达索普冰川海拔7100m处气泡封闭过程研究

A Study on the Air-Bubble Formation Process at Altitude of 7 100 m a.s.l. in the Dasuopu Glacier

通过对希夏邦马峰北坡达索普冰川气泡形成过程的研究表明，随着深度增加，粒雪中开放气孔体积逐渐减小，但粒雪层仍保持良好的气体渗透性，直到粒雪一冰转变层位开放气孔完全与大气隔离，形成彼此分离的孤立气泡．显然，冰内气泡包裹气体与同层位的冰存在年龄差，只有在气孔完全封闭后，气泡封闭的深度亦不相同，但气泡封闭处对应的密度都大致相当，为079～0．83Mg·m－3．达索普冰川粒雪层中开放气孔在40～47m深度范围内快速封闭，在45m处有50％的气泡形成计算得出气泡中气体与同层位冰的年龄差为59a，同层位气泡中的气体所代表的主体年代分配范围为11a．

The air-bubble formation process has been studied experimentally on the Dasuopu ice core from the northern slope of Mount Xixabangma. It is found that air-channel volumes decrease gradully as the depth increase, but the firn remains permeable in the depth above the horizon of firn transiting to ice.At the transition depth the air-channels are closed off to be isolated bubbles. Apparently, there exist age difference between air trapped in bubbles and surrounding ice. only after the air-channels are closed off completely, the age of the air increases with the surrounding ice in the same rate. Air-bubble formed in different depth at different sites depending on accumulation rate and mean annual temperature, but at the same mean density of 0.79 ~ 0.83 Mg. m-3. The air-channel in Dasuopu firn core closed rapidly in the depth of 40~47 m. There is 50% air-bubble formed in the depth of 45 m. It is caculated that the age difference between air and surrounding ice is 59 a, and the bulk age range of air trapped in ice bubbles is 11 a.