Mafic intrusions, lava flows, and felsic plutons in southwestern Laurentia have been hypothesized to be associated with the emplacement of a late Mesoproterozoic (Stenian Period) large igneous province. Improved geochronologic data resolve distinct episodes of mafic magmatism in the region. The ca. 1,098 Ma main pulse of southwestern Laurentia large igneous province (SWLLIP) magmatism is recorded by mafic intrusions across southeastern California to central Arizona. A younger episode of volcanism resulted in eruptions that formed the ca. 1,082 Ma Cardenas Basalt, which is the uppermost unit of the Unkar Group in the Grand Canyon. With the updated geochronological constraints, we develop new paleomagnetic data from mafic sills in the SWLLIP. Overlapping poles between the Death Valley sills and rocks of similar age in the Midcontinent Rift are inconsistent with large-scale Cenozoic vertical axis rotations in Death Valley. We also develop a new paleomagnetic pole from the ca. 1,082 Ma Cardenas Basalt (pole longitude = 183.9°E, pole latitude = 15.9°N, ${\mathrm{A}}_{95}$ = 7.4°, N = 18). The new paleomagnetic data are consistent with the pole path developed from time-equivalent rocks of the Midcontinent Rift, supporting interpretations that changing pole positions are the result of rapid equatorward motion. These data add to the record of Laurentia's rapid motion from ca. 1,110 to 1,080 Ma that culminated in collisional Grenvillian orogenesis and the assembly of Rodinia.

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来自西南部劳伦西亚大火成岩省和卡德纳斯玄武岩脉冲岩浆作用的古地磁记录支持快速的晚中元古代板块运动


据推测，劳伦西亚西南部的镁铁质侵入体、熔岩流和长英质岩体与中元古代晚期（Stenian Period）大型火成岩省的放置有关。改进的地质年代学数据解决了该地区镁铁质岩浆作用的不同事件。劳伦西亚西南部大型火成岩省 （SWLLIP） 岩浆作用约 1,098 马 的主脉冲是由加利福尼亚州东南部到亚利桑那州中部的镁铁质侵入记录的。火山活动的年轻时期导致喷发，形成了大约 1,082 马 Cardenas 玄武岩，这是大峡谷 Unkar 群的最上层单元。根据更新的地质年代学限制，我们从 SWLLIP 中的镁铁质基台中开发了新的古地磁数据。死亡谷基岩与中洲裂谷中相似年龄的岩石之间的重叠极点与死亡谷中大规模新生代垂直轴旋转不一致。我们还从大约 1,082 马卡德纳斯玄武岩中开发了一个新的古磁极（磁极经度 = 183.9°E，磁极纬度 = 15.9° ${\mathrm{N，A}}_{\mathrm{}}$ = 7.4°，N = 18）。新的古地磁数据与从中大陆裂谷的时间等效岩石发育的极路径一致，支持了磁极位置变化是赤道快速运动的结果的解释。这些数据增加了劳伦西亚从约1,110到1,080 马的快速运动记录，最终导致碰撞的格林维尔造山作用和罗迪尼亚的组装。