Carbonat-free sediment components of ODP Leg 115 holes
Fuente:
PANGAEA
Salvato in:
| Autori principali: | , |
|---|---|
| Natura: | Dataset Open Access |
| Lingua: | en |
| Pubblicazione: |
PANGAEA
1990
|
| Soggetti: | |
| Accesso online: | |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1867169502812176384 |
|---|---|
| author | Hempel, Peter Bohrmann, Gerhard |
| author_facet | Hempel, Peter Bohrmann, Gerhard |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | From the equatorial Indian Ocean, carbonate-free portions of sediment samples of Paleocene to Miocene calcareous oozes and chalks from Sites 707, 709, and 711 were studied using X-ray diffraction measurements and the scanning electron microscope. Downhole variations in biogenic opal, quartz, barite, and clinoptilolite were investigated. The abundance patterns of these major mineral phases show several similarities and may be used for additional lithologic correlations. Variations in biogenic opal contents reflect biogenic silica productivity. Beside the general pattern, a succession in biogenic silica decrease through time is generally recorded since the Oligocene. This succession started earliest at northernmost Site 711 and latest at southernmost Site 707, including Site 709 within these two. Opal-A variations as well as the barite distribution may be influenced by the paleoposition of the sites in relation to the high-productivity zone, which today lies south of the equator. Authigenic clinoptilolite apparently formed in two different modes. In deeper sediment intervals, clinoptilolite was the last mineral phase formed associated with enhanced silica diagenesis. In late Oligocene to middle Miocene sediments, clinoptilolite was the only authigenic silica phase encountered where otherwise strong opal dissolution was observed. The sponge spicules showed special dissolution features probably related to microbiological activity. Silica concretions mainly composed of opal-CT and authigenic quartz occur in carbonate-rich environments and are formed during later diagenesis when burial depth causes the sediments to reach higher temperatures. Opal-CT concretions in carbonate-free siliceous oozes were found at Site 711 and are probably formed during an early stage of silica diagenesis. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_755960 |
| institution | PANGAEA |
| language | en |
| publishDate | 1990 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Carbonat-free sediment components of ODP Leg 115 holes Hempel, Peter Bohrmann, Gerhard 115-707A; 115-707C; 115-709B; 115-709C; 115-711A; DRILL; Drilling/drill rig; Joides Resolution; Leg115; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean From the equatorial Indian Ocean, carbonate-free portions of sediment samples of Paleocene to Miocene calcareous oozes and chalks from Sites 707, 709, and 711 were studied using X-ray diffraction measurements and the scanning electron microscope. Downhole variations in biogenic opal, quartz, barite, and clinoptilolite were investigated. The abundance patterns of these major mineral phases show several similarities and may be used for additional lithologic correlations. Variations in biogenic opal contents reflect biogenic silica productivity. Beside the general pattern, a succession in biogenic silica decrease through time is generally recorded since the Oligocene. This succession started earliest at northernmost Site 711 and latest at southernmost Site 707, including Site 709 within these two. Opal-A variations as well as the barite distribution may be influenced by the paleoposition of the sites in relation to the high-productivity zone, which today lies south of the equator. Authigenic clinoptilolite apparently formed in two different modes. In deeper sediment intervals, clinoptilolite was the last mineral phase formed associated with enhanced silica diagenesis. In late Oligocene to middle Miocene sediments, clinoptilolite was the only authigenic silica phase encountered where otherwise strong opal dissolution was observed. The sponge spicules showed special dissolution features probably related to microbiological activity. Silica concretions mainly composed of opal-CT and authigenic quartz occur in carbonate-rich environments and are formed during later diagenesis when burial depth causes the sediments to reach higher temperatures. Opal-CT concretions in carbonate-free siliceous oozes were found at Site 711 and are probably formed during an early stage of silica diagenesis. |
| title | Carbonat-free sediment components of ODP Leg 115 holes |
| topic | 115-707A; 115-707C; 115-709B; 115-709C; 115-711A; DRILL; Drilling/drill rig; Joides Resolution; Leg115; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean |
| url | https://doi.org/10.1594/PANGAEA.755960 |