Waulsortian mudmound
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A Waulsortian mudmound is a calcareous geographical feature found in Early Carboniferous strata of Central Europe. It is a type of fossil-rich bioconstruction, formed by microbial activity in deep tropical waters during the mid-Dinantian (late Tournaisian to early Viséan geological age). Mud mounds are a type of high-relief biologically-mediated seafloor deposit, similar to a reef. Unlike a true reef, a mud mound is composed almost entirely of uncemented mud-sized matrix grains, and the isolated fossils do not form a significant skeletal framework.
Waulsortian mudmounds in particular are unbedded, micritic limestone, heavily jointed with calcite veining. There is some galena and sphalerite mineralisation in the joints. The fossils are mainly crinoid ossicles and fenestellid bryozoans, together with gastropods and brachiopods.
The term Waulsortian was first used in 1863 to describe an area of limestone near Waulsort in Namur, Belgium. Similar mudstone was recognised in the Clitheroe area of Lancashire England by Arthur Vaughan in 1916.[1]