Part 4: EXTRACTS FROM:THE SUMMARY REPORT OF THE JOINT CCOP/SOPAC-IOC-UNU WORKSHOP ONBASIC GEO- SCIENTIFIC MARINE RESEARCH REQUIRED FOR ASSESSMENT OF

MINERALS AND HYDROCARBONS OF THE SOUTH PACIFIC, SUVA, FIJI.3-7 OCTOBER 1983

PREFACE The representative of the UN University(Tokyo), Dr Eric C. Bird, stated the United

The Workshop was jointly sponsored by the Nations University, established in Tokyo inCommittee for Co-ordination of Joint 1975, has a programme designed to stimulate,Prospecting for Mineral Resources in South support and co-ordinate research and advancedPacific Offshore Areas (CCOP/SOPAC), the training in a variety of fields, includingInter-governmental Oceanographic Commission Development Studies. Its work is organised in a(IOC). of UNESCO, and the United Nations global network with Associated Institutions, andUniversity (UNU, Tokyo) to review and update as well as ~upporting UNU Fellowships forthe Programme of Research which had been advanced study it sponsors and co-sponsorsdeveloped by the CCOP/SOPAC-IOC Second workshops on specific themes. The presentInternational Workshop on Geology, Mineral workshop is one of these, and as Project Co-Resources and Geophysics of the South Pacific, ordinator for Coastal Resources Management inheld in Noumea, New Caledonia, in October the UNU's Development Studies Division my1980 (see IOC Workshop Report No. 27). task here is to develop proposals for possible co-

operation w ith CCOP/SOPAC on en-vironmental and socio-economic aspects of

SUMMARY REPORT marine mineral resources prospecting and

Th . . I d b M C exploitation in the South Pacific region.e participants were we come y r ruzMatos of CCOP/SOPAC and t~e mee.ti?g was The Workshop was attended by 55 scientists ofthen formally ?pened by the Acting Mmlste: o~ 13 countries (in alphabetical order): Australia,Ene:?" and Mineral Resources, The Hon. Livai Cook Islands, Fiji, France, Federal Republic ofNasihvata. Germany, Japan, Kiribati, New Zealand, Papua

Dr Gunter Giermann representing IOC, New Guinea, Solomon Islan ds , Unitedconveyed the greetings of the Secretary of IOC, Kingdom, United States of America, andDr Mario Ruivo, to the Workshop. He Vanuatu. Scientists from the USSR in a messageintroduced some new IOC concepts which bear to the Workshop regretted that they were unableon the South Pacific, including the overall to attend due to reasons beyond their control.programme called Ocean Science and LivingResources (OSNLR). Representatives ofUN/OETB, a co-sponsor of

H . f d h W k h h h the IOC OSNLR programme and ESCAP alsoe III orme t e or s op t at t e ..P G f WESTPAC h f attended. The Workshop decided to establish two

rogram~e roup. or. ' t e arm 0 Working Committees:the IOC m the Pacific, has Just formed a Groupof Experts and has adopted two programmes in C . A G I . al E I tion of. .. ornrmttee on eo oglc vo u I~arme geology and geophysics of particular Island Arcs and Arc Basins, and the Genesisinterest to IOC. WESTPAC also agreed to co- f M al d H d b C t ti. . 0 et an y rocar on oncen ra IOns.sponsor a joint body with CCOP/SOPAC which d .will be known under the name of SOP ACI an . . . . dSTAR. WESTPAC recommended that the IOC Commltt~e B on DlstnbutlO?, Character. anE . C ·1" F b 984· Genesis of Offshore Metalliferous Depositsxecutive ounci III Its e ruary 1 meeting,formally approve SOPAC/STAR. Committee A discussed the state of knowledge

He finally stated that the outcome of the and past work in the SOPAC region in the fieldspresent Workshop will not only update CCOP/ of Hydrocarbon resources in island arcSOPAC's own programme, but will also allow sedimentary basins as well as island arc tectonicSOPAC/STAR and IOCIWESTPAC to choose processes. It was decided to divide into two sub-some of the projects for their own support and committees, each of which produced key projectimplementation. recommendations:

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A-l: Sub-programme on Sedimentary Basin B-2: Near-surface submarine volcanoes:Development in Island Arcs metallogenesis and assessment ofA-I.1: Stratigraphic Correlation in the volcanic hazards;

Southwest Pacific; B.3: Nature, origin and development ofA-I.2: Evolution of Coral Reefs and Associated metalliferous deposits along active rifts;

