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首页> 外文期刊>Paleoceanography >Late albian paleoceanography of the western subtropical north Atlantic
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Late albian paleoceanography of the western subtropical north Atlantic

机译：西亚热带北大西洋的晚期阿拉伯古海洋学

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摘要

A late Albian-early Cenomanian record (similar to 103.3 to 99.0 Ma), including organic-rich deposits and a delta C-13 increase associated with oceanic anoxic event 1d (OAE 1d), is described from Ocean Drilling Program sites 1050 and 1052 in the subtropical Atlantic. Foraminifera are well preserved at these sites. Paleotemperatures estimated from benthic delta O-18 values average similar to 14 degrees C for middle bathyal Site 1050 and similar to 17 degrees C for upper bathyal Site 1052, whereas surface temperatures are estimated to have ranged from 26 degrees C to 31 degrees C at both sites. Among planktonic foraminifera, there is a steady balance of speciation and extinction with no discrete time of major faunal turnover. OAE 1d is recognized on the basis of a 1.2 parts per thousand delta C-13 increase (similar to 100.0-99.6 Ma), which is similar in age and magnitude to delta C-13 excursions documented in the North Atlantic and western Tethys. Organic-rich "black shales" are present throughout the studied interval at both sites. However, deposition of individual black shale beds was not synchronous between sites, and most of the black shale was deposited before the OAE 1d delta C-13 increase. A similar pattern is observed at the other sites where OAE 1d has been recognized indicating that the site(s) of excess organic carbon burial that could have caused the delta C-13 increase has (have) yet to be found. Our findings add weight to the view that OAEs should be chemostratigraphically (delta C-13) rather than lithostratigraphically defined.
机译：远洋钻探计划地点1050和1052中描述了阿尔比晚期晚塞诺曼纪记录（类似于103.3至99.0 Ma），包括富含有机物的沉积物和与海洋缺氧事件1d（OAE 1d）相关的δC-13增量。亚热带大西洋。有孔虫在这些地方保存完好。根据底栖三角洲O-18值估算的古温度平均水平，与中部基底部1050相似，为14摄氏度，与上基部1052相似，约为17摄氏度，而在这两个地方，地表温度估计均介于26摄氏度至31摄氏度之间网站。在浮游有孔虫中，物种和灭绝之间保持稳定的平衡，没有主要动物更新的离散时间。 OAE 1d的识别依据是C-13增量每千分之1.2（类似于100.0-99.6 Ma），其年龄和大小与北大西洋和特提斯西部记录的C-13偏移相似。整个研究期间，两个站点均存在富含有机物的“黑色页岩”。但是，单个黑色页岩床的沉积在站点之间并不同步，并且大多数黑色页岩是在OAE 1dδC-13增加之前沉积的。在已识别出OAE 1d的其他位置观察到类似的模式，这表明可能已经造成C-13增量增加的过量有机碳埋藏位置（尚未发现）。我们的发现增加了以下观点的观点：OAE应该在化学地层学上（δC-13）而不是在岩石地层学上定义。

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