VF01: Factors That Influence Eruption Styles from Magmatic To

IUGG, Melbourne, Australia 2011: Scientific Field Trips

VF01: Factors that influence eruption styles from magmatic to phreatomagmatic in intraplate basaltic volcanic fields: the Newer Volcanics Province of southeastern Australia.

The fieldtrip concept/theme: The Newer Volcanics Province is a 4.5Ma to 4.5ka intraplate, continental plains basaltic volcanic province. It occupies about 15,000 km2 extending westwards from the longitude of Melbourne to Mt. Gambier in southeastern South Australia. It contains over 400 individual “monogenetic” volcanoes, including small lava shield volcanoes, scoria/cinder cones, maars (some 3 kms+ in diameter), tuff cones and complexes of these, dispersed amongst small to moderate plains basalt lavas. Although some volcanoes are solely magmatic or phreatomagmatic, some also show variations from one style to the other at a variety of scales. A major focus of this fieldtrip will be to consider the factors that influence whether or not the eruption style is one or the other, the factors that cause a change from one style to the other in single volcanoes and the temporal and spatial scales at which such fluctuations occur. We will see many excellent exposures, see some great scenery and Australian native wildlife, as well as enjoy a range of great Australian wines and beers.

1. LEADER(S)

Leaders: Ray Cas, Teagan Blaikie, Julie Boyce, Patrick Hayman, Simone Jordan, Jacqueline Miles, Andrew Needham, Felicity Piganis, Gemma Prata, and Jozua van Otterloo.

Institutions: Monash University

Contact Details of Corresponding Leader: School of Geosciences, P.O. Box 28E, Monash University, Victoria, 3800, Australia; Email: [email protected]; Tel.: +61 3 9905 4897; Fax.: +61 3 9905 4903

2. INFORMATION TO ASSIST ATTENDEES WITH THEIR TRAVEL PLANS

Duration: 5 days

Start Date and Time: 8am, Saturday 9th July, 2011

Start Location: Melbourne Convention Centre

End Date and Time: 5.30pm, Wednesday 13th July, 2011.

End Location: Melbourne Convention Centre

Suggested Travel Arrangements from Melbourne to the start location: Not applicable; starts in Melbourne

3. ATTENDEE NUMBER CONSTRAINTS

(A) Minimum Number of Participants (to be financially viable, or enjoyable): 15

(B) Minimum Number of Participants before cancellation (equal to or less than ‘A’): 15

4. FIELD AREA INFORMATION

Description of the field area: Day temperatures will vary between 10 – 15oC, night temperatures between 2-8oC. Days could be sunny or rainy, and a cold wind could be blowing. The terrain is rolling, hills. A moderately high fitness level is required to climb scoria cones and descend into craters. Fieldwork will involve working on both roads and slippery grassy slopes and bushland

Description of Health and Safety Risks: The principal health risk is likely to be cold and wet weather. Snakes and spiders can be expected to be in hibernation, and are not a hazard at this time of year.

Description of Gear to be Supplied by Leaders: Field guide. Participants must bring and wear their own proper field boots, and be equipped with clothes for cold weather as well as water-proof rain gear, and a day pack.

Visa Requirements (if not Australia): Not Applicable

Currency of Country: Australian dollar

Electricity of Country (voltage, plug-type, etc): 240 volts. Participants are recommended to come equipped with a power plug adaptor or convertor for their electrical equipment.

Insurance: It is strongly recommended that participants take out their own personal travel insurance to cover the period of time they are attending this field trip/workshop.

5. ITINERARY

Day 1 (9 July): Depart Melborne at 8am, and travel southwest to Colac, then to the Red Rock Volcanic Centre to overview the Newer Volcanics Province and the multiple maar-scoria cone Red Rock Volcanic Complex, with over 40 eruption points. We will examine its interstratified magmatic and phreatomagmatic pyroclastic deposits, and consider the influences. We will have lunch at a vineyard there, and then drive northwest to the Mt Rouse scoria cone to examine the magmatic pyroclastic deposits of this volcano. We will stay overnight in the western Victorian town of Hamilton.

Day 2 (10 July): Depart Hamilton at 8am, and drive south to Mt Napier and its lava flow field. Mt Napier is a shield volcano with a summit scoria and spatter cone complex, which is the source of an extensive lava flow field. We will then drive to Mt Eccles to view the fissure vent system and deposits, as well as lava tube caves in the extensive lava flow field. We will have lunch at Mt Eccles, and then drive west to Mt Gambier in South Australia, where we will stay overnight. Day 3 (11 July): Start 8am. We will examine the Mt Gambier volcanic complex of multiple maars and scoria cones, where we will see base surge and pyroclastic flow deposits, a’a lava flows and violent strombolian deposits, then drive south to Mt Schank to examine the complex of spatter cones, maars and tuff cones and their deposits, including again violent strombolian deposits. We will stay overnight in Mt Gambier again.

Day 4 (12 July): Depart 8am and drive east back into Victoria, to the Tower Hill volcanic complex, which is a spectacular maar more than 3 kms in diameter, with a central spatter and scoria cone complex. We will examine the intricate alternation of magmatic scoria deposits and phreatomagmatic surge and surge modified fallout deposits, and spatter cones. This is an excellent location to discuss the factors causing alternation of eruption style from magmatic to phreatomagmatic at all temporal scales. Whilst having lunch we will be able to see koala bears, emus and kangaroos in the Tower Hill Nature Reserve. We will then drive to Port Campbell for an overnight stay, and will view the spectacular scenery of Victoria’s Great Ocean Road.

Day 5 (13 July): Depart 8am. From Port Campbell we will drive east to the 3 km diameter Purrumbete maar volcano, just southeast of Camperdown. This maar rim preserves spectacular base surge deposits and contains discordances indicating syn-eruption collapse of the maar rim into the crater. We will then drive back to Melbourne, arriving back at about 5.30pm.

6. COST

Field Trip Fee per Person: $825 AUD (incl. $75 GST)

Field Trip Fee includes: Field guide, accommodation, transport ex-Melbourne and meals.