Environments; B.4: Distribution, composition and environ-A-I.3: Hydrocarbon Source, Maturation and ment of deposition of cobalt-rich ferro-

Entrapment Models in Island Arc manganese crusts;Settings and Collision Terrains; B.5: Environments of deposition of

A-1.4: Sedimentary Basin Delineation and potentially economic nodules.Resource Assessment; Projects B.1, 2, 3 arnd 5 continue the general

A-I.5: Data Management thrust of projects established at the earlier Suva. and Noumea Workshops, whereas Project B.4 is

A-2: Sub-programme on the Tectonics and a new one. Linkages are apparent with theResource Potential of Island Arcs WESTPAC III programme "Back-arcA-2.1: Forearc and Backarc processes in the tectonics", and IGCP Projects 111 and 156.

Tonga-Lau region' . . ..d ifti ' . h F'" As several parucipants expressed mterest m

A-2.2: Backarc an n tmg processes m t e IJI . al f h all dPI f N h F' .. B . N mmer resources 0 nears ore areas, a sm aat .~rm~ ort. IJI as in- ew hoc Working Party was formed. The Party

Hebn es c regIOn; . develo ed one roject called C.1: SedimentA-2.3: Arc reversal and forearc processes m the b d t

p· f r.~ d I

S I d N H brid A u ge s m ree -lrmge agoons.o omon an ew e n es res;A-2.4: Initiation and Early Stages of Back-Arc The Workshop n?te~ with great satisfaction

Basin Evolution' that several organisations such as CCOPfA-2.5: Evolution of' Major Geomorphic SOPAC, IOCfW~STPAC, an~ their joint ~o~y

Terrains in the Papua New Guinea called STAR, decided to coordinate and assist mRegion ("Project 42"); the. im~lementation of. marine geoscience

A-2.6: Pre-Pliocene Break-up History of the projects m the South Pa~Ific', It felt .that. thereSouthwest Pacific: A Regional should be no new coordinating bodies m theFramework Study South Pacific in the fields of marine geology,

geophysics and resources research. It thereforeProjects A-I.1 and A-1.4 and all of A-2 was doubtf~ whether it. ,:"asnecessary to call for

continue the general thrust of projects established an InternatI?nal Exped1tIo~ to ~tud! the South-at the earlier Suva and Noumea Workshops. western Pacific, as the SOVIetscientists wanted.Project A-I.1 links with ESCAP's current CCOPfSOPAC and WESTPAC areSedimentary Basins Correlation Project which is requested to not only implement joint projectsIGCP Project 32. Project A-I.2 is a new project under SOPAq!STAR, but also to consult eachwhich follows a recommendation from other and industry on scientific projectsWESTPAC III (Sub-programme CREST). implemented individually by either of theseProject A-1.3 and A-1.5 are wholly new concepts bodies.focusing on regional exploration models and themanagement of exploration and scientific data GENERAL RECOMMENDATIONSrespectively.

The Workshop -Committee B discussed the state of knowledge (1) Recommends that the Chairman transmit

and past wor~ in the SOP.AC region in the field for approval the adopted Workshop Reportof offsh?re mineral deposits. It was agreed t?at (including Recommendations and Pro-five projects under the general programme title grammes of Research) to the next Session"Distribution, character and genesis of offshore of CCOPfSOPAC, to be held inmetallic deposits" were needed to address Nuku'alofa Tonga 11-20 October 1982outstanding regional scientific problems. These and to the Secretary'IOC for submission t~are: the next session of the IOC Executive

B.1: Phosphorite, phosphatic sediments and Council, to be held in Paris, 1-10 Februaryassociated ferromanganese crusts; 1984, as well as to the next session of the

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Programme Group for the Western Pacific Introduction(WESTPAC), to be held in 1985. From a geological and mineral/hydrocarbon

(2) Taking Note of a proposal by Soviet resources viewpoint, two major environmentsscientists, dated November 1982, to are present in the CCOP/SOPAC region. Theseorganise an International Expedition to are best identified in plate tectonic terms as theStudy the Southwestern Pacific, an exercise Pacific Plate province and the convergent marginsimilar in scientific approach to the IDOE province at its western boundary with theof the late Fifties; Australia- India Plate. The earth shapingRecommends that the Soviet scientists processes within this convergent margin aremake available a more detailed Programme complex and in places poorly understood. Theof Research with individual research complex evolution of plate boundaries in thisprojects, to p~t the Workshop members in region m~es the.tect?nic, ~edimentolo~ical, andthe position to judge whether such an deformatIOnal. histories .dlfficult t.o I?terpret.important new vehicle like an international Nevertheless, It IS essential that this history beexpedition will really be needed, or understood if we are to adequately understandwhether the present mechanisms consisting the framework and asess the resource potential ofof CCOP/SOPAC, WESTPAC and the region.SOPAC/STAR are sufficiently suited to .. . .supervise the proposed Programme of The mtegration of marme geological andResearch. geophysical data with the limited land-derived

