration of detrital minerals in the Mesozoic rocks of Yorkshire. Geol. Mag., 78, 97-112.

S0KAL, R.R. and SMEATH, P.H.A., 1963; Principles of numerical Taxonomy. Freeman, Lond., 359 p.

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APPENDIX A.

Statistical Parameters of Sediments in Jervis Bay 1. Station number 2. Mean Size including carbonates 3. Mean Size excluding carbonates 4. Sorting including carbonates 5. Sorting excluding carbonates 6. Skewness including carbonates 7. Skewness excluding carbonates 8. Kurtosis including carbonates 9. Kurtosis excluding carbonates 10. Sand/mud ratio including carbonates

1 2 3 4 5 6 7 8 9 10

Ml 1.02 2.00 1.54 0.76 -0.60 -0.02 0.87 1.01 465

M2 2.31 2.38 0.52 0.48 -0.90 -0.23 1.12 0.80 1410

M3 1.81 1.83 0.51 0.44 -0.29 0.26 0.74 0.55

3 1.71 1.65 1.43 0.88 -0.07 1.25 0.93 40

200 2. 22. 2.26 0. 30 0.28 -0.24 -0.03 0.88 2.48

30C 2. 20 2.20 0.30 0.30 -0.18 -0.18 0.82 0.82

4 2. 21 2.21 0.40 0.40 0.26 1.15 1.14 328

6 2. 11 2.01 0.76 0.65 0.21 1.51 1.37 8.7

7 2. 18 2.39 1.23 0.57 -0.14 2.19 1.02 28.5 3 i.o

1 2 3 4 5 6 7 8 9 10

9 2.71 2.69 0.78 0.72 0.08 1.02 1.39 2.9

10 2.56 2.47 0.75 0.63 0.09 1.53 1.53 1.75

12 2.49 2.41 0.69 0.60 0.24 0.93 0.93 10.6

14 2.55 2.57 0.35 0.32 -0.15 0.90 0.81 1832

16 2.57 2.48 0.67 0.51 0.05 1.52 1.16 5.7

18 2.73 2.69 0.71 0.57 0.34 1.06 1.31 7.7

20 2.58 2.58 0.43 0.41 0.02 1.12 1.12 177 i ON 25 1.92 1.93 0.43 0.43 o o 0.86 0.86

26 2.91 2.91 0.68 0.63 -0.25 0.99 0.87 3.9

28 2.35 2.33 0.62 0.58 0.04 0.98 1.36 16.7

30 2.42 2.42 0.54 0.48 -0.03 1.36 1.17 68

31 2.43 2.44 0.48 0.46 0.10 1.14 1.13 233

32 -0.23 0.17 1.46 1.47 0.33 0.93 0.73 1822

34 0.513 1.07 1.41 1.06 0.27 0.87 1.39 491

AC 1.891 1.90 0.53 0.49 -0.004+0-08+ 0.84 0.73 160

+ A2 2.40 2.41 0.59 0.56 -0.006+0-002 1.01 1.47 12.1

A A 1.93 1.95 0.49 0.47 0.07+ 0.06+ 1.07 1.06 387 1 2 3 4 5 6 7 8 9 10

46 1.18 1.57 0.70 0.71 0.45 1.56 0.98

47 2.70 2.71 0.42 0.40 -0.16 1.22 1.19 236 + + o o o O 50 2.59 2.58 0.76 0.74 0.97 0.96 49.6 +

52 2.38 2.38 0.56 0.52 o o 0.02 + 1.04 1.49 14. 8

54 2.20 2.22 0.42 0.39 -0.15+ -0.12+ 1.23 1.24 327 ‘ +

" C 0 o + 1 1 M O' 56 1.69 1.82 0.65 0.49 o 1.29 1.01 623 * + 1 — 1 o 58 -0.64 1.42 1.90 0.63 o -0.12+ 0.72 1.78 108

