New Radiocarbon Dates for the Vedde Ash and the Saksunarvatn Ash from Western Norway
New Radiocarbon Dates for the Vedde Ash and the Saksunarvatn Ash from Western Norway
复制标题
挪威西部维德火山灰和 Saksunarvatn 火山灰的新放射性碳测年法
作者：
H. H. Birks;S. Gulliksen;H. Haflidason;J. Mangerud;G. Possnert
Vedde灰层（新仙女木期中期）和Saksunarvatn灰层（全新世早期）是北大西洋、挪威海及其邻近地区重要的区域性地层事件标志。因此，必须尽可能精确地确定它们的年代。Saksunarvatn Ash的出现是第一次在挪威西部报道，这两种火山灰都是通过陆地植物材料和kramatkenes湖泊沉积物的AMS分析精确确定的。先前在挪威西部的遗址中发现的Vedde Ash的年代约为距今10,600年，在kr<s:1>克内斯的新仙女木期沉积物中很明显，其地球化学特征得到了证实。在全新世早期的kramatkenes湖泊沉积物中未见Saksunarvatn灰分。在去除有机质和硅藻后，通过地球化学方法确认了麻黄颗粒的身份，并对其地层浓度进行了估计。通过对陆生植物大型化石和整个沉积物的7个AMS测年曲线的拟合，确定了灰分的放射性碳年龄为8930 ~ 9060 yr B.P.，对应的年龄为9930 ~ 10010 calyr B.P.（公元前7980 ~ 8060 calyr）。
Abstract The Vedde Ash Bed (mid-Younger Dryas) and the Saksunarvatn Ash (early Holocene) are important regional stratigraphic event markers in the North Atlantic, the Norwegian Sea, and the adjacent land area. It is thus essential to date them as precisely as possible. The occurrence of the Saksunarvatn Ash is reported for the first time from western Norway, and both tephras are dated precisely by AMS analyses of terrestrial plant material and lake sediment at Kråkenes. The Vedde Ash has been previously dated at sites in western Norway to about 10,600 yr B.P. It is obvious in the Younger Dryas sediments at Kråkenes, and its identity is confirmed geochemically. The mean of four AMS dates of samples of Salix herbacea leaves adjacent to the tephra is 10,310 ± 50 yr B.P. The Saksunarvatn Ash is not visible in the early Holocene lake sediment at Kråkenes. After removal of organic material and diatoms, the identity of the tephra particles was confirmed geochemically, and their stratigraphic concentration was estimated. From curve matching of a series of seven AMS dates of terrestrial plant macrofossils and whole sediment, the radiocarbon age of the ash is 8930–9060 yr B.P., corresponding to an age of 9930–10,010 cal yr B.P. (7980–8060 cal yr B.C.).