NEW ZEALAND

DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Distribution and Morphology

of Chatham Rise Phosphorites

by

DAVID W. PASHO

Resource Management and Conservation Branch,Department of Energy, Mines, and Resources,

Ottawa, Canada. .

New Zealand Oceanographic Inslilule Memoir 77

Wellinglon

1976

Citation according to "World List of Scientific Periodicals· (4th edn)

Mem. N.Z. oceanogr. Ins!. 77

ISSN 008S· 7903

Received for publication: September 1974

Edited by R.W. Poole,Science Information DIvIsion, DSIR, and

R.J. Wanoa, N.Z. Oceanographic Institute, DSIR.V'''ityping by Rose·Marie Thompson

© Crown Copyright 1976

A.R. SHEARER, GOVERNMENT PRINTER, WELLINGTON, NEW ZEALAND - 1976

CONTENTS

Abstract

Introduction

Previous Work

Techniques

Geologic Setting

Topogra;>hy

Lithology

Sediments

Structure

Geologic History

Description of the Phosphorites

External Character

Macroscopic Examination of Nodule Interior

Microscopic Examination of Nodule Interior

Chemical Composition

Characteristics of Distribntion and Associations

Discussion 3.nd Conclusions

Depositional Setting

Phosphatisation

Subsequent History

Acknowledgments

References

Appendix I : Chatham Rise Stations, GMI Cruise I

Appendix Il : ;:;hatham Rise Stations, GMI Cruise II

AppendiX 1II : Listing of Availahle P2 0. Analyses on Phosphorite

Nodnles from Chatham Rise

FIGURES

Page

5

5

5

6

7

7

8

11

12

1213

13

14

15

18

19

2020

2020

21

2223

24

26

1.

2.3.

4.

5.6.

7.

Chatham Rise : bathymetry and station locations

Chatham Rise: lithology

Chatham Rise: phosphorite locations

Bathymetric profiles on the Chatham Rise

Typical Chatham Rise phosphorite nodules

Relationship of specific gravity and size in phosphorite nodules

Cross-section of phosphorite nodnle

.. 6 & 7

.. 8 & 9

10 & 11

12

13

1414

FIGURES - Continued

8. Photomicrograph of phosphorite nodule composed of foraminifera tests.. 15

9. Photomicrograph of phosphorite nodule containing few foraminifera tests 15

10. Photomicrograph of phosphorite nodule illustrating collophanereplacing chalk 15

11. Photomicrograph of phosphorite nodule illustrating collophaneinfilled fracture crosscutting glaucnnite rim 16

12. Photomicrograph of phosphorite nodule showing the transition fromglauconitised rim to collophane replacement zone 16

13. Photomicrograph of phosphorite nodule showing a concentration ofopaque material between glauconite rim and collophane zone 17

14. Photomicrograph of phosphorite nodule showing opaque material 17

15. Histogram of the P2 05 content in phosphorite nodules representing51 stations 18

16. Diagrammatic representation of two total sediment samples 20

TABLES

1.

2.

3.

4.

Relative frequency of mineral grains in the insoluble residue ofphosphorite nodules

Collected partial analyses of phosphorite nodules

P2 0 5 content of various size phosphorite nodules

Comparison of P2 0 5 content in nodules with different percentagesof foraminifera

18

19

19

19

Distribution and Morphology of Chatham Rise Phosphorites

by

David W. Pasho

Resource Management and Conservation Branch,Department of Energy, Mines, and Resources,

Ottawa, Canada.

ABSTRACT

This study is based on an extensive programme of sampling for phosphorite nodules,undertaken by Global Marine Inc., on !.he Chatham Ris6 during 1967 and 1968.

The data resulting from this survey substantially increase knowledge of the generalgeology and geomorphology of Chatham Rise. and reconstructions are presented of tbestrucQJ.re, stratigraphy and geological history of the region in the light of the newevidence.

The nature of the phosphorite nodules has been studied in considerable detail. andfresh information on the distribution and on the complex mineralogy and geochemistry ofthe phosphorite is discussed. Glauconite commonly accompanies the phosphorite on theChatha.m Rise a.s discrete sandsize grains and as thin coalings on nodules, and thisassociation is described in some detail.

Finally, an interpretation is given of the evolution of the ChaUHun Rise phosphoritenodules by phosphatiBation of late Miocene foraminiferal oozes, followed by uplift-.fragment-alion and weathering under subaerial conditions before resubmergenc.8.

INTRODUCTION

During 1967 and 1968, Global Marine Inc. conductedan extensive exploration programme on the ChathamRise. The work was undertaken in order to determinewhether phosphorites, known to occur on the Rise,represented a potential phosphate ore deposit. Approx­imately 329 bottom samples were taken during thecourse of this investigation.

The primary purpose of this study is to describethe phosphorites of the Chatham Rise and determinetheir origin. A secondary objective is to discuss thegeology of the Rise in the light of the new datacontributed by the sampling.

New Zealand Oceanographic Institute Memoir 77'11976ISSN 0083 - 7~O ~

5

PREVIOUS WORK

The occurrence of phosphorite nodules in a sampletaken on the Chatham Rise was reported by Reed &Hornibrook (1952) who attributed their presence toerosional removal of material except for that "preservedby phosphatisation". Norris (1964) describes nodulesfrom various regions of the Rise and takes exceptionto the erosional theory of Reed & Hornibrook, althoughnot specifying an alternative. Two papers have shownthe nodules to have possible economic value (Summer­hayes 1967; Watters 1968) and a third, while dealing

o

o

CONTOURS Il'l METRES

o FLEMING AND REED (19511• REED AND HORNIBROOK (1952)o NORRIS (1964), CULLE N(1965)• CULLEN (1967) l--f

PREVIOUS STUDIES

EXPLANATION

10 0 10 '2Q 30 40 50 KllomclfCS

THIS STUDY

GLOBAL MARINECRUISE II

• GLOBAL MARINECRUISE I

CHATHAM RISE, NEW ZEALANDBATHYMETRY & STATION LOCATIONS

10 0 10 20 30 40 50 Nal,lbCAl Mlles• , If', I I, t I

Fig. 1. Chath:un Rise. New Zealand: bathymetry and station locations.

with the same theme, adds new data resulting fromexploration of the deposits by Global Marine Inc.(Buckenham et 01. 1971).

were prepared and studied. Approximately 4a thinsections were made from 40 nodules. At least onenodule' was taken from each of the stations.

TECHNIQUES

Boltom Sampling: All the samples were taken with a45cm diameter pipe dredge. As the Chatham Risenodules did not approach the dredge diameter in size.the samples are considered to he representati ve withrespect to size. unlike those reported by Glasby &Singleton (19'75) who used a smaller diameterpipe dredge. Positions were obtained by celestialnavigation. Sample stations are listed in Appendix Iand II. and plotted on Fig. 1.

Sample Treatment: Duplicates of all samples takenon the Chatham Rise were given to the author byGlobal Marine Incorporated. Sediments and rocksfrom each station were logged and descrihed.

Cross-sections of 2 or 3 nodules from each of 20different sample stations that yielded phosphorite

Phosphate Analyses: Quantitative analyses for P20Swere performed on 20 samples from the ChathamRise. Unless a specific region of the interior wasselected, analyses were performed on splits of crushedwhole nodule cross-sections. These were gronnd tominus 120 mesh and oven dried for 24 hours at 110DC.Samples were prepared by fnsing the powder withLa20, and Li2B,07. and pressing the ground mix­ture into sample wafers. Analyses were performed ona Norelco l{-ray flnorescence unH.

Microscopic Techniques: The mineralogy of clasticsin Chatham Rise phosphorites was ascertained hydigesting the nodnles in HCl and performing a graincount on the clastics in the residue.

Relative percentages of various constituents in thenodules were determined by modal analyses of thinsections. Grain size distributions were arrived at bypoint-Counting grains within ::ile~e intervals.

6

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GEOLOGIC SETTING

TOPOGRAPHY

The Chatham Rise is a broad submarine highextending over 500 nautical miles from Banks Pen­insula on the South Island of New Zealand to a short'distance beyond the Chatham Islands (Fig, 1). Aver­aging approximately 60 nautical miles in Width. theRise crest covers over 40,000 square miles or two­thirds the area of the South Island. Outlined by the500 m contour, the crest of the Rise is separated fromthe shelf off Banks Peninsula by a narrow saddle justover 570m deep. The northern slope of the Riseextends to 2.500 m and is notably steeper than slopesbounding it on the south and east which deepen grad­ually to approximately 4,000m. Four banks and theChatham Islands form the major topographical featuresatop the Rise.

Mernoo Bank, described by Fleming & Reed (1951),is the westernmost bank and comes to within 56 m ofthe surface. It is roughly dome-shaped, being some-

7

what elongated along a north-east/south-west axis.The 200 m contour approximately marks the transitionfrom a relatively fiat summit to steep slopes on thenorth, south and west. Fleming & Reed (1951) suggestthat the valley-like channels, dissected plateaus, andcliff structures found on the bank result from sub­aerial processes. Notably, the valley-like channelswith branching sinuous courses radiating from thesummit region can be traced down slope to about100m, a depth consistent with the maximum reductionin sea level during the Pleistocene (Curray 1969).The gentle side slopes of the valleys, which contrastwith the very steep slopes often found in true sub­marine canyons do not point to formation by submarineprocesses.

