Large igneous province (LIP) volcanism has been proposed as a key trigger of several major climate and environmental perturbations during the Phanerozoic Aeon. Large-scale carbon emissions associated with one or both of magmatic degassing from the Greater Ontong-Java Plateau (G-OJP) and intrusion of organic-rich sediments by High Arctic LIP (HALIP) sills have been widely suggested as the trigger of the Early Aptian Oceanic Anoxic Event (OAE 1a: ~120 Ma). However, the respective roles of the two LIPs and associated carbon sources in causing this crisis remain debated. Here, six records of OAE 1a from the Pacific, Tethyan, Arctic, and South Atlantic realms are investigated, combining mercury (Hg) concentrations and osmium- (Os-) isotope ratios as proxies of LIP activity. Together with previously published datasets, the results indicate globally consistent Os-isotope evidence for LIP activity during OAE 1a, but geographically variable stratigraphic Hg trends. Clear mercury enrichments that match Os-isotope evidence of LIP activity, and suggest a Hg-cycle perturbation during the onset of OAE 1a, are documented at one Pacific site extremely proximal to the G-OJP, but not in Arctic, Tethyan or Atlantic records. This pattern highlights significant G-OJP volcanism during the onset of OAE 1a, and re-emphasises the limited potential for submarine LIP eruptions to cause Hg-cycle perturbations except in areas very proximal to source. The absence of clear Hg peaks in basal OAE 1a strata from the Arctic (or anywhere outside of the Pacific) does not support intense HALIP activity at that time, suggesting that the G-OJP was the more volcanically active LIP when OAE 1a commenced. Thus, G-OJP emissions of mantle carbon were more likely to have played a major role in initiating OAE 1a than thermogenic volatiles associated with the HALIP. A transient pulse of HALIP-related subaerial eruptions and/or thermogenic volatile emissions during the early–middle part of OAE 1a, potentially evidenced by more widespread Hg enrichments in strata from that time (including in the Arctic), might have prolonged the event. However, a non-volcanic cause of these later Hg influxes cannot be excluded. These findings challenge previous suggestions that magmatic CO₂ emissions from LIPs were incapable of causing major carbon-cycle perturbations alone, and highlight the need for further investigations to establish whether the high volume/emplacement rate of the G-OJP (potentially an order of magnitude greater than other LIPs) made it a unique case that stands in contrast to other provinces where the role of thermogenic volatiles was likely more crucial.

大型火成岩省（LIP）火山活动已被提出，是致远生代永旺期间若干主要气候和环境扰动的关键触发因素。人们广泛认为，与大安通-爪哇高原（G-OJP）岩浆脱气和高北极LIP（HALIP）基岩侵入富含有机物的沉积物中的一种或两种相关的大规模碳排放是早发的触发因素。 Aptian海洋缺氧事件（OAE 1a：〜120 Ma）。但是，两个LIPs和相关碳源在引发这场危机中的各自作用仍存在争议。在这里，我们研究了来自太平洋，特提斯，北极和南大西洋领域的六种OAE 1a记录，将汞（Hg）浓度和--（Os-）同位素比结合起来作为LIP活性的代表。连同以前发布的数据集，结果表明，OAE 1a期间LIP活性的全球一致Os同位素证据，但地层汞趋势存在地理差异。与Os同位素的LIP活性相匹配的清晰的汞富集，并表明在OAE 1a发作期间发生了Hg循环扰动，这是在距G-OJP最近的一个太平洋站点记录的，但在北极，特提斯或大西洋记录中却没有。这种模式凸显了OAE 1a爆发期间的重大G-OJP火山活动，并再次强调了海底LIP爆发引起Hg周期扰动的潜力有限，除非在源头附近。北极（或太平洋以外的任何地方）的原始OAE 1a地层中没有清晰的Hg峰值，这不支持当时的HALIP活跃活动，这表明，当OAE 1a开始时，G-OJP是更具火山活性的LIP。因此，地幔碳的G-OJP排放比起与HALIP相关的热挥发物更可能在引发OAE 1a中起主要作用。在OAE 1a的早期至中部，HALIP相关的空中喷发和/或热源性挥发性排放物的瞬态脉冲可能从那时起（包括北极地区）地层中的Hg富集更加广泛而得到证实。但是，不能排除这些后来的Hg涌入的非火山成因。这些发现挑战了以前的岩浆CO的建议。在OAE 1a的早期至中部，HALIP相关的空中喷发和/或热源性挥发性排放物的瞬态脉冲可能从那时起（包括北极地区）地层中的Hg富集更加广泛而得到证实。但是，不能排除这些后来的Hg涌入的非火山成因。这些发现挑战了以前的岩浆CO的建议。在OAE 1a的早期至中部，HALIP相关的空中喷发和/或热源性挥发性排放物的瞬态脉冲可能从那时起（包括北极地区）地层中的Hg富集更加广泛而得到证实。但是，不能排除这些后来的Hg涌入的非火山成因。这些发现挑战了以前的岩浆CO的建议。₂ LIPs的排放无法单独导致主要的碳循环扰动，并强调需要进一步研究以确定G-OJP的高体积/放置率（可能比其他LIPs高一个数量级）是否使其成为与其他省份不同的是，独特的案例与其他省份不同，在这些省份中，致热挥发物的作用可能更为关键。