渐新世“雪球事件”的发现及其意义——基于全球冰斗系统的解读与研究

Discovery and Significance of the Oligocene “Snowball Earth” Events—Interpretation and Research Based on Global Cirques System

摘要:

冰斗系统是冰斗作用以山体为载体进行剥蚀作用形成的结果，其在山体上形成的以缩口、三角脊、残弧等为代表的冰斗遗迹很难被后期的风化作用所消解，因此冰斗系统在解读古冰川作用中具有极为重要的意义。在对全球冰斗系统进行研究的过程中，发现了雪球事件，根据深海沉积物研究获得的环境变化信息，初步确定最近的一次雪球事件发生在渐新世，也即33.7~23.8Ma之间。研究发现雪球事件发生时，全球仅在赤道附近形成了4处陆生生物避难区，分别为刚果盆地、亚马逊盆地、阿拉弗拉海以及新加坡东部海域。研究认为，渐新世雪球事件塑造的冰斗地貌，是全球现代山区地貌的本底与基础。

Abstract:

Cirques system is the result of denudation which takes mountain as a carrier by cirques action. The cirques relics it formed such as Cirques system Entrance, Triangular Ridge and Around Eluvium are hard to be eliminated by subsequent weathering. Therefore, the cirques system is of important significance in interpreting the ancient glaciation. Based on the research of the global cirques system, “Snowball Earth” events have been found. Based on the environmental change information obtained from deep-sea sediment study. It is preliminarily determined that the latest snowball event occurred in the Oligocene, that is 33.7~23.8Ma. It is found that during the “Snowball Earth” events , only four terrestrial biological refuge areas have been formed around the equator, including the Congo basin, the Amazon basin, the Arafura Sea and the southeast seas of Singapore. According to the study, the cirques landform formed by the “Snowball Earth” events in the Oligocene is the basic form of the modern mountain landscape in the world.