近日，中国科学院南京地质古生物研究所詹仁斌团队研究了与上升流有关的含铁矿物、微生物与奥陶系气候的达瑞威尔临界点。该研究于2025年8月13日发表在《地质学》杂志上。
奥陶系显生宙鲕状铁矿（POIs）赋存于冷水环境，与其他POIs典型的温暖湿润气候形成鲜明对比。在这项研究中，这个地质谜题基于一套复杂的中古中国南方晚奥陶世POI主要含暖水热带沉积物和相对冷水环境下沉积的同时期含铁质沉积物和微生物岩。
研究组表明，华南奥陶系含铁铁矿虽然沉积背景不同，但岩石超微结构和δ56Fe同位素特征相似。这表明POI的形成不太可能由水温控制，而是可归因于微生物铁工厂，与冈瓦纳频繁的冷水入侵产生的活跃上升流有关。这一模式也解释了冈瓦纳近缘冷水区奥陶系铁酸盐矿床的主要赋存。达瑞威尔期生物繁盛的高峰期，恰逢冰室事件启动及古热带冷水舌发育时期，两者共同在华南板块形成了复杂的沉积环境。
附：英文原文
Title: Upwelling-related ferruginous ooids, microbialites, and the Darriwilian tipping point of Ordovician climate
Author: Xiaocong Luan, Colin D. Sproat, Jisuo Jin, Peir K. Pufahl, Rongchang Wu, Renbin Zhan
Issue&Volume: 2025-08-13
Abstract: Cool-water settings characterize Ordovician occurrences of Phanerozoic ooidal ironstones (POIs), contrasting sharply with the warm and humid climate typical of other POIs. This geological puzzle was deciphered in this study based on a complex suite of MiddleLate Ordovician POIs in South China hosted in tropical sediments of a warm-water origin, and coeval ferruginous ooid-bearing sediments and ferruginous microbialites that accumulated in a relatively cool-water setting. Here, we demonstrate that, despite their different depositional settings, all Ordovician ferruginous deposits of South China share similar petrographic ultrastructures and δ56Fe isotopic signatures. This suggests that the formation of POIs was not likely controlled by water temperature but instead is attributable to a microbial iron factory, associated with active upwelling generated from frequent cool-water incursions from Gondwana. This model also explains the predominant occurrence of Ordovician ferruginous deposits in cool-water realms in peri-Gondwana. The Darriwilian peak of their abundance corresponds to the onset of an icehouse episode and a paleotropical cold-water tongue that created complex depositional environments across the South China plate.
DOI: 10.1130/G53374.1
Geology：《地质学》，创刊于1973年。隶属于美国地质学会，最新IF：6.324
官方网址：https://pubs.geoscienceworld.org/geology
投稿链接：https://geology.msubmit.net/cgi-bin/main.plex