The magma-poor West Iberian Margin (WIM), as part of the Peri-Atlantic alkaline province, records multiple evidence for intra-plate post-rift magmatism. Based on high-resolution multichannel seismic data, this work discusses the presence of large volcanic and intrusive features in the Estremadura Spur, providing evidence for important magmatic activity during the drifting of the continental margin. Our observations reveal distinct voluminous fissure-fed effusive sequences and the details of the 2800 m-high Fontanelas compound volcano, including its external and internal architecture, secondary vents and associated lava flows, all of which were probably extruded at intermediate water depths. Numerous and morphologically diverse sills and sill complexes are also described, attesting to the presence of a Late Cretaceous shallow magmatic plumbing system in the area. Magmatism in this region is interpreted as having occurred during two main pulses and types of activity: (1) Coniacian to lower Campanian(?) age, characterised by fissural and fault-controlled volcanism, which mostly extruded massive lobate/sheet lava flows; and (2) a second voluminous intrusive and extrusive event of mid to late Campanian age, which includes the intrusion of the Estremadura Spur laccolith and the prominent Fontanelas compound volcano with associated dendritic lava flows. The inferred volumes of the first fissure-fed effusive event suggest a large eruption magnitude, comparable to some of the largest historical effusive eruptions. The second magmatic pulse led to the emplacement of discrete clusters of sills and sill complexes, as well as the construction of the ca. 2.8-km-high Fontanelas volcano, suggesting a syn-rift structural inheritance that controlled the location of the Estremadura Spur Intrusion and the Fontanelas volcanic area. Altogether, a total volume of rock exceeding 1.452 km³ is estimated to have been emplaced or extruded in this region in a relatively short period, attesting to the prominence of the magmatism in this sector of the WIM.

中文翻译：

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西伊比利亚边缘中部白垩纪晚期岩浆作用的性质、时间和强度

岩浆贫乏的西伊比利亚边缘 (WIM) 作为环大西洋碱性省的一部分，记录了板块内裂谷后岩浆作用的多个证据。本工作基于高分辨率多道地震资料，讨论了 Estremadura Spur 中存在大型火山和侵入特征，为大陆边缘漂移过程中重要的岩浆活动提供了证据。我们的观察揭示了巨大的裂缝供给的喷液序列和 2800 米高的丰塔拉斯复合火山的细节，包括其外部和内部结构、二级喷口和相关的熔岩流，所有这些都可能在中等水深处被挤压。还描述了许多形态多样的窗台和窗台复合体，证明该地区存在晚白垩世浅层岩浆管道系统。该地区的岩浆活动被解释为发生在两个主要脉冲和活动类型期间：（1）康尼亚纪至坎帕纪（？）年龄，以裂隙和断层控制的火山活动为特征，主要挤出大量叶状/片状熔岩流；(2) 坎帕纪中晚期的第二次大量侵入和喷出事件，其中包括 Estremadura Spur lacolith 和突出的 Fontanelas 复合火山以及相关的树枝状熔岩流的侵入。第一次裂隙注入喷发事件的推断量表明喷发规模很大，与一些历史上最大的喷发喷发相当。第二次岩浆脉冲导致了离散的窗台和窗台复合体群的就位，以及ca的建设。2.8 公里高的 Fontanelas 火山，表明同裂谷构造继承控制了 Estremadura Spur Intrusion 和 Fontanelas 火山区的位置。岩石总体积超过 1.452 公里^{估计3 号}在相对较短的时间内在该地区就位或挤压，证明了 WIM 该部门的岩浆作用的突出。