Pleistocene Glaciations in Qinghai-Tibet Plateau Explanation with Astroclimatology
Xu Qingqi(Institute of Vertebrate Paleontology and Paleoanthropology Academia Sinica)
There are three ice ages in Qinghai-Tibet Plateau during Pleistocene. The last glacial period (Baiyu) is correlated with oxygen isotope Stages 2-4 or Weichsel in Northern Europe, the penultimate (Guxiang) corresponds to Stage 6 or Warthe and the earliest one (Nieniexiongla) is correlative with Stages 14 and 16, or Mindel of the Alps, or Saale and Elst-er in Northern Europe. The period between Guxiang and Nieniexiongla is the Great Interglacial (Jiabula). Moraines of the Nieniexiongla glacial had undergone considerably long period (the Great Interglacial) of weathering, which turned them red in color.The average incoming solar radiation in the winter half-year of the northern hemisphere on the earth's surface in each oxygen isotope stage (Di) was calculated (Table 1). We get Xi in the similar way. We found that the relationship between Di and the temperature in the world is roughly in positive correlation. Table 1 shows that D16(457.27 ly/day), D14(457.84), D6(458.09) and D2-4(458.84) are much less than that of the other stages. Among these four stages, the older the stage (the less incoming solar radiation) is, the colder the climate and the larger the glacier. The Great Interglacial (Stages 7- 13), the absolute values of D7, D9, D13 are larger than that of D5, is much longer and warmer than the last interglacial. We ar-gue that the cold stage does not necessarily represent the glacial. The galcial is the outstanding cold stage only. While the intergalcial is not necessarily equal to the warm stage. The intergalcial may include not only the warm stages, but also some cold stages. Foe example, the Great Interglacial in Qinghai-Tibet Plateau includes 4 warm stages (Stages 7,9, 11, 13) and 3 cold stages (Stages 8, 10, 12).In short, the major climate fluctuations in the Qinghai-Tibet plateau are caused by variations of the incoming solar radiation that are caused by slow changes in the geometry of the eargh's orbit that occur in response to predictable changes in the gravitational field experienced by the Earth.