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首页> 外文期刊>Stratigraphy >Pennsylvanian to Lower Permian (Desmoinesian-Wolfcampian) fusulinid biostratigraphy of Midcontinent North America
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Pennsylvanian to Lower Permian (Desmoinesian-Wolfcampian) fusulinid biostratigraphy of Midcontinent North America

机译：北美中部宾夕法尼亚州至下二叠纪（Desmoinesian-Wolfcampian）融合林地层生物地层

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摘要

Midcontinent North American Middle Pennsylvanian-Lower Permian (Desmoinesian-Wolfcampian) fusulinid foraminiferal species range charts were plotted and new fusulinid zones were defined. The species range charts were plotted together with lithostratigraphic columns and cyclothemic sea level curves in order to compare biostratigraphic, lithostratigraphic, and glacio-eustatic patterns. The fusulinids Beedeina and Wedekindellina appeared during widespread early Desmoinesian transgressions and characterized that interval. The mid-Desmoinesian extinction of Wedekindellina and turnover of Beedeina species coincided with a lowstand followed by a widespread transgression, generally higher sea levels, and changing paleoclimatic patterns. Beedeina went to extinction near the Desmoinesian-Missourian sequence boundary. The earliest Missourian is barren of fusulinids in the Midcontinent, followed by a thin zone of Eowaeringella, and then the appearance of Triticites, which dominated fusulinid faunas through the remainder of the Upper Pennsylvanian. Lower and Middle Missourian Triticites have relatively small tests and plane septa. In the Upper Missourian, Triticites became medium-sized with more complex septal fluting, and Kansanella appeared. In the uppermost Missourian and lower Virgilian, most Triticites are medium-sized and evenly biconvex, and have weak septal fluting. Kansanella gradually declined through the lower Virgilian and disappeared in the lowest middle Virgilian. The middle Virgilian is dominated by medium to large Triticites with complex septal fluting, and Dunbarinella appeared and became locally common. The upper Virgilian has mostly large inflated Triticites and the first Leptotriticites. The uppermost Virgilian ('Bursumian') has large Triticites, diverse Leptotriticites, and the first primitive elongate Schwagerina. That fauna extends across the new conodont-based Pennsylvanian-Permian (Virgilian-Wolfcampian) boundary, and the first definitive Wolfcampian (Lower Permian) fusulinids did not appear until the Neva Limestone, which is a couple cycles above the new systemic boundary. Most significant fusulinid biostratigraphic changes correlate with major glacio-eustatic cyclothem boundaries, but not all major cyclothem boundaries have significant faunal turnovers. Fusulinid zonal boundaries that were based on only fusulinid species ranges were found to closely approximate maximum sea level lowstands. Most new genera and species appear in the regressive phases of the next cyclothem, probably because faunal migrations occurred during maximum flooding events, and subsequent highstand system tracts had more paleoenvironmental diversity and thus more niches to fill.
机译：绘制了北美洲中部宾夕法尼亚州中下二叠纪（Desmoinesian-Wolfcampian）融合林有孔虫物种范围图，并定义了新的融合林区。为了比较生物地层学，岩石地层学和冰川均流模式，将物种范围图与岩石地层柱和旋回海平面曲线一起绘制。梭状芽孢杆菌Beedeina和Wedekindellina出现在广泛的早期Desmoinesian侵害期间，并以该间隔为特征。 Wedekindellina的中Desmoinesian灭绝和Beedeina物种的周转与低水位相吻合，随后发生海侵，海平面普遍升高，古气候模式发生变化。 Beedeina在Desmoinesian-Missourian序列边界附近灭绝。最早的密苏里州在中部大陆上贫瘠的融合藻类化合物，其次是薄弱的Eowaeringella带，然后出现了Triticite，在整个上宾夕法尼亚州的其余地区都以融合藻类动物为主。密苏里州中部和下部的Triticites的试验和平面隔片相对较小。在上密苏里州，Triticite变成中等大小，有更复杂的间隔凹槽，出现了Kansanella。在密苏里州的最上层和维吉尔下层，大多数的三面体是中等大小的且均匀的双凸面，且间隔纹较弱。坎萨内拉（Kansanella）逐渐下降穿过较低的维吉尔人，并消失在最低的中维吉尔人中。中维吉尔人以中等至大型的三面体为主导，伴有复杂的中空槽，邓巴利氏菌出现并在当地普遍存在。上维吉尔人的大部分是大型的膨胀的三叠纪和第一个轻变三叠纪。最上层的维吉尔人（“ Bursumian”）有大型的Triticite，各种的Leptotriticite和第一个原始的细长Schwagerina。该动物群跨越了新的基于牙形刺的宾夕法尼亚州-二叠纪（维吉尔-沃尔夫坎普）边界，并且直到涅瓦石灰岩（Neva Limestone）才出现了第一个确定的沃尔夫坎普（下二叠纪）融合藻，这比新的系统边界高了几个周期。最重要的镰刀菌类生物地层变化与主要的冰川-欧共体旋回边界相关，但并非所有的主要旋回边界都具有明显的动物翻转。发现仅基于镰刀菌属物种范围的镰刀菌区带边界接近最大海平面低位。大多数新属和新种出现在下一个气旋的回归期，可能是因为在最大的洪水事件期间发生了动物迁徙，随后的高位系统域具有更多的古环境多样性，因此需要填补更多的生态位。

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