Silicon isotope fractionation by marine sponges and the reconstruction of the silicon isotope composition of ancient deep water

Abstract : The silicon isotope composition (d30Si) of biogenic opal provides a view of the silica cycle at times in the past. Reconstructions require the knowledge of silicon isotope fractionation during opal biomineralization. The d30Si of specimens of hexactinellid sponges and demosponges growing in the modern ocean ranged from -1.2‰ to -3.7‰ (n=6), corresponding to the production of opal that has a d30Si value 3.8‰ +/- 0.8‰ more negative than seawater silicic acid and a fractionation factor (a) of 0.9964. This is three times the fractionation observed during opal formation by marine diatoms and terrestrial plants and is the largest fractionation of silicon isotopes observed for any natural process on Earth. The d30Si values of sponge spicules across the Eocene- Oligocene boundary at Ocean Drilling Program Site 689 on Maud Rise range from -1.1‰ to -3.0‰, overlapping the range observed for sponges growing in modern seawater.
Type de document :
Article dans une revue
Geology, Geological Society of America, 2003, 31, pp.423-426
Liste complète des métadonnées

http://hal.univ-brest.fr/hal-00509455
Contributeur : Christina De La Rocha <>
Soumis le : jeudi 12 août 2010 - 15:12:01
Dernière modification le : jeudi 11 janvier 2018 - 06:22:24

Identifiants

  • HAL Id : hal-00509455, version 1

Collections

Citation

Christina De La Rocha. Silicon isotope fractionation by marine sponges and the reconstruction of the silicon isotope composition of ancient deep water. Geology, Geological Society of America, 2003, 31, pp.423-426. 〈hal-00509455〉

Partager

Métriques

Consultations de la notice

118