Scholarlink

<p>Sedimentary Mn carbonate deposits (SMCDs) constitute the dominant global reservoir of Mn, a critical metal essential for modern technologies, yet their formation timing and links to environmental perturbations remain elusive owing to sparse datable minerals and coarse chronostratigraphic resolution. Here, we report astronomical cycle signals preserved in P (indicative of marine productivity) and (Zr+K)/Al (indicative of detrital flux and relative sea level) from drill core ZK2407 of the Xialei SMCD (∼143 Mt Mn), South China, which is embedded in Late Devonian platform/slope facies strata of the Youjiang Basin. Leveraging the 405 kyr eccentricity cycle and conodont biostratigraphy, the astronomical timescale for the Xialei SMCD was established. The deposition of ore layers I and II+III in the Xialei SMCD took ∼130 and ∼550 kyr, respectively. Ore layer I aligns precisely with the Late Famennian Annulata Event (∼363.4 Ma), while ore layer II+III coincides with the Dasberg Event (∼361.9 Ma). As both mass extinctions were volcanically driven, these temporal couplings suggest large volcanic eruptions as the primary forcing for Mn metallogeny. Massive CO<sub>2</sub> emissions from large volcanism induced global warming and sea-level rise, fostering redox-stratified oceanic conditions conducive to SMCD formation. Mn concentrations covary positively in-phase with P and sea-level, indicating transgression-mediated co-transport of anoxic deep-sea hydrothermal Mn(II) and nutrients to the oxic shallow sea, where Mn(III/IV) oxides precipitated. The resulting heightened productivity drove organic matter burial, which subsequently facilitated the reductive transformation of these oxides into Mn carbonates during early diagenesis. Orbital forcing modulated the rhythm of Mn enrichment on astronomical timescales by periodically driving paleoenvironmental variations. This work delineates a temporal framework for the formation of SMCDs and demonstrates that the metallogeny of SMCDs resulted from paleoceanographic changes induced by large volcanism and orbital dynamics.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Late Devonian Mn mineralization as a result of volcanism- and orbital-forced palaeoceanographic changes

  • 期刊论文

  • 发表日期：

    2026年3月25日

查看全文
  • Yinqiang Zhao,
  • Chenchen Yang,
  • Hai Xu,
  • Sha Jiang,
  • Shangguo Zhou,
  • Qizuan Zhang,
  • Runsheng Yin

摘要

Sedimentary Mn carbonate deposits (SMCDs) constitute the dominant global reservoir of Mn, a critical metal essential for modern technologies, yet their formation timing and links to environmental perturbations remain elusive owing to sparse datable minerals and coarse chronostratigraphic resolution. Here, we report astronomical cycle signals preserved in P (indicative of marine productivity) and (Zr+K)/Al (indicative of detrital flux and relative sea level) from drill core ZK2407 of the Xialei SMCD (∼143 Mt Mn), South China, which is embedded in Late Devonian platform/slope facies strata of the Youjiang Basin. Leveraging the 405 kyr eccentricity cycle and conodont biostratigraphy, the astronomical timescale for the Xialei SMCD was established. The deposition of ore layers I and II+III in the Xialei SMCD took ∼130 and ∼550 kyr, respectively. Ore layer I aligns precisely with the Late Famennian Annulata Event (∼363.4 Ma), while ore layer II+III coincides with the Dasberg Event (∼361.9 Ma). As both mass extinctions were volcanically driven, these temporal couplings suggest large volcanic eruptions as the primary forcing for Mn metallogeny. Massive CO2 emissions from large volcanism induced global warming and sea-level rise, fostering redox-stratified oceanic conditions conducive to SMCD formation. Mn concentrations covary positively in-phase with P and sea-level, indicating transgression-mediated co-transport of anoxic deep-sea hydrothermal Mn(II) and nutrients to the oxic shallow sea, where Mn(III/IV) oxides precipitated. The resulting heightened productivity drove organic matter burial, which subsequently facilitated the reductive transformation of these oxides into Mn carbonates during early diagenesis. Orbital forcing modulated the rhythm of Mn enrichment on astronomical timescales by periodically driving paleoenvironmental variations. This work delineates a temporal framework for the formation of SMCDs and demonstrates that the metallogeny of SMCDs resulted from paleoceanographic changes induced by large volcanism and orbital dynamics.