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首页> 外文期刊>Journal of nannoplankton research: A publication of the International Nannoplankton Association >Calcareous nannofossil assemblages at the Cretaceous-Paleogene transition at Lali section, SW Iran
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Calcareous nannofossil assemblages at the Cretaceous-Paleogene transition at Lali section, SW Iran

机译：伊朗西南部白垩纪-古近纪过渡带钙质纳米化石组合

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摘要

Calcareous nannofossil assemblages were investigated at the Lali section in the Zagros Basin in Iran. The studied interval is one of the best outcrops where the Cretaceous-Paleogene (K/Pg) boundary can be investigated. The K/Pg lies at the upper part of the Gurpi Formation (Darvishzadeh et al., 2007). The studied interval extends from Zones CC25b/UC20aTP to NP3/NTp5A. Latest Maastrichtian assemblages are abundant and diverse, and no decrease was observed towards the boundary. Dominant species of the Maastrichtian were Watznaueria barnesiae, Micula decussata, Micula murus,Cribrosphaerella ehrenbergii, Cyclagelosphaera reinhardtii, Predisco sphaera cretacea, Lithraphidites spp., and Retecapsa spp. At the K/Pg boundary, a decrease in the abundance of Cretaceous species and an increase in the abundance of Thoracosphaera operculata were recorded, along with the appearance of Paleocene species. The relative abundance of T. operculata is approximately 48% at the K/Pg boundary,which is reduced to 7% towards the top of the studied interval. A high abundance of T. operculata at the K/Pg boundary interval has been reported from other parts of the world (Tantawy, 2003; Bernaola & Monechi,2007). Above the K/Pg boundary in the Danian sediments, Cretaceous species were observed along with the new Paleocene species. It must be mentioned that the relative abundance of the Cretaceous species decreased from the K/Pg boundary upward: A. cymbiformis (from 2% to 0%), Eiffellithus spp. (from 2% to 0%), W. barnesiae (from 11% to 1%), Retecapsa spp. (from 6% to 1%), M. decussata (from 7% to 0%), C. ehrenbergii (from 5% to 1%), and P. cretacea (from 4% to 1%).
机译：在伊朗扎格罗斯盆地的拉里段对钙质纳米化石组合进行了调查。研究间隔是可以研究白垩纪-古生界（K / Pg）边界的最佳露头之一。 K / Pg位于古皮组的上部（Darvishzadeh等，2007）。研究的间隔从区域CC25b / UC20aTP延伸到NP3 / NTp5A。最新的马斯特里赫特式聚会丰富多样，没有观察到边界减少。马斯特里赫特人的主要种是Watznaueria barnesiae，Micula decussata，Micula murus，Cribrosphaerella ehrenbergii，Cyclagelosphaera reinhardtii，Predisco sphaera cretacea，Lithraphidites spp。和Retecapsa spp。在K / Pg边界处，记录了白垩纪物种的丰度下降和胸果的丰度增加，以及古新世物种的出现。盖草的相对丰度在K / Pg边界处约为48％，在研究区间的顶部降低到7％。世界其他地区已报道了在K / Pg边界处有大量的T盖草（Tantawy，2003; Bernaola＆Monechi，2007）。在丹尼尔沉积物中K / Pg边界以上，观察到白垩纪物种和新古新世物种。必须提到的是，白垩纪物种的相对丰度从K / Pg边界向上降低：食蟹猴（A. cymbiformis）（从2％降至0％），Eiffellithus spp。 （从2％到0％），W.barnesiae（从11％到1％），Retecapsa spp。 （从6％到1％），M。decussata（从7％到0％），C。ehrenbergii（从5％到1％）和C. cretacea（从4％到1％）。

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