3 R d h f d d data for the region is an essential element in( ) ecommen s t e use 0 manne an . . .d b ibl . deriving the overall understanding necessary forunmanne su mersi es in programmes .

desi d tit d d d d an assessment of the mineral and hydrocarbonesigne 0 exp ore, s u y an un erstan .th t t t d iznifi f resources of the regIOn. We must not onlye na ure, ex en an sigrn icance 0 .

h d th al d its j th . d develop a fundamental understanding of they ro erm eposi s m e region, an . .. it th . . ti f crustal history of the region but we must alsomVI es e co-sponsonng orgarusa IOns 0

h W k h . I I understand the fundamental processes thatt e or sop, p a r t i cu ar y .CCOP/SOPAC d IOC fi d d control the parameters that influence resource

an ,to I~ ways an distribution.means to make use of submersibles.

(4) ~tcommends t~at i~ view of the int~rest?f The region affords excellent examples of manyISan~ states .m t e South Pacific I.n important tectonic, geomorphological andexploitable mineral resources of their sedimentary features associated with the activen~ar~hor.e z?nes, countries. of the .reg~on margins of oceanic plates. These include: thes ou d give increased attention to scientific active volcanic island arcs and their associatedpr?~lems conce~ed with the prospecting, trenches which characterize the zones of platemmmg and environmental management of convergence along the Melanesian Borderlandthese sea floor resources. A Workshop on and Tonga-Kermadec chain' fossil convergencethese topics should be held in the near zones such as the northern margin of the Northfuture. Fiji Basin; actively forming and inactive

(5) Taking Note of the paucity of good, cloud marginal basins with passive, oblique-slip, andfree satellite imagery in the SOPAC active trench margins, active and inactiveregion, interarc basins diverse in size and sedimentaryRecommends that NASA and other fill; and regions where the polarity of subductionagencies be strongly urged to collect and may have been reserved following a collision.make available satellite imagery in theSouthwest Pacific area including coverage Regional plate and microplate boundaries allout to at least 150 metres water depth. have complex evolutionary histories. ThePROGRAMMES OF RESEARCH geomorphological and tectonic diversity of the

A: REPORT OF COMMITTEE A ON region thus produced complicates the search forGEOLOGICAL EVOLUTION OF ISLAND resources but also provides necessary elements

ARCS AND ARC BASINS, AND THE required for the concentration of potentialGENESIS OF METAL AND HYDRO- resources such as hydrocarbons and mineral

CARBON CONCENTRATIONS deposits. Only through an adequate

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understanding of the processes involved in the Project A-1.2evolution of the various island arcs, basins and EVOLUTION OF CORAL REEFS ANDplateaus of the region can we adequately assess ASSOCIATED ENVIRONMENTSthe resource potential. This understanding will The main objectives of this programmeinvolve general studies of regional tectonics, are:seismicity, heat flow, sediment distribution, as (a) to define the extent age and geometry ofwell as focused studies on speci~c areas where reef systems in ; variety of regionalPresent background knowledge IS adequate to tti .. se mgs;suggest potential presence of resources. (b) to establish the relationship between reef

growth and (i) volcanic activity, (ii)Project A-1.1 tectonism, (iii) eustatic sea-level change,

STRATIGRAPHIC CORRELATION IN and (iv) world-wide climatic change;THE SOUTHWEST PACIFIC (c) to evaluate the inter-relationships between

A reliable time-stratigraphic correlation is the ~errigenous, volcanogenic and biogeniconly possible basis for confident appraisal of the mputs;. . . .most likely settings in which economic mineral (d) to det~rmme the o.ngm and preservatl~n ofand energy resources may occur. In order to organ~c carbon in reef and associatedachieve such a regional stratigraphic framework, deposits; and. .it is recommended that the following programme (e) to study related environmental Issues (seebe undertaken: report of Ad Hoc Working Party on1 C 11 ti . . d hesi f . . Mineral Resources of Nearshore Areas).. 0 a ion , revision an synt esis 0 existmg

time-stratigraphic and palaeogeographic Methods of investigation should includedata within the SW Pacific (*Refer also to shallow high-resolution (including multichannel)Project A-1.5 - Regional geologic data seismic, sediment mapping, stratigraphic coring,development for the SOPAC area) shallow vibrocoring, biostratigraphy, radio-

2. Any future basin assessment must include metric dating and geochemistry. Comparativenew, detailed time-stratigraphic studies. studies should be undertaken with reefs in a

This may be accomplished by: range of geographic and tectonic settings.