Protruding from the southern slope of the Rise isVeryan Bank, a relatively small steep-sided featurewith a fiat summit at 40m (Brodie 1964). Flat summIt,shape and recoveries of volcanic rocks lead Brodie tosuggest it is a truncated volcanic cone.

178°177°17601750173°E

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10 0 10 20 30 40 50 Nilllt.ea1 MeI iii 'i I " I!

CHATHAM RISE. NEW ZEALANDLITHOLOGY

10 0 10 2030 40 50 Kolomctres

CONTOURS'" METRES. ROCK TYPES

SCHIST

GREYWACKE

VOLCANICS

LIMESTONE

CHERT

c:=JCII3w:Mf ---1111I1I11I1ffi

Fig. 2. The Chatha.m Rise, New Zealand: lithology.

Reserve Bank is elongated east-west, parallel tothe axis of the Rise. Separated from Memoo Bank onthe west by a north-south saddle up to 385 m deep, itshallows to the east reaching a depth of under 200m.Further east it narrows and deepens.

Reserve and Matheson Banks are separated by abroad deep sl\ddle averaging over 400m in depth.From a regional depth of 400m, Matheson Bank risesabruptly from the north and south in a succession oflevels to depths under 200m (Fig. 4B in Cullen 1965).The Bank trc~ds in a north-west/south-east direction,terminating somewhat abruptJ~' on the east and deep­ening into a ridge on the west.

The Chatham Islands are emergent portions of abroad east-west trending arch beginning about 179°1Vand extending eastward past the Islands. Ch~tham

Island is the largest land mass of the group. Thesecond largest island is Pitt Island to the south-eastof Chatham Island. Several submarine benches havebeen reported around the Chatham Islands (Brodie illKnox 1957). The two deepest are at 293m and 119m!The former is believed by Brodie to be early Pleisto-

cene while the latter is a result of the lowest glacialsea level stand.

LITHOLOGY

The li thology of Chatham Rise is poorly known andcan only in part be pieced together from rocks exposedon Chatham Island and those taken in bottom samples.

Many of the rock fragments from the Chatham Rise'are believed to be locally deri ved (~"ig. 2). This isbased upon generally accepted criteria for autochthon­ous occurrence: large size, abundant rocks of similarlithology, fresh fracture or angularity, and fragile orpoorly consolidated rocks (Emery 1960). In certainareas of the Rise, however, mixed assemblages ofexotic rock types have been recovered that includered feldsparhic sandstone, gametiferous gramte andgranite gneiss, dioritic gneiss, dark greywacke,schist and "nd~site ,Cullen 1962). The red sandstone,in particular, shows undoubted evidence of glacialtransport, and it is considered that the assemblagesin which this rock occurs have been ice-rafted, pre­sumably :rom Antarctica,

8

1790 1800 179°W 1780 1770 1760 1750 1740

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The oldest rock type recovered from the Rise isfrom the Chatham Islands, and is a light grey, medium­grained, well-laminated schist which is correlated onpetrographic and lithologic grounds with the OtagoSchist on South Island (Allan 1929; Hay et al. 1970).Westward, along the strike of the schist on ChathamIsland, similar schists have been dredged (Reed &Homibrook 1952; Cullen 1965). These, and samplestaken during this study, indicate extensive exposures00 Matheson Bank, and to a lesser degree on the archextending to the west from the Chatham Islands.While the lack of schist in samples west of 1800

suggests it is not exposed, Houtz et al. (1967) be­lieve the base renector in seismic profiles overReserve Bank represents the westward extension ofthe schist. Otago Schist, although exposed only onthe eastern portion, may then extend beneath youngerformations along the remainder of the length of theRise.

On the South Island, Otago Schist has been inter­preted as a metamorphosed basal section of a thicksequence of greywackes which confonnably overliesit (Houtz et al. 1967; Brown et al. 1968). Greywackes.whIch grade into scmst on Chatham Island and appear

9

equivalent to these Triassic and Jurassic greywackes,are dredged from Widely scattered localities on theRise (Fig. 2). Some of these greywackes may bederived from a greywacke conglomerate, such as theCretaceous Headland Conglomerate found on PittIsland. Whether eroded from primary or secondarydeposits, their presence on Reserve Bank, MemooBank, Pitt Island, and Chatham Island indicates theiroriginal extent. The presence of schist on MathesonBank suggests erosional removal of greywacke coverfrom that feature.

Late Lower to early Upper Cretaceous deposits arerepresented by a series of conformable conglomerates,sandstones and calcareous tuffs, which constitutesthe Waihere Formation of Pitt Island. The basal Head­land Conglomerate (composed of rounded schist andgreywacke clasts) probably indicates a major uncon­formity between it and underlying beds (Hay et al.1970). The micronora from lignitic lenses within thesandstones suggests non-marine conditions whichgave way to marine conditions in which the tuff wasdeposited.

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1760 1770 1780

CHATHAM RISE,NEW ZEALANDPHOSPHORITE LOCATIONS

10 0 10 20 30 40 50 Nautal Miles

I j I I 'i iI, "10 0 102030 4050 Kilometres

CONTOURS IN METRES

PHOSPHORITE

NO PHOSPHORITE REPORTED

• SAMPLES REFERED TO IN THE TEXT

Fig. 3. The Chatham Rise. New Z;ealand: phosphorite locatIons.

Paleocene to Lower Eocene grirs, greensands,phosphatic nodules and limestones make up the Ti­oriori Group which disconformably overlies OtagoSchist on Chatham Island. Shallow marine conditionsare indicated.

Volcanics and limestones from upper Middle tolower Middle Eocene strata constitute the KekerioneGroup on the Chatham Islands. The volcanics com­prise basaltic lavas, calcareous fossiliferous tuff,and pillow lavas with lenses of limestone. Hardcrystalline limestone (Te Whanga Limestone) contain­ing angular schist fragments and a few phosphaticnodules is overlain by a soft limestone composed ofpolyzoa and foraminifera, which also contains l- ~lOs­phatic nodules (Te One Limestone). Some of theEocene limestones are similar to Bortonian (MiddleEocene) cross- bedded foraminiferal limestone fromMatheson Bank (Cullen 1965) (Fig. 2). These lime­stones from Chatham Island and Matheson Bankindicate shallow water conditions in both regionsduring the Middle Eocene.

10

Miocene argillaceous limestones have been reportedfrom a station between Chatham Island and MathesonBank by Cullen(1965) and phosphatised Upper Mioceneforaminiferal ooze fragments (the phosphorites of thisstudy, Fig.~) ~re abundant in many areas betweenReserve Bank and Chatham Island. These are theyoungest dated consolidated rocks known from sub­merged portions of the Rise. Similar rocks of Mioceneage have not been reported from the Chatham Islands.

Unconformably overlying Te One Limestone (Eo­cene) is a series of lava nows and interbedded cal­careous tuffs of Upper Miocene to Lower Plioceneage. They were, in part, extruded under water, asevidenced by pillow structures.

Upper Pliocene to lower Pleistocene shallow waterlimestones and tuffs rest disconformably upon theTe Whanga Limestone of Eocene age.

Although volcanic rocks are found on many areas ofthe Rise, it is not now possible- to date them, nor tocorrelate them with volcanics on the Chatham Islandsor the South Island.

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430

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Cherts have been recovered from the saddle be­tween Matheson and Reserve Banks. Except forsuggesting a Tertiary age by reason of their associ­ation with Miocene phosphatised oozes, it cannot besaid when they were deposited.

SEDIMENTS

Sediment distribution on the Chatham Rise hasbeen treated in some detail by Norris (1964), fromwhose work this discussion has largely been taken.Norris has categorised the sediments as allochthonousrock fragments. authigenic minerals, organic remains,faecal pellets, and monomineralic grains. While allo­chthonous rocks have been reported (Cullen 1962),they are quantitatively unimportant.

Of the authigenic minerals found, glanconite is themost common and to some extent forms a part of mostsediments. Very high concentrations, sometimes over50 per cent, are centred over Reserve Bank and to a

11

lesser extent north of Chatham Island. Glauconiteoccurs mainly as dark green ronnded grains, internalcasts of foraminifera, and as replacements of faecalpellets. Cnllen (1967) demonstrates that the age ofrounded grains from one location on Reserve Bank isbetween 5 and 10 million years. Based upon the age,rounding, sorting, concentration in the upper portionof cores, and extreme degree of concentration onshallows, Cnllen proposes they have been derivedfrom pre-existing rocks by winnowing and erosion.Several sediment samples from shallow areas con­taining mixed and reworked microfossil assemblagestend to support this idea. Kennett· & Casey (1969)report three samples from Matheson Bank which con­tain glauconite casts of Eocene foraminifera mixedwith Recent foraminifera. They suggest that a lime­s tone snch as the Eocene glauconitic-foraminiferalrocks from Matheson Bank would be an adequatesource of glauconite. A similar mixture of late Eoceneto early Miocene coccoliths and discoasters withRecen t coccoli thophores and foraminifera is found onMatheson Bank (Norris 1964).

Calcareous organic remains such as shell frag­ments and foraminiferal tests form a major portion ofthe Chatham Rise sediments. Regions shallower than150m and removed from sources of terrigenous mater­ial are covered with shell gravels. Shell fragmentsinclude few if any extinct forms and thus point to arecent origin.

Below 150m the calcareous fraction of the sedi­ment consists mostly of foraminifera. Foraminiferalremains are often sufficiently abundant to class thedeposits as foraminiferal oozes. Foraminifera may beexclusively Recent although, as previously noted,assemblages of Eocene and Recent age are reportedfrom Matheson Bank.

