Geologic record of partial ocean evaporation triggered by giant asteroid impacts, 3.29–3.23 billion years ago
Geologic record of partial ocean evaporation triggered by giant asteroid impacts, 3.29–3.23 billion years ago
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3.29-32.3亿年前巨型小行星撞击引发的部分海洋蒸发的地质记录
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
G. Byerly
中科院分区：
文献类型：
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作者：
D. Lowe;G. Byerly
虽然月球研究表明，在3.8-3.7 Ga时，内太阳系中的大型小行星撞击率下降到目前的低水平，但最近对绿岩带的研究表明，直径为20公里至70公里以上的小行星在3.2 Ga时仍在撞击地球，其撞击率大大高于月球研究的估计值。我们在这里提出的地质证据表明，这些陆地上的两个影响，在3.29 Ga和3.23 Ga，造成地球大气加热，海洋表面沸腾，蒸发几十米，也许100米的海水。快速的海洋蒸发导致海平面突然下降，暴露的海底受到侵蚀，并沉淀出代表海洋硅质烧结物的独特的层状二氧化硅层。这些事件会严重影响微生物群落，特别是浅水和光合生物。这些巨大的撞击深刻地影响了太古代地壳的发展，地表环境和生物进化，直到3.2 Ga，甚至更晚。
Although lunar studies suggest that large asteroid impact rates in the inner solar system declined to their present low levels at 3.8–3.7 Ga, recent studies in greenstone belts indicate that asteroids 20 km to 70+ km in diameter were still striking the Earth as late as 3.2 Ga at rates significantly greater than the values estimated from lunar studies. We here present geologic evidence that two of these terrestrial impacts, at 3.29 Ga and 3.23 Ga, caused heating of Earth’s atmosphere, ocean-surface boiling, and evaporation of tens of meters to perhaps 100 m of seawater. Rapid ocean evaporation resulted in abrupt sea-level drops, erosion of the exposed sea floor, and precipitation of distinctive layers of laminated silica representing marine siliceous sinter. Such events would have severely affected microbial communities, especially among shallow-water and photosynthetic organisms. These large impacts profoundly affected Archean crustal development, surface environment, and biological evolution until 3.2 Ga, or even later.