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Fig. 5 | Swiss Journal of Geosciences

Fig. 5

From: Compaction-formed platy limestone from the Middle Cambrian Zhangxia Formation (Western Hills, China): towards a new classification for bedded limestone

Fig. 5

a Oolitic grainstone with well-preserved ooids and two types of ooid-cortices. Inner cortices reveal recrystallisation of primary tangential micro textures to radial light-coloured textures. Outer cortices predominantly preserved their primary tangential textures. Ooids are surrounded by isopachous marine cement seams (arrows; Mg-calcite). Locally relics of micrite (M) recrystallized to microspar can be found. b Early compaction resulted in deformation and split off of outer cortices forming intraparticle pore space which was filled by marine cement (Z). Note common light-coloured triangular recrystallisation-areas (T) in the inner zone of primarily tangential cortices. Note also cement seams with relic textures of former bladed Mg-calcite (S). c Some ooids were completely dissolved. The oomolds first were filled by smaller and very large dolomite rhombohedra (d). The relic pore space subsequently was cemented by coarse granular calcite (c). d Composed ooids show the dissolution of outer cortices (primary aragonite), cementation of these molds by dolomite (D) and calcite (C), and the formation of microcrystalline dolomite (MD) in the inner part (primary Mg-calcite). e Fragments of echinoids and other fossils in a primary matrix-rich packstone were intensively compacted and reveal sutured grain contacts (arrows). f Pure mudstones are locally traversed by fractures filled with granular calcite (C)

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