While detrital sediments are found around ChathamIsland, land-derived material is largely excluded fromthe Rise because of topographic isolation from themainland, and thus forms only minor portions ofsediments in deeper areas of Rise crest. Norris (1964)suggests that the assemblage of minerals found insome Chatham Rise sediments (glass shards, feld­spars, hypersthene, augite, and quartz) can beaccounted for by wind transport of Taupo ash showersfrom the North Island.

STRUCTURE

Subsurface structme of the Chatham Rise is knownfrom a series of seismic renection profiles taken overthe Rise b)' scientists from the Lamont-Doherty Geo­logical Observltory (Houtz et at. 1967). The profiles

show the Rise to be anticli.nal along an east-westaxis. Truncation of tilted Upper Eocene strata on thecrest of the Rise indicates post-Eocene emergence.

Bathymetric cross-sections suggest normal fault­ing may have been important in forming the Banks.Around Matheson Bank, vertical offsets up to 50 m canbe seen (Fig.' 4). On the Chatham Rise, the majorityof U-aceable faults strike west-north-west but arediscontinuous and may be offset in some instancesby north-south trending faults.

Several structural trends and periods of deform­ation are distinguished on the Chatham Islands (Hayet at. 1970). East-west trends marked by faults,Strike of schistosity, and linear distribution of intru­sives are present in the northern section of ChathamIsland and may renect pre-eretaceous tectonic act­iVi.ty. Cretaceous structures, consisting of north-easttrending folds cut by later north-east trending tension­al faults with throws of less than 6 m, are found onPitt Island (Austin er al. 1972). Post-Eocene normalfaults, oriented north-east and north-west are inferredon Chatham and Pitt Islands, respectively, and gentlelate Tertiary - early Pleistocene folding about an east­west axis is found on Pitt Island.

During late Paleozoic and early Mesozoic times,the area occupied by the Chatham Rise was an east­ward extension of the New Zealand Geosyncline(Fleming 1962; Hay et at. 19'70). Beginning in mid-

43'20' 43"30' 44 10'

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:t_··-=..:.."'"--:::==::::=:::::::======:::"'~:·==:=-=l:

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::t=::::::::j~'===~::BATHYMETRIC PROFLES ON THE OiATHAM RISE

lOC.'1()HS G!'f[", ON flO I

, ~ 3.5 ! 1 • ~ IONil.UlCA.\.t.Il-(Sf-JI,....,..-''r,..1r-ii,',-"-J.i",,~,"" IW,lOoI£tRES, • • • 10

.3" :10' "3"50'

Fig. 4. Bathymetric profiles on the Chatham Rise.

12

44"00' •• 10'

Jurassic. the thick sequence of greywackes and inter­bedded basalts which formed the geosynclinal axialfacies was elevated during the Rangitata Orogeny(Brown et al. 1968). Emergence of the eastern portionof the Rise prior to the Lower Cretaceous is indicatedby Lower Cretaceous greywacke conglomerates andlignitic sandstones containing microfiora on PittIsland, as weU as Paleozoic - Lower Eocene bedsoverlying Otago Schist on Chatham Island. It mayalso be possible to infer a similar unconformity onMatheson Bank from the absence of aU but schistsand Eocene limestones in samples collected in arather dense pattern.

The rocks suggest that, by early Tertiary time,shallow marine to estuarine conditions prevailed onthe eastern part of the Rise. The lack of detritals inthese sediments (Hay et al. 1970) indicates theabsence of an elevated land mass. The conditionswere similar to those which existed on the easterncoast of the South Island and CampbeU Island (Browne 1 al. 1968). Apparently the region was at that timecharacterised by land areas of low relief and trans­gressive seas.

high land masses were still absent and thus rocksare very low in clastics. The Rise probably existedas a relatively shaUow, isolated feature. The environ­ment of deposition was similar to seamounts, ridgesand banks, where foraminiferal oozes are now accumu­lating (Emery 1960: Karig e1 al. 1970).

On the South Island, Pliocene - Pleistocene timewas dominated by the Kaikoura Orogeny (Brown e1 al.1968). Common unconformities and disconformitiesbetween strata of Eocene and early Pleistocene ageon Chatham Island probably refiect these tectonicmovements.- The occurrence of Miocene foraminiferalrocks on portions of the Rise where Eocene strata aretruncated indicates post·Miocene emergence which isalso probably related to the Kaikoura Orogeny. Shallowwater conditions since the late Miocene could alsoexplain the occurrence of winnowed glauconite (from5 to 10 million years old) and mixed fossil assem·blages. Some indication of the degree of verticalmovement on the eastern pan of the Rise is given bya late Pleistocene terrace around Chatham Islandwhich is as much as 293 m below present-day sealevel.

As indicated by the Widespread occurrence ofphosphatic foraminiferal oozes, much of the Rise wassnbmerged during the Miocene. Although the ChathamIslands may have been emergent. (Hay el al. 1970),

After early Pleistocene times, Chatham Island waslargely submerged by a marine transgression whichwas foUowed by emergence during the glacial lower­ing of sea level.

DESCRIPTION OF THE PHOSPHORITES

CX55C46CX109CX104A

Fig. 5. Typical Chatham Rise phosphorite nodules:1 "small" burrow; 2 "large" burrow; 3 coralattached to unglauconitised fracture surface.

instances. more than three periods of fracturing canbe identified on the same nodule. Typically, the old­est surfaces are well rounded and have a blackglauconite coating. Younger fracturing is character­ised by surfaces that are not so well rounded, lighterin colour (mostly green) and less thoroughly glaucon­itlsed. Most recent fractures have no glauconitecoating and very angular edges. In some mstances,unglauconitised surfaces are attributable to breakage

EXTERNAL CHARACTER

The size of phosphatic nodules is variable. Amajority of the larger nodules are less than 5 cm inlength although some reach 15cm. Microscopic exam­ination of sieved samples reveals that phosphoriteparticles are very common in fractions with grain­sizes ranging down to a few millimetres, and lesscommon in finer-grained fractions.

On the basis of available specimens, the amountof variation and average specific graVity of phos­phorite appears to decrease with increasing size(Fig. 6). Nodules less than 2 cm have densities thatvary between 2.5 and 3.0gcm-3, while nodules over5cm vary between 2.4 and 2.5gcm- 3 .

Because they have sustaiued several periods offractlll'ing, rounding, and boring by organisms, nodulesare extremely variable in ·shape. They may be weU­rounded, blocky, angular or highly perforated byborings. In many nodules several ages of fractlll'ingcan be distinguished by variations in colour anddegree of glauconitisation, as well as the angularityof corners formed by fracture intersection. In some

Phosphorite nodules from the Chatham Rise arehard, dense, and many have a smooth black glaucon­itised exterior surface wbich is rarely glazed orshmy. Encrusting organisms are not uncommon(Fig. 5).

13

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MACROSCOPIC EXAMINATION OF NODULE INTERIOR

In cross-section (Fig. 7), nodules are composed oftan to grey indurated foraminiferal ooze enclosed by arind of dark green glauconite. Texturally, the materialis rather uniform. Primary depositional structures suchas bedding or accretionary zonation are not present.

In many nodules the irregular distribution of brownand grey areas gives the nodules a mottled appear­ance. Where small brownish patches are densely andevenly scattered throughout, an argillaceous appear­ance results. Most tan and light brown areas arerandomly distributed and appear unrelated to nodnlegeometry. In sOlTIe nodules, however, the brown I'egiontends to be of rather uniform thickness, leaving aninner grey zone (Fig. 7).

Darker brown or yellow brown areas occur withinand adjacent to glauconitised surfaces. The regionsare rather na!'row and are not more than 2 01' 3 mmthick.

The glauconite rind covers all naturally-formedexternal surfaces with the exception of "young"fractures. Glauconite on older surfaces penetratesup to 2 mm into the interior while penetration onrecent surfaces is noticeably less.3,1

,

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•

SPECIFIC GRAVITY

Fig. 6. Relationship of specific gravity and size (given aslong axis length) in phosphori te nodules from ChathamRise. Data taken on nodules from eight stations.

Burrows are not uncommon within the nodules. Inaddition to those previously mentioned, smallerburrows are revealed in sections. While somewhatuniform in size (all less thac. ~:um in diameter), theyvary in terms of infilling, prese~ce of a light 'alter­ation zone", and glauconitisation of the wall (Fig. 7).

during sampling. These are distinguished by theirextremely fresh, unweathered appearance in contrastto the older unglauconitised surfaces which arecharacterised by pitting and by the adherence oforganisms (Sample CX37, Fig. 5). In a general way,the age of fracturing is related to the degree ofrounding; more aQgular nodules tend to have morerecent fractures.

Considering the density, size, and coherence ofthe nodules, it is doubtful whether any deep watermechanism could account for the fracturing. Rework­ing and abrasion in a shallow high-energy environmentare required. Several such periods of reworking wereapparently separated by times of deeper submergencewhen nodule surfaces were glauconitised.

Well preserved mollusc or worm burrows are notuncommon in nodules. They are typically tUbe-like,less than 1 em in diameter, and generally extendcompletely through the nodules. Fractures commonlycross-cut the tubes both perpendicularly and longi­tudinally (Fig. 5). Their interior surfaces are glau­conitised and appear comparable to the "oldest"fractured surfaces on the nodule, indicating that theburrows were made prior to the oldest discernibleperiod of glauconitisation. The lack of infillingindicates that the burrows .are post-lithificationfeatures.

