A billion-year shift in the formation of Earth's largest ore deposits

• 成果类型: Article
• 署名作者: Davies, Liam Courtney-; Fiorentini, Marco; Dalstra, Hilke; Hagemann, Steffen; Ramanaidou, Erick; Danisik, Martin; Evans, Noreen J.; Rankenburg, Kai; Mcinnes, Brent I. A.
• 署名单位: Curtin University; University of Western Australia; Rio Tinto; Commonwealth Scientific & Industrial Research Organisation (CSIRO); CSIRO Mineral Resources
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12570
• DOI: 10.1073/pnas.2405741121
• 发表日期: 2024-07-30
• 关键词: hamersley province; iron-ore; western-australia; high-grade; pb; EVOLUTION; constraints; HISTORY; carajas; AFRICA

摘要

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 similar to 1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at similar to 2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a similar to 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.