The Ordovician section of the Hällekis Quarry

Lower–Middle Ordovician bedded limestones of Sweden have been collectively referred to as the ‘orthoceratite limestone’. This world-famous cool to temperate water limestone is widely distributed in Scandinavia, and the table mountain Kinnekulle is ;regarded as its type area. The ‘orthoceratite limestone’ here has been the target of numerous focused studies and is among the most thoroughly documented intervals in the Ordovician, both regionally and globally.
The abandoned quarry at Hällekis, Kinnekulle, provides an easily accessible Middle Ordovician succession. The c. 40 m thick succession consists predominantly of ‘orthoceratite limestone’, often with corrosional hardgrounds (Lindskog and Eriksson, 2017; Lindskog et al., 2019). Macrofossils are generally relatively rare, but some beds contain abundant and spectacular accumulations of orthocone cephalopods and trilobites. Noteworthy is a grey, c. 1.5 m thick unit (the ‘Täljsten’ or ‘carving stone’) dominated by in situ preserved specimens of cystoid echinoderms. This interval contains relatively abundant chromite grains with chemical compositions that indicate a meteoritic origin. Together with the remarkable occurrence of more than one hundred macroscopic ‘fossil’ meteorites from the same interval in the Thorsberg quarry to the southeast, this has been linked to an asteroid disruption event in space (Schmitz and Häggström, 2006; Schmitz et al., 2019).