Why is stromatactis so rare in Mesozoic carbonate mud mounds? |
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Authors: | Fritz Neuweiler,Pierre-André Bourque,& Fré dé ric Boulvain |
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Affiliation: | Abteilung Geobiologie, GZG, Georg-August-Universität Göttingen, Goldschmidtstrasse 3, D-37077 Göttingen, Germany,;Département de géologie et de génie géologique, UniversitéLaval, Québec, Canada, G1K 7P4,;Laboratoires associés de Géologie-Pétrologie-Géochimie, bâtiment B20, Universitéde Liège Sart-Tilman, B-4000 Liège, Belgium |
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Abstract: | The sedimentary–diagenetic structure stromatactis is widespread in Palaeozoic spiculitic carbonate mud mounds, but occurs only sporadically in Mesozoic sponge carbonate mud mounds. Comparative analysis of Palaeozoic and Mesozoic stromatactis limestones suggests that this variation results from the degree of siliceous sponge skeletal rigidity and the amount of internal sediment accumulation in the original cavity network. Partial to entire filling by internal sediment resulted in a continuum, from a small amount of internal sediment and large amount of cement (stromatactis, common in the Palaeozoic), to only internal sediments (aborted stromatactis, common in the Mesozoic). These observations match independent lines of evidence concerning the siliceous sponge evolution and sediment recycling (e.g. bioerosion) across the Palaeozoic to Mesozoic biotic revolution. |
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