59 1.44 1.57 0.54 0.40 -0.002+ 0.14 + 1.46 1.14

61 2. 34 2.35 0.40 0.40 0.11 1.00 1.00

62 2. 86 2.86 0.54 0.53 -0.16 0.75 0.75 90.8

64 2.47 2.47 0.61 0.60 0.03 1.53 1.51 10.0

67 2.42 2. 52 0.41 0.33 -0.03+ -0.02+ 0.99 0.95 172

72 2.46 2.47 0.54 0.53 -0.03 1.33 1.32

74 2.70 2.74 0.58 0.33 0.04 1.98 1.02 106

76 Rock + + i J to to O o o o 78 2.42 2. 42 0.56 0.55 • 1.38 1.36 49 + M o 80 2.34 2.35 0.45 0.40 -0.11+ o 1.29 2.27 483 3 2 0

1 2 3 4 5 6 7 8 9 10

85 3.21 3.31 0.57 0.57 -0.39 1.51 1.63 13.3

87 2.67 2.67 0.48 0.44 -0.06 1.31 1.13 785

89 2.24 2.30 0.49 0.48 -0.11+-0.11+ 1.16 1.16 445

91 2.24 2.24 0.38 0.38 -0.10+-0.10+ 1.21 1.21

93 2.47 2.46 0.57 0.49 -0.02+ 0.08 1.35 1.15 72

95A 2.37 2.37 0.40 0.40 0.04 2.18 2.19

95B 2.25 2.25 0.32 0.32 -0.02 2.30 2.31

95C 2. 17 2.17 0.39 0.39 -0.07 1.09 1.08

97 2.79 2.79 0.52 0.51 -0.06 1.13 1.13 48

99 2.36 2.36 0.46 0.46 -0.l0+-0.09+ 1.21 1.20 279

101 2.19 2.20 0.39 0.39 -0.13+-0.12+ 1.14 1.14 296

103 2.17 2.17 0.41 0.40 -0.13+-0.12+ 1.12 1.11

105 2.02 2.20 0.70 0.55 -0.26+-0.26+ 1.62 1.83 304

10? 2.40 2.44 0.59 0.50 0.03 1.00 1.14 148

1 1 + + 1 1 — h- 00 t o o 109 2.37 2.37 0.48 0 o 0 0.80 0.78 306

113 2.18 2.19 0.40 0.40 -0.11 + -0.n + 1.12 1.12 800

115 1.90 1.95 0.66 0.55 -0.l0+-0.02+ 1.02 1.21 99

1 21 2.18 2.18 0.43 0.42 -0.09+-0.08+ 1.10 1.10 415 3 Z1

1____ 2 3 4 5 6 7 8 9 10

123 2.07 2.07 0.49 0.49 0.09 -0.09 1.09 1.09 169

125 3.37 3.54 0.60 0.39 -0.12 0.23 1.54 1.16 6.1

127 2.05 2.06 0.50 0.05 -0.10+ -0.10+ 1.06 1.06

129 2.06 2.17 0.52 0.43 -0.09+ -0.09+ 1.09 1.09 178

130 2.31 2.37 0.55 0.38 -0.22+ -0.02 1.71 2.39

132A 2.80 2.82 0.48 0.46 0.12 1.20 1.17

132B 2.66 2.67 0.40 0.40 -0.09 1.11 1.11

133 2.57 2.57 0.43 0.42 0.08 + 0.08+ 1.16 1.15 33.2

135 2. 32 2.32 0.53 0.52 -0.12+ -0.12+ 1.10 1.11 113

137 2.97 2.97 0.76 0.69 0.06 0.03 0.96 0.85 11.7

139 2. 12 2. 18 0.58 0.57 0.04 -0.06 1.10 1.10 152

141 2.32 2.33 0.48 0.46 0.01 0.02 1.23 1.23 220

144 2.32 2.23 0.79 0.79 0.05 + 0.17 + 0.86 0.89 27.5

146 1.83 1.84 0.52 0.50 0.03 0.08 0.78 0.76 431

1 48 2.29 0.48 -0.10 1.15

1 50 3.04 3.07 0.60 0.51 -0.20+ -0.12+ 1.32 1.07 8.1 1_____ 2 3 4 5 6 7 8 9 10

152A 2.35 2.35 0.41 0.41 0.03 1.00 1.00

152B 2.19 2.19 0.37 0.37 -0.17 1.08 1.08

153 2.78 2.78 0.51 0.50 0.03 -0.10 1.10 1.08 435

155 2.89 2.90 0.58 0.58 -0.32 0.86 0.84 149

