近日，中国地质大学邓军团队报道了华南晚泥盆世下雷锰矿床中的绿鳞石作为热液输入和海洋缺氧的记录。这一研究成果于2025年12月29日发表在《地质学》杂志上。

铁质前寒武纪沉积岩中的绿泥石被广泛认为是形成于富亚铁和缺氧环境中的原生矿物。然而，在显生宙岩石中鲜有关于原生绿泥石的报道，因为显生宙海洋被认为氧化程度更高，不利于绿泥石沉淀。

研究组报道了在晚泥盆世下雷锰矿床中发现的绿泥石纳米颗粒。这些纳米尺度（20−1000 nm）的自形至他形绿泥石颗粒，以随机取向的微晶形式包裹在富含燧石的锰矿和铁锰矿石的微晶石英晶体中。含绿泥石矿石显示出负的δ³⁰Si值（平均-0.5‰），与前寒武纪铁建造和热液硅质岩的值相近，表明有显著的热液贡献。这些特征支持以下解释：绿泥石形成于深水喷口附近的混合带，富含Fe²⁺和溶解态SiO₂的热液流体与海水混合，产生了有利于绿泥石生成的pH值和温度梯度。

随后，这些绿泥石纳米颗粒在距离形成区数百公里外堆积，根据沉积学、地层学和古地理学的证据，它们出现在上升流带下方形成的大陆架含金属矿石中。在远源陆架（风暴浪基面以下）存在这些含绿泥石的锰矿和铁锰矿床，记录了华南地区存在一个具有热液输入和缺氧底层水的严重区域氧分层水体。这种环境与前寒武纪海洋相似。因此，含绿泥石锰矿床为追踪显生宙盆地的热液金属通量和缺氧事件提供了新的记录载体，并对其他显生宙热液燧石和金属矿床的研究具有潜在意义。

附：英文原文

Title: Greenalite as a record of hydrothermal input and ocean anoxia, Late Devonian Xialei Mn deposit, South China

Author: Fangge Chen, Qingfei Wang, Peir K. Pufahl, Edward J. Matheson, Kunfeng Qiu, Haiyang Xian, Jingbo Nan, Jiaxin Xi, Di Ruan, Haoying Chen, Xinwei Hu, Huan Ma, Jun Deng

Issue&Volume: 2025-12-29

Abstract: Greenalite in iron-rich Precambrian sedimentary rocks is widely regarded as a primary mineral that formed in ferrous iron-rich and anoxic conditions. However, primary greenalite has rarely been reported in Phanerozoic rocks, as Phanerozoic oceans are considered to have been more oxygenated and less favorable for greenalite precipitation. Here, we report the discovery of greenalite nanoparticles in the Late Devonian Xialei Mn deposit. Nanoscale (201000 nm) euhedral to anhedral greenalite particles occur as randomly oriented crystallites enclosed in microcrystalline quartz crystals within chert-rich Mn and Fe-Mn ores. Greenalite-bearing ores show negative δ30Si values (avg. 0.5‰) close to those of Precambrian iron formations and hydrothermal silica, suggesting a substantial hydrothermal contribution. These characteristics support the interpretation that the greenalite formed in a mixing zone near deep-water vents where Fe2+-rich and SiO2(aq)-rich hydrothermal fluids mixed with seawater to produce gradients in pH and temperature amenable to greenalite genesis. The greenalite nanoparticles then accumulated hundreds of kilometers from this formation zone, being found in continental shelf metalliferous ores formed beneath upwelling zones, as indicated by sedimentologic, stratigraphic, and paleogeographic constraints. The presence of these greenalite-bearing Mn and Fe-Mn deposits on distal shelves (below storm wave base) records a profound regional oxygen-stratified water column in South China, characterized by hydrothermal input and anoxic bottom waters. These conditions are reminiscent of Precambrian oceans. Thus, greenalite-bearing Mn deposits provide a new archive to track hydrothermal metal fluxes and anoxia in Phanerozoic basins, with potential implications for other Phanerozoic hydrothermal chert and metal deposits.

DOI: 10.1130/G53951.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G53951.1/723850/Greenalite-as-a-record-of-hydrothermal-input-andredirectedFrom=fulltext