Southern Ocean influence on the eastern tropical North Pacific's intermediate-depth circulation during the Last Glacial Maximum
Southern Ocean influence on the eastern tropical North Pacific's intermediate-depth circulation during the Last Glacial Maximum
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DOI：
10.1002/2014pa002766
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发表时间：
2015-08-01
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影响因子：
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通讯作者：
Leduc, Guillaume
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作者：
Carriquiry, Jose D.;Sanchez, Alberto;Leduc, Guillaume
在墨西哥下加利福尼亚南部马格达莱纳边缘的沉积序列上测量了底栖有孔虫试验的氧和碳同位素组成。我们重建了自末次盛冰期（LGM）以来热带太平洋东北部发生的沿着水柱的水文变化，并将这些变化与西北太平洋（NWP，即，日本和俄罗斯附近海域）、东北太平洋沿着加利福尼亚边缘以及东南太平洋（智利附近海域）。横跨北太平洋和东南太平洋的有孔虫三角洲O-18深度剖面在末次盛冰期和全新世之间显示出相似的趋势，这表明在400米至2000米深度之间的海洋学条件变化非常相似。溶解无机碳（δ C-13（DIC））的同位素组成的变化，在下加利福尼亚州边缘自末次盛冰期以来的重建使用的三角洲C-13浅内底栖有孔虫U。peregrina和表底栖Cibicides mckannai。最引人注目的结果是一个显着的转向更积极的三角洲C-13值低于1200米深度在东北太平洋（NEP）在全新世（相对于末次冰期）。这一观察结果表明，富营养化的水团通风NEP在末次冰期。在盆地尺度上，NEP沃茨在中间深度的三角洲C-13值相对于NWP和东南太平洋在LGM期间更负，这表明NEP沿着富含营养物的水柱（即，下加利福尼亚边缘）被限制在今天观察到的该地区。
The oxygen and carbon isotopic compositions of benthic foraminiferal tests were measured on sedimentary sequences retrieved on the Magdalena Margin, off southern Baja California, Mexico. We reconstruct the hydrographic changes along the water column that occurred in the northeastern tropical Pacific since the Last Glacial Maximum (LGM) and compare those changes to the ones that occurred in the northwest Pacific (NWP, i.e., off Japan and Russia), in the northeast Pacific along the Californian Margin, as well as in the southeast Pacific (off Chile). The foraminiferal delta O-18 depth profiles across the North and southeast Pacific show similar trends between the LGM and the Holocene, indicating that changes in the oceanographic conditions between similar to 400 and 2000 m depth were very similar. Changes in the isotopic composition of dissolved inorganic carbon (delta C-13(DIC)) in the Baja California Margin since the Last Glacial Maximum were reconstructed using the delta C-13 of shallow endobenthic foraminifers U. peregrina and the epibenthic Cibicides mckannai. The most striking result is a marked shift toward more positive delta C-13 values below 1200 m depth in the northeast Pacific (NEP) during the Holocene (relative to the LGM). This observation suggests that a nutrient-rich water mass ventilated the NEP during the LGM. At a basin scale, the delta C-13 values of NEP waters at intermediate depths were more negative relative to the NWP and southeast Pacific during the LGM, suggesting that the nutrient-rich water column along the NEP (i.e., Baja California Margin) was confined in that area as observed today.