157 3.04 3.05 0.61 0.60 -0.21+ -0.20+ 0.91 0.90 36

159 2.02 2.20 0.83 0.42 -0.09 2.18 1.13 258

163 2.85 2.85 0.51 0.50 -0.04 0.79 0.79 113

165 2. 17 2.33 0.76 0.53 -0.10 1.53 0.79 1595

167A 3. 17 3.17 0.32 0.31 -0.10 0.82 0.78

167B 2.92 2.93 0.41 0.41 0.03 0.93 0.93 9710

169 2.20 2.20 0.40 0.40 -0.10 1.19 1.19

206 3.18 3.21 0.33 0.26 -0.32 -0.26 0.88 0.62 470

209 1.75 1.86 0.77 0.64 -0.04+ 0.03+ 1.03 0.90

210 1.69 1.69 0.42 0.41 -0.08+ -0.08+ 1.11 1.10

+ Calculated by computer - other skewness results calculated by graphical techniques APPENDIX B.

This appendix contains a summary of the meteorological data for Jervis Bay between 1960 and 1964. The raw data was

supplied by the Commonwealth Bureau of Meteorology, Melbourne and was condensed by the author.

Wind Direction in Jervis Bay between 1960 and 1964

i. 0900 hours - total number of observations 1745

ii. 1500 hours - total number of observations 1823

Direction i. ii

Calm 54 30

NNE 108 173

NE 84 337

ENE 9 46

E 22 57

ESE 10 26

SE 109 214

SSE 92 154

S 204 250 ssw 105 83 sw 122 54 Direction i. ii.

wsw 34 11 w 100 110

WNW 94 74

NW 379 115

NNW 65 14

N 154 75

1745 1823

B2 Summary of the state of the sea in Jervis Bay between

1960 and 1964

0 Calm (glassy)

1 Calm (rippled)

2 Smooth (wavelets)

3 Slight

4 Moderate

5 Rough

6 Very rough

i. 0900 hours observations

ii. 1500 hours observations n-i

State of the Sea i. ii.

0 1 2

1 145 133

2 465 538

3 734 977

4 164 176

5 81 86

6 17 21

1610 1933

B3 The swell direction in Jervis Bay between 1960 and

1964

i. 0900 hours observations

ii. 1500 hours observations

Swell direction i. ii.

No swell o 0

NE 5 6

E 390 381

SE 959 922

S 460 459

SW 0 3 w 0 0

NW 0 0 326

Swell direction i. ii.

N 1 1

No information 2 1

1817 1773

B4 State of swell at Jervis Bay between 1960 and 1964

o No swell

1 Low swell, short or average length

2 Long low swell

3 Short swell, moderate height

4 Average swell, moderate height

5 Long swell, moderate height

6 Shore heavy swell

7 Average length heavy swell

8 Long heavy swell

i. 0900 hours observations

ii. 1500 hours observations m

State of the swell i.

0 1 0

1 414 400

2 789 757

3 266 286

4 222 217

5 70 217

6 44 41

7 9 8

8 2 1 326

APPENDIX C.

Showing the sediment type based on percentage

of sand, mud and carbonate.

