A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin
A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin
复制标题
西伊比利亚边缘 U1385 站点（沙克尔顿站点）的参考时间尺度
DOI：
10.1016/j.gloplacha.2015.07.002
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发表时间：
2015-10-01
影响因子：
3.9
通讯作者：
Tzedakis, P. C.
中科院分区：
文献类型：
--
作者：
Hodell, D.;Lourens, L.;Tzedakis, P. C.
我们为西南伊比利亚边缘的 U1385 站点制作了综合深度尺度和年表。使用在所有孔中以 1 厘米分辨率通过岩心扫描 XRF 测量的 log(Ca/Ti)，构建了 166.5 米复合深度 (mcd) 的复合剖面，以校正每个岩心中的拉伸和挤压。底栖有孔虫的氧同位素与叠加的 8180 参考信号 (LR04) 相关，以生成氧同位素地层学和年龄模型。 U1385 站点沉积物颜色的变化包含非常强的进动信号，这些循环的幅度调制为开发轨道调谐年龄模型提供了强大的工具。我们通过将 L* 峰值与北纬 37 度的当地夏季日照最大值相关联来调整 U1385 记录。U1385 站点的海底 8180 记录，当放置在调整后的年龄模型上时，通常与各自时间不确定性内的其他时间尺度一致。年龄模型被转移到岩心下数据，以产生反映生物碳酸盐和碎屑沉积物相对变化的连续时间序列日志 (Ca/Ti)。生物碳酸盐在间冰期和间质气候状态下增加，在冰期和间质气候状态下减少。对数 (Ca/Ti) 中的大部分方差可以通过轨道频率（进动、倾斜和偏心率）的线性组合来解释，而残余信号则反映亚轨道气候变化。 U1385站点最后一个冰川周期的亚轨道对数(Ca/Ti)变率与格陵兰岛温度之间的强相关性表明，该信号可以用作过去1.5 Ma的千年尺度气候变率的代理。U1385站点的对数(Ca/Ti)表示的千禧年气候变率是过去1.5 Ma冰川气候的持续特征，包括早更新世的冰川期（“41-1cyr 世界”）当时的边界条件与晚更新世（“100-kyr 世界”）的边界条件显着不同。亚轨道变化在间冰期受到抑制，而在冰期则增强，特别是当底栖 Delta O-18 超过 3.33.5% 时。每次冰川起始都以强烈的千年变率的出现为标志，每次冰消期之前都有一个终末期事件。亚轨道变率可能是冰川气候的一个症状特征，或者可能在冰川周期的开始和/或终止中发挥更积极的作用。 (C) 2015 年作者。由 Elsevier B.V. 出版
We produced a composite depth scale and chronology for Site U1385 on the SW Iberian Margin. Using log(Ca/Ti) measured by core scanning XRF at 1-cm resolution in all holes, a composite section was constructed to 166.5 meter composite depth (mcd) that corrects for stretching and squeezing in each core. Oxygen isotopes of benthic foraminifera were correlated to a stacked 8180 reference signal (LR04) to produce an oxygen isotope stratigraphy and age model.Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulation of these cycles provides a powerful tool for developing an orbitally-tuned age model. We tuned the U1385 record by correlating peaks in L* to the local summer insolation maxima at 37 degrees N. The benthic 8180 record of Site U1385, when placed on the tuned age model, generally agrees with other time scales within their respective chronologic uncertainties.The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflect relative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacial and interstadial climate states and decreases during glacial and stadial periods. Much of the variance in the log(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereas the residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti) variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can be used as a proxy for millennial-scale climate variability over the past 1.5 Ma.Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climates over the past 1.5 Ma, including glacial periods of the early Pleistocene ('41-1cyr world') when boundary conditions differed significantly from those of the late Pleistocene ('100-kyr world'). Suborbital variability was suppressed during interglacial stages and enhanced during glacial periods, especially when benthic delta O-18 surpassed similar to 3.33.5%. Each glacial inception was marked by appearance of strong millennial variability and each deglaciation was preceded by a terminal stadial event. Suborbital variability may be a symptomatic feature of glacial climate or, alternatively, may play a more active role in the inception and/or termination of glacial cycles. (C) 2015 The Authors. Published by Elsevier B.V.