Abu-Libda, Osama: Jordan

AGSO: Canberra

Allen, Sharon: Uni of Tasmania

AMF: Adelaide

Armstead, Stephen: Lismore

Arundell, Lis: Perth

Basden, Helena: Sydney

Bishop, Mark: Uni of South Australia

Bowland, Trevor: Perth

Brown, M: Canberra

Brownlow, Jeff: Armidale

Bryan, Scott: Uni of QLD

Burrell, Paul: Parkes

Carr, Paul: Wollongong

Chalmers, David: Perth

Cotter, Stephen: Uni of Canberra

Coupard, Michel: Canberra

Dadd, Kelsie: Macquarie Uni

Denholm, Lindsay: Gosford

Fieldgate, Shane: Perth

Forster, Garth: Brisbane

Gamble: John: Victoria Uni, NZ

Geeve, Richard: Sydney

Hayward, Mark: Geol Survey of QLD

Hildyard, Stuart: Monash Uni

Hollis, Julian: Trentham

Hosking, William: Adelaide

Joyce, Bernie: Uni of Melbourne

Knutson, Jan: Bungendore

McDougall, I: Canberra

McPhie, Jocelyn: Uni of Tasmania

Meakin, Simone: Geol Survey of NSW

Middleton, Jill: Perth

Miles, Ian: Brisbane

Moore, Leah: University of Canberra

Morton, Cheryl: Kalgoorlie

Murray, Sue: Wollongong

Orth, Karin: Uni of Tasmania

Passmore, Maurice: Stanthorpe

Pirajno, Francesco: Perth

Pittari, Adrian: Melbourne

Rangott, Max: Orange

Raos, Ali: Uni of Tasmania

Rawlings, Dave: Uni of Tasmania

Raymond, Oliver: Canberra

Roach, Andrew: Brisbane

Roach, Ian: Canberra

Rosengren, Neville: Bendigo

Roser, Shiralee: Muswellbrook

Rowsell, Katharine: Northern Territory

Ruxton, Bryan: Canberra

Scutter, Ceinwen: Melbourne

Shuttleworth, Jenna: Melbourne

Simpson, Carol: Nelson Bay

Squire, Ric: Uni of Tasmania

Steemson, Matthew: Perth

Stewart, Andrew: Sydney

Sutherland, Lin: Australian Museum

Taylor, Paul: Sydney

Von Lichtan, Isabella: Uni of Tas.

Waters, John: Melbourne

Western Metals Ltd: Perth

White, Matt: Brisbane

Whitehead, Peter: James Cook Uni

Willey, Edwin: Toowoomba

Williams, Andrew: Brisbane

In May 1999, the Conference on Multiple Platform Exploration (COMPLEX) was run by the Ocean Drilling Program (ODP) in Vancouver, Canada. COMPLEX provided a forum to define high priority Earth Science objectives that can be achieved through ocean drilling using multi-platform technology post 2003. COMPLEX was organised into 14 theme sessions, several of which are of direct interest to the volcanological community. These include sessions on Constructing Ocean Lithosphere, Subduction Factory and Convergent Margin Processes, Geological Processes Related to Rifting, Evolution of the Crust and Lithosphere, and Catastrophic Events. Each session defined a number of themes or objectives that the working group members thought to be of the highest priority. COMPLEX followed the Conference on Cooperative Ocean Riser Drilling (CONCORD) held in Tokyo in 1997. The CONCORD report is available on request by emailing tanakata@jamstec.go.jp. The COMPLEX report is not yet available but a copy of the abstract volume is available from JOI Inc., 1755 Massachusetts Ave., NW, Suite 800, Washington D.C. 20036-2102.

Member of the Australian ODP SciComm

On many geological maps, diverse assemblages of volcanic rocks are grouped together and marked by a single colour. By necessity, detailed subdivision within volcanic sequences has rarely been part of regional scale mapping. At a less regional scale, the intimate association of many volcanic successions with economic mineral deposits, as in Volcanic Hosted Massive Sulphide (VHMS), epithermal and porphyry copper districts, requires more detailed mapping and subdivision.

