Palaeocene–Eocene Miospores from the Chicxulub Impact Crater, Mexico. Part 1: Spores and Gymnosperm Pollen
Palaeocene–Eocene Miospores from the Chicxulub Impact Crater, Mexico. Part 1: Spores and Gymnosperm Pollen
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DOI：
10.1080/01916122.2019.1630860
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发表时间：
2020-07
期刊：
影响因子：
1.5
通讯作者：
Vann Smith;S. Warny;D. Jarzen;T. Demchuk;V. Vajda
中科院分区：
文献类型：
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作者：
Vann Smith;S. Warny;D. Jarzen;T. Demchuk;V. Vajda
2016年夏天，国际海洋发现计划(IODP)364考察队对墨西哥白垩纪末希克苏鲁陨石坑的撞击后地层进行了取芯。岩心样品是从撞击后的序列中采集的，用于陆地孢粉分析，产生了罕见的大年至伊普里期高分辨率孢粉组合。这一记录构成了中美洲或墨西哥最早的古新世和伊普里期孢粉组合之一，与墨西哥大陆以前的研究相比，代表了更海岸的低地古环境。尽管在古新世碳酸盐岩中花粉和孢子的丰度很低，但在有机质含量较高的页岩层中，花粉和孢子的丰度增加，代表了古新世-始新世最高温度(PETM)和后来的伊普里期。在IODP 364中发现的孢子和裸子植物花粉虽然与被子植物花粉相比稀有，但它是世界性分类群的多样化组合，以及中美洲化石组合(如卷柏科)的一些特征，以及以前在墨西哥湾北部沿海平原古近纪发现的其他组合。该组合一般表明附近存在潮湿到季节性干燥的低地热带森林，一些分类群暗示海拔较高的森林。麻黄状花粉粒可能预示着更干旱的条件的存在。
ABSTRACT In the summer of 2016, the International Ocean Discovery Program (IODP) Expedition 364 cored through the post-impact strata of the end-Cretaceous Chicxulub impact crater, Mexico. Core samples were collected from the post-impact successions for terrestrial palynological analysis, yielding a rare Danian to Ypresian high-resolution palynological assemblage. This record constitutes one of the first Palaeocene and Ypresian palynological assemblages from Central America or Mexico, representing a more coastal lowland palaeoenvironment than previous studies from mainland Mexico. Although the abundance of pollen and spores is very low in the Palaeocene carbonates, abundance increases in the more organic-rich shale layers representing the Palaeocene–Eocene Thermal Maximum (PETM) and later Ypresian. The spores and gymnosperm pollen identified from IODP 364, although rare compared to the angiosperm pollen, are a diverse mix of cosmopolitan taxa, as well as some characteristic of fossil Central American assemblages (e.g. Selaginellaceae), and others previously identified from the Paleogene northern Gulf of Mexico coastal plain. The assemblage generally indicates the presence of nearby moist to seasonally dry lowland tropical forest, with some taxa suggestive of higher elevation forests. Ephedroid pollen grains may be indicative of the presence of more arid conditions.