@article {Iasky:2005:0812-0099:575,
title = "Gnargoo: a possible 75km-diameter post-Early Permianpre-Cretaceous buried impact structure, Carnarvon Basin, Western Australia",
journal = "Australian Journal of Earth Sciences",
parent_itemid = "infobike://tandf/aes",
publishercode ="tandf",
year = "2005",
volume = "52",
number = "4-5",
publication date ="2005-01-01T00:00:00",
pages = "575-586",
itemtype = "ARTICLE",
issn = "0812-0099",
eissn = "1440-0952",
url = "https://www.ingentaconnect.com/content/tandf/aes/2005/00000052/f0020004/art00008",
doi = "doi:10.1080/08120090500170377",
keyword = "impact structure, seismic-reflection surveys, Gnargoo, magnetic anomalies, Southern Carnarvon Basin, gravity anomalies",
author = "Iasky, R. P. and Glikson, A. Y.",
abstract = "The Gnargoo structure is located on the Gascoyne Platform, Southern Carnarvon Basin, Western Australia, and is buried beneath about 500m of Cretaceous and younger strata. The structure is interpreted as being of possible impact origin from major geophysical and morphometric signatures,
characteristic of impact deformation, and its remarkable similarities with the proven Woodleigh impact structure, about 275km to the south on the Gascoyne Platform. These similarities include: a circular Bouguer anomaly (slightly less well-defined at Gnargoo than at Woodleigh); a central
structurally uplifted area comprising a buried dome with a central uplifted plug; and the lack of a significant magnetic anomaly. Gnargoo shows a weakly defined inner 10km-diameter circular Bouguer anomaly surrounded by a broadly circular zone, 75km in diameter. The northsouth
Bouguer anomaly lineament of the Giralia Range (a regional topographic and structural feature) terminates abruptly against the outer circular zone which is, in turn, intersected on the eastern flank by the Wandagee Fault. A <28km-diameter layered sedimentary dome of Ordovician to
Lower Permian strata, surrounding a cone-shaped, central uplift plug of 710km diameter, are inferred from the seismic data. Seismic-reflection data indicate a minimum central structural uplift of 1.5km, as compared to a model uplift of 7.3km calculated from the outer
structural diameter. An interpretation of Gnargoo in terms of a plutonic or volcanic caldera/ring origin is unlikely as these features display less regular geometry, are typically smaller and no volcanic rocks are known in the onshore Gascoyne Platform. An interpretation of Gnargoo as a salt
dome is likewise unlikely because salt structures tend to have irregular geometry, and no extensive evaporite units are known in the Southern Carnarvon Basin. Morphometric estimates of the rim-to-rim diameter based on seismic data for the central dome correspond to the observed diameter deduced
from gravity data, and fall within the range of morphometric parameters of known impact structures. The age of Gnargoo is constrained between the deformed Lower Permian target rocks and unconformably overlying undeformed Lower Cretaceous strata. Because of its large dimensions, if Gnargoo
is an impact structure, it may have influenced an environmental catastrophe during this period.",
}