近日，德国歌德大学Wolf Dummann等利用火山灰沉积物，将海洋缺氧事件2与高北极火山活动联系起来。2024年10月8日出版的《地质学》发表了这项成果。

据悉，海洋缺氧事件2 (OAE 2)是发生在9400万年前的一次重大环境扰动事件。它与全球气候和碳循环的深刻变化有关，这些变化通常被归因于大火成岩省(LIP)火山活动的大规模碳释放。然而，人们对具体的LIP(s)所涉及的碳释放机制仍然知之甚少，如数值模型显示的碳释放率与LIP脱气估计之间的差异所表明的那样。

研究团队使用综合地层学的方法，对加拿大高北极海洋沉积物中的火山灰沉积物进行年代测定，完善了高北极大火成岩省(HALIP)的喷发历史。结果表明，在OAE 2之前的几十年里，硅质HALIP火山活动就开始了，暗示了强有力的因果联系。

数据显示，火山活动与碳同位素值的显著变化相吻合，这与HALIP岩浆的脱气和/或热成因气体释放有关。研究结果强调，两个LIPs-HALIP和Kerguelen高原的同时活动，可以解释OAE 2的高碳释放率，为其普遍的环境影响提供了一个假设。

附：英文原文

Title: Ash deposits link Oceanic Anoxic Event 2 to High Arctic volcanism

Author: Wolf Dummann, Volker Wennrich, Claudia J. Schrder-Adams, Niklas Leicher, Jens O. Herrle

Issue&Volume: 2024-10-08

Abstract: Oceanic Anoxic Event 2 (OAE 2) was a major environmental perturbation that occurred ～94 million years ago. It is associated with profound changes in global climate and carbon cycling, which are commonly attributed to large-scale carbon release from large igneous province (LIP) volcanism. However, the specific LIP(s) involved and the mechanisms of carbon release remain poorly understood, as indicated by discrepancies between carbon release rates suggested by numerical models and LIP degassing estimates. Our study refines the eruptive history of the High Arctic large igneous province (HALIP) by dating ashfall deposits in marine sediments from the Canadian High Arctic using an integrated stratigraphic approach. Our results show that silicic HALIP volcanism began tens of thousands of years before OAE 2, suggesting a strong causal link. Volcanic activity coincides with a marked shift in carbon isotope values, linked to the degassing of HALIP magmas and/or thermogenic gas release. We propose that the concurrent activity of two LIPs—the HALIP and the Kerguelen Plateau—could account for the high rates of carbon release inferred for OAE 2, providing a hypothesis for its pervasive environmental impact.

DOI: 10.1130/G52368.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52368.1/649069/Ash-deposits-link-Oceanic-Anoxic-Event-2-to-High