Primary and diagenetic microstructures in trilobite exoskeletons
Titel:
Primary and diagenetic microstructures in trilobite exoskeletons
Auteur:
Wilmot, Nadine V.
Verschenen in:
Historical biology
Paginering:
Jaargang 4 (1990) nr. 1 pagina's 51-65
Jaar:
1990
Inhoud:
Trilobite exoskeletons, despite having had a common original mineralogy, exhibit a variety of preservational textures which are related to the different diagenetic realms through which they have passed. These alterations of the cuticle can either destroy or enhance primary microstructures, and their effects are most easily observed in thin-sections, both under transmitted light and cathodoluminescence. The various features observed, and the processes that generated them, are discussed. Large borings, micritisation, mechanical breakage, and dissolution damage exoskeletons, whereas some types of replacement, such as silicification, preserve fine structural details. Pyrite quite commonly infills canals and highlights their positions. Variations in luminescence across trilobite cuticles, such as bright prismatic layers and dark central zones do not reflect primary differences in composition, but are diagenetic effects related to trace element content. It is important to distinguish diagenetic features from primary cuticular structures so that errors in functional interpretation are avoided. Previous misinterpretations involve Osmolska cavities and cell polygons.
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