Correlation and varves between massive layers from ODP Sites 169-1033 and 169-1034

High-resolution grey-value time series were extracted from digital images of varved sediments in Saanich Inlet, British Columbia (ODP Sites 1033 and 1034). Results allowed reconstruction of a 6000 yr long record with annual resolution. Composite records were compiled for Sites 1033 and 1034 by correlation of massive beds, which represent gravity flows, and of characteristic features in the varve patterns. The varve-count age-scale was calibrated with published radiocarbon ages. Results demonstrate that the ODP Leg 169S record is virtually complete.
Saanich Inlet varve record has the potential to provide a high-resolution climate record. Temporal variation in varve thickness is interpreted to reflect regional precipitation history, with thick varves representing wet conditions. Long-term changes in varve thickness during the past 6000 yr coincide with known changes in global climate, but without an obvious one to one correlation between wet/dry in Saanich Inlet and warm/cold periods elsewhere. Varve thickness indicates that the climate around Saanich Inlet was wet from the start of the varved sequence at 6000 to 3250 yr BP, between 2100 and 1750 yr BP (Roman Warm Period) and from 500 yr BP onward (including during Little Ice Age).

研究从加拿大不列颠哥伦比亚省萨尼奇湾（Saanich Inlet）的纹层沉积物（varved sediments）数字影像中提取了高分辨率灰度时间序列，采样站位为大洋钻探计划（Ocean Drilling Program，ODP）1033孔与1034孔。本数据集可重建出一套时长6000年、具备年分辨率的沉积记录。通过对代表重力流的块状层以及纹层构造中的特征标志物进行地层对比，完成了1033与1034孔的复合沉积记录构建。纹层计数年代标尺通过已发表的放射性碳定年数据完成校准。研究结果表明，大洋钻探计划169S航次（ODP Leg 169S）的沉积记录几乎完整。
萨尼奇湾纹层记录具备构建高分辨率气候代用记录的潜力。纹层厚度的时间变化被认为可反映区域降水历史：纹层厚度越大，对应降水越充沛的湿润气候环境。过去6000年里纹层厚度的长期变化与已知的全球气候变化趋势相吻合，但萨尼奇湾的干湿状况与其他区域的冷暖阶段并未呈现显著的一一对应关系。纹层厚度数据显示，萨尼奇湾周边的湿润气候出现在三个时段：纹层序列起始的6000至3250年前、2100至1750年前（罗马暖期），以及500年前至今（涵盖小冰期时段）。