Fig. 7. Cross-section of Chatham Rise phosphorite nodule:1 unfilled glauconitised burrow; 2 unfilled unglaucon­itised burrow wit.h alteration zone; 3 filled burrow,Note Mottled appearance and dark material nearexternal surface. Dotted area indiciltes portion a.nal·ysed separately for P20 5 (see text in secLion on·Chemical Composition"). Scale line is 1.0 em.

14

Polished sections of nodules were etched informic acid to distinguish less soluble phosphaticmaterial from more soluble calcium carbonate. Micro­scopic examination showed foraminifera tests withinlight regions to be most susceptible to solution.Almost all were totally dissolved, leaving well­defined moulds and casts. Within brown or yellowishregions, foraminifera ware less soluble and thusprobably phosphatic. Brown to yellowish material isfound both in the outer part of the zone inside theglauconite rind and as small randomly scatteredpatches which were less soluble than the lightcoloured, apparently less intensely phosphatisedooze.

In several sections, etching revealed small brassycrystals (pyrite ?) within foraminifera tests through­out the nodules.

MICROSCOPIC EXAMINATION OF NODULE INTERIOR

Microscopic examination of thin sections revealsthat Chatham Rise phosphorites are composed of well­lithified partially-phosphatised foraminiferal lime­stones or chalks. A majority of the nodules are morethan 30% (Fig. 8) foraminifera; some contain 10% orless (Fig. 9). The variation in foraminifera percentageis rather distinct, gradational types between 30 and10 being rare. Tests in both are distributed randomlythroughout a crypto-crystalline matrix. Foraminiferaare commonly whole and do not appear to have beenabraded. The tests range in size from 0.2 to 0.6 mm.

Partial dissolution of the nodules in HCl releasedforaminiferal moulds which could be identified. Allsamples examined yielded Late Miocene dates (O.L.Bandy & R.L. Fleischer, pel's. comm.).

Collophane appears light brownish yellow to darkreddish brown. It replaces foraminifera and matrixmaterial, usually without -:-bLiterating the foraminiferatests (Fig. 10). Dark brown collophane is common as

Fig. 8. Photomicrograph of phosphorite nodule composed offoraminifera tests (C5BB). Scale line is 0.1 mm.

15

a pseudomorphic replacement or test filling, Whereboth are phosphatic, the matrix collophane is usuallya lighter colour than that replacing the tests. Select­ive replacement is common but variable. Tests alonemay be replaced, or sometimes the matrix and materialwithin the test may be replaced. leaving the testuntouched. Most intense replacement of foraminiferaand matrix generally occurs in regions, or occasion­ally two distinct regions. on the outer edge of thezone inside the glauconite rim. Within the rest of thenodule replacement is random, although in some(Fig. 7) a central zone of less intense replacementis found.

(1"'- .?

G .'

(

Fig. 9. PhoLOmicrograph of phosphorite nodule conlainingfew foraminifera test.s (CX66B). Note opaque material(0) concentrated at the boundary of the glauconitisedrim (0) and the collophane replaced area (C). Scaleline is 0.1 mm.

Fig. 10. Photomicrograph of phosphorite nodule illustratingcollophane (C) replacing chalk (Ch) (CX89A). Notethe occasional, selective infilling of the foraminiferatests by collophane. Scale line is O.lmm.

Fig. 11. Photomicrograph of phosphorite nodule illustratingcollophane infilled fracture (C) cross~cutting theglauconite replacement rIm (G) (CX79B). Scale lineis 0.1 mm.

Collophane is found to replace glauconite thatoccurs as scattered fora'l1inifera test fillings. Re­placement is most intense on the exterior portions ofthe glauconite and may on occasions totally orpartially replace the enclosing test. Collophane mayalso occur as crack fillings which cross-cut glancon­ite replacemeut rims and foraminifera replaced by anearlier generation of collophane (Fig. 11). Foram­inifera tests within the glauconite rim are occasion~

ally replaced by collophane.

Glauco"ite occurs within the nodules as (1) a rimreplacement; (2) foraminifera filling; (3) crack fill­ings; and (4) rounded clastic grains.

Exterior surfaces on the nodules have been re­placed by glauconite (Fig. 12). The thickness of therim is variable but shows no relationship to surfaceirregularities. That the glauconite is not a coatingbut represents true replacement of foraminiferal oozeis indicated by the continuity of texture across thereplacement boundary. Partially obliterated foram­iniferal tests are common within the glauconite(Fig. 12). Where the leading replacement edge isdistinct, a foraminifer may lie partially within theglauconite, leaving the remainder of the test uare­placed. The nature of the transition from glauconiterim to unreplaced matrix is variable. Usually grassgreen glauconite grades to a light green or yellowglauconite which terminates at a boundary markedby a concentration of small disseminated opaqueparticles. A grey or brown layer containing coarseropaque matter may be present. Further in, a layer ortwo of matrix, and foraminifera replaced by collo­phane are found. Glauconite rims also grade directlyinto an evenly replaced collophane interior whichmayor may not have a disseminated opaque layer.

The concentration of collophane in a layer beneaththe glauconite rinds may be a result of inward phos-

phate migration during replacement by glauconiteresulting in regions of secondary collophane concen~

tration. Throughout the replacement rind, scatteredforaminifera may contain a darker glauconite than thatreplacing the matrix. While this may indicate thatthe interior of the foraminifera is more favourable toformation of dark glauconite, it is inconsistent withthe observation that not ail foraminifera contain thedarker variety, even when adjacent. More probablythe foraminifera with darker glauconite representthose infilled with glauconite prior to replacement.This would be consistent with Pratt's (1971) obser­vation that darker glauconites tend to be older thanlight forms.

Grass-green glauconite occasionally occurs asforaminiferal test fillings. Such glauconite-filledtests make up as much as 5% of all tests. They arerandomly distributed ·throughout the nodules and areadjacent to foraminifera that are not filled. Theirdistribution among unfilled tests and the definiteconfinement of glauconite within the test suggestseither that this glauconite formed prior to lithificationand is not a post-depositional replacement feature,or that the glauconite-filled tests represent reworkedmaterial from a glauconitic ooze. The latter idea isnot supported by the lack of abrasion of the t.ests.

Darker green varieties of glauconite fill cracksthat cross-eut glauconitised rims indicating laterperiods of glauconitisation (Fig. 12). This glauconitemay represent material deposited during glaucon­itisation of the successively younger angular exteriorsurfaces.

Opaque Minerals. Most nodules contain a notice­able amount of opaque material which is present asdisseminated particles, foraminifera test replace­ments or test fillings. The material may at least inpart be pyrite which was noted in foraminifera onetched interior sections.

Fig. 12. Photomicrograph of phosphonte nodule sllowmg metransition from tile glauconitised rim (0) to the collo­phane replacement zone (C) eC6-D). Note ghosts ofreplaced foraminifera tests a.nd late glauconite veinfilling. Sca.le line is 0.1 mID.

16

Disseminated opaque particles up to 0.2mm arefound scattered throughout unphosphatised materialor concentrated at collophane - non-collophaneboundaries (Fig. 9). Secondary origin is indicated bytheir delicate dendritic edges and replacementrelationships with foraminifera. The scarcity ofopaque particles in phosphatised areas, as comparedto their abundance in adjacent unreplaced regions,might be interpreted as the result of obliteration ofopaques during replacement. However, where opaqueparticles are found in collophane, they have the samedelicate dendritic edges and cross-cut foraminiferareplaced by collophane, and are thus of post-replace­ment origin. It would appear that non-phosphatematerial is more susceptible to replacement by theopaques.

Concentrations of particles are found at boundariesof the glauconite rim with the collopbane and un­replaced chalk (Fig. 13).

Opaque material may selectively replace foram­inifera tests, even those previously replaced bycollophane or glauconite; such replacement occursanywhere in the nodule. Infilling of foraminifera byopaque material is common and not necessarilyaccompanied by test replacement (Fig. 14).

Opaque particles were apparently the most recentlyformed material. The concentration at boundaries,especially those of glauconite replacement, mayindicate that the opaque material also was remobil­ised during the replacement process, and was eitherconcentrated at the replacement front, or formedpreferentially in unreplaced foraminiferal ooze.

Detri tal Grains. A small number of detrital mineralgrains were noted in thin sections. To facilitate theiridentification, nine phosphorite nodules from differentstations were dissolved in hydrochloric acid. Theinsoluble residue was scceened, and the plus 200mesh fraction retained for petrographic analysis.This portion of the insoluble residue was alwaysless than 1% by weight of the whole nodule sample.

Most of the grains measure between 0.62 andO.l25mm. With few exceptions, the grains are quiteangular showing no indication of abrasion on sharpcorners. Glass shards, quartz and feldspar are com­mon 01' even dominant in many of the assemblages.and are associated with subordinate epidote, sphene,zircon and homblende (Table 1).

Glass shards are present in all residues examinedand abundant in many of these. They are clear, veryangular and less than 0.125mm in size. A majorityare curved and many contain fine dark-colouredinclusions.

Quartz is similarly common and occurs as smallangular fragments less than 0.125mm or as slightlylarger rounded grains. All are clear and lack inclu­sions.

Feldspars are found in many samples. Most areuntwinned plagioclases which were distinguished

17

from minor quantities of orthoclase by theil' higherindex of refraction. The grains are angular, smalland often exhibit good cleavage.

