Paleomagnetic record of Site 177-1089
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| Autores principales: | , , , |
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| Formato: | Dataset Open Access |
| Lenguaje: | en |
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PANGAEA
2013
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| _version_ | 1867171814502825984 |
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| author | Stoner, Joseph S Channell, James E T Hodell, David A Charles, Christopher D |
| author_facet | Stoner, Joseph S Channell, James E T Hodell, David A Charles, Christopher D |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | We report geomagnetic directional paleosecular variation, relative paleointensity proxies and oxygen isotope data from the upper 88 m composite depth (mcd) at South Atlantic Ocean Drilling Program (ODP) Site 1089 (40°56.2?S, 9°53.64?E, 4620 m water depth). The age model is provided by high-resolution oxygen isotope stratigraphy, augmented by radiocarbon dates from the upper 8 mcd of nearby piston core RC11-83. Mean sedimentation rates at Site 1089 are in the range of 15 to 20 cm/kyr. Two intervals during the Brunhes Chron, at ?29.6 mcd (?190 ka) and at ?48 mcd (?335 ka), have component magnetization directions with positive (reverse polarity) inclination; however, the excursional directions are heavily overprinted by the postexcursional field. Magnetite is the dominant carrier of magnetic remanence, and occurs in the pseudosingle-domain (PSD) grain size. An additional higher-coercivity magnetic carrier, characterized by low unblocking temperatures (<350°C), is assumed to be authigenic pyrrhotite. A decrease in magnetization intensity down core is mirrored by a reduction in pore water sulfate, indicating diagenetic reduction of magnetite. Despite down-core changes in magnetic mineralogy, normalized intensity records from Site 1089 are comparable with high-resolution paleointensity records from the North Atlantic (e.g., ODP Sites 983 and 984). Sediment properties and sedimentation patterns within the Cape (Site 1089) and Iceland (Sites 983 and 984) Basins are distinctly different at both millennial and orbital timescales and therefore preclude lithologic variability from being the source of this correlation. Variations in normalized intensity from Site 1089 therefore appear to reflect changes in global-scale geomagnetic field intensity. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_808783 |
| institution | PANGAEA |
| language | en |
| publishDate | 2013 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Paleomagnetic record of Site 177-1089 Stoner, Joseph S Channell, James E T Hodell, David A Charles, Christopher D 177-1089; AGE; COMPCORE; Composite Core; DEPTH, sediment/rock; Joides Resolution; Leg177; Maximum angular deviation; NRM, Declination; NRM, Inclination; Ocean Drilling Program; ODP; Relative paleointensity proxy; South Atlantic Ocean We report geomagnetic directional paleosecular variation, relative paleointensity proxies and oxygen isotope data from the upper 88 m composite depth (mcd) at South Atlantic Ocean Drilling Program (ODP) Site 1089 (40°56.2?S, 9°53.64?E, 4620 m water depth). The age model is provided by high-resolution oxygen isotope stratigraphy, augmented by radiocarbon dates from the upper 8 mcd of nearby piston core RC11-83. Mean sedimentation rates at Site 1089 are in the range of 15 to 20 cm/kyr. Two intervals during the Brunhes Chron, at ?29.6 mcd (?190 ka) and at ?48 mcd (?335 ka), have component magnetization directions with positive (reverse polarity) inclination; however, the excursional directions are heavily overprinted by the postexcursional field. Magnetite is the dominant carrier of magnetic remanence, and occurs in the pseudosingle-domain (PSD) grain size. An additional higher-coercivity magnetic carrier, characterized by low unblocking temperatures (<350°C), is assumed to be authigenic pyrrhotite. A decrease in magnetization intensity down core is mirrored by a reduction in pore water sulfate, indicating diagenetic reduction of magnetite. Despite down-core changes in magnetic mineralogy, normalized intensity records from Site 1089 are comparable with high-resolution paleointensity records from the North Atlantic (e.g., ODP Sites 983 and 984). Sediment properties and sedimentation patterns within the Cape (Site 1089) and Iceland (Sites 983 and 984) Basins are distinctly different at both millennial and orbital timescales and therefore preclude lithologic variability from being the source of this correlation. Variations in normalized intensity from Site 1089 therefore appear to reflect changes in global-scale geomagnetic field intensity. |
| title | Paleomagnetic record of Site 177-1089 |
| topic | 177-1089; AGE; COMPCORE; Composite Core; DEPTH, sediment/rock; Joides Resolution; Leg177; Maximum angular deviation; NRM, Declination; NRM, Inclination; Ocean Drilling Program; ODP; Relative paleointensity proxy; South Atlantic Ocean |
| url | https://doi.org/10.1594/PANGAEA.808783 |