Acraman impact structure

Coordinates: 32°1′S 135°27′E / 32.017°S 135.450°E / -32.017; 135.450
Source: Wikipedia, the free encyclopedia.
(Redirected from
Acraman crater
)

For other uses, see Acraman (disambiguation).
Acraman crater
Acraman lake (circle), ringed by Lake Gairdner and others, outlining the Acraman crater depression
Impact crater/structure
ConfidenceConfirmed
Diameterup to 90 km (56 mi)
Age~590 Ma
Late Ediacaran
ExposedYes
DrilledNo
Bolide typeChondrite
Location
LocationGawler Ranges
Coordinates32°1′S 135°27′E / 32.017°S 135.450°E / -32.017; 135.450
CountryAustralia
StateSouth Australia
Acraman impact structure is located in South Australia
Acraman impact structure
Location of the impact structure in South Australia

Acraman impact structure is a deeply eroded

playa lake about 20 kilometres (12 mi) in diameter. The discovery of the impact structure and independent discovery of its ejecta were first reported in the journal Science in 1986.[2][3] The evidence for impact includes the presence of shatter cones and shocked quartz
in shattered bedrock on islands within Lake Acraman.

The impact structure is deeply eroded, and its original size must be inferred by indirect means. Some authors estimate an original diameter of up to 85 to 90 kilometres (53 to 56 mi),[4] while other suggest a smaller size, perhaps only 35 to 40 kilometres (22 to 25 mi), closer to that of the depression in which Lake Acraman is centred.[5] The larger size estimate would imply an energy release of 5.2 × 106 megatons of TNT.[4]

The impact event is estimated to have occurred about 590 million years ago during the Ediacaran; this age is not derived from the crater itself but from the position of ejecta within nearby sedimentary basins.[4]

The Lake Acraman Impact Structure is listed on the South Australian Heritage Register.[6]

Ejecta layer

A widespread layer of ejecta, believed to be from the Acraman impact structure, is found within Ediacaran rocks of the

Ediacara Biota
is noted, though probably not significant given the likely global consequences of the impact.

John Acraman

The Acraman impact structure, Lake Acraman and the nearby

Acraman Creek are named after South Australia Colonial businessman John Acraman.[citation needed
]

Gallery

  • Landsat image of Lake Acraman; screen capture from NASA World Wind
    Landsat image of Lake Acraman; screen capture from
    NASA World Wind
  • Oblique Landsat image of Lake Acraman draped over digital elevation model (10x vertical exaggeration), looking east towards the Flinders Ranges where ejecta has been found; screen capture from NASA World Wind.
    Oblique Landsat image of Lake Acraman draped over digital elevation model (10x vertical exaggeration), looking east towards the Flinders Ranges where ejecta has been found; screen capture from NASA World Wind.
  • Orange and brown soils mix with off-white saltpans, including Lake Gairdner and Lake Everard in this true-colour image.
    Orange and brown soils mix with off-white saltpans, including Lake Gairdner and Lake Everard in this true-colour image.

References

  1. ^ "Acraman". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 9 October 2017.
  2. S2CID 30059305
    .
  3. ^
    S2CID 11307364
    .
  4. ^
    S2CID 128751351
    .
  5. Bibcode:1990LPICo.746...47S
    .
  6. Department of Environment, Water and Natural Resources
    . Retrieved 26 June 2017.
  7. doi:10.1080/08120098908729511
    .
  8. S2CID 4310570
    .
  9. doi:10.1130/0091-7613(2003)031<0459:NBDSEO>2.0.CO;2
    .
  10. S2CID 129728586
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Acraman_impact_structure&oldid=1208920527"