Strontium isotope stratigraphy in the Late Cretaceous: intercontinentaI correlation of the Campanian/ Maastrichtian boundary
Strontium isotope stratigraphy in the Late Cretaceous: intercontinentaI correlation of the Campanian/ Maastrichtian boundary
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DOI：
10.1111/j.1365-3121.1992.tb00827.x
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发表时间：
1992-05
期刊：
影响因子：
2.4
通讯作者：
J. McArthur;W. Kennedy;A. Gale;M. Thirlwall;M. Chen;J. Burnett;J. Hancock
中科院分区：
文献类型：
--
作者：
J. McArthur;W. Kennedy;A. Gale;M. Thirlwall;M. Chen;J. Burnett;J. Hancock
在欧洲西北部的北方白垩岩中，马斯特里赫特阶的底部是由箭石Belemnella的进入所定义的。德国西北部的Kronsmoor剖面是欧洲白垩岩的标准剖面，在坎帕尼亚期/马斯特里赫特期（C/M）界线处的87 Sr/86 Sr为0.707723±9（10）。这一边界的同位素相关性，美国西部内陆，其中存在一个高度精炼的头足类生物地层，表明这一边界，定义在Kronsmoor，发生在Baculites jenseni带。这种对比与基于生物地层学标准的最新位置一致。根据87 Sr/86 Sr标准，Kronsmoor的边界与英国诺福克特兰奇的英国白垩层相对应，比其基于生物地层标准的位置低3.5 m。在Kronsmoor，87 Sr/86 Sr增加在一个准线性的方式通过大部分的部分，这表明，平均超过1万年的时间间隔，总的沉积速率和时间变化率的87 Sr/86 Sr是近似恒定的部分。对于美国样品，87 Sr/86 Sr的分带值定义了一个准线性趋势，这表明从Baculites compressus带（73.2±0.7 Ma，10）到Baculites grandis带（70.1±0.7 Ma，10）的分带持续时间具有中等均匀性。
In the Boreal Chalk of northwestern Europe the base of the Maastrichtian Stage is defined by entry of the belemnite Belemnella. In the Kronsmoor section, in northwestern Germany, which is a standard section for the European Chalk, 87Sr/86Sr at the Campanian/ Maastrichtian (C/M) boundary is 0.707723±9 (10). An isotopic correlation of this boundary to the US Western Interior, for which a highly refined cephalopod biostratigraphy exists, suggests that this boundary, as defined at Kronsmoor, occurs within the Baculites jenseni zone. This correlationagrees with the latest placement based on biostratigraphic criteria. On87Sr/86Srcriteria the boundary at Kronsmoor correlates to the English Chalk at Trunch, Norfolk, UK, at a level 3.5 m lower than its position based on biostratigraphic criteria. At Kronsmoor, 87Sr/86Sr increases in a quasi-linear manner through much of the section, suggesting that, averaged over intervals of 1 Myr, the gross sedimentation rate and temporal rate of change of 87Sr/86Sr were approximately constant through the section. For US samples, zonally-plotted values of 87Sr/86Sr define a quasi-linear trend, which suggests a moderate uniformity of zonal duration from the Baculites compressus zone (73.2±0.7 Ma, 10) to the Baculites grandis zone (70.1±0.7 Ma, 10).