Deep-sea biogenic silica: new structural and analytical data from infrared analysis - geological implications |
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| Authors: | François Fröhlich |
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| Institution: | Laboratoire de Géologie du Museum, 43 rue Buffon, 75005 Paris. France |
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| Abstract: | The main parameters of infrared spectra have been investigated for marine siliceous skeletons and for silica polymorphs. From infrared (IR)data, the mean values for the Si-O bond length (1.62 Å) and for the Si-O-Si angle (about 142°6) are inferred for biogenic silica. A model is proposed for the molecular structure of biogenic, amorphous silica, which consists of a discontinuous, three-dimensional framework of short chains of SiO4] tetrahedra, bounded with apical hydroxyls. According to the relationship between the structure of the silica polymorphs and their infrared spectra, it is shown that a quantitative analysis of biogenic silica seems to be possible in quartz-rich sediments. Some geological implications of these data are emphasized, including the processes of siliceous skeleton sedimentation and diagenetic evolution. |
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