据悉，条带状铁矿(BIFs)记录了地球岩石圈、水圈和大气之间的关系。然而，由于缺乏直接的地质年代学证据，对地球上最大矿床(由BIF托管)起源的限制研究受到制约。如果没有这一时间背景，遗传模型就不能与导致BIF随时间升级的构造-热和大气驱动因素相关联。
利用原位氧化铁U-Pb地质年代学，研究人员提供了一个追踪Hamersley省(Pilbara克拉通，西澳大利亚)所有大型BIF含赤铁矿矿床发展的直接事件时间表。直接测年结果显示，该区主要铁矿床形成于1.4-1.1Ga。这比以往的年龄限制晚了10亿至数亿年，原因是：(1)在约1.84Ga以前沉积的砾岩层中存在赤铁矿矿石碎屑，及(2)磷酸盐矿物定年，该省的铁成矿作用开始于约2.2至2.0Ga的大氧化事件期间。
赤铁矿碎屑定年证实了约2.2-2.0Ga事件的发生，反映了在Pilbara和Kaapvaal克拉通近端发生的广泛铁矿化在很大程度上被侵蚀了。现有的磷酸盐矿物年代学与获得的赤铁矿年代学没有重叠，因此不能与赤铁矿结晶和成矿联系起来。新的地质年代学最终将所有主要保存的赤铁矿矿床与一个更年轻的(1.4-1.1 Ga)形成时期联系起来，与哥伦比亚超大陆分裂后的亚特姆特利亚合并有关。
附：英文原文
Title: A billion-year shift in the formation of Earth’s largest ore deposits
Author: Courtney-Davies, Liam, Fiorentini, Marco, Dalstra, Hilke, Hagemann, Steffen, Ramanaidou, Erick, Daniik, Martin, Evans, Noreen J., Rankenburg, Kai, McInnes, Brent I. A.
Issue&Volume: 2024-7-23
Abstract: Banded iron formations (BIFs) archive the relationship between Earth’s lithosphere, hydrosphere, and atmosphere through time. However, constraints on the origin of Earth’s largest ore deposits, hosted by BIFs, are limited by the absence of direct geochronology. Without this temporal context, genetic models cannot be correlated with tectono-thermal and atmospheric drivers responsible for BIF upgrading through time. Utilizing in situ iron oxide U–Pb geochronology, we provide a direct timeline of events tracing development of all the giant BIF-hosted hematite deposits of the Hamersley Province (Pilbara Craton, Western Australia). Direct dating demonstrates that the major iron ore deposits in the region formed during 1.4 to 1.1 Ga. This is one billion to hundreds of millions of years later than previous age constraints based upon 1) the presence of hematite ore clasts in conglomerate beds deposited before ~1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at ~2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a ~2.2 to 2.0 Ga event, reflecting widespread, but now largely eroded iron mineralization occurring when the Pilbara and Kaapvaal cratons were proximal. No existing phosphate mineral dates overlap with obtained hematite dates and therefore cannot be related to hematite crystallization and ore formation. New geochronology conclusively links all major preserved hematite deposits to a far younger (1.4 to 1.1 Ga) formation period, correlated with the amalgamation of Australia following breakup of the Columbia supercontinent.
DOI: 10.1073/pnas.2405741121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2405741121