Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophyceae) from the Pande Formation (Kilwa Group), Tanzania
Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophyceae) from the Pande Formation (Kilwa Group), Tanzania
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坦桑尼亚潘德组（基尔瓦群）保存完好的上始新世至下渐新世钙质超微化石（Prymnesiophyceae）
DOI：
10.1017/s1477201909990010
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发表时间：
2009
影响因子：
2.6
通讯作者：
P. Pearson
中科院分区：
文献类型：
--
作者：
T. Jones;P. Bown;P. Pearson
迄今为止已知的保存最完好和多样的上始新世到下渐新世钙质超微化石（颗石藻）组合描述于坦桑尼亚Kilwa组的Pande Clays。该组合是非常多样的，这里描述的115种，这大大超过了目前全球汇编的最新始新世（NP 19/20）的超微化石物种多样性的67。在这些部分中观察到的增强的多样性集中在众多的Rhabdosphaeraceae（20种），Syracosphaeraceae和holocococcolith类群（19种），这是未知的任何其他同时代的位置。扫描电子显微镜（SEM）研究揭示了许多这些分类群在亚微米尺度上的精美保存，包括< 3 μm的全球壳的结构以及其他非常小的易碎分类群中的格栅和过程的细节-即使在现代沉积物中也很少保存的尺寸类别。在这些沉积物中存在至少四个专业的低透光层类群的独特组合-三个剑兰属物种和Algirosphaera fabaceus。在坦桑尼亚的古近纪沉积物中，这些高度专业化的球石的出现将之前已知的晚第四纪化石记录延长了数千万年。对这种多样的超微化石组合的精美保存的控制很难确定，但我们推测，一种多样的开放海洋，寡营养颗石藻组合被迅速掩埋并密封在富含粘土的相内，这种相更具有陆架环境的特征，这种组合迄今为止使坦桑尼亚的古近纪沉积物独一无二。一个新的属，Pocillithus，被描述，由非常小的脊柱轴承muroliths，可能与现存的窄边muroliths的不确定的亲和力。描述了10个新物种：小刺刺囊藻、麦克米伦网孔藻、小钙藻、莫氏球腔菌、拉菲球腔菌、黑刺卡尔特、沙菲黑刺囊藻、黑刺囊藻、隐直眼藻和弧直眼藻。
Synopsis The most well preserved and diverse upper Eocene to lower Oligocene assemblage of calcareous nannofossils (coccolithophores) known to date is described from the Pande Clays, Kilwa Group, Tanzania. The assemblage is exceptionally diverse, with a total of 115 species described herein, which significantly exceeds the current globally compiled nannofossil species diversity of 67 for the latest Eocene (NP19/20). The enhanced diversity observed in these sections is concentrated in the numerous Rhabdosphaeraceae (20 species), Syracosphaeraceae and holococcolith taxa (19 species) that are unknown from any other contemporaneous location. Scanning electron microscope (SEM) studies reveal exquisite preservation down to the sub‐micron scale in many of these taxa, including the architecture of < 3 μm holococcoliths and the details of grills and processes in other very small fragile taxa ‐ a size class which is rarely preserved even in Recent sediments. A distinct assemblage of at least four specialist lower‐photic zone taxa ‐ three Gladiolithus species and Algirosphaera fabaceus ‐ is present in these sediments. The occurrence of these highly specialised coccoliths in the Palaeogene sediments of Tanzania extends their previously known late Quaternary fossil record by tens of millions of years. The controls on the exquisite preservation of such a diverse nannofossil assemblage are difficult to determine but we speculate that a diverse open‐ocean, oligotrophic coccolithophore assemblage was being rapidly buried and sealed within a clay‐rich facies that is more characteristic of shelf‐environments, a combination that, to date, makes the Palaeogene sediments of Tanzania unique. One new genus, Pocillithus, is described, consisting of very small spine‐bearing muroliths that may be related to extant narrow‐rimmed muroliths of uncertain affinity. Ten new species are described: Pocillithus spinulifer, Reticulofenestra macmillanii, Calcidiscus parvus, Syracosphaera monechiae, Syracosphaera raffiae, Blackites culter, Blackites shafikii, Acanthoica backmanii, Orthozygus occultus and Orthozygus arcus.
影响因子：
5.8
作者：
Lear, Caroline H.;Bailey, Trevor R.;Rosenthal, Yair
通讯作者：
Rosenthal, Yair