Epidote grains are clear, equant, angular and ofhigh birefringence.

Zircon is present as chipped or fragmentedcrystals. Fragments are clear and. although broken,show no other signs of mechanical abrasion.

Sphene and hornblende. when present, are repre­sented by only a few grains. Sphene is clear andangular. Hornblende fragments are tabular and exhibitgl'een-yellow!green pleochroism.

Fig, 13. Photomicrograph of phosphorite nodule showing aconcentration of opaque material (0) at the boundaryof the glauconite rim (G) and collophane zone (C)(CX37A).

Fig. 14. Photomicrograph of phosphorite nodule showingopaque material (0) (CX66B). Note selective infillingof foraminifera tests.

Mineral CX59A CMA CII098 C56A C46A-D C68A. C69A C468-8 C46

Glass shards X C C X C C C X X

Quart % X C C X C C C X X

Feldspars C C C C C X X

Epidote U R R R X

Sphene R R R X

Zircon U U R U M

Hornblende R R R R R

Glaucophane R

C · cOl!UllOn (Z5-50\) M . moderately COmT~on (5-25\)

U · uncommon (l-5\) R . rare (less than 1\)

X · present, but insufficient number of total grains to be Meaningful

TABLE 1. Relative frequency of mineral grains in the insoluble residue of Chatham Rise phosphorite nodules.

A comparison of the PZ0 5 content of nodules high(30%) and low (10%) in foraminifera shows no signif­icant variation in either range or average (Table 4).

Analyses of various regions within several nodulesshowed virtually no variation in PZ 0 5 • Even analysesfrom the brownish outer and light tan inner areas of a .distinctly zoned nodule (CXlllA, Fig. 7) both indi­cated 16% P2 °6, These results are consistent withan electron microprobe analysis of a cross-section ofa nodule, which did not detect any major difference inthe composition across the surface of the nodulesection (Buckenham et al. 1971). These data aresignificant in that they indicate that the colour zon­ation noted in some nodules is not a result of differ­ential phosphate replacement as originally suspectedby the author (Pasho 1972).

Aeolian transport of the grains is suggested bytheir small size, good sorting and their unabradedcharacter. Experiments suggest that grains of thissize, 0.62 to 0.125 mm, can be transported by strongwinds only a few miles (Udden 1898), and it isassumed, therefore, that the detrital gtains in thephosphorite nodules have been derived from landmasses that existed nearby.

CHEMICAL COMPOSITION

Available analyses of phosphorite nodules (Table2) show that CaO, Pz05 and CO z make up over 70% ofthe nodules. Lesser amounts of Fe,03' F. 8i0 2 andinsolubles account for nearly all of the remainder.Most of the P zO 5 and F, and part of the CaO and CO.­make up the collophane within the nodules. Some Cauand CO z most probably exist as calcite. Silica, ironand insolubles are attribiJted to detritals, opaqueparticles and glauconite.

The phosphate content of samples from the ChathamRise, representing 51 station averages, ranges be­tween 16 and 25% and averages 20.5% P ° (Appen­iix 1II). A histogtam of the frequency ot ~ 05 per­centages shows a definite peak between 20 and 22%(Fig. 15).

A selection of nodules of different sizes from thesame stations, and nodules with different percentagesof foraminifera were analysed to discover if the vari­ability of Pz 05 (collophane) content could be attri­buted to either of these variables.

Based upon the analyses of three size gtoups fromthree stations, no definite pattern relating Pz 06 andsize was found. The only generalisation made here isthat the Pz 05 content of the 0.5 to 1.0cm nodules ishigher than the 2.5 to 3.5cm nodules at the samestation (Table 3).

18

(/J

W...J=>oozu..oa::w!II::E=>z

Fig. 15. Histogram of the P2.05 content in phosphoritenodules representing 51 stations on the Chatham Rise(Appendix Ill).

2 3 4 5 6 7 8

Pl0S 25.4 19.18 18.10 19' 21.8 19.51 20.43 20.74

CaO 42.70 47.50 44.00 49' 37.5 53.31 51.25 40.04

AizO l T T 0.30

FezO, 1.43 2.50 4.27 1.48 2.18 2.37

MgO T T T 0.50 0.49

Insolubles 4.00 O.lO 5.12

Organic N N N

CO, 12.40 20.92 19.11 14.1 9.3 15.3

F 1. SO 1. 30 1.60 2.4 2.56 2.28 2.65 2.04

RzO, 4.2

SiO z 4.5 6.9 0.45 I.l5

CaO/PzOs 1.68 2.48 2.37 2.58 1.68 2.73 2.51 2.29

COz/PzOs 0.49 1.09 1.06 o "4 0.43 0.74

F/PzOs 0.059 0.066 0.086 0.126 0.117 0.117 0.130 C.IOO

1. Monsoon 73 Analyst Smith-Emery, Los Angeles2. ~IDnsoon 74 Analyst Smith-Emery, Lo!'; Angeles3. ~~nsoon 7S Analyst Smith-Emery, Los Angeles Not averaged4. Global Marine CXS9 (Rouse 1969)

.5. Discovery 11-2733 (Reed and Hornibrook 1952) No analysis6. Global Marine CX4S (Burnett 1974)

T Trace7. Global Harine (:,<79 (Burnett 1974)

.8. Average N Nil

TABLE 2. Collected partial chemical analyses of Chatham Rise phosphorite nodules.

CHARACTERISTICS OF DISTRIBUTION ANDASSOCIATIONS

With few exceptions, phosphorite nodules arerecovered on the Chatham Rise only in the area be­lween Reserve Bank and the western shelf of Chat­ham Island (Fig. 3). Phosp~orite appears to be absent

Station O.S-I.Oem 1.S':2.0cm 2.5-3.Scm

C66 24.7 20.2 20.1

CXSS 22.3 18.8 21.2

C56 22.2 27.7 18.8

TABLE 3. P2 Os content of various size phosphoritenodules from three stations on Chatham Rise.

Percent foraminifera 10\ 30\

hUmber of nodules 4 5

PZO) range (1,,) 17.2-21.4 18.6-20.1

PzOs average (t) 18.8 19.5

TABLE 4. Comparison of P2 Os content in nodules withdifferent percentages of foraminifera.

19

from Mernoo and Veryan Banks and' the shallowerareas of the Chatham Island shelf. Over mosl of theregion, phosphatic samples are scattered, and sep­araled by non-nodular samples. A significanl concen­tration of phosphorite nodules occurs in the saddlebetween Matbeson and Merooo Banks. The greatmajority of nodules were recovered from between400 and 500m. No nodules are found shallower lhan200 m. Lack of samples from a depth greater than500 m prevents generalisation on the maximum depthat which tbey occur.

A variety of lithologic types and sediments areassociated with phospborite nodules. Limestones,cherl, schist and volcanics accompany nodules. Greenmud, foraminiferal ooze and glauconitic silts are tbecommon sediment types associated with nodules.The type of associated material depends entirely uponwhat. is present. in that. mgion; in other words, t.hereappears to 'be no relationship between phosphorit.edistribution and the distribution of associated litho­logic or sediment type. Phosphorite nodules may beentirely absent or make up the tolal of fragmentslarger than 2.4 em. Most commonly nodules make upless than 50% of t.he large grain sizes, averaging10 to 15%. Comparison of the size dist.ribution of tbeminus 3.Scm sediment and the distribution of phos­phorile grains within individual size fractions indi­cates phosphorite is basically confined to the plus0.599mm fraclions irrespective of the total sedimentdistribution pattern (Fig. 16).

Fig. 16. Diagrammatic repre~

sEmta!ion of two totalsediment samples fromthe Chatham Rise illu­strating the distributionof P20s in various sizefractions. (Data fromGlobal Marine Inc.).Class intervals areBri tish Standard meshsize.

- 0 on'If" (\J N -cJ-'oooo

eXI42

30 30

20 20

10 10

0 0

..~ 60

40 40

20 20

0 00 0 on '" '" on0 on '" '" 0- 0 on .... '" '" on '" 0.,; .,; .,; .. N 0 0 0 .,; .,;

'" - '"

SIZE(mm)

ex 89

>­z

"'ua:"'..

ono..N

>­z"'ua:

"'..

DISCUSSION AND CONCLUSIONS

DEPOSITIONAL SETTING

During the late Miocene, foraminiferal oozes andchalks were deposited over much of the area nowoccupied by the Chatham Rise. The accumulation ofsuch oozes and chalks, which contain rather insig­nificant amounts of detri tals, suggests that the regionwas a submarine bank or ridge, isolated from detritalsedimentation, in an area of high or moderate plank­tonic surface productivity. In such :t situation,relatively coarse skeletal debris is deposited,whereas only the finest detrital sediment from shoreran reach the bank. Further separation of fines mayhave resulted from winnowing by bottom currents.

The relatively minor amounts of glauconite, whichoccur mainly as test fillings, might he attributed tothe existence of reducing micro-environments withinthe individual tests. Such a condition may lead tothe alteration of clays filling the test to glauconite(Emery 1960; Ehlmann et al. 1963). Other conditionswhich are believed necessary for glauconite formationare not inconsistent with a bank top environment.They include a depth of formation he tween 10 and1800m; temperature as "probably not favoured bymarkedly warm waters· (Cloud 1955); and a lowsedimentary innux (Cloud 1955; Bell & Goodell 1967).

