Global mass wasting at continental margins during Ordovician high meteorite influx
Global mass wasting at continental margins during Ordovician high meteorite influx
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DOI：
10.1038/ngeo386
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发表时间：
2009
影响因子：
18.3
通讯作者：
J. Parnell
中科院分区：
文献类型：
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作者：
J. Parnell
大量证据表明，中奥陶纪时期（约 4.7 亿年前）小行星发生了分裂，并向地球快速输送了陨石，最引人注目的是在瑞典富含陨石的地层中记录的。,,,,。单一地点的大量陨石，跨越相对较短的时间间隔，意味着陨石通量比目前大两个数量级。我在这里调查公布的数据表明，中奥陶世沉积巨型角砾岩（由分散在精细基质中的大型岩石碎片组成）的沉积与高陨石通量一致。此类沉积物的广泛分布反映了全球范围内大陆边缘沉积物和岩石的下坡运动。我的计算表明，这一过程可能是由地震活动和陨石大量涌入造成的沉积物斜坡不稳定引发的。如果是这样，地质记录中巨型角砾岩的异常出现可能会为其他增强陨石向地球输送的事件提供证据。
A large body of evidence exists for the break-up of an asteroid in the Middle Ordovician period (around 470 million years ago) and the rapid delivery of meteorites to the Earth, most notably recorded in meteorite-rich strata in Sweden,,,,,. The large number of meteorites at a single locality, spanning a relatively short time interval, implies a meteorite flux two orders of magnitude greater than at present. Here I survey published data to show that the deposition of Middle Ordovician sedimentary megabreccias—consisting of large rock fragments dispersed in a fine matrix—was coincident with the high meteorite flux. The widespread distribution of such deposits reflects downslope movement of sediment and rock at continental margins on a global scale. My calculations show that this process could have been triggered by the seismic activity and destabilization of sediment slopes resulting from the high influx of meteorites. If so, the anomalous occurrence of megabreccias in the geological record may provide evidence for other episodes of enhanced meteorite delivery to the Earth.