The Dom João de Castro seamount in the Hirondelle Basin (Azores) is a central volcano on the ultraslow diverging Terceira Rift axis. The combination of structural and geochemical data provides insights into the evolution of central volcanoes in oceanic rift systems above the Azores melting anomaly. The orientation of fault scarps and volcanic structures at D. João de Castro and the adjacent Castro fissure zone indicate that the regional SW-NE extending stress field dominates the morphology of the NW Hirondelle Basin. The regional tectonic stress field controls the crustal melt pathways and leads to dike emplacement along fissure zones and the prevalent eruption of mafic lavas. The occurrence of mafic to felsic lavas at D. João de Castro gives evidence for both a deep and a shallow crustal melt reservoir generating a subordinate local stress field at the seamount. New Sr-Nd-Pb isotope data along with incompatible trace element ratios indicate that D. João de Castro and the Castro Ridges originated from similarly heterogeneous mantle source but did not form simultaneously. Our new model implies that central volcanoes along the Terceira Rift form by the growth of volcanic ridges and transitioned into circular edifices after magmatic systems generate local changes in the regional lithospheric stress field. The geometry of D. João de Castro and other magmatic systems along the Terceira Rift combined with the alkaline nature of the erupted lavas, and the large lithosphere thickness indicates that young oceanic rifts are more similar to continental rifts rather than mid-ocean ridges.

中文翻译：

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超慢裂谷系统中中央火山的演化：来自 D. João de Castro Seamount 的约束，亚速尔群岛

位于 Hirondelle 盆地（亚速尔群岛）的 Dom Joãode Castro 海山是位于特塞拉裂谷超慢分叉轴上的一座中央火山。结构和地球化学数据的结合提供了对亚速尔群岛融化异常上方海洋裂谷系统中中央火山演化的见解。D. Joãode Castro 和邻近的 Castro 裂隙带断层陡坡和火山结构的方向表明区域 SW-NE 延伸应力场主导了 NW Hirondelle 盆地的形态。区域构造应力场控制着地壳熔融路径，导致沿裂隙带的堤防就位和基性熔岩的普遍喷发。D. 镁铁质至长英质熔岩的出现。若昂·德卡斯特罗 (Joãode Castro) 提供了在海山产生次要局部应力场的深层和浅层地壳熔体储层的证据。新的 Sr-Nd-Pb 同位素数据以及不相容的微量元素比率表明 D. Joãode Castro 和 Castro Ridges 起源于类似的异质地幔源，但不是同时形成的。我们的新模型表明，沿特塞拉裂谷的中央火山由火山脊的生长形成，并在岩浆系统对区域岩石圈应力场产生局部变化后转变为圆形建筑物。D. Joãode Castro 和沿特塞拉裂谷的其他岩浆系统的几何形状与喷发熔岩的碱性相结合，