日本大阪公立大学Yoichi Ezaki团队报道了作为石炭纪Panthalassan阶海山主要造礁者的后泥盆纪层孔虫的重新出现和消亡。这一研究成果于2024年8月13日发表在国际顶尖学术期刊《地质学》上。

研究人员称，日本西南部Akiyoshi石灰岩群形成于密西西比纪(Visean)至中二叠世(Capitian)的Panthalassa洋的海山上。宾夕法尼亚纪早期(Bashkirian)礁核环境发育良好，并在横向上分化为多个礁环境。在大多数礁核环境中，由囊状或扁平层状和柱状垂直结构组成的层状骨架非常丰富，并与Chaetetes一起，对礁的构造做出了重大贡献。层状骨骼的形态清楚地显示出一种层孔虫类，亲和性可能是拉贝氏菌。在泥盆纪晚期物种灭绝之后，一种造礁的层孔虫谱系在Panthalassan海山的一个局部温暖的热带环境中重新出现。

持续的全球冰川作用可能导致海洋环流、上升流和营养供应增强，特别是在浅水海山周围，最终导致碳酸盐饱和度升高，这应该有利于高钙化的层孔虫和Chaetetes。Chaetetes—层孔虫礁仍然存在于Moscovian期，但很可能在Kasimovian期间随着全球急剧变冷和频繁的地面暴露而灭绝，取而代之的是Palaeoaplysina-叶状藻礁。Bashkirian期造礁层孔虫的出现表明，至少在Panthalassa，古生代层孔虫在晚泥盆纪灭绝后很长一段时间内仍在继续造礁。研究结果强调了像Akiyoshi这样很少保存的开放但孤立的海洋环境对全球生物地理学和进化的重要性。

附：英文原文

Title: Post-Devonian re-emergence and demise of stromatoporoids as major reef-builders on a Carboniferous Panthalassan seamount

Author: Yoichi Ezaki, Mitsuru Masui, Koichi Nagai, Gregory E. Webb, Koki Shimizu, Shota Sugama, Natsuko Adachi, Tetsuo Sugiyama

Issue&Volume: 2024-08-13

Abstract: Stromatoporoids were major reef-builders during the middle Paleozoic; however, no Carboniferous stromatoporoid reefs have been reported. The Akiyoshi Limestone Group of southwest Japan formed on a seamount in the Panthalassa Ocean from the Mississippian (Visean) to the middle Permian (Capitanian). The Early Pennsylvanian (Bashkirian) reef-core setting was well developed and laterally differentiated into several reef environments. Laminated skeletons made up of cystose or flat laminae and pillar-like vertical structures were abundant and, together with Chaetetes, contributed greatly to reef construction in most reef-core environments. The morphology of the laminated skeletons clearly indicates a stromatoporoid, probably labechiid, affinity. Thus, a lineage of reef-building stromatoporoids reappeared on a Panthalassan seamount in a locally warm-water tropical setting after the Late Devonian extinctions. Ongoing global glaciation may have resulted in enhanced ocean circulation, upwelling, and nutrient supply, especially around shallow-water seamounts, culminating in elevated carbonate saturation, which should have favored hypercalcified stromatoporoids and Chaetetes. The Chaetetes-stromatoporoid reefs remained in the Moscovian, but probably died out during the Kasimovian with intensive global cooling and frequent subaerial exposure, to be replaced by Palaeoaplysina-phylloid algal reefs. The occurrence of Bashkirian reef-building stromatoporoids indicates that Paleozoic stromatoporoids continued as reef-builders long after the Late Devonian extinction, at least in Panthalassa. This occurrence emphasizes the significance of rarely preserved open, but isolated oceanic settings like Akiyoshi for global biogeography and evolution.

DOI: 10.1130/G52420.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52420.1/646596/Post-Devonian-re-emergence-and-demise-ofredirectedFrom=fulltext