Concentrations of tektites and chemical elements in sediments from ODP Holes 121-758B and 124-769A

Recently published studies of Ocean Drilling Project (ODP) cores from near southeast Asia revealed microtektite contents much higher than those in previously studied cores, suggesting that Ir contents might be enhanced in the tektite-bearing horizons. We determined a positive Ir anomaly in ODP core 758B from the Ninetyeast Ridge, eastern Indian Ocean; the peak Ir concentration of 190 pg/ g was ~2X the continuum level. The net Ir fluence is 1.8+/-0.5 ng/cm2 over the depth interval from 10.87 to 11.32 m; a small additional peak also associated with microtektites contributes another 0.5 ng Ir/cm2. Concentrations of Ir in core 769A show more scatter, but a small Ir enhancement is associated with the peak microtektite abundance; our best estimate of the poorly constrained fluence is 1.3+/-0.7 ng/cm2. Data on deep-sea cores show that the microtektite fluence falls exponentially away from southeast Asia, the fluence dropping a factor of 2 in ~400 km. In southeast Asia the trend merges with a roughly estimated mass fluence of ~1.1 g/cm2 inferred from evidence of a melt sheet in northeast Thailand. Integration of the inferred distribution yields a total mass of Australasian tektites of 3.2x1016 g, much higher than previous estimates. Assuming a similar fallout distribution for the impactor and a chondritic composition allows us to calculate its mass to be 1.5x1015 g, about 3 orders of magnitude smaller than the minimum mass of the impactor responsible for the extinctions at the end of the Cretaceous.

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Schmidt, Gerhard, Zhou, Lei, Wasson, John T (1993). Dataset: Concentrations of tektites and chemical elements in sediments from ODP Holes 121-758B and 124-769A. https://doi.org/10.1594/PANGAEA.707906

DOI retrieved: 1993

Additional Info

Field Value
Imported on November 30, 2024
Last update November 30, 2024
License CC-BY-3.0
Source https://doi.org/10.1594/PANGAEA.707906
Author Schmidt, Gerhard
Given Name Gerhard
Family Name Schmidt
More Authors
Zhou, Lei
Wasson, John T
Source Creation 1993
Publication Year 1993
Resource Type application/zip - filename: Schmidt-1993
Subject Areas
Name: Chemistry

Name: Lithosphere

Related Identifiers
Title: Iridium anomaly associated with the Australasian tektite-producing impact; masses of the impactor and of the Australasian tektites
Identifier: https://doi.org/10.1016/0016-7037(93)90204-A
Type: DOI
Relation: IsSupplementTo
Year: 1993
Source: Geochimica et Cosmochimica Acta
Authors: Schmidt Gerhard , Zhou Lei , Wasson John T .