Dales Gorge - Impact Deposit

Alternate Names Brockman Iron Formation
Coordinates 22° 19' 48" S; 118° 13' 48" E
Notes
  1. Note the Lat and Long provided are for the first of two locations of samples taken for study by Franco and Hinnov 2008: Drill-Hole 47A -22.33, 118.23 (22°20′S, 118°14′E); Hole Y1 -22.42, 118.45 (22°25′S, 118°27′E)
Country Australia

Related Countries :
  1. Australia
Region Western Australia - Paraburdoo
Date Confirmed 1992
Notes
  1. Simonson, 1992 (petrography and stratigraphy)
Age (Ma) 2490 (Krull Davatzes et al., 2015)
Notes :
  1. (Sweeney and Simonson, 2008; Slikson and Allen, 2004)

Method :
  1. stratigraphic separation from dated tuffs
Impactor Type Unknown
Notes
  1. 31-49 km impactor diameter and 20.1-21.7 km/s impact velocity (Johnson and Melosh, 2012)

Advanced Data Fields

Notes

Local Language
N/A
Spherules
X (may have formed as ballistic melt rather than a condensed vapor deposit (Sweeney and Simonson, 2008))
Tektites
Unknown
Indivudual Glass Clasts
Unknown
Source Crater
Unknown
Geology
Brockman Iron Formation of the Hamersley Group; deposited below wave base in a mud-dominated setting affected by waves and currents
  1. correlated to the Kuruman spherule layer in the Transvaal Basin of South Africa (Simonson et al., 2009)
Other Shock Metamorphism
Unknown
Shatter Cones
No
Planar Fractures
No
Planar Deformation Features
No
Diaplectic Glass
No
Coesite
No
Stisovite
No

References

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B M Simonson (1992) Geological evidence for a strewn field of impact spherules in the early Precambrian Hamersley Basin of Western Australia, GSA Bulletin 104(7), p. 829-839, url

A Glikson, C Allen (2004) Iridium anomalies and fractionated siderophile element patterns in impact ejecta, Brockman Iron Formation, Hamersley Basin, Western Australia: Evidence for a major asteroid impact in simatic crustal regions of the early Proterozoic Earth, Earth and Planetary Science Letters 220(3-4), p. 247-264, url, doi:10.1016/S0012-821X(04)00062-7

DANIEL R Franco, LINDA A Hinnov (2008) Strong rhythmicity in the~ 2.46-2.50 Ga banded iron formation of the Hamersley Group (W. Australia): Evidence for sub-orbital to Milankovitch scale cycles, GSA Joint Annual Meeting-Abstracts 267

Dawn SWEENEY, Bruce M SIMONSON (2008) Textural constraints on the formation of impact spherules: A case study from the Dales Gorge BIF, Paleoproterozoic Hamersley Group of Western Australia, Meteoritics & Planetary Science 43(12), p. 2073-2087, John Wiley & Sons, Ltd, url, doi:https://doi.org/10.1111/j.1945-5100.2008.tb00662.x

B M Simonson, I McDonald, A Shukolyukov, C Koeberl, W U Reimold, G W Lugmair (2009) Geochemistry of 2.63-2.49 Ga impact spherule layers and implications for stratigraphic correlations and impact processes, Precambrian Research 175(1-4), p. 51-76, url, doi:10.1016/j.precamres.2009.08.004

B M Simonson, D Y Sumner, N J Beukes, S Johnson, J Gutzmer (2009) Correlating multiple Neoarchean-Paleoproterozoic impact spherule layers between South Africa and Western Australia, Precambrian Research 169(1-4), p. 100-111, url, doi:10.1016/j.precamres.2008.10.016

B C Johnson, H J Melosh (2012) Impact spherules as a record of an ancient heavy bombardment of Earth, Nature 485(7396), p. 75-77, url, doi:10.1038/nature10982

B C Johnson, H J Melsoh (2012) New estimates for the number of large impacts throughout Earth's history, Early Solar System Impact Bombardment II, url

Alexandra Krull Davatzes, Nicholas Swartz, Matthew Enos (2015) Petrologic and impact size controls on Precambrian spherule diameters, Large Meteorite Impacts and Planetary Evolution V 115, p. 1125, Geological Society of America Boulder