(a) Palaeontology: especially the detailed Proi t A-l 3. . f'mi c '1' rOJec .examination 0 rrncro-rossi s in order to correlate HYDROCARBON SOURCE

the rocks in which they are found with standard MATURATION AND ENTRAPMENTworld sequences MODELS IN ISLAND ARC SETTINGS(b) Land based studies: with the advice and AND COLLISION TERRAINSconcurrence of national Geological Surveys is recommend d h. . It IS recommen e tat:

(I) amend and/or redefme key onshorestratigraphic units critical to regional A. The possible occurrence of source rocks beoffshore stratigraphy where thi investigated, by taking suitable samplesconsidered desirable' IS IS both onshore and offshore (by drilling if

(ii) drill stratigraphic s~quences to acquire a neces~ary~ and carrying out the relevantbetter understanding of their facies, and to geo-~hemlCal ana~yses,revise and/or define stratigraphic units; to B. Studies be carried out o.f model p,layextend and enhance biostratigraphic concepts through. a~alysis of burial,correlation. thermal and tectonic history.'" .. C. Studies be made of the reservoir rocks types

(c) ~elsml~ str.atlgraphy: to IdentI~y offshore and their tectonic settings (such as reefsstrat~graphlc units, and to cor~elate WIth onsh?re and non-fan turbidites). The existence andstrat~g~aphy w.heneve.r possible; to examme extent of porosity and permeability shouldpossib e stratigraphic play concepts and be determined and occurrence of suitablehydrocarbon traps k' ffi '. d I .. roc S III su icient extent an vo ume III(d) Non -palaeontological proj ects: these appropriate type locations should beinclude development of local sea-level change verified.curves, magneto-stratigraphic measurement D, In order to achieve the above objectives inprojects, and appropriate radiometric dating, the best possible way, facies models should

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be developed by a study of contemporary (2) CCOP/SOPAC develop a directory ofenvironments and processes where previous geological and geophysicalpossible, including the accumulation of investigations within the member nationsorganic carbon. Particular attention should and identify the availability of data andbe given to modern reef systems (Project related products generated by theseA-I. 2) and modern non-fan turbidites investigations.(such as in the Huon. Gulf and possibly the (3) CCOP/SOPAC assist the memberNew Britain Trench). . countries in the acquisition and archiving

E. Studies should also be made of the seismic . of existing data.definition and seismic signatures (through (4) CCOP/SOPAC assist the membermodel and field studies) of relevant countries in the secure storage andenvironmental settings and conceptual accession of geophysical magnetic tapemodel plays. data.

(5) CCOP/SOPAC encourage and support the.P' A 1 4 further development of the ESCAP micro-

roject -. fossil reference collection to cover theSEDIMENTARY BASIN DELINEATION Southwest Pacific region.

AND RESOURCE ASSESSMENT (6) Those countries within CCOP/SOPACwhich have not drafted regulations or

It is recommended that: legislation requiring the lodgement of allA. Compilation of available geologic and geo- data and results obtained by future

physical data in the form of structure and geoscience investigations should beisopach maps, including overlays depicting encouraged and assisted to do so. Thisfacies changes in selected intervals be should include regulations for theundertaken. lodgement of any magnetic tape or other

B. New geological and geophysical data, computerised data.including mutlichannel seismic reflectionprofiles where appropriate, should be Project A-2.1collected in areas of relatively poor basin FOREARC AND BACKARC PROCESSESdefinition such as: IN THE TONGA-LAU REGION1. The insular margins of the Bismarck T

Sea onga Forearc2. Northern continuation of the Tonga It is recommended that a coherent plan of

Platform geological and geophysical studies to determine3. Lau Ridge the type, distribution, and geometry of the major4. Rennell Ridge rock units forming the Tonga forearc, and the5. The high plateaus between the Coral processes that emplaced deformed, and altered

Sea and Northern New Hebrides them, should be initiated. The work shouldTrench. initially involve multichanel reflection profiling

