Sedimentary Basins to Mountain Belts - 625-202

OBJECTIVES

The aim of this field excursion is to show you different sedimentary basins that have experienced different degrees of deformation – and the group of processes that contribute to the formation of mountain belts. You will get practical experience in identifying different sedimentary facies, structures in areas with more than one deformation and the identification of faults. This involves identifying small-scale structures, measuring and plotting orientation data, drawing cross sections and relating these to large-scale structures such as the overall tectonic regime that existed in this western portion of the Lachlan Fold Belt and the eastern edge of the Delamerian Fold Belt. As a bonus you will also see how some of this information is used to understand the geological environment that hosts the gold mineralization at Stawell.

PROGRAM

Saturday, 2nd April
Leave Melbourne at 8.00 am drive to Ballarat investigate the folded Ordovician sediments in the Norman Street cutting. Regional geology in Ararat region and drive through Halls Gap to overnight at Mt Zero Log Cabins.

Sunday, 3rd April
Visit to the Grampians - Mount Zero region and Mount Dryden

Monday, 4th April
Magdala Mine at Stawell, visit and core logging exercise (return to Melbourne at approx 6.00 pm)

REQUIREMENTS

Transport will be provided (no private cars will be allowed) and accommodation has been reserved for you at the Mt Zero Log Cabins (03-5384 3226 ) where there are cooking and BarBQ facilities. For this reason there is an accommodation/transport charge for this excursion. The cost for this excursion is $120 (includes GST) and is payable to the Front Office, 4th floor Earth Sciences Building by Thursday 24th March, 2005.

You will need to bring a sleeping bag, towel and pillow etc personal gear (be prepared for wet and cold weather). If you have a sleeping mat this may also be worth bringing as the number of beds are limited.

Food: You will also need to bring food, evening meal for Saturday and Sunday nights, breakfast on Sunday and Monday and lunch on Saturday and Sunday. On the Monday a lunch will be provided by Stawell Gold Mines Pty Ltd. There may be the opportunity to have a shopping stop in Halls Gap on the Sunday afternoon, which will enable you to replenish your food requirements. There is no need to bring plates; pans etc as these are all supplied in the accommodation units that have full cooking facilities.

Geological equipment: should include clipboard, hand lens, hammer, compass, note book, Texta pen, pencils, safety glasses (if you have them). An A4 clipboard and some sheets of graph paper would allow you to easily draw some of the geological cross sections that you will see.

Fieldwork during the day will involve looking at road and cliff exposures with some climbing on tracks in the Grampians, so wear appropriate footwear. The weather can be cool and/or wet, and quite often windy, so make sure you bring warm clothes and wet weather gear. It is advisable to look at a long term weather forecast before you depart Melbourne.

BEHAVIOUR IN THE FIELD

This trip includes a visit to inland outcrops and will also examine a number of road exposures and visit the Grampians National Park and will be on private properties. In particular:

1. At road cuttings be aware of any traffic on the roads.
2. Do not climb fences. Take care in getting through them.
3. Do not light fires in unauthorized locations.
4. Firearms and dangerous knives are banned at all times. Do not bring any.
5. Take all your rubbish back to the camp for disposal.
6. Do not hammer at key geological sites, particularly those pointed out by staff as exhibiting special geological features.
7. No alcohol to be consumed in University or hired vehicles used on excursions.
8. At Mount Zero Cabins there is to be absolutely no noise after 11.00 pm, as there are other campers and neighbours who require peace and quite.

SAFETY IN THE FIELD

Fieldwork frequently puts geologists in hazardous situations. Therefore use your common sense in the field:

• If someone is injured or is ill in the field, make sure a staff member is informed. There will be first aiders on staff to assist. An incident report form should also be filled out upon returning from the trip if there has been an injury.
• If there is any situation on the excursion in which you feel unsafe or unconfident, do not proceed. Inform a staff member of your situation.
• Make sure you have a regular tetanus booster in case you cut yourself on rusty wire or metal. You may not always be close to a vehicle and/or medical help.
• Carry a small first aid kit and be familiar with the current first aid treatment of injuries such as sprains, cuts, snake bites, heat distress and exposure.
• Wear adequate, easily visible clothing for the conditions in which you are working.
• Carry a water bottle and be prepared for strong sun. Use plenty of sun-screen, have a hat and sun-glasses.
• Do not attempt to climb rock faces or cliffs of any type without the permission and supervision of a staff member.
• Do not drop rocks or any other object over cliffs
• Do not stand near the edge of significantly vertical drops as the edge may give way. When approaching a rock face, always look up to check if there are loose rocks which could fall

   

SAFETY AT STAWELL GOLD MINE

On this trip you will examine a number of exposures in cuttings in the vicinity of the Stawell Gold Mine and also examine diamond drill core in the Core Farm. In particular as a representative from the University of Melbourne you should note:

