A review of the occurrence and the origin of glendonite and glendonite concretion

Glendonite is a calcite pseudomorph after ikaite and is found in sedimentary rocks worldwide. Glendonite concretions are spherical to ellipsoidal carbonate concretions containing glendonite at their center. Glendonites and glendonite concretions have been widely used as indicators of low temperatures because ikaite, a precursor of glendonite, is stable only in low-temperature environments. The process that forms glendonite concretions means that they are also potential indicators of the chemical environments of sediment porewaters. However, the physicochemical conditions required for the formation of ikaite in sediments remain poorly constrained. As the conditions of formation of both ikaite in modern sediments and glendonite in sedimentary rocks are clarified, the use of glendonite and glendonite concretions as environmental indicators will increase.