Absence 01 MIOcene deposits on the far westernand far eastern stretches of the Chatham Rise could

be explained by the emergence of these areas duringthat time. If these areas were exposed, they' wereprobably of low relief.

The setting, as described here, is quite similar tothe situation existing on the Santa Rosa-CortezRidge of the Southern California Borderland (Dchupi1954, 1961).

PHOSPHATISATION

The sporadic and irregular distribution of first­generation collophane-replacement features, and thelack of significant variations in P2 0 5 content withinindividual nodules are consistent with phosphahs­ation of the chalk during diagenesis. A possiblysimilar l!lodern example of the phosphatisation offoraminifera in an unconsolidated sediment from thewestern shelf of Baja California has been describedby d'Anglejan (1967,1968).

SUBSEQUENT HISTORY

Following diagenesis the deposit was uplifted,perhaps during the Plio-Pleistocene Kaikoura Orogeny.Subaerial erosion resulted in the initial fragmentationof the phosphatised ooze. Weathering of fragmentsduring subaerial exposure may have produced the

20

penetrating brown zones noted in some nodules.Subsequent periods of submergence, with glaucon­itisation of fracture surfaces, and re-emergence areindicated by the numerous relative ages of glaucon­itised and unglauconitised fractures. That post­Pleistocene glauconitisation has occurred is inde­pendently supported by the occurrence of glacialerratics with a glauconite coating (Cullen 1962).Later fracturing with no glauconitisation was appar­ently the last stage leading to the present form of thephosphorite nodules.

As indicated by the extent of phosphatised oozefragments, much of the Chatham Rise must have beenabove sea level at various times since the late Mio­cene. Significant reworking has occurred on Reserveand Matheson Banks where phosphorites are mixedwith Mesozoic greywackes and pre-Mesozoic schistsrespectively. Whether phosphatised oozes everexisted on Memoo Bank or the Chatham Islands isopen to question. If so. the deposits have been eitherextensively eroded or are blanketed by yonngersediment.

ACKNOWLEDGMENTS

Thanks are expressed to Global Marine Inc., andin particnlar William Rader, who made samples anddata available to the author. .

To D.S. Gorsline and J. Bischoff for their con­structive criticism and review of this manuscript, andD.J, Cnllen for snpplying reference material otherwisedifficnlt to obtain, I extend my appreciation.

Mnch of this work was conducted in laboratories ofthe Department of Geological Sciences at the .Uni­versity of Sonthern California. and was partiallysnpported nnder Contract 14-08-0001-12849 for theU,S. Geological Snrvey.

21

REFERENCES

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AUSTIN, P.M.; SPRIGG, R.C.; BRAITHWAITE, J.C. 1972:Stntctural development of the eastern Chatham Rise andof the New Zealand region. Pp 201·1;i in Fraser, R.(Comp.) "Oceanography of the South Pacific". N. Z.National Commission Cor UNESCO, Wellington. 524p.

BELL, D.L.; GOODELL, H.G. 1967: A comparative studyof glauconite and the associated clay fractioil in modemmarine sediments. Sedimentology 9 : 169-202.

BRODIE, J.W. 1964: Bathymetry of the New Zealand region.MemoIr N.Z. OcearlOgraphic Institute J1. (N.Z. Depar/­ment of Scienlific and Industrial Research Bulletin /61.)55p.

BItOWN, D.A.; CAMPBELL, K.S.IV.; CROOK, K.A.IV. 1968:"The Geological Evolution of Australia and New Zea.land-. Pergamon Press. 409 p.

BUCKENHII.M, M.H.; ROGERS, J.; ROUSE, J.E. 1971:Assessment of Chatham Rise phosphorites. Proceed·ings of the Australasiall Institute of Mining and Metal­lurgy, Annual Conference 1971, 8 : 1-13.

BURNETT, W.C. 1974: Phosphorite deposits from the sea.Ooor orf Peru and Chile: radiochemical a.nd geochemicalinvestigation concerning their origin. [Report]. HawaiiInstitute of Geophysics. HIG-74-3: 163p.

CLOUD, P .E. 1955: Physical limi ts of glauconite formation.Bulleti" of the America" Association of PetroleumGeologists 39: 484-92.

CULLEN, D.,1. 1962: The significance of a glacial erraticfrom the Chatham Rise, east of New Zealand. N.Z.Jourl/al of Geology and Geophysics 5(2) : 309-13.

CULLEN, D.J. 1965: Autochthonous rocks from the ChathamRise, east of New Zealand. N.Z. Journal of Geologyand Geophysics 8(3) : 465-74.

CULLEN, D,J, 1967: The age of glauconite from the Chat­ham Rise, east of New Zealand. N.Z. Journal of Marineand Freshwater Research /(4) : 399.406.

CURRAY, J.R. 1969: History of continental shelves. InThe new concepts of continental margin sedimentation.A merican Geological Institute. Short Course LectureNotes: JC-VI-l to JC·IV-18.

d'ANGLEJAN, B.F. 1967: Origin of marine phosphorites offBaja Califo~lia,;Mexico. Marine Geology 5 : 15·44.

d'ANGLEJAN, B_ F. 1968: PhoslJuate diagenesis of carbon­ate sedimeuts as 8. mode of in situ formation of marinephosphori tes : Observations in a core from the easternPacinc. Canadian Journal of Earth Sciences 5 : 81·7.

EHLMANN. A.J.; HULINGS, N.C.; GLOVER, E.D. \983:Stages of glauconite formation in modern foraminiferalsediments. Journal af Sedimentary Petrology 33 : 87·96.

EMERY, K.O. 1960: "Tbe Sea 0[[ Soutbern California"John Wiley. New York. 366p.

FLEMING. C.A. 1962: New Zealand biogeography. A pale-

22

ontologist's approlch. Tuatara 10(2) : 53-1G8.

FLEMING. C.A.; REED, J.J. 1951: Mernoo Bank. east ofCanterbury, New Zealand. N.Z. Journal of Science andTechnology 832(6) ; 17-30.

GLASBY, G.P.; SINGLETON, R.J. 1975: Underwaterphotographs of manganese nodules from the SouthwesternPacific Basin. N.Z. Journal of Geology and Geophysics18(4): 597-604.

HAY, R.F.C.: MUTCH, A.R.; WATTERS, W.A. 1970: Geo­logy of the Chatham Islands. N.Z. Geological SurveyBulletin 83: 86 p.

HOUTZ, R.; EIViNG, J.; EWING, M.; LONARD!, A.G.1967: Seismic reflection profiles of the New ZealandPlateau. Journal of Geaphysical Research 72 : 4713-29.

KARlG, D.E.; PETERSON, M.N.A.; SHORE, G.C. 1970:Sediment capped guyots in the Mid·Pacific Mountains.Deep Sea Research 17: 373-8.

KENNETT, J.P.; CASEY, R.E. 1969: Foraminiferal evi·dence for a pre·Middle Eocene age of the Chatham Rise.New Zealand. N.Z. Journal of Marine and FreshwaterResearch 3(1) : 20-8.

KNOX. G.A. 19~7: General account of the Chatham Islands1954 Expedition. Memoir N.Z. Oceanographic Instilute2. (N.Z. Departmem of Scientific and Industrial ResearchBulletin 122). 37p.

NORRIS, R.M. 1964: Sediments of eha-tham Rise. MemoirN.Z. Oceanographic Institute 26. (N.Z. Department ofScientific and Industrial Rese::~:-" Bulletill 159). 39p.

PASHO, D.W. 1972: Character and origin of marine pIIOS·phorites. University of SOllth~ml California. GeologyPublication 72-3 : 1-18S.

PRATT, R.M. 1971: Lithology of rocks dredged from theBlake Plateau. Southeastern Geology 13 : 19·38.

REED, J.J.; HORNIBROOK, H.deB. 1952: Sediments [romthe Chatham Rise. N.Z. Journal of Science and Tech­nolagy 834(3).: 173-89.

ROUSE. J .E. 1969: Phosphorite from the Chatha.m Risesediments in New Zealand. Annual Report N.Z. Fer­tiliser Manufacturers ASSOCiation. /968-69 : 29-31.

SUMMERHAYES, C.P. 1967: Marine environments ofeconomic mineral deposition around New Zealand : areview. N.Z. Journal of Marine and Freshwater Re­search 1(3): 267-82.

UCHUPI. E. 1954: Submarine geology of Ule Santa Rosa­Cortez Ridge. Unpublished M.S. thesis. Deparunent ofGeological Sciences, University of Southern California,Los Angeles. 72p.

UCHUPI, E. 1961: Submarine geology of the Sama Rosa­Cortez Ridge. Journal of Sedimentary Petrolog)' 31 :534-5.

UDDEN, J.A. 1898: The mecha.nical composition of winddeposits. Augustana Librar)' Publications 1 : 65p.

WATTERS, W.A. 1968: Phosphorite and apatit.e occurrencesand possible reserves in New Zealand and outlyingIslands. N.Z. Geologtcal.:lurvey Report 33 : 15 p.

APPENDIX I

CHATHAM RISE STATIONSGMI Cruise I

Roman numerals indicate a resampling of the samestation. Capital letters indicate a unique station,but one which was not in the original cruise plan.Depth uncorrected for regional variation of sound velocity.

