Special Paper 356: Multiple spherule layers in the late Maastrichtian of northeastern Mexico
Special Paper 356: Multiple spherule layers in the late Maastrichtian of northeastern Mexico
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特别论文 356：墨西哥东北部马斯特里赫特阶晚期的多个小球层
DOI：
10.1130/0-8137-2356-6.145
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发表时间：
2002
影响因子：
1.8
通讯作者：
J. López
中科院分区：
文献类型：
--
作者：
G. Keller;T. Adatte;W. Stinnesbeck;M. Affolter;Lionel Schilli;J. López
在墨西哥东北部La Sierrita地区砂岩-粉砂岩杂岩和白垩纪-第三系(K-T)边界之下，在10米内发现了多达4个球状层，揭示了比之前想象的更复杂的K-T情景。这些球状层是在门德兹组的远洋泥灰岩中沉积的；最古老的层在K-T边界以下10米处。泥灰岩为最新的马斯特里赫期钙质超微化石Micula print sii带和浮游有孔虫带CF1(Plummerita Hantkeninoides)，后者跨越300K.Y.马斯特里赫特人的。最古老的球粒层沉积在CF1带底部附近，标志着原始球粒的形成事件。这表明存在一些泥灰岩碎屑和海底有孔虫，它们经常被焊接的玻璃包围，以及许多具有纹影特征的焊接球体，表明沉积发生在玻璃仍然热和延展性的时候。根据常见的泥灰岩碎屑、陆源输入、重新改造的底栖和浮游有孔虫以及凝聚的球粒，可能部分或全部从原始球粒沉积中改造了地层较年轻的球体。这些数据表明，在马斯特里赫特晚期至少发生了一次球体形成事件，并为K-T转变过程中的多个灾难性事件提供了强有力的证据。
The discovery of as many as 4 spherule layers within 10 m of pelagic marls below the sandstone-siltstone complex and Cretaceous-Tertiary (K-T) boundary in the La Sierrita area of northeastern Mexico reveals a more complex K-T scenario than previously imagined. These spherule layers were deposited within pelagic marls of the Mendez Formation; the oldest layer is as much as 10 m below the K-T boundary. The marls are of latest Maastrichtian calcareous nannofossil Micula prinsii zone and planktic foraminiferal zone CF1 (Plummerita hantkeninoides) age; the latter spans the last 300 k.y. of the Maastrichtian. The oldest spherule layer was deposited near the base of zone CF1 and marks the original spherule-producing event. This is indicated by the presence of a few marl clasts and benthic foraminifera that are frequently surrounded by welded glass, and many welded spherules with schlieren features, indicating that deposition occurred while the glass was still hot and ductile. It is possible that some, or all, of the three stratigraphically younger spherule layers have been reworked from the original spherule deposit, as suggested by the common marl clasts, terrigenous input, reworked benthic and planktic foraminifera, and clusters of agglutinated spherules. These data indicate that at least one spherule-producing event occurred during the late Maastrichtian and provide strong evidence for multiple catastrophic events across the K-T transition.