Station Sediment No. (1) Sand (2) % Mud (3) % Carbonate(4) Type*

3 45.7 0.9 53.4 SC

4 96.1 0.13 3.77 S

6 55.9 3.38 40.7 CS

7 65.6 1.1 33.3 cs

9 26.4 14. 25 59.35 SMC

10 27.3 16.7 56.0 SMC

12 74. 9 5.3 19.8 CS

14 56.35 0.015 23.635 CS

16 77.1 4.5 18.4 CS

18 53.6 8.6 37.8 CS

20 82.9 0.17 16.09 CS

26 64. 1 21.7 14.2 MCS

28 76.99 3.39 19.62 CS

30 85.66 0.64 13.7 CS

31 87.2 0.12 12.68 CS

33 54.75 0.02 45.23 CS

34 60.5 0.1 39.4 CS

40 95.3 0.2 4. 5 s

42 72.3 4.0 4.5 s

44 90.9 0.16 8.94 cs 329

(2) (3) (4) 1

46 70.4 Nil 29.6 CS

47 82.07 0.16 17.77 cs

50 92.29 0.73 6.98 s

52 81.25 3.38 15.37 cs

54 86.8 0.15 13.05 cs

56 84. 1 0.6 15.3 cs

58 20.47 0.46 79.07 sc

59 85.0 Nil 15.0 cs

62 90.57 0.32 9.11 s

64 78.2 6.46 15.34 cs

67 87.52 0.29 12.19 cs

74 87.46 0.30 12.24 cs

78 91.8 1.0 7.2 s

80 91.3 0.1 8.6 s

85 64.9 3.2 31.9 cs

87 93.38 0.03. 6.59 s

89 97.57 0.1 2.32 s

91 98.9 Nil 1.1 s

93 68.1 0.7 31.2 cs

97 89.82 0.68 9.5 s

99 97.85 0.15 2.0 s

101 98.16 0.17 1.67 s

103 96.7 Nil 3.3 s

105 83.88 0.16 15.96 cs 330

(1) (2) (3) (4)

107 87.33 0.27 12.4 CS

109 94.77 0.13 5.1 s

113 96.07 0.06 3.87 s

115 81.6 0.5 17.9 CS

121 97.76 0.07 2.17 s

123 97.58 0.3 2.39 CS

125 41.1 5.2 53.7 sc

127 97.28 Nil 2.72 S

129 88.84 0.15 11.01 CS

133 89.4 1.2 9.4 S

135 96.02 0.34 3.64 S

137 67.5 7.29 29.6 CS

139 93.84 0.07 6.09 S

141 91.55 0.11 8.34 S

144 92.1 3.14 4. 76 S

146 95.17 0.06 4.77 S

150 53.25 4.08 42.67 CS

153 93.17 0.09 6.74 S

155 90.23 0.26 9.51 S

157 86.5 1.16 12.34 CS

159 81.71 0.08 18.21 CS

163 95.22 0.38 4.4 s

165 88.84 0.01 11.15 CS 331

(1)______(2)______[3]______[4]______[51

169 98.6 Nil 1.4 S

206 78.49 0.04 21.47 CS

S Sand

CS Calcareous Sand

SC Sandy calcarenite

SMC Sandy muddy calcarenite

MCS Muddy calcareous sand. 332

APPENDIX D.