Station Latitude Longitude Depth Station Latitude Longitude Depth(C) (OS) (m) (e) (OS) (m)00 • 0

I 43 48 175 01 E 437 56 J 43 35 179 10 W 4002 43 46 175 2S E 360 56 I3 43 43 176 00 E 346 56 A 43 38 179 OS W 4004 43 44 176 29 E 400 57 43 43 179 00 W 3865 43 40 177 00 E 455 58 43 49 179 00 W 3.16 43 43 177 23 E 375 59 43 45 179 17W 3567 43 45 178 00 E 432 60 43 44 179 30 W 3248 43 SO 178 29 E 412 60 A 43 40 179 30 W 3459 43 45 179 02 E 433 61 43 32 179 30 W 39410 43 37 179 29.5 E 412 62 43 20 179 30 W 48211 43 47 179 59.0 liP 400 63 43 28 179 45 W 43012 43 57 179 30 W 318 :: 11 43 36 180 00 W 39013 44 02 178 54 W 369

14 44 54 178 30 W 409 64 A 43 31 180 00 h' 39315 43 52 178 00 W 409 65 43 27 179 58 E 39316 44 03 177 28 W 391 66 43 18 179 59 E 45517 44 24 177 00 W 500 67 43 24 179 44 E 43218 44 09 176 57 W 282 68I}

43 30 179 30 E 39119 44 04 177 00 W 164 6820 44 13 176 32 W 120 69 r} 43 23 179 30 E 39421 44 23 176 32 h' 164 6922 44 36 176 32 W 70 43 26 179 IS E 38223 44 30 176 00 W 71 43 37 179 00 E 38224 44 18 176 00 W 73 72 43 26 178 58 E 38625 44 27 175 30 W 437 73 43 18 179 00 E 40026 44 12 175 30 "" 182 74 43 26 178 46 E 34027 44 02 175 30 W 127 74 A 43 43 178 42 E 33228 43 SO 175 40 W 231 75 43 32 178 30 E 3382. 43 40 175 40 W 292 76 43 20 178 30 E 36430 44 00 176 00 W 91 77 43 II 178 27 E 38631 43 46 176 00 W 127 78 43 20 178 12 E 31832 43 34 176 00 W 22. 79 43 29 178 01 E 33233 43 22 176 00 W 400 80 43 20 178 00 E 28634 43 16 176 32 W 270 81 43 10 177 58 E 36435 43 . 27 176 32 W 109 82 44 14 175 52 E 41036 43 35 176 32 • 55 83 44 14 175 55.6 E 13137 43 48 176 57 W 104 84 44 14 176 OS.S E 10438 43 36 177 00 • 106 85 44 14 176 16 E 14639 43 24 177 00 W 91 86 44 02 176 16 E 41840 43 12 177 00 "" 391 87 44 20 175 00 E 27841 43 IS 177 27 W 354 88 43 21 174 SO E 33842 43 25 177 27 itt' 258 89 43 10 174 SO E 32843 43 36 177 27. 258 90 43 06 175 02 E 12044 43 48 177 27 • 292 91 43 IS 175 02 E 15745 43 44 177 42 W 376 92 43 26 175 02 E 37346 ) 43, 45 178 00 W 364 93 43 38 175 02 E46 1 94 43 34 175 16 E 20046 A I} 43 39 178 00 \1,' 364 95 43 22 175 17 E 10046 A 96 43 12 175 17 E 14046 8 I} 43 35 178 00 W 364 98 43 12 175 33E 10046 B 99 43 2J 175 29 E 11847 43 28 178 00 • 364 100 43 07 176 10 E 45548 43 17 178 00 W 354 101 43 15 176 21 E 34249 43 19 178 15 1'.' 392 102 43 IS 176 45 E 284SO 43 20 178 30 \'i 405 103 43 OS 176 45 E 39151 43 32 178 30 • 400 104 43 03 177 os E 35552 43 40 178 IS W 377 105 43 II 177 08 E 22653 43 43 178 30 W 445 106 43 17 177 28 E 28054 43 31 178 45 W 437 107 43 22 177 25 E 27355 43 25 179 13 W 437 108 43 IS 177 20 E 222

23

APPENDIX II

CHATHAM RISE STATIONSOMI Cruise II

Roman numerals indicate a resampling of the samestation. Capital letters indicate a unique station,but one which was not in the original cruise plan.Depth uncorrected for regional variation of sound velocity_

Station Latitude Longi tude Depth Station Lati tude Longitude Depth(eX) ('5) (m) (ex) ('5) (m)• • • •1 43 35 179 28 W 417 59

lIJ43 33 179 43 E 402

2 43 37 179 28 W 373 593 43 39 179 28 W 373 60 43 31 179 43 E 4204 43 41 179 28 W 365 61 113 43 31 179 36 E 4135 43 43 179 28 W 365 616 43 45 179 28 • 62 43 32 179 36 E 4137 43 47 179 28 W 314 63 43 34 179 36 E 4318 43 49 179 28 W 299 64 43 35 179 36 E 3989 43 51 179 28 W 289 65 43 36 179 36 E 409

10 43 53 179 28 • 292 66 ,,1 43 37 179 36 E 40911 43 55 179 28 W 289 6612 43 57 179 28 W 303 67 43 38 179 36 E 40913 43 59 179 28 W 321 68 43 39 179 36 E 41314 44 01 179 28 l'.' 343 59 43 40 179 36 E 42015 4' 03 179 28 "" 406 70 43 42 179 36 E 43116 44 04 179 36 W 71 43 39 179 29 [ 42017 44 03 179 36 W 347 72 43 38 179 28 E 41718 44 01 179 3S 111 343 73 43 36 179 30 E 41319 44 00 179 3S W 376 74 43 35 , 79 31 E 41120 '3 57 179 35 W 380 75 43 34 179 33 E 40921 43 53 179 3S W 380 76 43 32 179 34 E 39622 43 51 179 38 • 369 77 43 31 179 29 E 43123 43 47 179 3S w 365 78 43 20 179 29 E 43124 '3 4.4 179 36 W 395 79

11}43 23 179 29 E 395

25 43 40 179 36 W 413 7926 43 42 179 44 W 402 80 43 23 j 79 27 E 39327 43 46 179 44 W 376 81 43 29 1i9 29 E 39628 43 48 179 44 W 365 82 43 32 179 29 E 39329 43 SO 179 44 W 376 83 43 35 179 29 E 41730 43 54 179 44 W 395 84 43 39 179 29 E 42431 43 SO 179 SO W 402 85 43 41 179 30 E 44232 43 46 179 SO W 365 86 43 36 179 22 E 42433 43 42 179 SO W 384 87 111 43 34 179 22E 40234 43 '" 179 SO W 406 8735 43 34 179 SO 1IIT 424 88 43 33 179 22 E 41536 43 49 179 56 \\' 402 89 1I} 43 32 179 22 E 39837 ,,1 43 42 179 56 E 398 8937 90 43 31 179 22E 39538 43 38 179 56 E 413 91 43 30 179 22E 43839 43 34 179 56 E 409 92 43 28 179 22E 40240 43 30 179 S6 E 424 93 43 27.5 179 22E 39541 43 26 179 S6 E 94 43 27 179 22 E 40942 457 95 43 25 179 22E 39843 43 28 179 49.5 E 442 96 '3 ?- 179 22E 409_0

44 43 29 179 SO E 409 97 43 22 179 22 E 42445 liT 43 32 179 SO E 395 98 43 23 179 IS E 44245 99 43 25 179 IS E 44246 ;43 33 179 SO E 402 100 43 27 179 15 E 43547 43 34 179 SO E 395 101 43 29 179 15 E 41848 43 35 179 SO E 402 102 43 31 179 15 E 42449 111 43 37 179 SO E 395 103 43 32.$ 179 15 E 41149 104 Il} 43 35 179 IS E 413SO 43 38 179 SO E 402 104 A51 43 40 179 48 E 406 105 43 38 179 IS E 39552 43 42 179 50 E 395 106 43 40 179 IS E 40953 43 44 179 50 E 420 107 43 39 179 07 E 42654 43 41 179 43 E 418 108 43 37 179 07 E 39555 11) 43 39 179 43 E 402 109

Ir}43 35 179 07 E 369

55 10956 43 38 179 43 E 402 110 43 33 179 07 E 39857 43 37 179 43 E 406 III 43 31 179 07 E 41358 43 35 179 43 E 402 112 43 26 179 01 E 420

