Larger benthic foraminifera from the Middle Eocene to Oligocene of Tanzania

Larger benthic foraminifera from the Middle Eocene to Oligocene of Tanzania
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坦桑尼亚中始新世至渐新世较大的底栖有孔虫

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发表时间：
2012
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影响因子：
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通讯作者：
P. Pearson
P. Pearson
中科院分区：
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文献类型：
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作者：
L. Cotton;P. Pearson

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大型底栖有孔虫（LBF）在坦桑尼亚南部的古近纪沉积物中很常见，而且种类繁多，但 以前很少研究。最近一项名为坦桑尼亚钻井项目的陆上钻井计划已经回收了大量石油。 这一系列的古气候和古生物学研究的比例。沉积物主要是半远洋粘土， 重力沉积流石灰岩和钙屑岩。LBF集中发生在次级层中，并存在于一些 粘土地平线浮游有孔虫，超微化石，在某些情况下，粘土的稳定同位素研究允许更大的底栖生物 有孔虫范围与全球地层学有关。在这里，我们使用其中的九个钻探地点来检查始新世中期的LBF 到渐新世在这段时间内，一些全球性的长期和广泛的LBF属周转事件是已知的。 然而，生物地层学的问题意味着确切的时间，因此机制仍然不确定。我们的研究表明 坦桑尼亚LBF属的范围在已知的全球范围内。此外，LBF组合中存在变化， 在巴顿期间，当地第一次和最后一次出现的属的数量，这可能与中期的开始有潜在的联系 始新世气候适宜期
Larger benthic foraminifera (LBF) are common and diverse throughout the Paleogene sediments of southern Tanzania, but have previously been little studied. A recent programme of onshore drilling known as the Tanzania Drilling Project has recovered large proportion of this succession for palaeoclimatic and palaeontological study. The sediment is largely a hemipelagic clay with secondary gravity sediment flow limestones and calcarenites. LBF occur concentrated in the secondary beds and are present in some clay horizons. Planktonic foraminiferal, nannofossil and, in some cases, stable isotope studies of the clays allow the larger benthic foraminiferal ranges to be tied to global stratigraphy. Here we use nine of these drill sites to examine the LBF from the Middle Eocene to Oligocene. Within this interval several global turnover events of long-ranging and widespread LBF genera are known to occur. However, problems with biostratigraphy mean the exact timing and therefore mechanisms remain uncertain. Our study shows that ranges of Tanzanian LBF genera are within known global ranges. Additionally, there is a change in the LBF assemblage with a number of local first and last occurrences of genera during the Bartonian, which may have potential links to the onset of the Mid Eocene Climatic Optimum.