Carbonate Fraction Stations

1. Station Number

2. Percentage of acid soluble material (by weight)

3. Mean size of the acid soluble material

4. Standard Deviation of the acid soluble material

5. Percentage mud sized acid solubles

1 2 3 4 5

Ml 55.8 0.23 1.59 85.2

M2 35.7 1.91 0.60 58.7

M3 14. 6 1.27 0.68 No mud

3 51.7 0.36 1.88 71.2

200 11.6 1.88 0.08 No mud

300 0.7 2.50 0.45 No mud

4 3.6 2.38 0.42 59.0

6 32.6 2.38 1.08 70.6

7 30.9 0.73 2.15 68.7

9 39.1 2.73 1.14 58.7

10 15.6 2.53 1.15 70.8

12 15.7 2.38 1.00 43.4

14 23. 6 2.34 0.53 71.0

16 13.0 2.70 1.06 31.1

18 33. 4 2.76 0.79 34.2 333

1__ 2 3 4 5

20 15.7 2.64 0.72 70.9

25 1.5 1.67 0.59 No mud

26 10.3 2.88 1.12 15.3

28 17.3 2.46 0.99 43.9

30 12.9 2.40 0.85 56.9

31 12.4 2.39 0.68 70.6

33 45.2 -0.54 1.22 62.8

34 39.3 -0.51 1.17 54. 4

40 4.1 1.69 0.81 68

42 18.9 2.32 0.96 -

44 8.8 1.66 0.78 -

46 29.6 0.55 0.80 No mud

47 17.5 2.40 0.75 68.5

50 5.7 2.83 1.13 63.8

52 12.0 2.34 0.95 -

54 12.9 1.54 0.89 -

56 15.2 0.74 0.54 60

58 78.6 1.18 1.57 -

59 15.0 0.86 0.52 No mud

61 4. 2 2.72 0.59 No mud

62 8.3 2.73 0.94 70.8

64 11.7 2.60 0.85 36.4

67 1.9 2.14 0.81 — 334

1___ 2 3 4 5

69 12.0 No mud

72 5.6 2.38 0.67 No mud

74 11.6 68.3

78 6.15 2.31 0.96 -

80 8.5 2.15 0.69 -

85 27.6 3.12 0.79 57.0

87 6.5 2.59 1.04 71.0

89 2.2 1.89 0.96 57.1

91 1.1 1.70 1.06 No mud

93 30.5 2.53 0.74 -

95A 3.9 2.28 0.50 No mud

95B 1.3 2.19 0.42 No mud

95C 1.8 1.92 0.67 No mud

97 8.1 2.81 0.96 67.4

99 1.8 1.73 1.14 60.7

101 1.5 1.55 0.97 -

103 3. 3 1.43 0.90 No mud

105 15.8 1.22 0.97 -

107 12.0 1.69 1.07 59.5

109 4. 9 2.17 0.87 62.5

113 3. 8 1.87 0.37 -

115 17.4 1.32 0.88 -

121 2.0 1.79 1.08 71.4 33d

1___ 2 3 4 5

123 2.1 1.57 1.13 50.0

125 42.5 3.02 0.90 68.4

127 2.72 1.83 0.92 No mud

129 10.6 1.58 1.04 73.9

130 11.9 1.09 0.68 No mud

132, 9.9 2.23 0.82 No mud

132 3.6 2.32 0.53 No mud

133 7.6 2.97 0.77 62.6

135 3.1 1.87 1.26 61.3

137 24.0 2.69 1.08 65.1

139 5.5 1.90 1.05 89.3

141 8.0 1.94 0.97 74.5

144 4.3 2.71 0.92 12.8

146 4.6 1.15 0.95 72.7

148 Not calculated

150 34.4 2.86 0.95 67.0

152, 0.5 2.18 0.67 No mud

152 0.0 1.86 0.78 No mud

153 6.6 2.20 1.05 62.5

155 9.1 2.84 0.59 62.1

157 10.7 2.67 1.16 59.0 G C £38

1 2 3 4 5

159 17.9 -0.20 1.58 81.4

163 3.9 2.80 0.76 57.3

165 11.1 0.69 0.60 86.6

167A 6.1 2.91 0.49 No mud

1 67B 3.6 2.80 0.59 0.66

169 1.4 1.88 1.22 No mud

206 21.27 2.867 0.49 80.0

209 10.00 1.06 0.92 No mud 337

APPENDIX E.

X-Ray for magnetic Tourmaline from the heavy mineral concentrate from Jervis Bay.

