In response to the query by "[log in to unmask]"
Sounds like a real can of worms.... (sorry!!)
Are you sure that your serpulid tubes are unaltered? What was their
original mineralogy? Try staining them with potassium ferricyanide to be
sure. Jurassic calcitic serpulid tubes that I have seen seem to have highly
microporous walls which tend to get thoroughly infused with cement. To be
sure, it is usually a luminescent, non-ferroan cement, but there is no
reason why it shouldn't be strongly ferroan (and thereby virtually
nonluminescent). Aragonitic serpulid tubes neomorphically replaced by
Fe-rich calcite might also appear effectively non-luminescent.
Wefer & Berger (1991) suggest that d18O values of calcitic serpulid tubes
are close to equilibrium with average seawater, and that d13C values
display a vital effect with several permil negative shift. They cite a
paper by Videtich (1986) describing seasonal variation in d18O and parallel
behaviour of d13C in aragonite serpulids. Morrison & Brand (1986) suggest
that both d18O and d13C are depleted in aragonitic serpulid tubes, but cite
no reference. However, there appears to be very little data to base firm
* Morrison, J.O. & Brand, U. 1986. Geochemistry of recent marine
invertebrates. Geoscience Canada, 13, 237-254.
* Wefer, G. & Berger, W.H. 1991. Isotope palaeontology: growth and
composition of extant calcareous species. Marine Geology, 100, 207-248.
* Videtich, P.E. 1986. Stable-isotope compositions of serpulids give
insights to calcification processes in marine organisms. Palaios, 1,
Dr Jim P. Hendry
Department of Geology
School of Geosciences
The Queen's University of Belfast
Belfast BT7 1NN
Tel: 01232 245133 ext 3449
Fax: 01232 321280
E-mail: [log in to unmask]