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| Titel |
Skeletal growth phases of the cold-water coral Lophelia pertusa shown by scanning electron microscope and electron backscatter diffraction |
| VerfasserIn |
Vincent Mouchi, Pierre Vonlanthen, Eric P. Verrecchia, Quentin G. Crowley |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133410
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| Publikation (Nr.) |
 EGU/EGU2016-14018.pdf |
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| Zusammenfassung |
| Lophelia pertusa is a cold-water coral, which may form reefs by the association of multiple
coralites within which a polyp lives. Each individual polyp builds an aragonite skeleton by an
initial phase of early mineralization (traditionally referred to as centres of calcification) from
which aragonite fibres grow in thickening deposits. The skeleton wall features successive
optically opaque and translucent bands previously attributed to different regimes of growth as
either uniform in crystal orientation (translucent bands) or with a chaotic organization
(opaque bands). The processes involved in any organizational changes are still
unknown.
Microlayers in the coral wall, which represent separate periods of skeletal growth, have
been recently identified and described. These growth patterns are readily visible under
scanning electron microscope (SEM) after etching in dilute formic acid, but they do
not necessarily form continuously visible structures. Here we present high quality
SEM images and electron backscatter diffraction (EBSD) maps to study aragonite
fibre orientation across the wall of L. pertusa. Both microlayers and opaque and
translucent bands are compared to the crystallographic orientation of the aragonite
fibres.
EBSD maps and SEM images indicate that aragonite fibres do not exhibit a chaotic
orientation, even in opaque bands. The absence of continuity of microlayers is partially
explained by an association of multiple crystallographic preferred orientations of aragonite
fibres. In the case of L. pertusa, careful textural characterisation is necessary prior to
elemental or isotope analysis in order to select a skeletal transect representing a linear and
continuous time period. |
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