C. Synthesis of basin types (i.e. definition and as refraction seismology and surface rockclassification of basins); this effort should sampling. DSDP-type drilling should bebe incorporated into the CCOP/SOPAC promoted. Evidence should be soughtgeophysical atlas.' . concerning the origin of the forearc's basement

complex; the history of subsidence and uplift(e. g. vertical tectonics); magmatic activity;

Project A~1.5 emplacement of ultrabasic masses; tectonicDATA MANAGEMENT reaction to the subduction-driven collision of the'

It is recommended that: Tonga forearc and the Louisville Ridge, and; the(1) CCOP/SOPAC find ways and means to direct tectonic consequence of the subduction

assist member countries in archiving process itself; thick sequence.geoscience data and related products. This .assistance should include training Tonga Backarc (Lau Bas in)individuals from member countries in the It is recommended that the formation of Lauefficient operation of archive systems. Basin and the consequent thermal and rifting

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events of the former Tonga-Lau volcanic arc resolution bathymetric and seismic methods.receive thorough scientific attention. Geologic Bottom geochemical .sampling should also besampling including DSDP-type scientific undertaken to detect anomalous metaldrilling, is emphasized. Multichannel reflection concentrations.profiling intended to resolve pre-rift, rift and ... .post-rift structures bordering both the Tonga and FIJI ~l~tform Arc. Development: T~rralllLau-Ridge flanks of the basin is needed. recogmhon as a guide to the evaluation ofGeophysical techniques (e. g. multichannel and hydrocarbon potentialrefraction seismology, heatflow measurements, It is recommended that compilation of existingetc.) are needed to locate magma chambers and seismic data be undertaken and that additionalthermal anomalies whre mineralisation processes single and multi-channel seismic data bemay be concentrated. acquired in the nearshore and offshore waters of

It is further recommended that the collection the Fiji Platform proximal to the arcuateof regional information focus on resolving a structu~e. Delineation of the con.tiguous seafloornumber of key relations, which include (1) the mag~eti~ .ano~aly co~figuratlon m.ay alsotiming of initial pre-rift thermal events along the provide insight mto rotation and tectonism of thelength of the basin, (2) the initiation and lateral platform.progress of rifting (lengthwise) along the margins N H b .dAD I Th. . ew e n es rc eve opment: eof the basin, (3) the age and magmatic evolution. .f th ti T f (4) th I d potential for hydrocarbon accumulation and

o e ac rve .0 ua arc, e stye an progress metal enrichmentof the spreadmg process that has expanded the .basin to its present size, and (5) the entire It IS recommended that:opening process in relation to subduction events (a) detailed marine geophysical surveysoccurring at the regional plate boundary along including the collection of single and multi-the Tonga Trench. channel reflection, gravity and magnetics

be undertaken in the eastern margin of theProject A-2.2 Central Basin and across the less well-BACKARC AND RIFTING PROCESSES IN known basins off the Banks, Torres and

THE FIJI PLATFORM-NORTH FIJI Santa Cruz Islands;BASIN-NEW HEBRIDES ARC REGION (b) heat flow data to test the thermal regime be

. acquired from all basins;Magmatic arcs in the region are identified and (c) onshore bio-and lithostratigraphic correla-

the subduction polarity of some of the arcs has ti b d b t d' t . I d .IOn e rna e e ween a ~acen ISan s mnow been defined. The Fore Arc and Back Arc th f d b k . d th. . . e orearc an ac arc regIOns an atTerrain and the nrmng of the development of the . b d ith d d d. . compansons e rna e WI re gestructures need to be Identified. I . th . t basi b tsamp es in e m ra-arc asm e ween;Formation of North Fiji Basin and Spreading (d) the limited preliminary source rock studiesHistory and the evaluation of hydrothermal undertaken to date be continued andmetallic mineral deposits augmented by sampling from all

It is recommended that geophysical/geological formati?ns with potential for hydrocarboninvestigations of the North Fiji Basin be g~neratlOn; .expanded. Types of surveys should include high (e) with respect to the potenti~l for hydrot~er-resolution sea floor mapping techniques mal .met~l con~entratlOns, detailed(SeaMARC II or equivalent) bottom- t sampling IS required over the known

, wa er h d hermal j denosi . .sampling/bottom camera and mid t y rot erma Iron eposit associated with, wa er bmari I' ffgeochemical anomaly detection. su mar~ne vo cams~ 0 Epl; a search be

. . ... . made m appropnate areas along theRlftm~ on the FIJI ~latform: Extens ion complete length of the magmatic arctecto~lcS and t~e possible development of (Central Chain) for similarly situatedsulphide ore bodies deposits;

