New geochronologic and paleomagnetic data from the North American Midcontinent Rift (MCR) reveal the synchronous emplacement of the Beaver River diabase, the anorthosite xenoliths within it, and the Greenstone Flow—one of the largest lava flows on Earth. A U-Pb zircon date of 1091.83  0.21 Ma (2) from one of the anorthosite xenoliths is consistent with the anorthosite cumulate forming as part of the MCR and provides a maximum age constraint for the Beaver River diabase. Paired with the minimum age constraint of a cross-cutting Silver Bay intrusion (1091.61  0.14 Ma; 2), these data tightly bracket the age of the Beaver River diabase to be 1091.7  0.2 Ma (95% CI), coeval with the eruption of the Greenstone Flow (1091.59  0.27 Ma; 2)—which is further supported by indistinguishable tilt-corrected paleomagnetic pole positions. Geochronological, paleomagnetic, mineralogical and geochemical data are consistent with a hypothesis that the Beaver River diabase was the feeder system for the Greenstone Flow. The large areal extent of the intrusives and large estimated volume of the volcanics suggest that they represent a rapid and voluminous ca. 1,092 Ma magmatic pulse near the end of the main stage of MCR magmatism.

中文翻译：

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含斜长岩捕虏体的海狸河辉绿岩和地球上最大的熔岩流之一的同步就位

来自北美中部大陆裂谷 (MCR) 的新地质年代学和古地磁数据揭示了海狸河辉绿岩、其中的斜长岩捕虏体和绿岩流（地球上最大的熔岩流之一）的同步侵位。来自其中一个斜长岩包体的 U-Pb 锆石日期为 1091.83   0.21 Ma (2 ) 与作为 MCR 一部分的斜长岩累积形成一致，并为 Beaver River 辉绿岩提供了最大年龄限制。与横断面银湾侵入体的最小年龄限制 (1091.61   0.14 Ma; 2 ) 相结合，这些数据将 Beaver River 辉绿岩的年龄严格限定为 1091.7   0.2 Ma (95% CI)，与火山喷发同时期绿石流 (1091.59   0.27 Ma; 2)——这得到了难以区分的倾斜校正古地磁极位置的进一步支持。地质年代学、古地磁、矿物学和地球化学数据与海狸河辉绿岩是绿岩流的供给系统的假设一致。侵入岩的大面积范围和火山岩的大估计体积表明它们代表了一个快速而庞大的约。1,092 Ma 岩浆脉冲，接近 MCR 岩浆活动主阶段末期。