Mercury (Hg) enrichment and elevated ratios of Hg to total organic carbon (Hg/TOC) in sedimentary rocks have often been linked to volcanism from large igneous provinces (LIPs). Primary Hg and TOC contents of sediments can be altered by secondary processes like extreme weathering. These effects must be evaluated before tying Hg anomalies in weathered rocks directly to LIP events. However, the effects of incipient weathering on Hg contents and Hg/TOC ratios are not known. In this study, we elucidate the behavior of Hg during incipient weathering by investigating visually pristine black shales from outcrops of the Ravnefjeld Formation in East Greenland (GRL) and comparing them to drill core equivalent intervals acquired from the same outcrop area and correlative shales from the mid-Norwegian shelf (MNS). By using geochemical investigations and principal component analysis, we characterize the main host phases of Hg and relate the different Hg contents of pristine samples from GRL and MNS to different Hg inputs during shale deposition. Compared with pristine drill core samples, incipiently weathered outcrop shales have up to 77% lower Hg contents and up to 64% lower Hg/TOC ratios. Incipient weathering causes the early degradation of Hg signals, which masks the primary Hg and Hg/TOC signals in sedimentary rocks. Therefore, we suggest that the presence and effects of weathering in sedimentary rock should be evaluated before discussing Hg signals.

沉积岩中汞 (Hg) 的富集和汞与总有机碳 (Hg/TOC) 的比例升高通常与大型火成岩区 (LIP) 的火山活动有关。沉积物的原生汞和总有机碳含量可以通过极端风化等二次过程改变。在将风化岩石中的汞异常直接与 LIP 事件联系起来之前，必须评估这些影响。然而，初期的影响风化对 Hg 含量和 Hg/TOC 比率的影响尚不清楚。在这项研究中，我们通过调查来自东格陵兰 (GRL) 的 Ravnefjeld 组露头的原始黑色页岩，并将它们与从同一露头区域获得的钻芯等效层段和来自格陵兰岛的相关页岩进行比较，从而阐明 Hg 在初期风化过程中的行为。挪威中部大陆架（MNS）。通过使用地球化学调查和主成分分析，我们表征了 Hg 的主要宿主相，并将来自 GRL 和 MNS 的原始样品的不同 Hg 含量与页岩沉积过程中的不同 Hg 输入联系起来。与原始钻探岩心样品相比，初风化露头页岩的汞含量降低了 77%，Hg/TOC 比降低了 64%。初期风化导致汞信号的早期退化，它掩盖了沉积岩中的主要 Hg 和 Hg/TOC 信号。因此，我们建议在讨论汞信号之前应评估沉积岩中风化的存在和影响。