晚新生代气候变化特征与第四纪下限

第四纪下限问题争论不休的原因,在于缺乏一个在全球范固内适用的原则与标准。如果把“晚新生代地球上频繁而剧烈的冰期/间冰期气候波动的开始”,作为第四纪下限的标志,则在全球范围内具有普遍的适用性。来自世界各地的各种气候指标,表明晚新生代地球上频繁而剧烈的冰期/间冰期气候波动,开始于距今260—240万年前。因此,第四纪下限放在距今260—240万年前。是比较合适的。

CLIMATIC CHANGES OF LATE CENOZOIC AND LOWER BOUNDARY OF QUATERNARY

There is a long argument on the lower boundary of Quaternary due to lacking of a universal standard to determine the boundary. The author gives his opinions on standards which have been commonly used. Each of the standards has its own limitations. And the most probable one is the "beginning of frequent and rapid (glacial/interglacial) climatic fluctuations in late Cenozoic." The author thinks this standard the most suitable to the lower boundary of Quaternary. Paleoclimatic records from various parts of the world indicate that this kind of climatic fluctuation started at about 2.5ma B. P.(2.6-2.4ma B.P.), so the lower boundary of Quaternary should be 2.6-2.4ma B.P. in age. This bou ndary also corresponds to obvious turning points of palaeontological evolutions and geomagnetic changes, and thus can be easily accepted.