1. Standard analysis 2. Powder Photo.° 3. Diffraction Cu target, Ni Filter Cu target, Ni Filter pattern4" Fe target, Mn Filter d 8 I/Ii d 8 I/I± d 8 ^i -

6.38 30 6.6 80 6.33 55 4.22 65 4.3 60 4.21 50 3.99 85 4.0 60 3.97 40 3.48 60 3.5 80 3.46 60 2.96 85 2.95 90 2.94 80 2.58 100 2.55 100 2.58 100 2.40 20 2.36 10 2.39 20 2.38 20 2.2 5 2.37 30 2.04 45 2.03 60 2.03 25 1.92 35 1.9 20 1.92 10 1.88 8 1.88 1*0 1.78 10 1.77 5 1.66 25 1.65 15 1.66 25 1.57 1 1.60 10 1.56 45

* abreviated from Inorganic Powder Diffraction file ASTM Publ. POl5-171 1967. o Analysis J.Pennington, A.N.U. Dept.of Geology, Canberra.

_l U I! TT tl TT tt 33 0

APPENDIX F.

Heavy Mineral percentage abundance by numbers ratios in Jervis Bay and Zircon/Tourmaline:

1. Station Number

2. Percentage zircon

3. Percentage tourmaline

4. Percentage epidote

5. Percentage total opaque minerals (inc. leucoxene)

6. Percentage leucoxene

7. Percentage minor minerals

8. Percentage monazite

9. Percentage rutile

10. Zircon/tourmaline ratio

Tr. Trace, i.e.less than 1%

1 2 3 4 5 6 7 8 9 10

M2 5.4 10.8 8.1 70.3 62.2 5.4 _ _ 0.500

3 9.6 8.5 11.7 64.9 12.8 2.1 2.1 Tr 1.130

200 12.7 24. 8 17.1 41.9 23.2 2.0 - Tr 0.512

4 5.8 25.6 3.3 62.8 30.6 1.7 Tr - 0.226

6 13. 4 8.5 13. 4 62.8 11.0 Tr 1.2 - 1.580

7 12.5 20.0 8.8 57.4 33.7 1.3 - - 0.625

9 8.1 4.8 9.7 74. 2 19.4 1.6 - 1.6 1.690

10 7.7 26.4 4. 4 53.8 21.4 6.6 Tr 0.292 1 2 3 4 5 6 7 8 9 10

12 8.1 29.7 8.1 44. 6 31.1 9.5 — _ 0.273

14 9.1 27.3 10.9 49.1 20.0 3. 6 - - 0.334

16 12.8 6.4 31.9 48.9 23.4 -- - 2.000

18 3.9 21.6 3.9 68.7 51.0 1.9 - - 0.180

20 14. 6 22.7 6.5 53.0 17.3 2.6 Tr - 0.644

26 14.4 16.7 4. 4 62.2 28.4 1.5 - Tr 0.863

28 10.7 23.2 7.1 54. 4 25.8 3.6 - - 0.460

30 7.6 28.2 12.0 49.9 32.6 2.7 - Tr 0.269

34 - 40.0 5.7 54.3 28.6 - - - No zircon

47 6.7 28.0 13.3 49.3 24.0 1.3 - 1.3 0.239

