Apatite varieties in the shell of the Cambrian lingulate brachiopod Obolus apollinis Eichwald
2004; Estonian Academy Publishers; Volume: 53; Issue: 4 Linguagem: Inglês
10.3176/geol.2004.4.02
ISSN1736-7913
AutoresT Kallaste, T Kurvits, J Nemliher, I Puura,
Tópico(s)Marine and environmental studies
ResumoAn XRD study of heat-treated shell samples of the lingulate brachiopod Obolus apollinis Eichwald from the upper Cambrian (Furongian) of NW Russia (basal Tosna Formation, Lava River section) revealed the presence of two phases of apatite persisting the temperatures from 200 to 700 °C.At higher temperatures, 900 and 1000 °C, only one phase was detected.The lattice parameters of the two phases suggest possible preservation of carbonate-hydroxylapatite within the compact laminae of initially organo-phosphatic lingulate shells.The formation of another phase, carbonate-fluorapatite, is attributed to the precipitation of apatite to the free space available after disintegration of organic tissues of the shell and to partial recrystallization of initial shell apatite.
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