Geology and Ore Deposits of Thailand and Laos

February 2010

A 10-day excursion to Thailand and Laos is being organised by the CODES-SEG.
The highlights of the excursion are the visits to:

• Introductory workshop on geology and ore deposits of the region by trip leaders (Dr Khin Zaw, Dr Sebastien Meffre)
• Several major ore deposits in the region (Chatree, Padaeng, Phu Thap Fah, Phu Kham and Sepon)
• Several interesting geologic sites (a high-grade metamorphic complex, melange outcrop, gemstone mine site)
• Few historic sites.

The excursion is intended to run for 10 days from 21st February - 2nd March 2010.
Members of the industry are invited to participate in this opportunity to see some unique ore deposits in the region (cost AUD4000/person). A limited number of places are available.

Download the itinerary

Register your interest

For further information, continue to visit the CODES-SEG website or contact to the SEG Student Chapter (Lindsey Clark lvclark@utas.edu.au).

The mineralisation and volcanism of Indonesia

25th January - 4th February 2009

The CODES, University of Tasmania, SEG student chapter completed a highly successful field excursion to Indonesia from January 25th to February 4th. The trip was primarily organized by CODES student chapter members Bronto Sutopo and Fiona Best. Field guidance was provided by Igan Sutawijaya from the Volcanology Survey of Indonesia and Dr. Mega Fatimah Rosana from Padjadjaran University, Indonesia. Six industry representatives and eight students from CODES attended the trip, with participants originating from Australia, Britain, Canada, Columbia, Indonesia, Italy, Japan, Peru, Russia and Thailand.

The field trip was entitled ‘The mineralisation and volcanism of Indonesia’ and aimed to provide participants with the opportunity to observe economic epithermal and porphyry deposits, to study the lavas of active volcanoes, and to gain an overall understanding of the geodynamical evolution of Indonesia. The field trip was a very adventurous and exciting geological journey and in 11-days participants visited five Indonesian islands, three mine sites and two active volcanoes. The field trip group assembled in Jakarta, West Java, on the 25th January.

The beginning of the field trip coincided with the Indonesian Association of Economic Geologists (MGEI), ‘Sumatra metallurgy at a glance’ Conference, so in the evening field trip participants attended two specially prepared presentations - ‘1883 Krakatau Eruption’ by Prof. Adjat Sudrajat (Padjadjaran University), and ‘The Status of Gold Resources and Exploration in Indonesia’ by Sukmandaru Prihatmoko (MGEI). The group spent the next three days being guided around West Java by Igan Sutawijaya and Dr Mega Fatimah. Day one involved travelling to Carita and visiting a large collection of Pliocene silicified trees which are preserved so beautifully that in places you can see the cell structure of the original wood. On day two, the group endured a rather wet and bumpy boat ride to Krakatau (Sunda Strait), where they observed several generations of lava flows at the base of the volcano and then scrambled through the steam to see the craters (approximately 300 m elevation).

On the final day on Java, the group visited Pongkor gold mine (owned by PT Aneka Tambang) where they were taken 500 m underground by geologist Joseph Purnama to observe the mineralised quartz-adularia-sericite veins. That evening the group took an overnight flight to Timika, West Papua. Participants spent the next two days in Papua where they were hosted by PT Freeport Indonesia and given the opportunity to learn about the Grasberg porphyry copper deposit. The group received lectures on the regional geology and characteristics of the Grasberg deposit by Clyde Leys, Paul Warren and Lasito Soebari, and then observed the porphyry ore bodies, sulphide-rich skarns and country rocks in core. On the second day in Papua participants travelled to the huge Grasberg open-pit mine, located at >4000 m elevation in the beautiful Sudirman mountains. Sugeng Widodo, Nur Wiwoho, Julius Sirait and Herwin Aziz gave participants an excellent geological tour of the mine. After a rather convoluted journey via Bali and Lombok, and involving air, land and water transportation, the group arrived on Sumbawa on 1st February. The aim of the trip to Sumbawa was to visit and gain an understanding of the Batu Hijau gold-rich porphyry copper deposit.

