Diamantina River ring feature

Coordinates: 22°09′S 141°54′E / 22.15°S 141.9°E / -22.15; 141.9 The Diamantina River ring feature is a circular geological feature hypothesized to be associated with a buried impact crater in what is now the Channel Country in Central West Queensland, Australia in the region west of the small town of Winton.^[1] Some scientists from Geoscience Australia have proposed that this impact event happened about 300 million years ago.^[2] The Diamantina River ring feature has also been called the Winton crater.^[3]

Site[]

The zone in which the Winton asteroid impact theoretically happened lies in a sparsely populated area in the Australian Outback centred roughly at

22°09′S 141°54′E / 22.15°S 141.9°E / -22.15; 141.9. It is roughly circular and its diameter measures some 120 kilometres (75 mi)^[1] (and it thus has an area of about 11,300 square kilometres (4,400 sq mi)). The depopulated town of Middleton and Dagworth Station – famous for the part it played in the creation of "Waltzing Matilda" – lie within the anomaly discovered here. Skirting the anomaly zone for more than half its circumference, mostly on the north and east sides, round from its headwaters to well below its confluence with the Western River, is the Diamantina River, an intermittent stream with, in most places, several braided channels of the kind that give the Channel Country its name.^[4] It was this particular hooked shape in the upper Diamantina that first raised questions.

Name[]

It was a while after the discovery of this round zone in Queensland and the formulation of the theory about its cosmic creation before the matter of a proper name had been settled. Geoscience Australia referred to the “Woodstock-Winton circular drainage ring” in a map caption (Woodstock is another station in the zone where research was done) in reference to the Diamantina's course there,^[2] whereas Winton's local news outlet, the Winton Herald, refers to the “Winton Asteroid Theory”.^[5] However, the scientific community now seems to have settled upon "Diamantina River ring feature".^[1]

Discovery[]

The Diamantina River's hook-shaped upper reaches had long been a puzzle to science. To Dr. Andrew Glikson, whose research interests include "early crustal evolution with focus on the role of asteroid impacts",^[6] the near-circular course was the first indication that there might be an anomaly in the crust in this region. Glikson's research into the matter revealed several noteworthy things about this round zone.^[2]

For instance, the circular zone inside the upper Diamantina is a "magnetically quiet zone", according to data yielded by studies of the local magnetic fields, whereas the neighbouring rock shows a more linear pattern in its magnetic signatures. Reflection seismology, used on a line transecting the zone's outer rim, also revealed “dramatic” differences between the rock within the anomaly and outside it. It can thus be inferred that the possible cause is a disturbance of the deep crust by something like a great impact. Gravimetry revealed some interesting information about the anomaly's centre, which itself contains a gravimetric anomaly. This told the researchers about differences in rock densities as compared to neighbouring areas of crust, likewise suggesting that there could long ago have been a major impact event.^[2]

On the whole, the information gathered at Woodstock Station is comparable to that found at buried asteroid impact structures, but currently, final proof is lacking. The Diamantina River ring feature was, after all, discovered in 2015.^[2]

Proof[]

Proof is the one thing currently wanting in any quest to label the Diamantina River ring feature an asteroid impact structure. However, the scientists involved see that as rather a straightforward matter of drilling core samples in the zone and then analyzing them. Richard Blewett from Geoscience Australia quoted the needed depth for these samples as “about three kilometres”,^[7] whereas Geoscience Australia says in its own report, somewhat more conservatively, that the depth will have to be “many hundreds of metres”.^[2] Analysis of the core samples would involve, among other things, the detection of “shock textures” in the rock, caused by the great energy of an asteroid impact.^[5]

Impact event[]

The impact event is, as of this writing, only theoretical. Its reality is far from certain. Richard Blewett, mentioned above, admits that there are other possible explanations for the geological anomaly on the upper Diamantina, but adds “but they become difficult to explain”.^[7]

Whether the Diamantina River ring feature was truly created by an asteroid falling out of the sky or not, the scientists at Geoscience Australia have some very definite ideas about this theoretical natural missile. It is believed, for instance, that the event happened some 300 million years ago, in the Palaeozoic.^[5] At that time, Australia lay quite a long way south of where it now lies. It had not yet rifted apart from Antarctica; both continents, and others, were joined as parts of Gondwana.^[7]

The theoretical asteroid itself is reckoned to have measured ten kilometres across, and when it struck, the energy that it released was equivalent to 650 million Hiroshima A-bombs (and thus roughly 41 zettajoules). Richard Blewett believes that the course of Earth's history would have been changed by the enormous blast unleashed by such a strike, and pointed out that there has been an association between these events and great changes in the course of evolution.^[7] Geoscience Australia, on the other hand, only pointed out the importance that such an event has to understanding the evolution of Earth's crust and the economic significance, as such formations may contain petroleum or other mineral wealth.^[2]

See also[]

• List of possible impact structures on Earth
• Lawn Hill crater
• Tookoonooka crater

References[]

Bibliography[]

• Glikson, A.; R.J. Korsch, and P. Milligan. 2016. The Diamantina River ring feature, Winton region, western Queensland. Australian Journal of Earth Sciences 63. 1–11. Accessed 2019-04-06.