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The Cretaceous/Tertiary-boundary impact and its global effects with reference to Australia

Created 16/10/2025

Updated 16/10/2025

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Considerable evidence exists for a major impact at Chicxulub, Mexico, and its effects at the Cretaceous/Tertiary boundary (KTB). It includes a buried crater, subglobal ejecta, and global fireball deposits that incorporate shocked minerals and non-terrestrial spinels. Platinum-group-element enrichments (Ir anomaly) and marked C- and O-isotope shifts at the KTB coincide with an extinction event. Australia contributes little to the KT impact story so far, but was isolated from the severest impact and extinction effects. A Chicxulub strike (C- or L-chondrite impactor) explains many KTB features, but does not satisfy all KTB studies. Continuing KTB impact debates include the size of Chicxulub crater, the extent of tsunami deposits, the number of impacts, and the origin of heterogeneous spinels. The role of KT plume volcanism (whether impact-induced or not) and the nature of KTB extinctions (whether caused by climatic cooling or warming and whether sharp, gradual, or latitudinally reduced) are also in debate. This synthesis suggests that the Chicxulub impact produced a crater 180 km wide and possibly induced tsunamigenic activity; that compositional differences between impact deposits might reflect more than one impact coinciding with the KTB; that the Deccan volcanism predates the KTB in India; and that several KTB sections evince gradual extinctions at high latitudes. Australia formed part of a more subdued southern extinction zone. Recent KTB studies tentatively suggest maximum impact and subordinate volcanic effects within lower latitudes. A search for fireball deposits and KTB fossil suites in Australia, which lay outside the Chicxulub ejecta apron, is needed to improve its KTB story.

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Field Value
Title The Cretaceous/Tertiary-boundary impact and its global effects with reference to Australia
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/3b8a8587-87eb-4bc5-8677-1904056f3d16
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage Australia
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "The Cretaceous/Tertiary-boundary impact and its global effects with reference to Australia". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/the-cretaceous-tertiary-boundary-impact-and-its-global-effects-with-reference-to-australia