Greater detail of subdivision engenders a rethink of the stratigraphic nomenclature as currently applied to volcanic rocks. Discrepancies exist between their treatment in the Australian Stratigraphic Guide to Nomenclature (Staines, 1985) and the International Stratigraphic Guide (Salvador, 1994). The Australian Guide allows the inclusion of intrusive and extrusive units into a formation, whereas in the International Stratigraphic Guide and North American Codes (North American Committee of Stratigraphic Nomenclature, 1983), formations and intrusions are mutually exclusive. Both the International and North American Guides recommend the use of complex in the situation where both intrusive and extrusive volcanic units occur together.

The stratigraphy of volcanic successions can be complicated, even in young provinces. Individual volcanic centres commonly overlap and/or coalesce. They may produce a variety of lithologies which vary markedly in areal extent, and compositionally diverse units may occur together. Topography changes rapidly as volcanic centres grow and collapse, and this affects the distribution pattern of many rock types. In ancient successions, erosional, structural and metamorphic changes further increase the difficulty in identifying unique mappable units.

The lack of a systematic approach to classifying volcanic stratigraphy has made life interesting for volcanologists working at CODES (University of Tasmania). Existing regional maps have, on occasion, provided poor and even misleading information to later workers, especially as a guide to exploration. A new system would need to incorporate ways to help those less familiar with volcanic terranes to locate themselves within a volcanic succession.

Given the fruitful discussions in TAG on igneous nomenclature, it may be timely to open discussion on the issue of stratigraphic nomenclature in volcanic terranes, LAVA being the obvious forum. Geologists working on a day-to-day basis with these issues are in a good position to formulate a revised guide and recommend practice for volcanic nomenclature in Australia. This would prove advantageous to all future workers dealing with the naming and subdivision of volcanic sequences.

In the next issue of LAVA News, the volcanology group from CODES will be presenting a proposal towards a flexible, non-genetic, hierarchical stratigraphic scheme, with reference to problems that various members of the group have encountered. We would like other members of LAVA to offer their criticisms/comments/suggestions, with an ultimate goal of putting forward a cohesive proposal for refinement of the current scheme or even a new scheme, to generate some consistency in volcanic stratigraphic nomenclature.

LAVA Committee

National American Committee on Stratigraphic Nomenclature, 1983. North American Stratigraphic Code: The North American Commission on Stratigraphic Nomenclature. AAPG Bulletin 67, 841-875.

Staines H. R. E., 1985. Field geologist's guide to lithostratigraphic nomenclature in

Australia. Australian Journal of Earth Sciences 32, 83-106.

Salvador A (ed)., 1994. International Stratigraphic Guide; a guide to stratigraphic

classification, terminology and procedure. International Union of Geological Sciences,

Trondheim. 214 p.

The stratigraphy of the MVP consists of basal sub-alkali lavas (ol. tholeiite, trans. basalt) capped by ankaramite (cpx-porphyritic lava) and alkali lavas (alk. ol. basalt, ne. basanite and ol. nephelinite). This succession is identical to that seen in many ocean island volcanoes, particularly Hale-akala and Mauna Kea. The strat-igraphy implies different stages in the volcanic evolution of the MVP:

1. Initial volcanism was of an Hawaiian style, forming a number of linked sub-alkali lava shields in the central MVP. These are seen as gently-dipping lavas in the base of the pile.

2. The end of the shield-building phase is marked by the eruptions of thick ankaramite lavas. These are largely confined near-vent and can have vesicular upper surfaces. The upper-most flow has a well-developed bauxite weathering profile.

3. Resurgent alkali volcanism, resulted in Strombolian and some Surtseyan or hydrovolcanic activity.

Rare primary volcanic features are preserved within the lava pile. These include scoria and weathered tuffs intercalated with basalts. Massive to matrix-supported hyaloclastites are relatively common, occurring in a handful of locations. Several hyalo-clastite locations also contain mod-erately- to poorly-preserved pillow basalts which merge upwards or sideways into massive hyaloclastite. The inner slopes of a single alkali basaltic maar are preserved near Bombala. Tuffaceous beds show scoured bases, normal grading, milled granitic lapilli, small basaltic ballistics and shattered plant remains.

