ExPlorOz Facts Re Crater

Submitted: Thursday, Oct 12, 2006 at 18:36
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Fact Geography: Wolf Creek, WA has the largest meteorite crater in Australia, 853.44m diameter and 61m deep

We might have to get the ruler out again

Gosses Bluff is located west of Alice Springs and south of the Macdonnell Ranges, in the arid Missionary Plain in the Northern Territory. The bluff itself is a circular ring of hills 5km in diameter and 200m high, in the centre of a crater. It was formed 142 million years ago

The Tookoonooka crater in south central Queensland is about 55km in diameter. It was discovered in the early 1980s when petroleum exploration revealed an anomalous circular structure. Tookoonooka has a central uplift dome that is 22km in diameter.

The Bedout structure 300km west of Broome, in the Canning Basin off the coast of Western Australia, has been sited as one of the possible impacts that contributed to one of the greatest extinction events known. At the end of the Permian Period, around 250 MYA, it has been estimated that more than 90% of marine species, and 70% of terrestrial species, may have become extinct. The extinction event seems to have been a sudden, global occurrance, lasting less than a million years (which in geological terms is very rapid).
The Bedout structure (pronounced "Bedoo") has a central uplift of around 40km in diamater, with a transient crater size of around 100km diameter. The original crater probably measured around 200km in diameter in total, comparable to the Chicxulub crater in Mexico which may have contributed to the extinction of (non-avian) dinosaurs at the end of the Cretaceous Period.

The Woodleigh crater was found on Woodleigh Station, east of Shark Bay in Western Australia. The crater may be up to 120km in diameter, although some estimates are closer to 40km. The larger estimate suggests a bolide (asteroid or comet) 5km in diameter, which would make this the fourth largest impact structure in the world. However, a study presented at the Geological Society of America's 38th Annual Meeting in 2003 suggests a diameter closer to 60km.
The impact structure is entirely underground. The central uplift structure 20km in diameter was first detected by drilling activities in the late 1970s, however its significance as an impact structure was only realised in 1997 during a gravity survey.
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Reply By: equinox - Thursday, Oct 12, 2006 at 18:57

Thursday, Oct 12, 2006 at 18:57
or this one:

Fact Geography: The largest desert in Australia is the Great Sandy Desert in WA-NT.

Wrong!!!!

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Follow Up By: Footloose - Thursday, Oct 12, 2006 at 19:05

Thursday, Oct 12, 2006 at 19:05
I see two possible problems comparing deserts. Where they start and where they stop.
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 19:27

Thursday, Oct 12, 2006 at 19:27
Footloose
One thing about a Meteorite is you may not know from where it starts but we sure as hell know where it stops
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Follow Up By: Footloose - Thursday, Oct 12, 2006 at 19:59

Thursday, Oct 12, 2006 at 19:59
Doug, all I know about em is that if one hits me on the head I won't have to worry about it.
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Follow Up By: equinox - Thursday, Oct 12, 2006 at 20:45

Thursday, Oct 12, 2006 at 20:45
Agree Footie- I dont know

The dictionary (Macquarie) says 1. an area so deficient in moisture as to support only a sparse, widely spaced vegetation, or none at all.

Heres a link to Geoscience Australia's Desert Comparisons.

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Follow Up By: Member - JohnR (Vic)&Moses - Friday, Oct 13, 2006 at 08:00

Friday, Oct 13, 2006 at 08:00
F'loosie, I agree "I see two possible problems comparing deserts. Where they start and where they stop. " Even across seas and lakes. It is now said that the Sahara has crossed into southen France and Spain. Wonder how far North that may go?

