普若岗日冰原毗邻地区风沙地貌及其环境演变

Aeolian Geomorphology and Environmental Evolution Around Puruogangri Ice Field, Tibetan Plateau

冰川作用形成的大面积的冰碛物沉积及寒冻风化是高寒区风沙沉积的主要物质来源 .风沙地貌的发育与高寒区环境密切相关 ,冻结作用使沙丘发育以加积作用为主 ,形成了高大的新月形沙丘 .沙丘的侵蚀与移动主要发生在暖季 ,新月形沙丘运动速度相当缓慢 ,年平均水平移动量约 1 .8～ 0 .5cm·a- 1 ,加积速率约 0 .3～ 0 .0 8cm·a- 1 .普若岗日冰原毗邻地区的环境变化主要受温度条件制约 ,沙丘腐殖质层沉积年代与我国东部沙区古沙丘、敦德冰芯具有一定的相关性 ,可以认为西南季风的强度对本区具有重要的作用 .高原下垫面的变化造成太阳辐射差异 ,是引起西南季风强弱 ,造成高原腹地温度与降水随之变化的重要原因 .

Glacial abrasion, vast moraine deposits due to glacial retreat and frigid weather provide a mass of material for Aeolian deposits in the high and cold regions. Aeolian geomorphologic development is closely relating to high and cold environments. Dunes develop mainly in aggradation form because of congelation, resulting in huge crescent dunes. Migration and erosion of dunes mainly occurs in warm season. Migration of crescent dunes is very slow, with mean annual velocity of about 1.8 ～ 0.5 cm·a -1 , together with aggradation rate of about 0.3 ～ 0.08 cm·a -1 . Environmental evolution around the Purogangri Ice Field mainly depends on temperature condition. The dating of dune humus has a certain degree relation with the dating of ancient dunes in eastern deserts in China and the dating of Dunde Ice Core. So it can be seen that the intensity of southwest monsoon plays a very important role in this region. In view of formation mechanism of monsoon, change in underlying surface of the plateau results in difference in radiation, which is an important factor for the intensity of southwest monsoon and the change of temperature and precipitation in the hinterland of the plateau.