The remains of the lava pile are now punctuated by a series of volcanic plugs. Several of the larger plugs have lava flows of different basalts forming concentric rings around their bases. The majority of plugs are primary/near-primary basanites and nephelinites, many containing abun-dant small crustal and mantle xenoliths and/or amphibole xeno-crysts. A few plugs consist of feldspar-rich differentiates: tephrite; and K-trachybasalt.

Mantle xenoliths generally show weakly foliated textures and little modal metasomatism, apart from one spinel lherzolite mylonite and rare pargasite- and phlogopite-bearing lherzolites and wehrlites. Equilibra-tion pressures and temperatures calculated for the MVP xenolith suite show that the palaeogeotherm was similar to that of the Newer Volcanic Province. This could have been maintained in a fluctuating state into the Miocene, given the close proximity of other lava fields in the Snowy Mountains of that age. This has drastic implications for conclu-sions derived from apatite fission track data from the local area⁵.

Crustal and mantle xenoliths, together with clinopyroxene core crystallisation pressures, confirm that the local crust is ca. 50km thick, also defined independently via seismic tomogra-phy⁶. This, Compared to 30-40km thick crust in other parts of the Lachlan Fold Belt, adds weight to the magmatic underplating/isostatic rise model for the evolution of the SE Highlands.

Sr and Nd isotopic data and Ba/Nb-La/Nb Sr isotopic analogues suggest a magmatic evolution involving the progressive mixture of more asthenospheric to more lithospheric source material, similar to recent Hawaiian magma-genetic models⁷. However, at no point does this require the necessity for a mantle plume to initiate magmatism.

A new magma-genetic model is envisaged for the MVP and eastern Australian lava fields based on earlier passive margin diapiric models^8,9. The new model requires asthenosph-eric diapirs to rise to the lithosph-ere/asthenosphere boundary (the Low Velocity Zone). Here, diapirs either become "docked" in the base of the overlying lithosphere, or remain at the LVZ. Those diapirs which become "docked" will produce lava fields with an ocean island-type stratigraphy (e.g. the MVP). Volcanism in these provinces commences with diapir-derived tholeiites with asthenospheric isotopic signatures. Volcanism be-comes more alkalic as heat, melts and volatiles spread into the surrounding mantle, producing melts with gradually more lithospheric isotopic signatures. The expected life-span of these lava fields is ca. 20-30 Ma. "Undocked" diapirs contribute pools of magma to the LVZ that are sampled randomly as suitable lithospheric magma conduits pass overhead due to plate tectonic drift. The life-spans of these lava fields may be no more than 100-200 ka. Fractionation of primary magmas occurs during ascent, at the crust/mantle boundary and at the base of the Palaeozoic crust.

CRC LEME, ANU

Ian.Roach@anu.edu.au

Widespread andesite ash from Mount Lamington volcano in Northeast Papua occurs in rainforests with annual rainfalls of 2000 to 3000mm and mean annual temperatures of from 16 to 22^oC. The proximal ashes, 10 to 30 km from the volcano are 12 to 15m thick and the distal ashes at Kosipe, 140 km from the volcano, are 2.3m thick. The ash was deposited nearly uniformly over the last 90,000 years with short pauses allowing topsoil formation (Ruxton 1966). The ashes are nearly all andosols (eutrandepts and dystrandepts) with rapid pemeability (Bleeker 1983). They have A/C profiles with olive brown bases and yellow brown upper parts sometimes capped by very dark brown topsoils. The pH varies from 4 in the leaf litter and up to 6 at depth. The leaf litter is 15cm thick at 1800m altitude. The organic matter contents of the present topsoils is 5 to 15 per cent.

