Palaeoecology of the Upper Tournaisian (Mississippian) crinoidal limestones from South Belgium

Abstract

1. Introduction The Mississippian (Lower Carboniferous) and particularly the Tournaisian is known as the golden age of crinoids (Kammer & Ausich, 2006). In suitable settings, the crinoids lived in vast meadows that formed the carbonate rock through the accumulation of their skeletal elements and named regional encrinites (sensu Ausich, 1997). Tournaisian encrinites are wide developed all over the world with renown examples from Ireland (Waters & Sevastopulo, 1984), N America (Ausich, 1999a,b), S China (Chen & Yao, 1993), Iran (Webster et al., 2003), etc. The expansion of crinoids during the Tournaisian is interpreted as a recovery phase following the Late Devonian extinctions, as it induced a rapid re-colonisation of the ecological niches by crinoids and then a rapid evolution (McGhee, 1996). The autoecology of crinoids is relatively well understood (Ausich & Bottjer, 1982, 2007; Ausich & Simms, 1999; Ausich et al., 1999a) in contrast to their synecology (i.e. interactions with the environment and with other organisms) despite their ability to shape their environment. In South Belgium, Tournaisian encrinites are abundant and locally called “Petit Granit” where quarried as cut stones for building and carving purposes. Several units were – and still are – intensively quarried for these purposes: the Hastiere Formation (Fm), Landelies Fm, Ourthe Fm, Flemalle Membre (Mbr) and Soignies Mbr. The most valuable and renowned are the encrinites of the Ourthe Fm in the Condroz area (cen