(Table 1) Age model of DSDP Site 72-516
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| Sprache: | en |
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2000
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| _version_ | 1867169106151604224 |
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| author | Pagani, Mark Arthur, Michael A Freeman, Katherine H |
| author_facet | Pagani, Mark Arthur, Michael A Freeman, Katherine H |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Changes in ocean circulation are often credited as the primary control on large-scale climate change during the Miocene. This study investigates the latest Oligocene to middle Miocene evolution of Southern Ocean circulation by evaluating stable isotopic trends of shallow- and deep-dwelling planktonic foraminifera, as well as epsilon-p records reconstructed from the carbon isotopic composition of diunsaturated alkenones in the southwestern Altantic Ocean (Deep Sea Drilling Project site 516). Changes in epsilon-p at site 516 closely paralleled the opening and deepening of the Drake Passage as inferred from seafloor magnetic anomalies. A large negative shift in epsilon-p at ~20.3 Ma is interpreted to reflect an increase in upper water column nutrient concentrations, caused by the onset or strengthening of the Antarctic Circumpolar Current (ACC). Measurable alkenone concentrations disappear by ~17 Ma, prior to a collapse in surface-to-thermocline d18O and d13C gradients. This is interpreted as reflecting a severe decrease in mixed layer nutrient concentrations and reduced proto-Antarctic Intermediate Water influence. The d18O gradient was reestablished by 14.5 Ma, coincident with the hypothesized East Antarctic ice sheet expansion, suggesting a direct relationship between increased strength of the ACC and the largest climate shift of the middle Miocene. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_848096 |
| institution | PANGAEA |
| language | en |
| publishDate | 2000 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | (Table 1) Age model of DSDP Site 72-516 Pagani, Mark Arthur, Michael A Freeman, Katherine H 72-516; 72-516F; Age model; Age model, paleomag, Berggren et al (1985); Ageprofile Datum Description; Deep Sea Drilling Project; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; Event label; Glomar Challenger; Leg72; South Atlantic/CONT RISE Changes in ocean circulation are often credited as the primary control on large-scale climate change during the Miocene. This study investigates the latest Oligocene to middle Miocene evolution of Southern Ocean circulation by evaluating stable isotopic trends of shallow- and deep-dwelling planktonic foraminifera, as well as epsilon-p records reconstructed from the carbon isotopic composition of diunsaturated alkenones in the southwestern Altantic Ocean (Deep Sea Drilling Project site 516). Changes in epsilon-p at site 516 closely paralleled the opening and deepening of the Drake Passage as inferred from seafloor magnetic anomalies. A large negative shift in epsilon-p at ~20.3 Ma is interpreted to reflect an increase in upper water column nutrient concentrations, caused by the onset or strengthening of the Antarctic Circumpolar Current (ACC). Measurable alkenone concentrations disappear by ~17 Ma, prior to a collapse in surface-to-thermocline d18O and d13C gradients. This is interpreted as reflecting a severe decrease in mixed layer nutrient concentrations and reduced proto-Antarctic Intermediate Water influence. The d18O gradient was reestablished by 14.5 Ma, coincident with the hypothesized East Antarctic ice sheet expansion, suggesting a direct relationship between increased strength of the ACC and the largest climate shift of the middle Miocene. |
| title | (Table 1) Age model of DSDP Site 72-516 |
| topic | 72-516; 72-516F; Age model; Age model, paleomag, Berggren et al (1985); Ageprofile Datum Description; Deep Sea Drilling Project; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; Event label; Glomar Challenger; Leg72; South Atlantic/CONT RISE |
| url | https://doi.org/10.1594/PANGAEA.848096 |