2.50MaB.P.的地质事件与全球变化的关系

本文初步总结了2.50MaB.P.青藏高原隆升等构造运动、黄土的出现、哺乳动物群不连续、微玻璃陨石的出现、植被的演变、某些陆相介形虫绝灭等中国的地质事件,并归纳了此时全球范围内地质事件的报道。海、陆环境中这些地质事件的发生不仅与地球的内动力过程,亦与其外动力过程有关。影响大气环流的各种因子在当时可能皆发生程度不同的变化。2.50MaB.P.的地质事件,可以说是整个日-地系统急剧变化的表现。

THE RELATIONSHIP BETWEEN THE GEOLOGICAL EVENTS AT 2.50 Ma B.P.AND GLOBAL CHANGE

The present paper summarized preliminarily the geological events at 2.50 Ma B.P.inChina.These events include the following:the Qinghai-Xizang (Tibet) Plateau was upliftingas the Indian Plate was underthrusting the Eurasian one,i.e.the start of the 4th Episode ofHymalaya Movement at the same time,the Sanggan-Fenwei fault depression zone in NorthChina and the Tan (cheng)-Lu(jiang) fault system in East China,which all have a trend ofNNE direction,were rising as the extruding effects of North America Plate,the stratigraphichiatus with different degrees occurred on the marginal areas of the two tectonic units;theloess accumulation had occurred;up to now the mammalian fauna of 2.50—1.80 Ma B.P.havenot been determined in north China,it seems to be that there was a discontinued fauna sequen-ce;microclass-aerolite occurred near the boundary between loess and Pliocene red soil in Luo-chuan section of Shaanxi Provinces as well as the horizons of the same time at the boreholes inthe eastern plain of Beijing,it appears that there was the occurrence of astronomical activity;in the northern part of Huaihe River Plain of Anhui Province,the juncture area of the nor-thern and southern climatic zones in China,as well as the Yanqing Basin,Beijing,at 2.50 MaB.P.the pollen of subtropical vegetation increased abruptly;in the terrestrial ostracod faunaCyprinotus formalis Schneider and Ilyocypris qingxuensis Wang disappeared for non-ecologi-cal reason.In the world at this time the paleo-oceanological situation have many changes andthe vegetation,mammalian fauna and tectonic movement also have great changes in manyareas.The thermal system in the world came to the phase with short period (100000—150000a) oscillation.From the long geological cycle it can be seen that the climatic situation since 2.50 Ma B.P.might be the inevitable outcome in the evolutional process of the Earth;from the short geolo-gical cycle it can be seen that the geological events at 2.50 Ma B.P.are the outcome of platemovement,change of magnetic field and geoid change.But the determination of energy sys-tem can only be obtainel from the solar system.According to the astronomical principle it canbe convinced that there are many factors affecting the atmosphere circulation.At the westerlyin the North Hemisphere the distribution of the average troughs and ridges might have formedat 2.50 Ma B.P.,providing a base for the formation of monsoon;as in the lacustric,glacialand loess sequences it had been determined that the climatic change was related with the solarradiation,so that it has been convinced that the Earth's track had changed.The cycle,seasonand tensile angle of the Planetary Synod also play important role for the time,cycle andrange of the temperature changes.The geological events at 2.50 Ma B.P.marked the Earth had come to a phase when the re-lationship between the Earth and the Solar became closer;frequent changes with large ampli-tude is the reflection of the frequent changes of the entire Solar-Earth system.