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The Southwestern Laurentia large igneous province (SWLLIP) comprises voluminous, widespread ca 1.1 Ga magmatism in the southwestern United States and northern Mexico. The timing and tempo of SWLLIP magmatism and its relationship to other late Mesoproterozoic igneous provinces have been unclear due to difficulties in dating mafic rocks at high precision. New precise U-Pb zircon dates for comagmatic felsic segregations within mafic rocks reveal distinct magmatic episodes at ca. 1098 Ma (represented by massive sills in Death Valley, California, the Grand Canyon, and central Arizona) and ca. 1083 Ma (represented by the Cardenas Basalts in the Grand Canyon and a sill in the Dead Mountains, California). The ca. 1098 Ma magmatic pulse was short-lived, lasting 0.25-0.24 +0.67 m.y., and voluminous and widespread, evidenced by the ≥100 m sills in Death Valley, the Grand Canyon, and central Arizona, consistent with decompression melting of an upwelling mantle plume. The ca. 1083 Ma magmatism may have been generated by a secondary plume pulse or post-plume lithosphere extension. The ca. 1098 Ma pulse of magmatism in southwestern Laurentia occurred ∼2 m.y. prior to an anomalous renewal of voluminous melt generation in the Midcontinent Rift of central Laurentia that is recorded by the ca. 1096 Ma Duluth Complex layered mafic intrusions. Rates of lateral plume spread predicted by mantle plume lubrication theory support a model where a plume derived from the deep mantle impinged near southwestern Laurentia, then spread to thinned Midcontinent Rift lithosphere over ∼2 m.y. to elevate mantle temperatures and generate melt. This geodynamic hypothesis reconciles the close temporal relationships between voluminous magmatism across Laurentia and provides an explanation for that anomalous renewal of high magmatic flux within the protracted magmatic history of the Midcontinent Rift. [ABSTRACT FROM AUTHOR]

The goal of this study was to investigate whole-body kinematic adaptations when running on an unstable, irregular, and compliant surface in comparison to running on asphalt. We hypothesised that the gait pattern (H1) and its stride-to-stride variability (H2) would be affected by the unstable surface but that variability related to some movement features would be reduced over multiple testing days indicative of gait optimisation (H3). Fifteen runners ran on a woodchip and asphalt track on five testing days while their whole-body movements were captured using inertial motion capture and examined using joint angle and principal component analysis. Joint angles and stride-to-stride variability in eight principal running movements were subjected to surface by day analyses of variance. The woodchip track compared to asphalt resulted in (H1) a more crouched gait pattern including more leg flexion and forward trunk lean and (H2) higher stride-to-stride variability in most investigated principal running movements. However, (H3) stride-to-stride variability did not systematically change over testing days. Running on an unstable, irregular, and more compliant surface leads to the adoption a gait pattern and control strategy that are more robust against disturbances caused by the surface but may pose certain risks for overuse injury in trail runners. [ABSTRACT FROM AUTHOR]