1. You may be required to sugn a visitors indemnity form when visiting the mine.
2. If you are unsure of any aspect of safety both on the surface (or underground) do not hesitate to ask a Melbourne University Staff Member or employee of Stawell Gold Mines Pty Ltd.
3. Only use the paths recommended by Melbourne University Staff or employees of Stawell Gold Mines Pty Ltd. No unauthorised wandering away from the excursion group will be allowed.
4. Obey all signs in particular a No Entry sign of any description means no entry this area is unsafe, a sign with a hard hat and glasses means no entry without proper protective equipment.
5. No smoking on site
6. No alcohol to be consumed before going underground.
7. Always get out of the way of oncoming vehicles and be very aware around roads on both the surface and underground – always remember this is an active mine.
8. Take all your rubbish back to the camp for disposal

ASSESSMENT

Field exercises: You will be required to hand-in during the excursion two field exercises.

Assignment:

Exercise 1
Draw an accurate sketch of the road section assigned to you at the Norman Street cutting.

Exercise 2
Make sketches of the prominent features in the cross sections that you have observed at Ararat. How do these correlate with the log that you have recorded in the diamond drill core through the Magdala Mine? At the same time comment on the differences/similarities with the mineralisation seen at Ballarat.

Exercise 3
In the Mt Zero region, working in groups of four, collect geometrical data, in the areas allocated to you in order to characterise the orientation of the fault surfaces and their sense of movement.

You are then required to combine this information into an essay that is a synthesis of the regional geology in the Ararat-Grampians-Stawell region together with any structural data that you collected in the northern portion of the Grampains. The title of the essay should be:

“Mountain Belts in Victoria – do they exist and what is their role in controlling the distribution of Victoria’s gold deposits”

The format of the essay should be in the style of any article published in GEOLOGY (www.geosociety.org/pubs/ ) and should be no more than five pages in length including figures. This needs to be submitted to the Office by Monday 2nd May 2005.

Assignment to be handed in on Tuesday 26th April, 2005. To the Front Office (Room 401), 4th floor Earth Sciences Building.

Note that this assessment is worth 10% of the total subject mark.

REFERENCES

References with an asterisk relate to this excursion and are available from the library reserve collection.

Cayley, R.A. and Taylor, D.H. 1997. Grampians special map area geological report. Geological Survey of Victoria, Report 107.

Cayley, R.A. and Taylor, D.H. 2001. Geological survey report for the Ararat 1:100000 map sheet. Geological Survey of Victoria, Report 115.

Gray and others, 2003. In Birch W.D. ed. Geology of Victoria pp.15-70. Geological Society of Australia Special Publication 23. Geological Society of Australia (Victorian Division).

*Miller, J.M. and Wilson, C.J.L., 2002. The Magdala Lode System, Stawell, southeastern Australia: structural style and relationship to gold mineralization across the western Lachlan Fold Belt. Econ. Geol. 97, 325-349.

Miller, J. McL. and Wilson. C.J.L., 2004. Stress controls on intrusion-related gold lodes: Womga gold mine, Stawell, Western Lachlan Fold Belt, southeastern Australia. Economic Geology, 99(5), 941-963.

Miller, J. Mc L. and Wilson. C.J.L.,2004. Application of structural analysis to faults associated with a heterogeneous stress history: the reconstruction of a dismembered gold deposit, Stawell, western Lachlan Fold Belt, Australia. Journal of  Structural Geology, 26, 1231-1256.

*Miller, J.M., Dugdale, L.J. and Wilson, C.J.L., 2001. Variable hangingwall palaeotransport during Silurian and Devonian thrusting in the western Lachlan Fold Belt – missing gold lodes, synchronous Melbourne Trough sedimentation and Grampians Group fold interference. Aust. J. Earth Sci. 48, 901-909.

Miller, J.M., Norvick, M.S. and Wilson, C.J.L., 2002. Basement controls on rifting and the associated formation of ocean transform faults – Cretaceous continental extension of the southern margin of Australia. Tectonophysics 359, 131-155.

*Phillips, G., Miller, J.M and Wilson, C.J.L. 2002. Structural and metamorphic evolution of the Moornambool Metamorphic Complex, western Lachlan Fold Belt, southeastern Australia. Aust. J. Earth Sci. 49, 891-913.

Squire, R.J. and Wilson, C.J.L. 2005. Interaction between collisional orogenesis and convergent-margin processes: evolution of the Cambrian proto-Pacific margin of East Gondwana.  Journal Geol Society of London, 162, 1-13.

*Wilson, C.J.L., Will, T.M., Cayley, R.A. and Chen, S. 1992. Geological framework and tectonic evolution in western Victoria, Australia. Tectonophysics, 214, 93-127.