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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >Correlated terrestrial and marine evidence for global climate changes before mass extinction at the Cretaceous–Paleogene boundary
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Correlated terrestrial and marine evidence for global climate changes before mass extinction at the Cretaceous–Paleogene boundary

机译：白垩纪-古生代边界大规模灭绝前全球气候变化的相关陆地和海洋证据

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Terrestrial climates near the time of the end-Cretaceous mass extinction are poorly known, limiting understanding of environmentally driven changes in biodiversity that occurred before bolide impact. We estimate paleotemperatures for the last ≈1.1 million years of the Cretaceous (≈66.6–65.5 million years ago, Ma) by using fossil plants from North Dakota and employ paleomagnetic stratigraphy to correlate the results to foraminiferal paleoclimatic data from four middle- and high-latitude sites. Both plants and foraminifera indicate warming near 66.0 Ma, a warming peak from ≈65.8 to 65.6 Ma, and cooling near 65.6 Ma, suggesting that these were global climate shifts. The warming peak coincides with the immigration of a thermophilic flora, maximum plant diversity, and the poleward range expansion of thermophilic foraminifera. Plant data indicate the continuation of relatively cool temperatures across the Cretaceous–Paleogene boundary; there is no indication of a major warming immediately after the boundary as previously reported. Our temperature proxies correspond well with recent pCO2 data from paleosol carbonate, suggesting a coupling of pCO2 and temperature. To the extent that biodiversity is correlated with temperature, estimates of the severity of end-Cretaceous extinctions that are based on occurrence data from the warming peak are probably inflated, as we illustrate for North Dakota plants. However, our analysis of climate and facies considerations shows that the effects of bolide impact should be regarded as the most significant contributor to these plant extinctions.
机译：白垩纪末大灭绝时的陆地气候知之甚少，这限制了人们对在硼化物撞击之前发生的生物多样性环境驱动变化的了解。我们通过使用北达科他州的化石植物估算白垩纪最后一个约110万年（约66.6-6550万年前，马）的古温度，并利用古地层学将结果与来自四个中高等高位有孔虫的古气候数据相关联纬度网站。植物和有孔虫都显示变暖在66.0 Ma附近，变暖峰从≈65.8Ma到65.6 Ma，冷却在65.6 Ma附近，表明这是全球气候变化。暖峰与嗜热菌群的迁入，最大的植物多样性以及嗜热有孔虫的极向范围扩张相吻合。植物数据表明，整个白垩纪-古生界一直保持着相对凉爽的温度。正如先前报道的那样，没有迹象表明边界之后立即出现了严重的变暖。我们的温度指标与来自古碳酸盐碳酸钙的最新pCO2数据非常吻合，表明pCO2和温度之间存在耦合。就生物多样性与温度相关的程度而言，根据北达科他州植物的情况，根据升温峰值的发生数据估算的白垩纪末期物种灭绝的严重性可能被夸大了。但是，我们对气候和相态因素的分析表明，硼化物撞击的影响应被认为是造成这些植物灭绝的最重要因素。

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