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.

中文翻译：

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来自墨西哥希克苏鲁伯撞击坑的古新世-始新世小孢子。第 1 部分：孢子和裸子植物花粉

摘要 2016 年夏天，国际海洋发现计划 (IODP) 364 号探险队在墨西哥白垩纪末期希克苏鲁伯撞击坑的撞击后地层中取芯。从撞击后序列收集岩心样本用于陆地孢粉学分析，产生罕见的大年至伊普雷西亚高分辨率孢粉组合。该记录构成了中美洲或墨西哥最早的古新世和伊普雷西亚孢粉学组合之一，代表了比墨西哥大陆以前的研究更沿海的低地古环境。尽管古新世碳酸盐岩中花粉和孢子的丰度非常低，但在代表古新世-始新世热最大值 (PETM) 和后来的伊普勒斯阶的富含有机物的页岩层中，丰度增加了。从 IODP 364 鉴定的孢子和裸子植物花粉，虽然与被子植物花粉相比很少见，但它们是世界性分类群的多样化组合，以及中美洲化石组合（例如卷柏科）的一些特征，以及先前从古近纪北部海湾鉴定的其他植物墨西哥沿海平原。该组合通常表明附近存在潮湿至季节性干燥的低地热带森林，其中一些分类群表明海拔较高的森林。麻黄花粉粒可能表明存在更干旱的条件。该组合通常表明附近存在潮湿至季节性干燥的低地热带森林，其中一些分类群表明海拔较高的森林。麻黄花粉粒可能表明存在更干旱的条件。该组合通常表明附近存在潮湿至季节性干燥的低地热带森林，其中一些分类群表明海拔较高的森林。麻黄花粉粒可能表明存在更干旱的条件。