50 10.8 20.3 16.7 50.4 23.4 Tr - - 0.532

54 7.0 19.3 24. 5 45.7 28.1 1.8 - 1.8 0.364

56 8.1 23.0 17.6 47.3 28.4 4.1 - - 0.352

59 5.1 20.0 19.6 52.2 25.5 1.5 - 1.5 0.251

60A 9.4 42.6 11.4 33.3 13.6 3.3 - - 0.220

62 28.5 13.0 5.4 51.8 16.9 Tr - 1.4 2.19

64 6.4 19.2 13.6 52.7 20.0 6.3 - 1.8 0.334

67 3.5 26.1 32.2 20.5 13. 1 11.3 - - 0.133

72A 9.5 11.8 19.0 65.9 39.7 2.4 - - 0.805

85 8.4 16.8 18.6 55.2 33.8 Tr _ _ 0.500

87 7.0 14. 7 29.6 45.5 17.8 3.3 -- 0.476

95A 6.2 20.6 23.8 52.3 36.5 0.301 340

12 3 4 5 6 7 8 9 10

95C 8.8 16.0 4.9 67.9 25.4 Tr - 1.7 0.550

97 13.1 12.9 24. 7 48.6 19.5 - 1.6 Tr 1.015

99 2.4 14.2 32.3 48.2 17.3 3.2 - - 0.169

103 8.3 27.8 23. 6 36.2 18.1 4.6 - - 0.300

107 4.9 10.6 30.3 52.4 25.4 1.6 - - 0.875

109 8.8 20.3 23. 1 43.0 11.1 4.8 -- 0.433

121 3.6 28.4 24. 2 39.8 15.0 4.1 - - 0.127

123 4.3 26.5 22.2 46.0 23.0 2.6 - - 0.162

125 6.0 36.0 21.0 34.0 17.0 Tr - - 0.167

129 6.8 17.0 40.5 21.0 13.5 10.1 - 3. 4 0.400

132A 5.5 9.7 29.2 55.6 37.5 Tr - - 0.567

133 15.5 16.1 17.3 49.4 20.8 - 1.6 - 0.962

135 9.1 20.3 19.4 47.5 23. 1 3.4 - Tr 0.448

137 1.3 10.0 28.1 58.1 39.4 2.5 - - 0.130

139 10.0 26.4 21.7 36. 4 17.0 4.6 - Tr 0.379

141 10.3 19.2 28.1 37.0 18.5 5.5 - - 0.636

144 7.2 26.7 21.0 35.5 13.0 5.7 - - 0.270

146 8.7 27.6 22.4 35.5 12.3 5.1 - Tr 0.315

148 4.9 19.9 15.4 54. 5 25.9 5.3 - - 0.246

150 4.7 14.0 22.8 54. 4 38.0 3.5 - Tr 0.336

152 17.6 21.4 60.7 42.8 Tr -- No zirco:

153 6.0 15.6 11.5 64.7 25.5 1.9 - Tr 0.385

155 9.7 19.8 5.7 62.5 29.9 1.8 Tr 0.490 341

1 2 3 4 5 6 7 8 9 10

157 9.0 10.6 12.5 66.0 32.2 Tr _ 0.850

159 12.7 21.1 7.0 57.7 35.2 1.4 - - 0.600

163 9.1 16.0 9.5 63.0 36.2 1.3 Tr Tr 0.568

165 3.7 10.7 7.4 77.8 33.3 Tr - - 0.346

167A 6.0 10.0 22.0 60.0 38.0 - - 2.0 0.600

169 1.4 20.3 1.4 73.0 27.0 2.7 Tr - 0.069

Currambeen Creekl6.1 11.4 . 5.4 65.3 .16.8 Tr APPENDIX G.

