Mudstone that consists of greater than 50 percent carbonate minerals of any origin
in the mud size fraction.
Not a subcategory of carbonate sedimentary rock because definition does not specify
'carbonate minerals of intrabasinal origin', but is agnostic on origin of carbonate.
Schnurrenberger et al. 2003 point out that it is very difficult (at least in lacustrine
rocks) to distinguish chemically precipitated or diagenetic carbonate from primary
biogenic carbonate. This distinction between biogenic, detrital, and pedogenic or
authigenic carbonate material is thus not a good one to use in a general purpose classification
system. Schnurrenberger, D., Russell, J. and Kelts, K., 2003, Classification of lacustrine
sediments based on sedimentary components: Journal of Paleolimnology, v.29, p141-154.