The Paleocene to Early Eocene Faroe Islands Basalt Group (FIBG) comprises a c. 6.5-km-thick lava flow–dominated sequence located within the centre of the North Atlantic Igneous Province (NAIP). The currently defined pre-breakup and syn-breakup sequences of the FIBG are separated by a significant volcanic hiatus, during which time the coal-bearing Prestfjall Formation was deposited. This major volcanic hiatus is identified across large parts of the NAIP and was preceded on the Faroe Islands by a reduction in eruption rate evidenced by an increased number and thickness of inter-lava sedimentary beds between the simple lava flows of the pre-breakup Beinisvørd Formation. High tempo eruptions resumed after this hiatus with the development of the compound lava flow fields of the Malinstindur Formation which reveal limited evidence for inter-lava breaks. In order to investigate this key transition, flow by flow geochemical sampling of a composite c.1.1-km-thick lava flow sequence spanning this transition were collected and analysed. Three chemically distinct groups are defined based on rare earth elements (REEs) and incompatible trace element signatures. Two high-Ti groups (TiO2 > 2 wt%), B2 and B3, dominate the sampled Beinisvørd Formation and display light REE-enriched signatures (La/YbN c. 2.9–5.9) and evidence for garnet in the source melting region (Dy/YbN c. 1.5–1.6). At the very top of the Beinisvørd Formation, a distinct group of lava flows, B1, displaying lower TiO2 for a given MgO wt% (TiO2 c. 1–2 wt%), weakly light REE-enriched profiles (La/YbN c. 1.7–2.4) and a spinel-dominated mantle melting signature (Dy/YbN c. 1.1–1.2) is identified. Sr, Nd and Pb isotopic signatures for the three groups overlap, revealing limited evidence of crustal contamination, and therefore supporting a mantle melting origin for inter-group variations, rather than source composition or contamination. The group B1 lava flows form a unique stratigraphic occurrence on the islands and provide clear evidence for both a reduction in the initial pressure of melting, alongside an increase in the overall degree of partial melting relative to groups B2 and B3. Increased partial melting is interpreted as evidence for the early onset of rifting and lithospheric thinning to the north of the Faroe Islands. The accompanying reduction in initial pressure of melting provides the first petrological evidence that a transient reduction in mantle temperature leads to the province-wide volcanic hiatus. Our study demonstrates an intimate linkage between rifting history and fluctuations in mantle temperature highlighting that any over-arching model for the evolution of the NAIP must take both into equal account.

中文翻译：

---

瞬态地幔冷却与北大西洋火成岩省的区域火山关闭和早期裂谷有关

古新世至早始新世法罗群岛玄武岩群 (FIBG) 包括一个 c。位于北大西洋火成岩省 (NAIP) 中心的 6.5 公里厚的熔岩流主导的序列。当前定义的 FIBG 的预破碎和同向破碎序列被一个显着的火山间隙隔开，在此期间沉积了含煤的 Prestfjall 地层。在 NAIP 的大部分地区都发现了这一主要的火山中断，并且在法罗群岛之前，火山喷发率下降，这证明了在崩解前贝尼斯弗德地层的简单熔岩流之间熔岩间沉积层的数量和厚度增加. 随着 Malinstindur 组复合熔岩流场的发展，在这次中断之后，高速喷发重新开始，这揭示了熔岩间破裂的有限证据。为了研究这一关键转变，我们收集并分析了跨越该转变的复合 c.1.1 公里厚熔岩流序列的逐流地球化学采样。根据稀土元素 (REE) 和不相容的微量元素特征，定义了三个不同的化学组。两个高钛基团（TiO2 > 2 wt%），B2 和 B3，在采样的贝尼斯沃德地层中占主导地位，并显示出富含 REE 的轻特征（La/YbN c. 2.9-5.9）和源熔融区石榴石的证据（Dy /YbN c. 1.5–1.6）。在 Benisvørd 地层的最顶部，一组独特的熔岩流 B1 显示出给定 MgO wt% (TiO2 c. 1-2 wt%) 较低的 TiO2，富含 REE 的弱光剖面 (La/YbN c. 1.7-2.4) 并确定了以尖晶石为主的地幔熔融特征 (Dy/YbN c. 1.1-1.2)。先生，这三组的 Nd 和 Pb 同位素特征重叠，揭示了地壳污染的有限证据，因此支持组间变化的地幔熔融起源，而不是源组成或污染。B1 组熔岩流在岛上形成了一个独特的地层，并为初始熔化压力的降低以及相对于 B2 和 B3 组的整体部分熔化程度的增加提供了明确的证据。部分融化的增加被解释为法罗群岛北部早期裂谷和岩石圈变薄的证据。伴随着熔融初始压力的降低提供了第一个岩石学证据，表明地幔温度的短暂降低导致了全省范围的火山中断。