Point count data for light minerals in Jervis Bay

+ 1. Station and size grade 3/35

2. Total quartz

3. Quartz, single grain, straight extinction

4. Quartz, single grain, undulose extinction

5. Quartz, multiple grain, straight extinction

6. Quartz, multiple grain,.undulose extinction

7. Rock fragments

8. Feldspar

9. Heavy Minerals

10. Opaques

11. Other Minerals

+ 1 2 3 4 5 6 7 8 9 10 11

3/35 96.1 9.5 42.8 7.0 36. 8 3.6 1.0 0 0 0

3/80 94. 4 21.3 49.6 6.0 17.5 5.6 0 0 0 0

10/35 80.4 19.7 38.5 2.5 19.7 16.4 2.5 0 . 8 \ 0

10/80 78.9 32.0 34.3 4. 6 8.0 15.4 4.6 1.1 0 0

16/35 73.2 21.3 29.3 9.3 13.3 21.3 5.3 0 0 0

16/80 80.9 28.9 41.3 4.1 6. 6 7.4 9.1 .8 .8 .8

20/45 75.7 31.0 35.6 3.4 5.7 16.1 8.0 0 0 0 4 3

+

1 2 3 4 5 6 7 8 9 10 11

20/80 81.8 31.8 25.0 11.4 13.6 11.4 6.8 0 0 0

25/35 91.7 14. 8 45.4 7.4 24. 1 4.6 3.7 0 0 0

25/80 94.5 26.4 57.1 3. 3 7.7 4. 4 1.1 0 0 0

33/35 75.0 26.4 36.1 9.7 2.8 20.8 4.2 0 0 0

33/80 81.5 24. 8 41.6 2.7 12.4 14. 2 4.4 0 0 0

59/35 74. 4 32.2 26.6 6.7 8.9 20.0 5.0 0 . 6 0

59/120 76.2 28.2 36.5 1.9 9.6 18.6 . 6 3.8 0 0

67/45 75.0 22.6 40.5 1.2 10.7 14. 3 10.7 0 0 0

67/120 79.7 27.8 39.1 3.0 9.8 15.8 2.3 2.3 0 0

85/45 89.8 22.1 51.1 1.5 14.1 5.9 2.9 0 0 0

85/80 90.1 27.0 49.2 4. 1 9.8 7.4 2.5 0 0 0

99/35 87.8 39.9 34. 1 2.9 10.9 7.2 5.1 0 0 0

99/80 94. 9 25.5 49.0 5.1 15.3 3.1 2.0 0 0 0

125/80 84. 7 22.0 57.6 0 5.1 11.9 3.4 0 0 0

120/45 92.4 29.8 54. 2 2.3 6. 1 3.8 3.8 0 0 0

129/120 77.9 33. 1 39.0 .7 5.1 14.7 7.4 0 0 0

157/45 77.6 32.9 32.9 1.2 10.6 12.9 8.2 0 0 1.2

157/120 90.5 19.0 54. 8 2.4 14. 3 4.8 4.8 0 0 0

169/35 95.7 40.7 37.4 2.2 15.4 3.3 1.1 0 0 0

169/80 95.7 37.6 49.5 1.0 7.5 3.2 1.1 0 0 0 344

APPENDIX I.

Mineralogical data collected from both X ray analysis

and microscopic examination of the terrigenous mud fraction of

the sediments from Jervis Bay. Carbonate mud percentages given

in Appendix D.

1. Quartz (including biogenic silica)

2. Feldspar

3. Kaolinite

4. Heavy minerals (including: zircon, tourmaline, epidote,

hornblende and opaque minerals)

5. Muscovite

6. Other clay minerals

Method of Determination:

+ Unoriented aggregate and microscopic examination

o Oriented aggregate

Station No.______1______2______3______4______5______6_____

Ml + 97 Tr Tr Tr

3 +

4 + 98

6 + 94 Tr 34 b

Station No. 1 2 3 4 5 6

7 + 90 5

9 + 95 1

10 + 98 1 Tr Tr

12 + 96

16 + 97

18 + 96

20 + 98 Tr Tr

26 + 903

28 +

30 + 95 4 Tr

34 + 98 Tr Tr

47 + 98 Tr

62 + 97 2

64 + 94 4 Tr Tr

87 + 98 Tr Tr

97 + 96 3 Tr

125 + 94 4 Tr Tr Tr Tr

137 + 94 3 Tr 1 Tr Tr

9 o 30 50 10 10

97 o 25 5 30 Tr 35 Tr

125 o 25 5 25 40 Tr

137 o 20 Tr 40 Tr 35 Tr 346

The percentages shown in this table are estimates based on relative peak heights of the most intense peak for any given mineral or minerals. Hence because of the method employed comparison between samples is only subjective.