Equinox, there is a desert in North Island New Zealand too of course so they aren't always hot deserts, just huge rainfall shadows. To wit, the Gobi.
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Reply By: Kiwi Kia - Thursday, Oct 12, 2006 at 19:07

Thursday, Oct 12, 2006 at 19:07
Better watch out Doug, geological events have a habit of repeating !
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 19:12

Thursday, Oct 12, 2006 at 19:12
Kiwi Kia

No mate not a habit of ...but will repeat. Then it will be interesting to see what the Greenies do . probably blame Kim Jong Il or John Howard
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 22:13

Thursday, Oct 12, 2006 at 22:13
Kiwi Kia
When the crater of Lake Acraman was formed on what we call Eyre Peninsular, it probably would have been 100s of Klm to the South of where it is now because the continent is on a slow drift North
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Follow Up By: Kiwi Kia - Friday, Oct 13, 2006 at 11:44

Friday, Oct 13, 2006 at 11:44
Given the age of emplacement of the ejecta into the syncline sediment I would think that it would have been more likely that it was a couple of thousand km south from its present position.
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Reply By: Rick (S.A.) - Thursday, Oct 12, 2006 at 19:08

Thursday, Oct 12, 2006 at 19:08
Doug, not to be outdone, and in the interests of national rivalry, I submit the following:

The Acraman Impact structure,
centred on a crater at Lake Acraman in the Gawler Craton, South Australia, is one of the largest known in Australia and IN THE TOP TEN KNOWN GLOBALLY. The bolide diameter was approximately 4.8 km with a collapse crater 85-90 km across, and the ejecta is spread over a radius of greater than 560 km. The estimated impact energy is greater than 106 megatons, which exceeds the threshold for global catastrophe. The Acraman Impact Event occurred just prior to the evolution of animals, which preceded the Cambrian explosion, and is therefore a critical event in the evolution of Earth's biosphere.

For us mere non professional mortals, the Acraman site sits over the top of Eyre Peninsula, S-W of Lake Gairdiner. Some of the rocks thrown out by the meteor hit landed in the Flinders Ranges, approx 350 km to the east.

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Follow Up By: Kiwi Kia - Thursday, Oct 12, 2006 at 19:24

Thursday, Oct 12, 2006 at 19:24
Ok, but where exactly on the surface of the earth was the proto Eyre Peninsula when all this occured :-))
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 19:24

Thursday, Oct 12, 2006 at 19:24
Rick
Yes I have looked at that one too, actually looked at them all to much with Google Earth and now used up all my 500mb ,and was shaped back to 70kbps, then went over 600mb , now i'm on 33kbps and it's painfully slow waiting for web pages to load up, but the good news is at the end of this month it will go back to normal speed and I have changed my plan to 5GB of downloads , I should have done that last month and it would have been ok
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Follow Up By: Member - JohnR (Vic)&Moses - Thursday, Oct 12, 2006 at 20:05

Thursday, Oct 12, 2006 at 20:05
Tried to find it a cople of years back Rick, so only too pleased to have another look one day. Should get Oziexplorer to find the location and Google Earth then.

Kia, a bit South of where it is now.
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 20:10

Thursday, Oct 12, 2006 at 20:10
JohnR
After the TV news I will put a couple of photo's on my 4x4 website , one will be a Google and the Lat/Long for you , I will come back here and add the url link ain about an hour

Doug
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Follow Up By: equinox - Thursday, Oct 12, 2006 at 20:26

Thursday, Oct 12, 2006 at 20:26
Have been out that way in the early nineties, with a fellow technician and a geologist - he showed me how a lot of the fragments are magnetic - very interesting

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Follow Up By: Member - Phil G (SA) - Thursday, Oct 12, 2006 at 20:52

Thursday, Oct 12, 2006 at 20:52
Gday Rick. Pretty interesting story. One of those little known treasues in teh Gawler Ranges. We visited there some years ago in a club trip with Malcolm Butler as a guide. Accessed from Yardea station. Passed a couple of smaller "craters" on the way in.
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 21:28

Thursday, Oct 12, 2006 at 21:28
JohnR
Here are the photo's at this link

members.westnet.com.au/dtilley/impacts.htm

Doug
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Follow Up By: Member - JohnR (Vic)&Moses - Thursday, Oct 12, 2006 at 22:58

Thursday, Oct 12, 2006 at 22:58
Thanks for that Doug, I wished I had known which road led out there at the time. Went up the road to the West for a bit but could not find a road in there.

