Grain size record of Oligocene to Pleistocene sediments from Broken Ridge
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| Natura: | Dataset Open Access |
| Lingua: | en |
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PANGAEA
1991
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| _version_ | 1867169503224266752 |
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| author | House, Martha A Rea, David K Janecek, Thomas R |
| author_facet | House, Martha A Rea, David K Janecek, Thomas R |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | At Ocean Drilling Program Sites 752 and 754, located on Broken Ridge in the eastern Indian Ocean, we recovered a sequence of shallow-water pelagic sediments that span the past 90 m.y. The Oligocene to Pleistocene portion of these sediments are unconsolidated carbonate oozes that display a coherent variation in bulk grain size. We believe these sediments to be winnowed, and suggest that their grain size is a measure of that winnowing energy. The largest increase in grain size, interpreted to represent an enhancement in the energy of ocean currents, occurs in the earliest late Miocene. This increase occurs about 20 m upcore from the oxygen isotope indication of ice-volume increase about 13 Ma, and is about 3 m.y. younger. If this distinct temporal separation between proxy indicators of ice volume and of current intensity observed in the Broken Ridge cores is correct, the general impression of paleoclimatologists that the planetary temperature gradient and therefore atmospheric and oceanic circulation intensity varies directly with ice volume needs to be reconsidered. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_759769 |
| institution | PANGAEA |
| language | en |
| publishDate | 1991 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Grain size record of Oligocene to Pleistocene sediments from Broken Ridge House, Martha A Rea, David K Janecek, Thomas R 121-752A; 121-754A; DRILL; Drilling/drill rig; Joides Resolution; Leg121; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean At Ocean Drilling Program Sites 752 and 754, located on Broken Ridge in the eastern Indian Ocean, we recovered a sequence of shallow-water pelagic sediments that span the past 90 m.y. The Oligocene to Pleistocene portion of these sediments are unconsolidated carbonate oozes that display a coherent variation in bulk grain size. We believe these sediments to be winnowed, and suggest that their grain size is a measure of that winnowing energy. The largest increase in grain size, interpreted to represent an enhancement in the energy of ocean currents, occurs in the earliest late Miocene. This increase occurs about 20 m upcore from the oxygen isotope indication of ice-volume increase about 13 Ma, and is about 3 m.y. younger. If this distinct temporal separation between proxy indicators of ice volume and of current intensity observed in the Broken Ridge cores is correct, the general impression of paleoclimatologists that the planetary temperature gradient and therefore atmospheric and oceanic circulation intensity varies directly with ice volume needs to be reconsidered. |
| title | Grain size record of Oligocene to Pleistocene sediments from Broken Ridge |
| topic | 121-752A; 121-754A; DRILL; Drilling/drill rig; Joides Resolution; Leg121; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean |
| url | https://doi.org/10.1594/PANGAEA.759769 |