Development of the freeze–thaw processing technique for disaggregation of indurated mudrocks and enhanced recovery of calcareous microfossils

Alice E. Kennedy and Angela L. Coe
Journal of Micropalaeontology, 33, 193-203, 1 July 2014, https://doi.org/10.1144/jmpaleo2013-020

Article Figures & Data

Figures

  • Fig. 1.
    Fig. 1.

    Histogram showing the percentage disaggregation of samples to less than 500 µm from the four different methods.

  • Fig. 2.
    Fig. 2.

    Histogram showing the percentage composition of the fractions smaller than 500 µm and its distribution between the <63 µm clay fraction and 63–500 µm fraction from which the foraminifera could be extracted. The histogram shows, for all samples, Method 4 and Method 4 combined with Method 2; it also shows for samples MD-170 and Tse 00.60 only, Method 4 combined with high-pressure water spray (PW). The 63–500 µm fraction from Method 4 was used to test for further clay removal through the addition of Method 2 for samples MA-13, MD-78, MD-146 and MD-166/Tse 00.61 and through pressure washing for samples MD-170 and Tse 00.60. For samples MD-170 and Tse 00.60 a new aliquot of the samples was used to test Method 4 combined with Method 2.

  • Fig. 3.
    Fig. 3.

    Histogram showing the abundance of foraminifera and line graph showing the number of species for each of the samples processed by each of the methods.

  • Fig. 4.
    Fig. 4.

    The diversity of foraminifer assemblages in picked sedimentary rock using the Simpson, Margalef, Shannon H, Menhinick and Fisher alpha indices as well as the dominance and evenness for each sample calculated using PAST software.

  • Fig. 5.
    Fig. 5.

    The predicted number of foraminifera in the 63–500 µm fraction assuming the initial processed weight was 100 g and that the entire sample which was successfully disaggregated was picked for foraminifera.

  • Fig. 6.
    Fig. 6.

    (a) SEM image of a pyritized microgastropod processed with H2O2 showing pitting and dissolution damage. (b) SEM image of pyritized microgastropod processed by freeze–thaw.

  • Fig. 7.
    Fig. 7.

    SEM images of the foraminifer Eoguttulina liassica (Strickland, 1864): (a) pyritized, and processed with H2O2; (b) pyritized, and processed without H2O2; (c) non-pyritized, and processed without H2O2.

Tables

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