Nannofossil assemblages, fine fraction stable isotopes, and the paleoceanography of the Valanginian-Barremian (Early Cretaceous) North Sea Basin
Nannofossil assemblages, fine fraction stable isotopes, and the paleoceanography of the Valanginian-Barremian (Early Cretaceous) North Sea Basin
复制标题
超微化石组合、细粒稳定同位素以及凡兰吉阶-巴列姆阶（早白垩世）北海盆地的古海洋学
DOI：
10.1029/95pa00977
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
T. Bralower
中科院分区：
文献类型：
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作者：
John R. Williams;T. Bralower
在早白垩世北海盆地边缘的三个剖面中研究了钙质超微化石组合。收集了绝对（每克超微化石数量）和相对（不同分类群组合的百分比）丰度数据。绝对丰度（每克可达100亿超微化石）略高于以前报道的其他地层区间。不同剖面组合数据趋势的地层相关性表明存在大型、均匀的水团，长期稳定（0.5至1百万年）。时间段.这些水团含有一种特有的微型浮游生物，这似乎主要是由可能与地表沃茨变化有关的肥力变化所驱动的，而地表水源的变化又可能是由相对海平面控制的。精细部分同位素数据显示波动较短的时间周期（0.1至0.5百万年）。我们假设，其中一些同位素波动是由海平面的相对变化控制的，海平面的相对变化影响了来自径流的地表沃茨水和从北海输入的地表水的平衡。这些海洋学的变化似乎只在离散的间隔影响超微化石组合。
数据可在缩微胶片上与整篇文章一起使用。来自美国地球物理联合会的订单，地址：2000佛罗里达大道，西北，华盛顿，20009。文件P95-001;订单必须随附2.50美元付款。
Calcareous nannofossil assemblages have been investigated in three sections from around the margins of the Early Cretaceous North Sea Basin. Both absolute (number of nannofossils per gram) and relative (percent of the assemblage of different taxa) abundance data have been collected. Absolute abundances (up to 10 billion nannofossils per gram) are somewhat higher than those reported previously from other stratigraphic intervals. Stratigraphic correlation of trends in assemblage data in different sections points toward the existence of large, uniform water masses, stable over long (0.5 to 1 m.y.) time periods. These water masses contained a characteristic nannoplankton, which appears to have been driven largely by variations in fertility possibly tied to changes in sources of surface waters, which in turn may have been controlled by relative sea level. Fine fraction isotopic data show fluctuations on shorter time periods (0.1 to 0.5 m.y.). We postulate that some of these isotopic fluctuations were controlled by relative changes in sea level which affected the balance of surface waters derived from runoff and those imported from the Boreal Sea. These oceanographic changes appear to have affected nannofossil assemblages only in discrete intervals.
Data are available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009. Document P95-001; $2.50 payment must accompany order.