(Table 2) Age determination of sediment cores from the continental shelf of Mac Roberston Land, East Antarctica@en

Geochemical records are presented for five sediment cores from basins on the continental shelf of Mac. Robertson Land, East Antarctica. The cores contain 2-4 m thick sequences of hemipelagic, siliceous mud and ooze (SMO) deposited under seasonally open marine conditions. The inner and middle shelf SMO sequences are massive dark olive green material, whereas the outer shelf SMO sequences are dark olive material interspersed with light olive green layers ~1-10 cm thick. The biogenic material is dominated by marine diatoms including Fragilariopsis curta, Fragilariopsis cylindrus, and Chaetoceros spp. in the dark-colored SMO and Corethron criophilum in the light-colored layers. Radiocarbon dates suggest that the cores provide continuous accumulation records extending from < 1 kyr before present (B.P.) back as far as 4-15 kyr B.P., with estimated accumulation rates of 0.07-5 mm/yr. The three core records from the middle and outer shelf suggest six episodes of increased accumulation of biogenic material at ~5.5 kyr B.P. (all three cores), 1, 2, and 6.2 kyr B.P. (two of the three cores), and 3.8 and 10.8 kyr B.P. (one core), most of which coincide with Corethron layers. We interpret these features as the result of enhanced diatom production over the outer shelf, possibly related to climatic warm periods. The absence of such features in the inner shelf core records is thought to reflect a relatively constant level of seasonal diatom production in adjacent waters maintained by a coastal polynya.本数据集提供了东南极洲麦克·罗伯逊地（Mac. Robertson Land）陆架盆地5个沉积岩芯的地球化学记录。这些岩芯保存了2~4米厚的半远洋硅质泥质软泥（hemipelagic, siliceous mud and ooze, SMO）沉积序列，形成于季节性开放海洋环境中。陆架内带与中带的SMO序列为块状深橄榄色沉积物，而陆架外带的SMO序列则以深橄榄色基质为主，夹杂厚度约1~10厘米的浅橄榄色夹层。生源物质（biogenic material）以海洋硅藻为主：深色SMO中以短小脆杆藻（Fragilariopsis curta）、圆柱脆杆藻（Fragilariopsis cylindrus）及角毛藻属（Chaetoceros spp.）占优，浅色夹层中则以嗜冷中心藻（Corethron criophilum）为主导。放射性碳定年（radiocarbon dates）结果显示，各岩芯拥有连续的沉积记录，年代跨度从距今不足1千年（before present, B.P.）直至距今4~15千年，估算沉积速率（accumulation rates）为0.07~5毫米/年。中、外陆架的3个岩芯记录共识别出6期生源物质沉积增强事件，分别出现于距今约5.5千年（3个岩芯均有记录）、1千年、2千年及6.2千年（2个岩芯记录），以及3.8千年和10.8千年（仅1个岩芯记录）；其中多数事件与嗜冷中心藻夹层相吻合。我们将上述沉积特征解读为外陆架硅藻生产力提升的产物，这一现象可能与气候暖期存在关联。而内陆架岩芯记录中未出现此类事件，这被认为反映了沿岸冰间湖（polynya）维持了邻近海域季节性硅藻生产力的相对稳定水平。