Mount Lamington andesite ashes have either unimodal size distributions of well sorted sand sized ash or bimodal size distributions with an additional peak in the fine silt. Unimodal ashes weather by parabolic kinetics and bimodal ashes weather by first order kinetics. Some sites have mixed kinetics according to whether glass content, total element loss, silica loss, or cation loss is plotted against time. In the parabolic ashes if the thousand year results are extrapolated back to the first year then the cation loss is similar to the first years leaching of the Mount Saint Helens ash.

In detail there is step weathering where dust, micropumice, and pumice jackets gradually weather away in 10,000 years and after that, etching of augite, plagioclase and hornblende becomes evident. Step weathering shows up in the plot of cumulative loss of solutes against depth.

Some older ashes in the parabolic profiles show a shortfall of weathering. They were deposited in the glacial some 16,000 to 18,000 years ago. If the Arrhenius equation is used then the temperatures at the time of deposition were 9 to 11^oC lower than now. This temperature drop is the same as that deduced from palynology in the Highlands of Papua New Guinea.

The ash is made up of dominant glass (56%), subdominant plagioclase (27%), very common hornblende (15%) and very minor biotite. The glass weathers first to allophane which complexes to a very stable allophane-humus. At increasing altitude the organic matter content increases with the decreasing temperature in an Arrhenian manner allowing calculation of the activation energy of this humus at around 25 kcal mole^-2 (Ruxton in press) which is equal to many silicate minerals.

LAVA Member, Canberra

Bleeker, P. 1983. Soils Of Papua New Guinea. ANU Press, Canberra.

Fisher, R.V. & Schminke, H.U. 1984. Pyroclastic Rocks. Springer-Verlag. Berlin.

Reynolds, R.C. Jr. & Johnson, H.M. 1972. Chemical Weathering in the Temperate Glacial Environment of the Northern Cascade Mountains. Geochimica et Cosmochimica ACTA. 36, 527-554.

Ruxton, B.P. 1966. Correlation and Stratigraphy of Dacitic Ash-Fall Layers in Northeastern Papua. Journal Geological Society of Australia, 13(1), 41-67.

Ruxton, B.P. 1988. Towards A Weathering Model of Mount Lamington Ash, Papua New Guinea. Earth-Science Reviews, 25, 383-397.

Ruxton, B.P. 1999. Apparent Activation Energy of Humus Under Tropical Rainforest and Related Factors. International Humic Substances Society Proceedings, In

The Yali pumice formation is a >170 m-thick succession of unlithified rhyolitic tube pumice that covers 2.8 km². Carbonate-cemented pumice breccia and fossiliferous limestone cap the formation, which indicates a submarine depositional setting. The formation has been up-faulted and is overlain by subaerial fallout.

The lithofacies characteristics help constrain the eruption style, depositional processes and proximity to source. In particular, the pumice forms moderately to well sorted, cm-m-thick beds, which include very little matrix (>20wt% <1 mm). The coarser pumice clasts (64 cm-1.5 m) are very fragile and have quenched margins and internal polyhedral joints. They commonly occur in well sorted, tabular beds with no matrix dense lithic clasts. They probably represent floating pumice, spalled from a vesicular dome or lava, that became water-logged and settled to the sea floor. The smaller pumice clasts are prismatic and blocky and lack the surface features usually associated with quenching. These smaller pumice clasts are thought to be largely derived from disintegration of the coarser pumice clasts. They are the dominant component of lensoid and diffusely stratified beds, which were most likely deposited by short-lived submarine grain flows down the flanks of the growing cone.

Thus, a combination of dome growth and explosive eruptions produced the Yali pumice formation. Spalling of vesicular blocks from a frothing dome extruding on the seafloor was accompanied by relatively weak, partly steam-driven explosions. In this case, the thickness and uniformity of the pumice breccia reflects proximity to source.

This research suggests that thick successions of submarine pumice breccia can be generated by effusive intrabasinal volcanoes, and need not necessarily imply either an extrabasinal source or major pyroclastic eruptions. In addition, thick dome-related pumice breccias are likely to form proximal to source and accumulate rapidly, synchronous with eruptions.