It is recommended that comprehensive (f) supplementary investigations begeophysical/geological studies of the northern undertaken with relevance to thema:gin of the Fiji platform be initiated. Shelf and development of the arc includingbasm morphology should be delineated using high radiometric dating of Miocene andesitic

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intrusives of the forearc Western Belt Project A-2.5volcanics, and a survey of the little known EVOLUTION OF MAJOR GEOMORPHICWest Santo Basin and West Torres Massif TERRAINS IN THE PAPUA NEW GUINEAto the north of the D'Entrecasteaux Zone, REGION ("Project 42")

Project A-2 ..3 It is recommended that a single broad-transectARC REVERSAL AND FOREARC style of investigation embodying the attributes of

PROCESSES IN THE SOLOMON AND the previous SEAT AR transects proposed for theNEW HEBRIDES ARCS PNG region, be initiated. This will be

NEW HEBRIDES SOLOMON ISLANDS particularly well suited to the solution of theARC REVERSAL major geodynamic problems relating to the

It is recommended that a work programme be accumulation of mineral and hydrocarbonimplemented to include (a) evaluation of existing resources in the region.data to indicate areas for limited on-landgeological investigations to obtain the closest The methods that need to be applied include,possible time constraints on the emplacement age among 0 thers, geolo gical mapping,of the ophiolite bodies and time of arc reversal, paleomagnetic studies, deep crustal studies,together with (b) offshore multichannel seismic airborne and marine geophysics, Determinationreflection profiling to identify gently-inclined of the age of the Solomon Sea Basin is critical tothrust surfaces beneath and east of the eastern understanding the kinematics of the region,chain, and southwestward-verging thrusts orassymetric anticlines in the Aoba and NewGeorgia Sound Basins, Project A-2.6

Fore-arc magmatism and mineralisation in PRE-PLIOCENE BREAK-UP HISTORY OFthe Solomon Arc THE SOUTHWEST PACIFIC:

A REGIONAL FRAMEWORK STUDYIt is recommended that the following investi-gations in the western Solomons be implemented It'd d th t th C llowi 0' t" , , . IS recommen e a e ,0 owmg pr ~ecWith the aim of developing a predictive-process I t be i ltd Th '11lead to a, . e emen s e Imp emen e, ese WImodel of forearc magmatism and associated t d t di f th b ak history of, " , grea er un ers an mg 0 e re upmineralisation: a) petrogenesis of fore-arc th A t r ti tal 'and therna mas' b) aeroma netic and areal ravit e ,us ra la~ con men , margl~

g ". g ,g y tectonic evolution of the regIOn, particularly thecharacteristics of fore-arc magmatic zone; c) di t hi t d ecognition of terrains:, , , , ,se Imen ary ISory an r I I ,precise dating of adjacent volcanic centres, inorder to determine their relationship to (a) east-west multichannel seismic reflectiondeformation in the forearc; d) modelling of triple lines across Lau, Three Kings, Loyalty andjunction behaviour and its effects on the Norfolk ridges, their margins and adjacentasthenosphere beneath the fore-arc; e) closely basins, to establish structural relationshipsspaced sediment sampling in the vicinity of fore- of sedimentary basins present and allowarc volcanic centres such as Kavachi to study the better correlation between ridges;local volcaniclastic contribution, and anomaloustrace metal concentrations in sediments, (b) rock dredging 01 Miocene and older

sedimentary sequences along the margins

P· A 2 4 of these ridges in areas where they haveroject -. I ff d b b I'INITIATION AND EARLY STAGES been east a ,ecte, y su sequent vo carne

OF BACK-ARC BASIN EVOLUTION eve~ts, to establish the nat~r~ of the, sedimentary sequences, the on gin of the

It IS recommended that to understand the sediments and environment of deposition;processes involved, detailed marine geologicaland geophysical surveys be undertaken including (c) rock dredging of basement sequences toprecision swath mapping and submersible establish pre-break up form of theinvestigations, It is also recommended that Australian continental margin, presentdevelopment of hydrothermal systems during distribution of pre-break up terrains andrifting of old crust, particularly as related to subsequent vertical tectonic history of eachmetallogenic implications, be investigated, ridge system,

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/B: REPORT OF COMMITTEE B ON values are 10 to 100 times the concentrations in

DISTRIBUTION, CHARACTER, AND deep-sea ferromanganese nodules. The massiveGENESIS OF OFFSHORE METALLIC sulphides and associated "black smoker"

