Composition and distribution of silica in sediments of the Broken Ridge
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| Auteurs principaux: | , , , |
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
1991
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| _version_ | 1867169503100534784 |
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| author | Littke, Ralf Fourtanier, Elisabeth Thurow, Juergen W Taylor, Elliott |
| author_facet | Littke, Ralf Fourtanier, Elisabeth Thurow, Juergen W Taylor, Elliott |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Within a dipping sequence of middle Cretaceous to Eocene sediments on Broken Ridge, opal-A, opal-CT, and quartz occur as minor constituents in carbonate and ash-rich sediments. Biogenic opal-A is mainly derived from diatoms and radiolarians. Opal-A and almost all siliceous microfossils disappear within a narrow (<20-m-thick) transition zone below which authigenic opal-CT and quartz are present. These latter silica polymorphs occur together within a 750-m-thick interval, but the ratio of quartz/opal-CT increases with increasing age and depth within the pre-rift sediment sequence. The boundary between opal-A- and opal-CT-bearing sediments is also a physical boundary at which density, P-wave velocity, and acoustic impedance change. This physical transition is probably caused by infilling of pore space by opal-CT lepispheres. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_759053 |
| institution | PANGAEA |
| language | en |
| publishDate | 1991 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Composition and distribution of silica in sediments of the Broken Ridge Littke, Ralf Fourtanier, Elisabeth Thurow, Juergen W Taylor, Elliott 121-752A; 121-752B; 121-754; 121-755A; COMPCORE; Composite Core; DRILL; Drilling/drill rig; Joides Resolution; Leg121; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean Within a dipping sequence of middle Cretaceous to Eocene sediments on Broken Ridge, opal-A, opal-CT, and quartz occur as minor constituents in carbonate and ash-rich sediments. Biogenic opal-A is mainly derived from diatoms and radiolarians. Opal-A and almost all siliceous microfossils disappear within a narrow (<20-m-thick) transition zone below which authigenic opal-CT and quartz are present. These latter silica polymorphs occur together within a 750-m-thick interval, but the ratio of quartz/opal-CT increases with increasing age and depth within the pre-rift sediment sequence. The boundary between opal-A- and opal-CT-bearing sediments is also a physical boundary at which density, P-wave velocity, and acoustic impedance change. This physical transition is probably caused by infilling of pore space by opal-CT lepispheres. |
| title | Composition and distribution of silica in sediments of the Broken Ridge |
| topic | 121-752A; 121-752B; 121-754; 121-755A; COMPCORE; Composite Core; DRILL; Drilling/drill rig; Joides Resolution; Leg121; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean |
| url | https://doi.org/10.1594/PANGAEA.759053 |