The Duluth Complex is one of the largest mafic intrusive complexes on Earth. It was emplaced as the Midcontinent Rift developed in Laurentia’s interior during an interval of magmatism and extension from ca. 1109 to 1084 Ma. This duration of magmatic activity is more protracted than is typical for large igneous provinces interpreted to have formed from decompression melting of upwelling mantle plumes. While the overall duration was protracted, there were intervals of more voluminous magmatism. New 206Pb/238U zircon dates for the anorthositic and layered series of the Duluth Complex constrain these units to have been emplaced ca. 1096 Ma in less than one million years (duration of 500,000 ± 260,000 years). Comparison of paleomagnetic data from these units with Laurentia’s apparent polar wander path supports this interpretation. This rapid emplacement bears similarities to the geologically short duration of well-dated large igneous provinces. These data support hypotheses that call upon the co-location of lithospheric extension and anomalously hot upwelling mantle. This rapid magmatic pulse occurred more than 10 million years after initial magmatism following more than 20◦ of latitudinal plate motion. A likely scenario is one in which upwelling mantle encountered the base of Laurentian lithosphere and flowed via “upside-down drainage” to locally thinned lithosphere of the Midcontinent Rift. Swanson-Hysell et al., Geology, doi:10.1130/G47873.1 2

中文翻译：

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北美中大陆裂谷内大规模德卢斯复合体侵入体的快速进驻

德卢斯复合体是地球上最大的镁铁质侵入复合体之一。它是在 Laurentia 内部形成的中大陆裂谷在岩浆作用和从大约 10 年的延伸期间形成的。1109 至 1084 马。这种岩浆活动的持续时间比被解释为由上升流地幔柱的减压熔化形成的大型火成岩省的典型持续时间更长。虽然总持续时间延长，但有大量岩浆活动的间隔。德卢斯杂岩斜长岩和层状系列的新 206Pb/238U 锆石年代限制了这些单元已被安置在大约 1096 Ma 不到一百万年（持续时间为 500,000 ± 260,000 年）。将这些单元的古地磁数据与 Laurentia 的明显极地漂移路径进行比较，支持这种解释。这种快速的就位与年代久远的大型火成岩省在地质上的持续时间很短有相似之处。这些数据支持了岩石圈伸展与异常热的上涌地幔共同定位的假设。这种快速的岩浆脉冲发生在 20 度纬度板块运动之后的初始岩浆活动之后 1000 万年以上。一种可能的情况是，上升流地幔遇到劳伦岩石圈的底部，并通过“倒置排水”流入中大陆裂谷局部变薄的岩石圈。Swanson-Hysell 等人，地质学，doi:10.1130/G47873.1 2 这种快速的岩浆脉冲发生在超过 20° 的纬度板块运动之后的初始岩浆活动之后的 1000 万年以上。一种可能的情况是，上升流地幔遇到劳伦岩石圈的底部，并通过“倒置排水”流入中大陆裂谷局部变薄的岩石圈。Swanson-Hysell 等人，地质学，doi:10.1130/G47873.1 2 这种快速的岩浆脉冲发生在 20 度纬度板块运动之后的初始岩浆活动之后 1000 万年以上。一种可能的情况是，上升流地幔遇到劳伦岩石圈的底部，并通过“倒置排水”流入中大陆裂谷局部变薄的岩石圈。Swanson-Hysell 等人，地质学，doi:10.1130/G47873.1 2