LAVA Member

CODES SRC

Sixteen Decade Volcanoes have been a focus of concerted research and outreach work during the IDNDR which is now coming to an end. Projects at each volcano involve intensive, international, interdisciplinary work to improve and demonstrate tools for volcanic disaster prevention. Decade Volcanoes which have been the focus of attention include: Avachinsky-Koryaksky, Colima, Etna, Galeras, Mauna Loa, Merapi, Mount Ranier, Nyoragongo, Sakurajima, Santa Maria, Santorini, Taal, Teide, Ulawun, Unzen and Vesuvius. Three of these volcanoes are in our area: Merapi, Taal and Ulawun.

Merapi - A major collaborative program between the Volcanological Survey of Indonesia and German GFZ, particularly strong in geophysical monitoring, has commenced. Some collaborative work continues with France, USA, New Zealand, Japan, and other countries. Merapi may have more international collaboration than any other Decade Volcano.

Taal - A broad stratigraphic framework was established, complemented by more detailed studies of 5 ka BP eruptions. Current work involves examining the sequence of activity within single eruptions, and notable variation from proximal to distal facies. Workshops were held for scientists and local leaders.

After an early change of venue for this meeting from Bandung to Bali, due to civil unrest in Indonesia, there has recently been further debate about whether this meeting should be held at all, given recent happenings in East Timor, and more recently in Lombok and other parts of Indonesia. It would be fair to say that this debate has largely been stimulated by researchers from our region who are very concerned about the situation in Indonesia. To balance the argument some have put forward the concept that it would be inappropriate to penalise Indonesian researchers for the activities of their government, which is beyond their control. Some reason that this is a time when we should be as supportive of our Indonesian colleagues as possible. It was also acknowledged that members of the Indonesian organising committee have already put in a considerable effort with respect to organisation of this meeting. The formal line from the IAVCEI Executive as at the beginning of November 1999 follows:

The volcanological community in Australasia would like to acknowledge the hard work done by Grant Heiken as IAVCEI President and Wally Johnson as IAVCEI Secretary General over the past four years. Having the office of Secretary General in Australia has resulted in closer ties of the Australasian volcanological community with international colleagues. Thanks to Caroline Giddings for her ongoing work in the IAVCEI Australia office.

For the 1999-2003 period Steve Sparks is President and Steve McNutt is Secretary General.

LAVA Committee

University of Canberra

Exploring Volcanoes: Utilisation of Their Resources and Mitigation of Their Hazards

Topics of Symposia:

Utilisation of energy and other volcanic resources

Volcanogenic sediments

Volcano geophysics

Volcano seismology

Volcanic gases

Magmatic processes

Hazard mitigation

Physical volcanology

Mineralisation related to magmatism

Structure of volcanic island arcs

Crater lakes

Surtseyan volcanism

Secretariat: Volcanological Survey of Indonesia

Jalan Diponegoro 57 Bandung 40122 Indonesia

For further information please visit: http://www.vsi.dpe.go.id/iavcei.html

20-23 August 2000

Daun/Vulkaneifel

Germany

More information online at:

http://www.uni-jena.de/chemie/geowiss/maar2000/

Far Western Section

Hosted by CSU Hayward

8-10 September 2000

Feather River Inn

Blairsden, California

Ebrooks@csuhayward.edu

13-25 September 2000

Contact: Pat Shannon, Dept. Geology, University College, Dublin Belfield, Dublin 4 Ireland

Ph 353/608 1074 Fax 353/671 1199

November 2000, Tasmania, Australia

Sponsored by CODES SRC and The Society of Economic Geologists.

Your invitation to participate.....

The meeting will focus on current issues and research into massive sulphide deposits and the physical volcanology of their host successions. Particular emphasis will be placed on parallels between modern, active seafloor hydrothermal systems and their ancient analogues

Volcanologists and economic geologists from academia, geological surveys and the mining and exploration industries are urged to attend. Be there!

Speakers - scientific sessions will include invited keynote addresses and volunteered papers.

