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Geochemical comparison of K-T boundaries from the Northern and Southern HemispheresClosely spaced (cm-scale) traverses through the K-T boundary at Stevns Klint (Denmark), Woodside Creek (New Zealand) and a new Southern Hemisphere site at Richards Bay (South Africa) were subjected to trace element and isotopic (C, O, Sr) investigation. Intercomparison between these data-sets, and correlation with the broad K-T database available in the literature, indicate that the chemistry of the boundary clays is not globally constant. Variations are more common than similarities, both of absolute concentrations, and interelement ratios. For example, the chondrite normalized platinum-group elements (PGE) patterns of Stevns Klint are not like those of Woodside Creek, with the Pt/Os ratios showing the biggest variation. These differences in PGE patterns are difficult to explain by secondary alteration of a layer that was originally chemically homogeneous, especially for elements of such dubious crustal mobility as Os and Ir. The data also show that enhanced PGE concentrations, with similar trends to those of the boundary layers, occur in the Cretaceous sediments below the actual boundary at Stevns Klint and all three the New Zealand localities. This confirms the observations of others that the geochemistry of the boundary layers apparently does not record a unique component. It is suggested that terrestrial processes, eg. an extended period of Late Cretaceous volcanism can offer a satisfactory explanation for the features of the K-T geochemical anomaly. Such models would probably be more consistent with the observed stepwise, or gradual, palaeontological changes across this boundary, than the instant catastrophe predicated by the impact theory.
Document ID
19890012029
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Tredous, M. (Witwatersrand Univ. Johannesburg, South Africa)
Verhagen, B. TH. (Witwatersrand Univ. Johannesburg, South Africa)
Hart, R. J. (Witwatersrand Univ. Johannesburg, South Africa)
Dewit, C. B. (Witwatersrand Univ. Johannesburg, South Africa)
Smith, C. B. (Witwatersrand Univ. Johannesburg, South Africa)
Perch-Nielsen, K. (Witwatersrand Univ. Johannesburg, South Africa)
Sellschop, J. P. F. (Witwatersrand Univ. Johannesburg, South Africa)
Date Acquired
September 5, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Lunar and Planetary Inst., Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality
Subject Category
Geophysics
Accession Number
89N21400
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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