Phil, the Gawler is an interesting range to travel through and camp in. Nice and remote too for South Aussie. I remember it was warm enough not to have the ends on the camper tent while we were there. Had a nice warm shower with a view too with the remoteness.
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Follow Up By: Dave198 - Thursday, Oct 12, 2006 at 23:22

Thursday, Oct 12, 2006 at 23:22
For any of you going to the Flinders Ranges and travelling along the Aroona Valley from Bunyeroo Gorge to Brachina Gorge.
You can see the ejecta layer from the Acraman event (impact) on the right hand side of the road looking roughly eye level across at the walls of the ranges.
It is a bit difficult to see between the trees, and is only a couple of Kms from the Bunyeroo Gorge
It appears as a dark greenish colour and is roughly about 1 ft. thick. It rises and falls with the folding that has occured with the Ranges.
The Acraman Campground is along that road also.
Dave
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Follow Up By: Member - Doug T (W.A) - Friday, Oct 13, 2006 at 06:42

Friday, Oct 13, 2006 at 06:42
Dave198
Very good , I'll give you 9 for that and you can go home early,... can't give 10...you might get cocky.....I checked it on the web and found the report below.I find it amazing that all aspects of weight,volume,distance and speed are totally irrelevant when it comes to what can happen during an impact.

Doug

Quote:
Several kilometers to the east the Brachina Gorge opens into the broad Bunyeroo Valley, where the Aroona and Bunyeroo Creeks join the main river. Somewhere below us was a bed of impact debris which had been thrown into the region by an asteroid which had crashed into the region some 300 km to the west.This bolide, believed to be about 4 km in size, created a crater 30 km wide and several kilometers deep. The Precambrian Lake Acramen impact crater splattered billions of tons of material across the Adelaide geosyncline, leaving the debris horizon preserved in the Bunyeroo Formation.

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Reply By: ExplorOz Team - David - Thursday, Oct 12, 2006 at 19:44

Thursday, Oct 12, 2006 at 19:44
Intresting - We sourced this information years and years ago from a number of publications - Hum.... We are happy to be corrected please submit the corrections to us using Feedback and we will glady adjust. Please try to make sure the updates are as accurate as possible but let us know none the less.
David (DM) & Michelle (MM)
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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 20:01

Thursday, Oct 12, 2006 at 20:01
David
Thank you for your reply and interest in the subject, I might add that I;m basicly obsessed in Impact sites and Volcanoes,
anyhow here are a few links where I am getting all my Info from

www.unb.ca/passc/ImpactDatabase/index.html

home.alphalink.com.au/~dannj/craters.htm

Site Link

Site Link

Site Link

I can't give you any better than that David , though there are a couple of those links that are not Australian but do contain very good information

Doug

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Follow Up By: Member - Doug T (W.A) - Thursday, Oct 12, 2006 at 20:05

Thursday, Oct 12, 2006 at 20:05
David
Also must take into account that it is Wolfe Creek that is the one most tourist go to see and know about.

Doug
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Reply By: Member - Ric K (WA) - Thursday, Oct 12, 2006 at 22:33

Thursday, Oct 12, 2006 at 22:33
...... AND i believe that the smallest is just off the Dalaranga Rd Between Cue and Yalgoo in WA, 17 ks east of the road 21meters in diameter actually named "dalaranga"
regards Ric
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Follow Up By: Member - Doug T (W.A) - Friday, Oct 13, 2006 at 07:03

Friday, Oct 13, 2006 at 07:03
Ric

Dalgaranga is how it is spelt
This crater is listed in the Impact Database but i had a further look on the web and found this ....

It's also a very young crater, initial estimates putting its age at about 3,000 years, and it's one of the smallest authenticated craters known. The meteorite which caused the crater was one of the very rare stony-iron types. Meteorites can make two kinds of crater. Smaller meteorites simply put a dent in the ground. Larger meteorites (over 100 tonnes) can form explosion craters. It is thought that the Dalgaranga meteorite was just over 100 tonnes.
web site....
Site Link
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Follow Up By: Member - Doug T (W.A) - Saturday, Oct 21, 2006 at 23:06

Saturday, Oct 21, 2006 at 23:06
Ric K
Hi
Been away on a job for just over a week , went to Marble Bar and Pt Hedland working back to Eneabba so was a good week, NOW ..... Veevers is smaller than Dalgaranga
Check this out on the web Rick
Site Link

Doug
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