论雷暴风化作用

ON THUNDERSTORM WEATHERING

在位于冀东地区海拔1840多米的都山顶峰,笔者首次发现了雷暴风化作用,并目睹了雷暴风化作用的进行。在都山顶部,发现了雷暴风化砾石堆,分析了雷暴风化作用的物理依据,估算出一次雷暴作用所释放能量的0.07％—0.007％就可使1m^3的花岗岩断裂。阐述了雷暴风化作用的时空分布规律,指出雷暴风化作用主要发生在低纬度近海山地地区。气候比较温暖且降水量较多的地史时期是雷暴风化作用较发育的阶段。对于中国东部中低山地有争议的部分冰川砾石,有可能为雷暴风化作用形成的雷暴风化砾石经泥石流搬运后再沉积的产物。因为江西庐山等地都是雷暴风化作用较易发生的低纬度近海山区。

At the top of Dushan Mountain with an elevation of more than 1 840m in the east part of Hebei Province, China, the authors discovered a peculiar weathing products resulted probably from thunderstorm and observed the thunderstorming process with their own eyes for the first time. The weathering boulders probably formed by thunderstorm are accumulated in an area of more than 10km long, 30-50m wide and 10-30m deep pile on the top of Dushan Mountain. The diameter of the boulders are usually 2-3m and may reach a maximum of more than. 10m. The physical basis of thunderstorm weathering is analysed. The energy needed to fracture granite of 1 m3 in volume was provided theroretically calculated to be 0.07%-0.007% of the energy released from a thunderstorm. The regularity of tempo-spatial distribution of thunderstorm weathering is set forth. Thunderstorm weathering is supposed to mainly happen at the low-latitude near-sea mountainous areas. The Archean hydrogenic sedimentary series indicates the accomplishment of the earth's hydrosphere and probably also the beginning of thunderstorm weathering. In the history of our earth, the periods with rich rainfall and warm climate would be also the periods with more thunderstorm weathering, such as the Archaeozoic, Mesoproterozoic, Cambrian, Ordovician and Tertiary. It is put forward that some of the disputed glacial boulders in middle-lower mountain areas in eastern China might be the result of thunderstorm weathering, and these boulders might have been carried to the foot of these mountains or even farther by mud-rock flows and deposited there; for the glacial areas such as Lushan Mountain in Jiangxi Province and Shahe in Hebei Province are all the low-latitude near-sea mountainous areas where thunderstorm weathering was more liable to take place.