24

Station Latitude Lonsitude Depth Station Latitude Longitude Depth(CX) (OS) (-) (CX) ('S) (m)• •113 II} 43 30 179 01 E 380 168 43 48 178 52 W 407113 169 43 44 178 52 • 396114 43 32 179 01 E 347 170 43 40 178 52 • 438115 II} 43 38 179 01 E 369 171 43 39 178 52 • 468115 172 43 35 178 45 • 466116 43 36 179 01 E 356 173 43 32 178 38 • 431117 43 38 179 01 E 369 174 43 37 178 38. 438118 43 40 179 01 E 329 175 43 42 178 38 • 449119 43 42 178 48 E- 400 176 43 47 178 38 • 464120 43 34 179 20 W 417 177 43 51 178 38 • 459121 43 36 179 20 • 395 178 44 00 178 38 • 438122 43 38 179 20 • 387 179 44 01 178 38 • 438123 43 42 179 20 • 380 180 44 02 178 38 • 446124 32 47 179 20 W 380 181 44 06 178 38 • 464125 43 49 179 20 • 347 182 44 07 178 32 • 446126 43 54 179 20 • 309 183 44 01 178 32 W 468127 43 58 179 20 • 248 184 43 54 178 32 • 458128 44 00 179 20 • 318 185 43 48 178 32 • 449129 44 04 179 20 • 318 186 43 42 178 32 • 438130 44 08 179 20 • 402 187 43 38 178 32 • 420131 44 11 179 13' 402 188 43 34 178 32 • 420132 44 07 179 13' 189 43 34 178 32 • 420133 44 03 179 13 l~ 299 190 43 28 178 32 • 438134 43 59 179 13. 270 191 43 22 177 SO • 438135 43 58 179 13. 219 192 43 27 177 50 • 438136 43 54 179 13 • 230 193 43 32 177 SO • 427137 43 SO 179 13. 369 194 43 33 177 50 • 387138 43 46 179 13 • 380 195 43 38 177 SO • 385139 43 42 179 13 • 406 196 43 43 177 SO • 304140 43 38 179 13. 424 197 43 48 177 SO W 380141 43 37 179 06 • 409 198 43 53 177 SO • 438142 43 39 179 06 • 424 199 43 53 177 57 • 438143 43 41 179 06. 417 200 43 48 177 57 • 406'44 43 45 179 06 • 402 201 43 43 177 58 • 382145 43 50 179 06 • 393 202 43 38 177 58 • 38014.6 43 54 179 06 • 340 203 43 33 177 59 • 365147 43 57 179 as • 376 204 43 32 177 58 • 376148 43 58 179 06 • 409 205 43 27 177 57 • 402149 44 00 179 06 • 380 206 43 25 177 57 • 438ISO 44 01 179 06. 358 207 43 14 178 03 • 420151 44 02 179 06 • 256 208 43 16 178

03 _40~152 44 OS 179 06 • 303 209 43 23 178 03 • 365153 44 10 179 06 • 438 210 43 35 178 03 • 384154 44 06 179 00 • 420 211 43 39 178 03 • 384ISS 44 02 179 00 • 336 212 43 44 178 03 _380156 43 58 179 00 • 318 213 43 49 178 03 • 424157 43 54 178 59 • 398 214 43 55 178 04 • 453158 43 48 178 57 • 424 215 43 55 178 17 • 421159 43 44 178 56 • 417 216 43 SO 178 17 • 402160 43 39 178 56 • 395 217 43 45 178 17 • 380161 43 52 178

45 _438 218 43 45 178 17 • 380162 43 59 178 46 • 438 219 43 35 178 17 • 411163 44 03 178 46 • 431 220 43 25 178 17_ 420164 44 06 178 52 ti 409 221 43 20 178 11 • 424165 44 02 178 52 • 395 222 43 IS 17e 11 • 409167 43 52 178 52 111' 420

25

APPENDIX III

Listing of available P20S analyses on phosphoritenodules from Chatham Rise.

No. Stat ion Analysed Portion \P20S Reference

Monsoon 73 "'nole nodule 25.4 Global Marine •2 Monsoon 7' "'hole nodule 19.2 Global Marine •3 Monsoon 75 Whole nodule 18. I Global Marine, Discovery 11 - Analyses of six nodules 21.8 Reed and Hornibrook

2733 (1959)

5 C'6 Average of three analyses on variousportions of the same nodule 17.2 This work

6 C46A-O Whole nodule 17.7 This work

7 C468- 8 ~nole nodule 19.9 This work

8 C56 Average of three she fraction analyses 22.9 This work

9 C56" Whole nodule 19.2 This work

10 C64. \IInole nodule 20.2 This work

11 C66 Average of three site fraction analyses(See Table 3) 21.7 This work

12 C6SA Whole nodule 18.9 This work

13 C69. Average of two analyses on exterior andinterior portions of the 5~e nodule 21.4 This work

I' eX3? Bulk sample 16.S Global Marine

IS CX39 Bulk sample 21.7 Global Marine •16 CX4S 19.5 Burnett (197')

17 CX46 Bulk sample 18.5 Global Marine •18 CX47 Bulk sample 16.9 Global Marine •19 CXS4 Bulk sample 20.3 Global Marine •20 CXSS Average of three she fraction analys.s This work(see Table 3) 20.8

20.0S5 Bulk sample 21. 2 Global Marine •

21 CX56 B~lk sample 21.4 Global Marine

22 CX57 Bulk sample 23.3 Global Marine •23 CXS9A Whole nodule 19.9 This work

59 19 t Rouse (1969)

24 (X61 Bulk sample 17.8 Global ~1arine •25 CX6lA Average of two analyses on exterior and

interior portions of the same nodule 16.5 This work

26 CX62 Bulk sample 21. 3 Global Marine

27 CX65 Bulk sample 20.7 Global Marine •28 CX66 Bulk sample 21.8 Global ~Iarine

29 eX;;7 Bulk sample 21.9 Global Marine

30 CX69 Bulk sample 20.4 GIClbal Marine •31 cxn Bulk sample 24.9 Global Marine •32 cxn Bulk SaI:lple 22.' Global Marine

33 exn Bulk sample 21.0 Global ~larine •

34 eX79 Bulk sample 20.0 ) Global "larine

eX79 20.4 ) 20.2 Burnett (197'))35 eX91 Whole nodule 21.5 This work

36 eX93 Bulk sample 20.5 Global "larine

37 CX94 Bulk sa1llple 21.3 Global Harine

38 CXl04A h'hole nodule 20.2 This work

39 eXI05 Bulk sample 21.5 Global Marine

26

No. Station Analysed Portion \P20S Reference

40 CXI06 Bulk sample 23.1 Global ~tarine '*

41 CXI09B Whole nodule 18.8 This work

42 CX114 Bulk sample 20.6 Global Marine

43 CX1l5 Bulk sample 22.4 Global Marine·

44 CX141 Bulk sample 17.6 Global Marine ..

45 CX142 + 3/4 in Bulk sample 17.8 Global Marine

46 CX159 Bulk sample 22.6 Global Marine '*

47 CX178 Bulk sample 24.4 Global Marine •48 CXl83 Bulk sample 23.0 Global Marine •49 eX188 Bulk sample 20.0 Global Marine •50 CXl96 Bulk s8Jllple 20.7 Global Marine •51 eX203 Bulk sample 16.6 Global Marine ..

Average 20.45

• Analysed by Smith-Emery, Los Angeles• Analysed by M.H. Buckenham. University of Otago. New Zealandt Value not included in average

27

N.Z. OCEANOGRAPHIC INSTITUTE MEMOIRS

Other memoirs in this series include -

DELL. R.K.; JONES.N.S.; YALDWYN.J.C. 1960: BiologicalResults of the Chatham Islands 1954 Expedition. Part l.Decapoda Brachyura.; Cumacea; Decapoda Natantia.Mem. N.Z. Oceanogr. Inst. 4.

FELL, H.B. 1960: Biological Results of the Chatham Islands1954 Expedition. Part 2. Arcbibenthal and LittoralEchinodenns. Mem. N.Z. Oceanogr. Inst. 5.

NORRIS, R.M. 1964: Sediments or Chath3.lJl Rise. Mem. N.Z.Oceanogr. Inst. 26.

PANTIN, H.M. 1966: Sedimentation in Hawke Bay. Mem.N.Z. Oceanogr. Inst. 28.

SQUIRES, D.F. 1964: Biological Results or the ChathamIslands 1954 Expedition. Parte. Scleractinia. Mem. N.Z.Oceanogr. lnst. 29.

KNOX, G.A. 1960: Biological Results of the ChathamIslands 1954 Expedition. Part 3. Poly chaeta Errantia.Mem. N.Z. Oceanogr. Ins I. 6.

HEDLEY, R.H.; HURDLE, C.M.; BURDETT, I.D.J. 1965:A ForaminiCeral ;.'auna {rom the Western Continental Shelf,'North Island. New Zealand. Mem. N.Z. Oceanogr. Inst.25.

BERGQUIST, P.R.; PIKE, R.B.; HURLEY. D.E.; RALPH,P.M. 1961: Biological Results of the Chatham Islands1954 Expedition. Part 5. Porifera : Demospongiae;Porifera : KeratoBa; Crustacea Isopoda Bopyridae;Crustacea Isopoda -: SeroIidae; H)·droida. Mem. N.Z.Oceanogr. Inst. 13.

DELL, R.K.; EDMONDS, S.J.Chatham Islands 1954Mollusca; Sipunculoi<lea.

1960: Biological Results or theExpedition. Part 4. MarineMem. N.Z. Oceanogr. Ins!. 7.

KRAUSE, D.C. 1966: Geology and Geomagnetism of theBounty Region East of the South Island, New Zealand.Mem. N.Z. Oceanogr. lnst. 30.

CULLEN. D.J. 1967: The Submarine Geology of FoveauxStrait. Mem. N.Z. Oceanogr. Inst. 33.

McDOUGALL, J.C.; BRODIE, J.W. 1967: Sediments of theWestern SheH, North Island, New Zealand. Mem. N.Z.Oceanogr. Inst. 40.

KRAUSE, D.C. 1967: Bathymetry and Geologic Structure ofthe North-western Tasman Sea. - Coral Sea- South SolomonSea Area of the South-western Pacific Ocean. Mem. N.Z.Oceanogr. Inst. 41.

PANTIN, H.M. 1972: Internal Strueture in Marine Shelf,Slope, and Abyssal Sediments Bast of New Zealand.Mem. N.Z. Oceanogr. Inst. 60.

28