Mercury (Hg) anomalies in sedimentary rocks have been increasingly used in paleoclimatology studies for tracing volcanic signals, as Hg emissions from volcanic activity can cause contemporaneous sedimentary Hg enrichment. However, non-volcanic sedimentary controls on Hg have clear potential to mask these signals. These factors include host phase variability linked to environmentally controlled sourcing and settling changes, and/or variable preservation conditions associated with weathering, oxidation and diagenesis. Such factors can limit the efficacy of Hg as a paleo-volcanism proxy. In this study, sedimentary effects on Hg concentration within a complex depositional system in southwest England (St. Audrie's Bay) across the end-Triassic have been analyzed, together with published data from coeval end-Triassic sections globally – an interval of time coeval with the Central Atlantic Magmatic Province (CAMP). Our statistical analysis of Hg and associated geochemical data highlights significant fluctuations in sedimentary Hg due to relative supply differences in Hg and host phases, as well as the changing types and preservation conditions of host phases. End-Triassic sections globally show a consistent undersupply of Hg relative to organic matter across the end-Triassic mass extinction (ETME). To better assess the magnitude and significance of possible Hg enrichments in sedimentary rocks, we present a statistical method for quantifying Hg anomalies to robustly distinguish Hg variations linked to host phase/depositional changes from paleo-volcanism. Our method supports the existence of transient but asynchronous Hg anomalies linked to volcanism from the CAMP across the end-Triassic in most global sections, albeit not in the St. Audrie's Bay section.

中文翻译：

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汞富集作为古火山活动的代理：沉积偏差和跨三叠世末的批判性分析


沉积岩中的汞 （Hg） 异常越来越多地用于古气候学研究，以追踪火山信号，因为火山活动排放的汞会导致同时期沉积物中的汞富集。然而，对汞的非火山沉积控制显然有可能掩盖这些信号。这些因素包括与环境控制的来源和沉降变化相关的宿主相变化，和/或与风化、氧化和成岩作用相关的可变保存条件。这些因素会限制 Hg 作为古火山活动代理的功效。在这项研究中，分析了英格兰西南部（圣奥德里湾）跨三叠世末期复杂沉积系统对汞浓度的沉积影响，以及来自全球同代末三叠世剖面的已发表数据——与中大西洋岩浆省 （CAMP） 同时代的时间间隔。我们对汞和相关地球化学数据的统计分析突出了由于汞和宿主相的相对供应差异，以及宿主相的类型和保存条件的变化，沉积汞的显著波动。全球三叠纪末剖面显示，在三叠纪末大灭绝 （ETME） 期间，相对于有机物，汞供应始终不足。为了更好地评估沉积岩中可能的汞富集的幅度和重要性，我们提出了一种量化汞异常的统计方法，以有力地区分与宿主相/沉积变化相关的汞变化与古火山活动有关。我们的方法支持在大多数全球剖面中存在与三叠纪末 CAMP 火山活动相关的瞬态但不同步的 Hg 异常，尽管不在圣奥德里湾剖面。