(Table 1) Pore-water composition of ODP Leg 126 sites
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| Format: | Dataset Open Access |
| Sprache: | en |
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PANGAEA
1992
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| _version_ | 1867169986073591808 |
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| author | Egeberg, Per Kristian |
| author_facet | Egeberg, Per Kristian |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | The Ocean Drilling Program Leg 126 sites may be classified into two categories depending on the presence (Group I: Sites 787, 792, and 793) or absence (Group II: Sites 788, 790, and 791) of steep concentration gradients. Shipboard X-ray diffraction analyses of bulk sediments from Group I sites revealed the presence of a number of diagenetic minerals (some of which are incompatible), but no systematic diagenetic zonation. The results of the chemical analyses of the pore waters from Group I have been used to estimate the activities of dissolved species. Thermodynamic analyses of the composition of the pore waters and the stability of authigenic minerals (gypsum, zeolites, feldspars, smectites, chlorites, and micas) show that the pore waters are close to equilibrium with most of the observed phases. Thus, only a small perturbation of the system (substitution in minerals and fluctuations in pore-water composition, in particular, in pH and SiO2 activity) will cause any of these phases to precipitate. Therefore, one would not expect mineralogical observations to show systematic vertical zonations at these sites. It is suggested that chlorites and high-temperature zeolites are not diagenetic sensu stricto, but were eroded from volcaniclastic highs. The absence of concentration gradients at the Group II sites has been analyzed in terms of reaction kinetics, hydrothermal advection, and temperature distribution. The absence of diagenetic imprints on the pore-water concentration profiles at these sites is probably caused by the slow nucleation of silica phases. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_774252 |
| institution | PANGAEA |
| language | en |
| publishDate | 1992 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | (Table 1) Pore-water composition of ODP Leg 126 sites Egeberg, Per Kristian 126-787B; 126-788C; 126-790A; 126-790B; 126-790C; 126-791A; 126-791B; 126-792A; 126-792B; 126-792E; 126-793A; 126-793B; Alkalinity, total; Calcium; Chlorine; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Iron 2+; Joides Resolution; Leg126; Lithologic unit/sequence; Magnesium; North Pacific Ocean; Ocean Drilling Program; ODP; pH; Philippine Sea; Potassium; Sample code/label; Silicon dioxide; Sodium; Sulfate The Ocean Drilling Program Leg 126 sites may be classified into two categories depending on the presence (Group I: Sites 787, 792, and 793) or absence (Group II: Sites 788, 790, and 791) of steep concentration gradients. Shipboard X-ray diffraction analyses of bulk sediments from Group I sites revealed the presence of a number of diagenetic minerals (some of which are incompatible), but no systematic diagenetic zonation. The results of the chemical analyses of the pore waters from Group I have been used to estimate the activities of dissolved species. Thermodynamic analyses of the composition of the pore waters and the stability of authigenic minerals (gypsum, zeolites, feldspars, smectites, chlorites, and micas) show that the pore waters are close to equilibrium with most of the observed phases. Thus, only a small perturbation of the system (substitution in minerals and fluctuations in pore-water composition, in particular, in pH and SiO2 activity) will cause any of these phases to precipitate. Therefore, one would not expect mineralogical observations to show systematic vertical zonations at these sites. It is suggested that chlorites and high-temperature zeolites are not diagenetic sensu stricto, but were eroded from volcaniclastic highs. The absence of concentration gradients at the Group II sites has been analyzed in terms of reaction kinetics, hydrothermal advection, and temperature distribution. The absence of diagenetic imprints on the pore-water concentration profiles at these sites is probably caused by the slow nucleation of silica phases. |
| title | (Table 1) Pore-water composition of ODP Leg 126 sites |
| topic | 126-787B; 126-788C; 126-790A; 126-790B; 126-790C; 126-791A; 126-791B; 126-792A; 126-792B; 126-792E; 126-793A; 126-793B; Alkalinity, total; Calcium; Chlorine; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Iron 2+; Joides Resolution; Leg126; Lithologic unit/sequence; Magnesium; North Pacific Ocean; Ocean Drilling Program; ODP; pH; Philippine Sea; Potassium; Sample code/label; Silicon dioxide; Sodium; Sulfate |
| url | https://doi.org/10.1594/PANGAEA.774252 |