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Geomorphic and palaeoclimatic implications of an oxygen-isotope chronology for australian deeply weathered profiles

Journal Article


Abstract


  • >A technique for obtaining age estimates for regolith profiles in Australia, based on the oxygen���isotope composition of the clay mineral assemblage in a profile, is applied to a variety of regolith profiles and kaolinitic sediments from across Australia. Excluding monsoonal regions in the north of the continent, it is possible to distinguish profiles formed in the Late Mesozoic���Early Tertiary (��18O values between +15 and +17.5%����) from profiles formed in post���mid���Tertiary times (>+17.5%��). In addition it is concluded that there remain widespread remnants of a deep���weathered regolith which developed in pre���Late Mesozoic (Early Cretaceous or Jurassic?) times when Australia was at high latitude. The low ��18O values associated with clays formed in pre���Late Mesozoic times (+10 to +15%o) suggest that deep weathering took place in a cool to cold and presumably humid climate, contrary to the traditional belief that deep weathering requires tropical to subtropical temperatures. The formation of deep���weathered profiles at high latitude in a comparatively cold climate may be linked in part to higher past atmospheric CO2 levels. �� 1993 Taylor & Francis Group, LLC.

UOW Authors


  •   Chivas, Allan (external author)

Publication Date


  • 1993

Citation


  • Bird, M. I., & Chivas, A. R. (1993). Geomorphic and palaeoclimatic implications of an oxygen-isotope chronology for australian deeply weathered profiles. Australian Journal of Earth Sciences, 40(4), 345-358. doi:10.1080/08120099308728086

Scopus Eid


  • 2-s2.0-0027881449

Start Page


  • 345

End Page


  • 358

Volume


  • 40

Issue


  • 4

Place Of Publication


Abstract


  • >A technique for obtaining age estimates for regolith profiles in Australia, based on the oxygen���isotope composition of the clay mineral assemblage in a profile, is applied to a variety of regolith profiles and kaolinitic sediments from across Australia. Excluding monsoonal regions in the north of the continent, it is possible to distinguish profiles formed in the Late Mesozoic���Early Tertiary (��18O values between +15 and +17.5%����) from profiles formed in post���mid���Tertiary times (>+17.5%��). In addition it is concluded that there remain widespread remnants of a deep���weathered regolith which developed in pre���Late Mesozoic (Early Cretaceous or Jurassic?) times when Australia was at high latitude. The low ��18O values associated with clays formed in pre���Late Mesozoic times (+10 to +15%o) suggest that deep weathering took place in a cool to cold and presumably humid climate, contrary to the traditional belief that deep weathering requires tropical to subtropical temperatures. The formation of deep���weathered profiles at high latitude in a comparatively cold climate may be linked in part to higher past atmospheric CO2 levels. �� 1993 Taylor & Francis Group, LLC.

UOW Authors


  •   Chivas, Allan (external author)

Publication Date


  • 1993

Citation


  • Bird, M. I., & Chivas, A. R. (1993). Geomorphic and palaeoclimatic implications of an oxygen-isotope chronology for australian deeply weathered profiles. Australian Journal of Earth Sciences, 40(4), 345-358. doi:10.1080/08120099308728086

Scopus Eid


  • 2-s2.0-0027881449

Start Page


  • 345

End Page


  • 358

Volume


  • 40

Issue


  • 4

Place Of Publication