Influence of orbital parameters on Pleistocene loess deposition in central Alaska
Influence of orbital parameters on Pleistocene loess deposition in central Alaska
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DOI：
10.1038/337151a0
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发表时间：
1989
期刊：
影响因子：
64.8
通讯作者：
J. Beget;D. Hawkins
中科院分区：
文献类型：
--
作者：
J. Beget;D. Hawkins
从陆地上获得的长期气候记录很少。在海洋岩芯中发现的更新世气候变化的同位素记录反映了由于地球轨道几何形状的变化而导致的世界范围内的冰量和温度变化。可与之相比的陆地记录很少。黄土(风积的淤泥)可能是最接近海洋沉积物的陆地类似物，因为两者都是由细粒沉积物的或多或少的连续沉积造成的。在这里，我们检验了黄土剖面磁化率变化反映气候强迫的假设。我们在统计上测试了记录过去25万年BP的高精度、轨道调谐的海洋氧同位素曲线与阿拉斯加中部一段厚黄土的磁化率剖面之间的相互关系。高度显著的相关性(P>；0.0001)表明，北极黄土在间冰期早期形成了坚厚的古土壤，对应于同位素第7和第5阶段。较薄的土壤形成于第7阶段和第3阶段的间歇性事件。黄土数据的自相关和时间序列分析显示，光谱峰值位于125,000，41,000和23,000年BP，首次表明陆地轨道周期影响并被记录在高纬度陆地风沙沉积的替代气候数据中。
Few long proxy climatic records are available from terrestrial locations. The isotope records of Pleistocene climate change found in marine cores reflect worldwide ice-volume and temperature changes forced by variations in the Earth's orbital geometry. Comparable terrestrial records are rare. Loess (wind-deposited silt) is perhaps the closest terrestrial analogue to marine sediments in that both result from more-or-less continuous deposition of fine-grained sediment. Here we examine the hypothesis that mag-netic susceptibility variations through loess sections reflect climate forcing. We statistically tested cross-correlations between high-precision, orbitally tuned marine oxygen isotope curves recording the past 250,000 yr BP, and magnetic susceptibility profiles through a thick loess section in central Alaska. Highly significant (P> 0.0001) correlations indicate strong, thick palaeosols formed in Arctic loess during early parts of interglacial periods correspond-ing to isotope stages 7 and 5. Thinner soils formed during interstadial events corresponding to early stage 7 and stage 3. Autocorrelation and time-series analysis of the loess data show spectral peaks at 125,000, 41,000 and 23,000 yr BP, showing for the first time that terrestrial orbital periodicities influenced and are recorded in proxy climatic data from terrestrial aeolian deposits at high latitudes.