Field Trips - field trips in the Mount Reid Volcanics, western Tasmania will be offered both pre- and post-meeting; one will have an emphasis on the massive sulphide deposits and the other on volcanic facies architecture.

Conference Leaders - Dr Jocelyn McPhie (Senior Lecturer in Volcanology) international expert in volcanology and author of the extremely popular Volcanic Textures. Her work at CODES focuses on the connection between mineralisation and volcanic processes, the facies architecture of subaerial and subvolcanic successions and the volcanic environment most suitable for ore deposit formation.

Dr. Bruce Gemmell (Senior Lecturer in Economic Geology) internationally recognised for research on volcanic-hosted massive sulphide deposits and epithermal (Ag) silver -rich deposits. His work at CODES focuses on modern and ancient massive sulphide and epithermal deposits and volcanic arcs, with particular emphasis on the links between magmatic processes, hydrothermal fluids and ore formation. In additional, he has co-authored a computer-based shortcourse on hydrothermal alteration.

For more information contact the Conference Secretariat:

Conference Design Pty Ltd

P.O. Box 342, Sandy Bay

Tasmania 7006, Australia

At risk of being somewhat contraversial… there was some discussion amongst attendees after the 1999 Birmingham IUGG meeting that the large IUGG umbrella style meeting does not serve IAVCEI members well. At the outset we should acknowledge the fantastic effort made by the organisers of this event. The problem is not an artefact of where the conference is held or who runs it, (although comparisons with AGC and AGU have been made), but rather the unintentional marginalisation of a significant number of the IAVCEI membership. At this meeting, for example, there were few dedicated symposia for volcanology, and IAVCEI even found it necessary to detail in their newsletter which symposia would be appropriate for IAVCEI members to contribute to. Most attendees did acknowledge the very high quality of the volcanological field trips, but these were largely run by and for IAVCEI members. In contrast the smaller dedicated IAVCEI meetings are generally well supported and provide a less intimidating forum for those entering the volcanological arena. However, IAVCEI find themselves between a rock and a hard place (if you’ll excuse the pun and cliché) as they rely on the support of IUGG, but have waning numbers attending the IUGG meetings – not a good thing. Maybe the fault is ours and we need to stand up and support dedicated symposia at these meetings with a show of numbers? Wherever the responsibility lies, it is an area of concern.

LAVA Committee

University of Canberra

These new publications and videos may be of interest....

Edited by Armin Freundt and Mauro Rosi, ISBN:0-44-82959-8 334 pgs US$135.00.

www.elsevier.nl/inca/publicatiions/store/6/0/1/5/4/4/index.http

Included in series Developments in Volcanology, 4

The Geological Society is distributing this new video by David Lea and Professor Steve Sparks

http://bookshop.geolsoc.org.uk
(see New Books)

By Haraldur Sigurdsson

272 pgs US$30.00

ISBN 0-19-510665-2

Oxford University Press

http://www.oup-usa.org/index/index/.html

Edited by Haraldur Sigurdsson, Bruce Houghton, John Stix and Steve McNutt

Academic Press

ISBN 012643140X

See the latest TAG for local discount option for this publication.

ISBN 1-86239-020-7 192 pgs US$98.00

By Richard V. Fisher

Princeton University Press

ISBN 0-691-00226-6 160 pgs US$24.95

For more details on these publications visit the IAVCEI Commission on Explosive Volcanism homepage: http://vishnu.glg.nau.edu/cev/

We have had a number of inquiries from non-resident volcanologists who want to join LAVA, but not the GSA. Under the rules of the society, this is only possible if the worker is a professional in disciplines other than the Earth Sciences i.e: if you are working in a fringe area, not strictly geological. A brief outline of membership categories is below:

Affiliate Member (Australian resident)

Corresponding Member (non-resident)

Associate Member (non-resident earth scientist)

To join LAVA and/or the GSA, contact:

Misha Frankel

Business Manager

706 Wynyard House

301 George Street

Sydney NSW 2000

Australia