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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Hotspot activity and plume pulses recorded by geometry of spreading axes
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Hotspot activity and plume pulses recorded by geometry of spreading axes

机译：通过扩展轴的几何形状记录的热点活动和羽流脉冲

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摘要

Anomalous plan view geometry (planform) of spreading axes is shown to be a faithful indicator of hotspot influence, possibly capable of detecting pulses of hotspot discharge. A planform anomaly (PA) occurs when the orientation of second-order ridge segments is prominently oblique to the spreading direction. PA is found in the vicinity of hotspots at shallow ridges (<1.5 km), suggesting hotspot influence. In places the PA and shallow bathymetry are accompanied by geochemical anomalies, corroborating hotspot influence. This linkage is best expressed in the western Gulf of Aden, where the extent of the PA from the Afar hotspot coincides with the extent of La/Sm and Sr isotopic anomalies. Using fracture mechanics we predict PA to reflect overpressurized melt that dominates the stresses in the crust, consistent with hotspot regime. Accordingly, the temporal variations of the planform previously inferred from magnetic anomalies around the Kolbeinsey Ridge (KR), north of Iceland, record episodes of interaction with the hotspot and major pulses of the plume. This suggestion is corroborated by temporal correlation of episodes showing PA north of Iceland with plume pulses previously inferred by the V-shaped ridges around the Reykjanes Ridge (RR), south of Iceland. In contrast to the RR, the temporal correlation suggests simultaneous incidence of the plume pulses at Iceland and KR, hundreds of kilometers to the north. A deep northward branch of the Iceland plume active during pulse-periods may explain these observations.
机译：扩展轴的异常平面图几何形状（平面图）显示为热点影响的忠实指示符，可能能够检测到热点放电脉冲。当二阶脊段的方向明显偏离扩展方向时，就会发生平面异常（PA）。在浅脊（<1.5 km）的热点附近发现了PA，表明该热点有影响。在某些地方，PA和浅测深仪伴有地球化学异常，证实了热点影响。这种联系最能体现在亚丁湾西部，那里来自阿法尔热点的PA的范围与La / Sm和Sr同位素异常的范围一致。使用断裂力学，我们预测PA反映出主导地壳应力的过高压力熔体，这与热点区域一致。因此，先前根据冰岛北部Kolbeinsey Ridge（KR）周围的磁异常推断出的平面图的时间变化记录了与热点相互作用和羽流的主要脉动。冰岛北部的PA与冰岛南部Reykjanes岭（RR）周围的V形山脊先前推断出的羽状脉动的时间相关性，证实了这一建议。与RR相比，时间相关性表明在北距数百公里的冰岛和KR，羽流脉冲同时发生。在脉冲期间活跃的冰岛羽状深部北分支可能解释了这些现象。

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