(Table 1) Summary of accelerator mass spectrometer (AMS) radiocarbon ages in ODP Sites 169-1033 and 169-1034

Continuous coring in Saanich Inlet (Ocean Drilling Program, ODP Leg 169S), British Columbia, Canada, yielded a detailed record of Late Quaternary climate, oceanography, marine productivity, and terrestrial vegetation. Two sites (1033 and 1034) were drilled to maximum depths of 105 and 118 m, recovering sediments ranging in age from 13,300 to less than 300 14C yr. Earliest sediments consist of dense, largely massive, gray glaciomarine muds with dropstones and sand and silt laminae deposited during the waning stages of glaciation. Deposition of organic-rich olive gray sediments began in the fjord about 12,000 14C yr ago, under well-oxygenated conditions as reflected by the presence of bioturbation and a diverse infaunal bivalve community. At about 10,500 14C yr, a massive, gray unit, 40-50 cm thick, was emplaced in a very short span of time. The unit is marked by a sharp lower contact, a gradational upper contact and an abundance of reworked Tertiary microfossils. It has been interpreted as resulting from massive flood events caused by the collapse of glacial dams in the Fraser Valley of mainland British Columbia. Progressively greater anoxia in bottom waters of Saanich Inlet began about 7000 14C yr ago. This is reflected in the preservation of varved sediments consisting of diatomaceous spring-summer laminae and terrigenous winter laminae. Correlation of the sediments was based on: marked lithologic changes, the presence of massive intervals (reflecting localized sediment gravity flow events), the Mazama Ash, occasional thin gray laminae (indicative of abnormal flood events in nearby watersheds), varve counts between marker horizons, and 71 accelerator mass spectrometry (AMS) radiocarbon dates.加拿大不列颠哥伦比亚省萨尼奇湾（Saanich Inlet）的海洋钻探计划（Ocean Drilling Program, ODP）第169S航次连续取芯作业，获取了晚第四纪气候、海洋学、海洋生产力与陆地植被的详细沉积记录。本次钻探共布设两个站位（1033与1034），最大钻进深度分别达105米与118米，回收沉积物的14C年龄介于13300年至不足300年。最早期沉积物为致密、整体块状的灰色冰海泥，含有坠石与砂、粉砂纹层，沉积于冰川消退阶段。约12000个14C年前，峡湾环境开始沉积富含有机质的橄榄灰色沉积物，当时水体处于富氧状态——该环境特征可由生物扰动痕迹与多样的底内双壳类群落得到印证。约10500个14C年前，一套厚度40至50厘米的巨厚灰色沉积单元在极短时间内沉积形成。该沉积单元以清晰的底部接触界面、渐变的顶部接触界面以及大量再沉积的第三纪微体化石为特征，被认为是不列颠哥伦比亚大陆弗雷泽河谷冰川坝坍塌引发的大规模洪水事件的产物。约7000个14C年前起，萨尼奇湾底层水体的缺氧程度逐渐加剧，这一变化可通过纹层沉积物的保存状态得到反映：其纹层由硅藻组成的春夏季层与陆源冬季层构成。本次沉积物对比工作基于以下依据：显著的岩性变化、巨厚沉积层段（指示局地沉积物重力流事件）、马扎马火山灰（Mazama Ash）、偶见的薄层灰色纹层（反映邻近流域异常洪水事件）、标志层间的纹层计数，以及71个加速器质谱（accelerator mass spectrometry, AMS）放射性碳测年数据。