Over the next two days PT Newmont Tenggara Timur geologists Johan Arif and Dudy Setyandaka briefed the group on the geology and mineralisation of the ore body, allowed participants to view core from the mineralised bodies and country rock and took the group to view the open pit mine. The group spent the final two days in Bali visiting the active Mount Batur volcano. Under the guidance of Igan Sutawijaya, the group learned about the history and evolution of Mount Batur, observed the lava flows and ignimbrites at the base of the volcano, and visited the active crater. The field trip was a very exciting and educational geological journey which was only made possible due to the valuable help and support of several companies and individuals.

The CODES SEG Student Chapter would like to thank: (1) AngloGold Ashanti, Barrick, CODES, Gold Fields, Newcrest, Newmont, SEG, St. Barbara and Teck for their generous and invaluable financial support; (2) Igan Sutawijaya from the Volcanology Survey of Indonesia, and Dr Mega Fatimah Rosana and Professor Adjat Sudradjat from Padjadjaran University, Indonesia, for sharing their knowledge with the group and being extraordinary field guides; and (3) PT Aneka Tambang (Pongkor), PT Freeport Indonesia (Grasberg), and PT Newmont Tenggara Timur (Batur Hijau) for not only permitting the group to visit their mines, but for their hospitality and all the hardwork involved in making the visits so successful. Fiona Best

Cape Grim, North-Western Tasmania

28th February - 3rd March 2009

The Volcanology Group at CODES, University of Tasmania, together with the CODES SEG student chapter, organised a joint field trip to examine world-class pillow lavas in NW Tasmania. The four day-long trip in March 2009 was partially subsidised by the SEG student chapter. The group was composed of 15 people from CODES - mostly post-graduate students, two undergraduate students, and two staff.

The pillow lavas occur within a Tertiary-age subaqueous mafic succession that is exposed across much of the NW coast. Major interest was given to two localities with extensive outcrops of subaqueous Tertiary basalts and basanite: Cape Grim, which situated in a remote and private area at the extreme NW-shore of Tasmania, and the Stanley Peninsula. At Cape Grim, a coarse pillow fragment breccia is very well preserved on a large tidal platform and on an adjacent coastal cliff.

The best outcrops show a three dimensional view into the internal structure of the pillow fragments, extensional cracks and rinds which form during the emplacement of the lava in a subaqueous environment. Textures exposed at this locality are the object of a current study by Dr. Yoshihiko Goto (Muroran Institute of Technology, Hokkaido) and Prof. Jocelyn McPhie (CODES), who are proposing a new view on the propagation of pillow lavas on the seafloor. Additionally, Cape Grim is one of the type-localities of the mineral species Natrolite (a type of zeolite), which was found in vesicles and fractures of the pillow lavas.

Several kilometres along the coast, the group studied an exposure of the fine-grained, probably shallow-water Woolnorth Tuff and cross-cutting mafic dykes. The Stanley Peninsula contains several outcrops which were recently the subject of two detailed publications by Dr. Y. Goto and Prof. J. McPhie. The most prominent feature of Stanley is its “Nut”, a ~140m-high massive mafic intrusion, which makes a perfect lookout over the coastal landscape and Tertiary volcanic formations. At the base of the intrusion a small, well-preserved coastal outcrop shows a typical example of a basanite peperitic dyke. Another locality reveals a magnificent example of mega-pillow lava. The tens-of-meter-long structure contains polyhedral columnar jointing and exposes the evidence of lateral transport of the lava into major tubes, then scattered into smaller pillows.

Nearby, quenched-fractured sheets of lava alternate with pillow lavas and thin beds of hyaloclastite. A beach on the W-coast exposes wonderful examples of fluidal emplacement of pillow lavas, which resemble subaerial pahoehoe flows. The group appreciated the comforts and camaraderie we shared at the Stanley Cabin and Tourist Park, where in-depth volcanological discussions ensued late into the evenings!

We would like to express our gratitude to the SEG for sponsorship, as well as to Prof. J. McPhie for her enthusiasm to participate and encouraging discussions in the field. Sarah Gordee and Martin Jutzeler