DEPOSITS chimneys discovered so far are located along the. axes of medium to fast spreading centres in the

Introduction P if (6 10 rn/ )acme - c yr.Since the 1980 Noumea Workshop consider-

able work has been done on phosphorites,manganese nodules, and metalliferous

di Ph h h b ht b CCOP Project B-1se ments: osp ate as een soug y PHOSPHORITES, PHOSPHATIC/SOPAC in lagoons, ~nd by CCOP/SOPAC a~d SEDIMENTS AND ASSOCIATEDNZOI o~ of~shore ndges and ~eamou~ts, With FERROMANGANESE CRUSTSsome scientific success. Major reviews ofmanganese nodule occurrences and some .sampling were carried out by CCOP/SOPAC, Areas of interestreviews of nodule data were prepared by NZOI, South Pacific north of 23°S, and betweenand the Japanese Geological Survey was active in 1500E and 155°W concentrating on shallowthe northern part of the region. A review of banks along the northern margin of the Northgeochemical data for CCOP/SOPAC pointed to Fiji Basin, on the sea floor around knowna number of regions· where metalliferous phosphorite-rich islands, on the northernsediments might be found. Metalliferous Tasman Sea and Coral Sea seamounts, guyotssediments were found by CCOP/SOPAC offEpi and banks, selected lagoons and east of Newin Vanuatu and by a Tripartite cruise in the Zealand on the Chatham Rise.North Fiji Basin. Ajoint NZOIlImperial Collegecruise discovered hydrothermal manganese Scientific and resource objectivescrusts on the western Kermadec Ridge, and Determination of the distribution ofmetal enrichments in Lau Basin sediments. phosphatic and associated ferromanganese

Cobalt-enriched crusts and nodules have been deposits in the designated area; radiometricfound on sediment-free upper slopes of islands dating of such material; geochemical analysisand seamounts in the western Pacific. Their with a view to discovering the provenance, andeconomic potential stems from the fact that mode of deposition as well as geologicalcobalt concentrations up to about 2% in samples association (e.g. phosphate-ferromanganesefrom the upper slopes of the Hawaiian associations); and interpretation of relationships,archipelago, Mid-Pacific Mountains, Line if any, between phosphorites on seamounts andIslands and elsewhere have been measured. those exposed on Pacific Islands. Location ofThese enhanced cobalt concentrations, make the commercially exploitable deposits.upper slopes attractive targets for exploration.

The recent reviews of manganese occurrencesin the region have shown clearly that ore-grade Project B-2nodules are only likely to be present beneath the NEAR-SURFACE SUBMARINEbiological high-productivity zone along the VOLCANOES: METALLOGENESIS ANDequator from 100S to lOoN, between the Gilbert ASSESSMENT OF VOLCANIC HAZARDSand Line Islands. The subcommittee believesthat reconnaissance sampling should largely be Areas of interestreplaced by detailed studies of smaller A . c. brnari I f. ctive near-sur lace su marme vo canoes 0prospective areas. h h P'fi' I di ff hE't e sout west acr ic, inc u mg 0 s ore pi,

Metalliferous deposits in shallow-water areas Rabaul harbour, Ka~achi, and the submarineare associated with volcanoes or vents in island volcano east of the D Entrecasteaux Islands.arcs. In spreading centres in deep waterelsewhere in the world sulphide deposits Scientific and resource objectivescommonly contain such metals as copper, zinc, To locate and study hydrothermal deposits,lead and silver in varying concentrations up to and to evaluate the potential hazards, of active10, 50, 0.25, and 0.05 %, respectively. These near-surface submarine volcanoes.

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Project B-3 submarine lagoonal phosphorites in theNATURE, ORIGIN AND DEVELOPMENT southwest Pacific.OF METALLIFEROUS DEPOSITS ALONG (3) To encourage and promote closer

ACTIVE RIFTS cooperation with IGCP Projects 111Areas of Interest (Manganese) and 156 (Phosphorites).

T h . all . if d d (4) To study nearshore, shallow-water areasec rue y active n ts an sprea mg centres ..,. hi th . al basi t h S h surrounding Island countnes to assess theWit m e margm asms 0 t e out west . .. . .

Pacifi h th M B' h N th F'" extent and distribution of industrial/aCIIC, suc as e anus asm, t e or IJI .,B . th LB' d th W dl k B . construction matenals, placer and lodeasm, e au asm, an e 00 ar asm. . al d th . I' alrruner s, an e potentia environmentScientific and resource objectives impact of their extraction.

