The Azores Plateau is an active magmatic region in the Central North Atlantic Ocean. In this study, we present a comprehensive data set of major element compositions and ⁸⁷Sr/⁸⁶Sr ratios of pore waters from surface sediments (0–9 mbsf) of the Azores Plateau. Based on distinct geochemical signatures we can separate normal marine from hydrothermally affected sediments. Normal marine sediments can further be differentiated by their ash content. Pore waters of ash rich gravity cores (GCs) do not show any deviations from seawater values except of a minor increase in Sr. In contrast, ash poor GCs generally show a trend for decreasing Ca with increasing depth, accompanied by a minor SO₄ decrease and a more pronounced Sr increase. We suggest that these deviations are caused by processes such as anaerobic oxidation of methane and carbonate recrystallization. At four additional sample locations we observed a decrease in Mg and SO₄ accompanied by a Ca increase in the pore waters, a pattern typical for hydrothermal fluids. The existence of hydrothermal systems in this region are corroborated by multi-channel seismic data, suggesting that sill or dyke intrusions are present in the subsurface close to the core locations. Overall, our observations offer preliminary indications for the existence of submarine hydrothermal systems on the Azores Plateau away from the Mid- Atlantic Ridge.

亚速尔群岛高原是北大西洋中部活跃的岩浆区域。在这项研究中，我们提供了一个主要元素组成的综合数据集，以及亚速尔高原地表沉积物（0-9 mbsf）的孔隙水的⁸⁷ Sr / ⁸⁶ Sr比。根据不同的地球化学特征，我们可以将正常海洋与受热液影响的沉积物分开。正常的海洋沉积物可以通过其灰分进一步区分。富含灰分的重力岩心（GC）的孔隙水与海水值没有任何偏离，只是Sr略有增加。相反，缺乏灰分的GC通常表现出随深度增加而Ca降低的趋势，并伴有少量的SO _4。减少，而Sr增加更为明显。我们认为这些偏差是由甲烷的厌氧氧化和碳酸盐重结晶等过程引起的。在另外四个样品位置，我们观察到Mg和SO ₄的减少，同时孔隙水中的Ca增加，这是热液流体的典型模式。多通道地震数据证实了该地区水热系统的存在，表明在靠近核心位置的地下存在基岩或堤坝侵入。总体而言，我们的观察结果为远离大西洋中脊的亚速尔高原上的海底热液系统提供了初步的指示。