Fig. 2. Sedimentology of the Spence Shale. (a) Lag deposit near base of ‘cycle 3’, consisting of biogenic debris, probably of echinoderm, brachiopod and trilobite remains. It should be noted how bedding bends around the millimetre-size echinoderm bioclasts. The matrix is carbonate-rich siliciclastic mudstone with varying amounts of sub-millimetre carbonate debris. (b) Carbonate-rich siliciclastic mudstone near top of ‘cycle 3’, with several millimetre-long black organic-rich flakes oriented parallel to bedding. Abundant silt-size carbonate particles in the matrix should be noted. Scale bar is 1 mm.
Julien Kimmig, Luke C. Strotz, Sara R. Kimmig, Sven O. Egenhoff and Bruce S. Lieberman
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