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首页> 外文期刊>Paleoceanography >Insights from the Paleogene tropical Pacific: Foraminiferal stable isotope and elemental results from Site 1209, Shatsky Rise
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Insights from the Paleogene tropical Pacific: Foraminiferal stable isotope and elemental results from Site 1209, Shatsky Rise

机译：古近纪热带太平洋的见解：Shatsky Rise站点1209的有孔虫稳定同位素和元素结果

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摘要

[1] Stable isotope and elemental measurements were conducted on foraminifera from a sequence of calcareous pelagic ooze at Ocean Drilling Program Site 1209 to document the thermal evolution of the North Pacific water column over Shatsky Rise and to address long-standing questions about the nature of oceanic circulation in the early Paleogene. A major change in seasonality and water column structure in the early Eocene marks a change in tropical Pacific climate and circulation just prior to the early Eocene climatic optimum. Subsequent long-term cooling is interrupted by a transient positive delta(18)O excursion identified in planktonic and benthic foraminifera during the late early Eocene that is interpreted as evidence for ephemeral formation of deep water from a low-latitude, saline source. Paired analysis of benthic Mg/Ca and delta(18)O was undertaken to assess the relative contribution of temperature and seawater oxygen isotope composition to the benthic delta(18)O record. Stratigraphic trends of benthic delta(18)O and Mg/Ca decouple during two intervals in the early Eocene and early middle Eocene. Although variable seawater delta(18)O is the most likely candidate to explain decoupling of benthic delta(18)O and Mg/Ca, it is difficult to argue for substantial change in continental ice volume during a presumably ice-free interval of time.
机译：[1]在Ocean Drilling Program Site 1209上，从一系列钙质浮游软泥中的有孔虫进行了稳定的同位素和元素测量，以记录Shatsky Rise上北太平洋水柱的热演化，并解决了长期存在的问题古近纪早期的海洋环流。始新世早期的季节和水柱结构发生了重大变化，标志着热带太平洋气候和环流发生了变化，而这恰恰是始于始新世气候最佳时期之前。随后的长期冷却被始新世早期晚期的浮游和底栖有孔虫中发现的短暂正三角洲（18）O偏移中断，这被解释为由低纬度盐源短暂形成深水的证据。对底栖Mg / Ca和δ（18）O进行配对分析，以评估温度和海水氧同位素组成对底栖δ（18）O记录的相对贡献。始新世早期和中新世早期两个时期底栖δ（18）O和Mg / Ca的地层趋势解耦。尽管可变的海水三角洲（18）O最有可能解释底栖三角洲（18）O与Mg / Ca的分离，但很难为大陆冰量在可能无冰的时间间隔内发生实质性变化辩护。

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