南极亚极地冰缘环境中分选环形成机制的观测与研究

FIELD OBSERVATION AND RESEARCH OF SORTED CIRCLE MECHANISM IN SUBANTARCTICA PERIGLACIAL ENVIRONMENT, ANTARICA

南极亚极地冰缘环境中分选环边缘砾石砾径与其斜度坡度呈正相关,可用y=-5.0606+1.42828x表示。若砾径小于15厘米时符合y=-6.15778+1.56273x方程,大于15厘米时则符合v=-17.1913+1.97643x,说明当分选环边缘砾石砾径大于15厘米时摩擦阻力和砾石间结合力迅速增大。分选环中心表面小砾石运动具有周期性,总的位移是向边缘。中心表层冻胀力比深层大,中心冻胀强,向四周逐渐减小。体积较大的物体受冻胀力影响大。

During the 1989-1990 expedition to the King Geroge Island, Antarctica, we researched the sorted circle which is a pcriglacial phenomenan of widely distribution in the subantarctica environment. The statistics indicate that the relationship between the gravel size of sorted circle edge and slope of ground surface conforms to the y= -5.0606+1.42828x equation and shows positive interrelated. If the edge gravel size is smaller than 15 cm, the relationship between edge gravel size and slope can be showed with y=-6.15778+1.56273x. In this equation range the sorted circles developed well and were superior in numbers. On the contrary, if the edge gravel size is larger than 15 cm, the y=-17.1913+1.97643x can express their relationship, which reflect that the friction drag and the combined force between gravels increase quickly. The small gravels distributed on the surface of sorted circle centre moved to the edge in the freeze-thaw season (the late spring, early summer and late autumn, early winter) and to the centre in thaw season (summer), so it reciprocated cyclically in a year period. The general displacement showed toward the edge. According to the observation of the frost heave, the frost heaving of surface layer is biger than its depth layer in the sorted circle centre. The considerable bodies were got more influence of the frost heave which was stronger in the centre of the sorted circle and reductive to edge gradually.