Geology Reference
In-Depth Information
0.5 cm
Fig. 20.16.
Bivalve and brachiopod shells embedded in a fine-grained peloidal matrix. The sharp outlines of the bivalve
shells indicate that dissolution of the aragonitic shell material occurred after cementation of the matrix. Interestingly, the
bivalve shells are partly filled with fine-grained sediment. This indicates that after aragonite dissolution fine-grained material
was swept into the pore network filling the space of the dissolved shells. This must have taken place very early in diagenetic
history of the sediment when soft mud was still available. Mixing of fine-grained and very fine-grained sediment indicates
burrowing activity. Silurian (Wenlock): Gotland, Sweden.
1 - Brachiopod shell, 2 -Bivalve shell, partly filled with micritic material after dissolution of the aragonitic shell
References
Roberts, J.M., Wheeler, A., Freiwald, A., Cairns, S. (2009):
Cold-Water Corals. - Cambridge Univ. Press, 334 pp.,
Cambridge
Titschack, J., Radke, U., Freiwald, A. (2009): Dating and
characterization of polymorphic transformation of
aragonite to calcite in Pleistocene bivalves from Rhodes
(Greece) by combined shell microstructure, stable isotope,
and electron spin resonance study. - J. Sed. Research
79
, 332-346
Vennin, E., Aretz, M., Boulvain, F., Munnecke, A. (eds.)
(2007): Facies from Palaeozoic Reefs and Bioaccumula-
tions. - Mémoires du Muséum national d'Histoire
naturelle, 195, 341pp.
