近日，美国艾灵顿地质服务局Vann Smith及其团队最近的研究，揭示了德克萨斯海湾沿岸古新世下威尔科克斯群中Classopolli最新的避难所。2024年1月22日出版的《地质学》杂志发表了这项成果。

人们曾一度认为，Cheirolepidiaceae科在白垩纪—古近纪(K/Pg)界线或更早的时候在北美灭绝了；然而，在古新世，类似的生态避难所在中国、阿根廷和潜在的美国落基山脉都有过报道。在以Sr/Ba(盐度地球化学代用指标)高为特征的三角洲前缘、泻湖和滨地沉积古环境中，Classopolli孢粉的相对丰度最高，在较老的古新世地层中，其丰度一般向下增加。

钻井样品中的Classopolli孢粉相对丰度较高、改变的中生代孢粉化石形态比较罕见、Classopolli孢粉保存以及Classopolli荧光光谱与其他原位古新世原位花粉的相似性通常较好，为Cheirolepidiaceae科至少在古新世晚期，德克萨斯州沿海盐沼泽中的生存提供了强有力的证据。

据研究人员介绍，根据对四口井的孢粉分析，美国德克萨斯州东南部墨西哥湾海岸，是古新世下威尔科克斯群中Cheirolepidiaceae科(Classopolli孢粉形态属)的一个新的生态避难所。

附：英文原文

Title: A late refugium for Classopollis in the Paleocene Lower Wilcox Group along the Texas Gulf Coast

Author: Vann Smith, Angela Hessler, Lorena Moscardelli, David Bord, Iulia Olariu, Maria Antonieta Lorente, Evan Sivil, Xiuju Liu

Issue&Volume: 2024-01-22

Abstract: We report a new ecological refugium for the Cheirolepidiaceae family (pollen form genus Classopollis) in the Paleocene Lower Wilcox Group in the Gulf Coast of southeastern Texas based on palynological analysis of four wells. The Cheirolepidiaceae were once thought to have gone extinct at the Cretaceous-Paleogene (K/Pg) boundary or earlier in North America; however, similar ecological refugia for this family in the Paleocene have previously been reported in China, Argentina, and potentially the Rocky Mountains of the United States. The highest relative abundances of Classopollis pollen were found in delta front, lagoon, and shoreface depositional paleoenvironments marked by high mud-fraction Sr/Ba (a geochemical proxy for salinity), and abundances generally increased down section in older Paleocene strata. The high relative abundance of Classopollis pollen in the well samples, the rarity of reworked Mesozoic palynomorphs, the generally good preservation of Classopollis pollen, and the similarity of Classopollis fluorescence spectra to other in situ Paleocene pollen all provide strong evidence for the survival of the Cheirolepidiaceae family in the coastal salt marshes of Texas through at least the late Paleocene.

DOI: 10.1130/G51772.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51772.1/633456/A-late-refugium-for-Classopollis-in-the-Paleocene