To locate and study submarine hydrothermalmetalliferous deposits in basins containing activerifts. Comparison should be made with rift- C: REPORT OF THE AD HOC WORKINGrelated hydrothermal deposits on mid-ocean PARTY ON MINERAL RESOURCES OFridges. NEARSHORE AREAS

IntroductionProject B-4 .

DISTRIBUTION, COMPOSITION AND Although the mmer:u resou.rces of ~e~rshoreENVIRONMENT OF DEPOSITION OF areas were not c~nsldered m detail. I? theCOBALT-RICH FERROMANGANESE Workshop . Comml~tees, several participants

CRUSTS expr~ssed interest in these, and an ad hoc. working party was set up. It recommended that a

Areas of interest scientific programme should be outlined forBathymetrically favourable sites in the Line further development at a subsequent Workshop

Islands, Phoenix Islands, Cook Islands, northern on Marine Research in Nearshore Areas. Such aTonga and Samoa. Workshop would benefit studies aimed at theScientific and resource objectives assessment of nearshore mineral resources.

To investigate the extent, composition and Such a progra~me sh~uld includeenvironment of deposition of Cobalt-rich g~om~rphologl~al, sedl~e?tologlCal and relatedferromanganese crusts in the southwest Pacific. biological studies of existmg reef, lagoon and

coastal environments; the mapping andProject B-5 correlation of submerged palaeocoastal and

ENVIRONMENTS OF DEPOSITION OF palaeofluvial features (notably incised andPOTENTIALLY ECONOMIC NODULES infilled river valleys traversing nearshore shelves

A f· t t and slopes), with reference to tectonics andreas 0 In eres . . d' h . f f.. a Isostatic a uustments; t e mappmg 0 patterns 0The oequaton.al bas~s between ~bout 10 N seagrass and mangrove communities in relation

and 10 S, and in particular the regIOn between to nearshore sediment distribution and flow'the Line and Gilbert Islands and the northern analysis of beach and nearshore hydrodynamics;Cook Islands. documentation of sea level changes; andScientific and resource objectives quantification of sediment yields from rivers, and

To determine the locations and environments from the erosion of coastal cliffs, rock platforms,of potentially economic nodules in the equatorial and reef formations.western Pacific. It is also recommended that pilot researchRecommendations projects in at least some of these fields be initiated

. Withthe support of IOC and other UN agencies,Committee B recommends: in association with universities and research

(1) To continue studies on the nature, extent, institutes in the South Pacific. A pilot project onenvironment of deposition and economic the budgeting of reefal sediment inputs to thepotential of offshore metalliferous deposits Suva lagoon, where coralline sand and gravel arein the southwest Pacific. being extracted, has already been planned, and

(2) To continue investigations of the distribu- will prepare the way for more extensivetion and geological relationships of assessments of nearshore sand and gravel

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resources and of the environmental effects of zones of all coral-fringed South Pacific islands.their mining from nearshore lagoonal areas.

Project C-l Scientific objectivesSEDIMENT BUDGETS IN REEF- Determination of sediment budgets, flow

FRINGED LAGOONS patterns, and depositional distributions in lagoonsectors between outlying coral reefs and island-

Area of interest mainland coastlines as a basis for generallyInitially, as a pilot project, the Suva lagoon, applicable classification and mapping ~f these

S.E. Viti Levu, Fiji; eventually the near-shore dynamic environments.

LIST OF PARTICIPANTS

Austin, W.H. Greene, H.G. Moaina, R.B.Baleivanualala, V. Hamburger, M. Prevot, R.Bird, E.C.F. Helsley, C. Rahiman, A.Bolton, B.R. Herzer, R. Recy, J.C.Burne, R.V. Honza, E. Richmond, R.N.Colwell, J. Howell, D.G. Rodda, P.Cronan, D.S. Irata, M. Rowland, R.W.Crook, K.A.W. Katz, H.R. Scholl, D.Cullen, D.]. Kear, D. Simpson, A.Doutch, F. Kroenke, L.W. Shimazaki, Y.Eade,J.V. Krutein, M. Smith, R.Eden, R. Louat, R. Taafaki, T.Exon, N.F. Macfarlane, A. Taylor, B.Falvey, D. Machesky, L.F. Taylor, F.Fisk, M.B. Marlow, M. Thrasher, G.Frankel, E. Matos, C. Tiffin, D.Giermann, G. McMurtry, G.M. Utanga, A.T.Glasby, G.P. Mitchell, A. Vedder, ].G.

Walshaw, R.D.

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