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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
1981
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| Online Access: | https://doi.org/10.1594/PANGAEA.819504 |
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| _version_ | 1867171366460981248 |
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| author | Vincent, Edith |
| author_facet | Vincent, Edith |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | A detailed Neogene carbonate stratigraphy obtained from Hess Rise, in the temperate zone of the North Pacific, allows a cross-latitudinal correlation of carbonate fluctuations throughout the Pacific. The correlations are based on paleomagnetically dated biostratigraphic events. The carbonate record at Site 310, on Central Hess Rise, at a water depth of about 3500 meters, was obtained with a sampling interval representing time intervals of roughly 20,000 years in the Plio-Pleistocene, 30,000 years in the uppermost Miocene younger than about 6.2 m.y., and 140,000 years in the remainder of the upper Miocene and the middle Miocene. This record allows identification at Site 310 of specific carbonate events recognized throughout the equatorial Pacific, showing the ocean-wide nature of these events. The carbonate records compared with Site 310 are based on (time-) sampling intervals similar to those of Site 310. The comparison records are all located in the high-productivity belt of the equatorial Pacific, from depths near 2000 meters in the Panama Basin (DSDP Sites 157 and 158) to depths near 4500 meters, not far above the CCD (various piston cores). Specific carbonate events were not detected in the Plio-Pleistocene carbonate record at Site 466, on southern Hess Rise. This record was obtained with a sampling interval equivalent to a time span of about 60,000 years. This site, located at a water depth of about 2700 meters, has a Plio-Pleistocene sedimentary history similar to that at nearby Site 310, with approximately the same accumulation rate. Long-term cycles are superimposed on the short-term carbonate fluctuations in the equatorial Pacific sequences. The periodicity of these cycles, although not regular, is on the order of 0.5 m.y. for the upper Pleistocene, and on the order of 1 to 1.5 m.y. for the lower Pleistocene, Pliocene, and Miocene. Some of these long-term cycles are apparent in the carbonate stratigraphy at Site 310, especially in the Pleistocene and Miocene, but are not seen in the Pliocene. In Cores V24-59 and RC12-66, the Gauss includes the interval with the lowest calcium carbonate content of the entire Neogene, and sediment in this sequence accumulated more slowly than before or after. In contrast, at both Sites 310 and 157, this sequence accumulated at an average rate higher than overlying and underlying sediments. At Site 310, it contains the highest CaCO3 average concentration of the entire Neogene. At Sites 310 and 466, there is an overall correlation between lower carbonate content and poorer foraminifer preservation in the Pleistocene, but no such correlation exists in the Pliocene and upper Miocene. Dissolution spikes were found to be associated with climatic deterioration (marked by a distinct 18O enrichment in benthic foraminifers) and with a lightening in the benthic carbon-isotope record. They appear to be of global significance. These excursions provide chemostratigraphic signals of utmost importance for chronostratigraphic correlations. This does not imply, however, that carbonate fluctuations were produced by only one or two master variables. At different times, the mix of processes responsible for the carbonate-fluctuation patterns may have varied considerably. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_819504 |
| institution | PANGAEA |
| language | en |
| publishDate | 1981 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Neogene carbonate stratigraphy at DSDP Hole 32-310 Vincent, Edith 32-310; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Leg32; North Pacific/CONT RISE A detailed Neogene carbonate stratigraphy obtained from Hess Rise, in the temperate zone of the North Pacific, allows a cross-latitudinal correlation of carbonate fluctuations throughout the Pacific. The correlations are based on paleomagnetically dated biostratigraphic events. The carbonate record at Site 310, on Central Hess Rise, at a water depth of about 3500 meters, was obtained with a sampling interval representing time intervals of roughly 20,000 years in the Plio-Pleistocene, 30,000 years in the uppermost Miocene younger than about 6.2 m.y., and 140,000 years in the remainder of the upper Miocene and the middle Miocene. This record allows identification at Site 310 of specific carbonate events recognized throughout the equatorial Pacific, showing the ocean-wide nature of these events. The carbonate records compared with Site 310 are based on (time-) sampling intervals similar to those of Site 310. The comparison records are all located in the high-productivity belt of the equatorial Pacific, from depths near 2000 meters in the Panama Basin (DSDP Sites 157 and 158) to depths near 4500 meters, not far above the CCD (various piston cores). Specific carbonate events were not detected in the Plio-Pleistocene carbonate record at Site 466, on southern Hess Rise. This record was obtained with a sampling interval equivalent to a time span of about 60,000 years. This site, located at a water depth of about 2700 meters, has a Plio-Pleistocene sedimentary history similar to that at nearby Site 310, with approximately the same accumulation rate. Long-term cycles are superimposed on the short-term carbonate fluctuations in the equatorial Pacific sequences. The periodicity of these cycles, although not regular, is on the order of 0.5 m.y. for the upper Pleistocene, and on the order of 1 to 1.5 m.y. for the lower Pleistocene, Pliocene, and Miocene. Some of these long-term cycles are apparent in the carbonate stratigraphy at Site 310, especially in the Pleistocene and Miocene, but are not seen in the Pliocene. In Cores V24-59 and RC12-66, the Gauss includes the interval with the lowest calcium carbonate content of the entire Neogene, and sediment in this sequence accumulated more slowly than before or after. In contrast, at both Sites 310 and 157, this sequence accumulated at an average rate higher than overlying and underlying sediments. At Site 310, it contains the highest CaCO3 average concentration of the entire Neogene. At Sites 310 and 466, there is an overall correlation between lower carbonate content and poorer foraminifer preservation in the Pleistocene, but no such correlation exists in the Pliocene and upper Miocene. Dissolution spikes were found to be associated with climatic deterioration (marked by a distinct 18O enrichment in benthic foraminifers) and with a lightening in the benthic carbon-isotope record. They appear to be of global significance. These excursions provide chemostratigraphic signals of utmost importance for chronostratigraphic correlations. This does not imply, however, that carbonate fluctuations were produced by only one or two master variables. At different times, the mix of processes responsible for the carbonate-fluctuation patterns may have varied considerably. |
| title | Neogene carbonate stratigraphy at DSDP Hole 32-310 |
| topic | 32-310; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Leg32; North Pacific/CONT RISE |
| url | https://doi.org/10.1594/PANGAEA.819504 |