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(Table 1) Revised and corrected composite depth sections of ODP Site 160-964

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Mendeley Data2023-02-27 更新2024-06-29 收录
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High-resolution color reflectance records of KC01 and KC01B (Calabrian Ridge, Ionian Sea) are presented and compared with a modified spliced high-resolution color reflectance record of Ocean Drilling Program (ODP) Site 964. This comparison revealed that KC01B is characterized by intensive deformation between ~27 and 28.5 m piston depth and that some sapropels are tectonically reduced in thickness. Moreover, the piston coring has caused considerable stretching in the top of KC01 and KC01B. Using a new splice of ODP Site 964 as guide, previous astronomical tuned timescales of KC01B and ODP Site 964 were evaluated. This evaluation resulted in a new sapropel-based astronomical timescale for the last 1.1 Myr. The new timescale implies a much more uniform change in sedimentation rate for the Ionian Sea cores. Two prominent excursions to lighter values in the d18O record of the planktonic foraminiferal species Globigerinoides ruber occur during marine isotopic stages 12 and 16 applying the new timescale. These shifts correspond with maxima in obliquity and are punctuated by minima in the precession cycle. They are absent in global ice volume records and are interpreted as reflecting a (summer) low-salinity surface water lens that floats on top of extremely saline intermediate and deep waters at times of the very low sea levels during these glacial periods. All biostratigraphic and magnetostratigraphic events found in KC01B and ODP Site 964 were re-dated according to the new timescale, and the ages of 33 tephra layers were reviewed. The new ages for the Calabrian Ridge 2 and 3 magnetic events in the Brunhes are concordant with minima in the global Sint800 composite record, derived from worldwide deep-sea records of relative paleointensity and have been attributed to the Big Lost and La Palma excursions, respectively.

本文呈现了卡拉布里亚海岭(Calabrian Ridge)、爱奥尼亚海(Ionian Sea)区域KC01与KC01B的高分辨率颜色反射率记录,并将其与经过修正拼接的大洋钻探计划(Ocean Drilling Program, ODP)964站位的高分辨率颜色反射率记录进行对比。此次对比显示,KC01B在活塞取芯(piston coring)深度约27至28.5米区间内呈现强烈变形特征,且部分腐泥层(sapropels)的厚度因构造作用发生减薄。此外,活塞取芯操作使得KC01与KC01B的顶部沉积层发生了显著拉伸。以新拼接的ODP 964站位记录为参照,本文对KC01B与ODP 964站位既往的天文调谐时间标尺(astronomical tuned timescale)进行了评估。本次评估构建了基于腐泥层的过去110万年新天文调谐时间标尺。该新标尺表明,爱奥尼亚海沉积岩芯的沉积速率变化更为均一。采用该新标尺后,浮游有孔虫红拟抱球虫(Globigerinoides ruber)的氧同位素(δ¹⁸O)记录中,在海洋同位素阶段12与16期间出现了两次显著的轻值偏移。此类偏移对应黄赤交角(obliquity)的峰值时段,且被岁差(precession)周期的谷值所分隔。此类信号在全球冰量记录中并未出现,据此可将其解释为:在这些冰期极低海平面时段,存在一层(夏季)低盐度表层水透镜体,漂浮于高盐度中层水与深层水之上。依据该新标尺,本文对KC01B与ODP 964站位中发现的所有生物地层学(biostratigraphic)与磁地层学(magnetostratigraphic)事件重新定年,并对33层火山灰层(tephra layers)的年代进行了厘定。布容极性时(Brunhes)内卡拉布里亚海岭2号与3号磁事件的新定年结果,与基于全球深海相对古强度(relative paleointensity)记录构建的SINT800全球复合记录(Sint800 composite record)的谷值相一致,且分别被归因于大失落偏移(Big Lost excursion)与拉帕尔马偏移(La Palma excursion)。

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2023-01-14
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