龙羊峡谷更新世以来气候演变特征及其对拉西瓦水电站坝区花岗岩风化作用的影响

龙羊峡谷为黄河上游水电富矿河谷段，拉西瓦水电站位于龙羊峡谷出口地段，研究龙羊峡谷更新世以来气候演变特征对于探讨拉西瓦水电站坝区自然环境发展演化与工程岩体地质过程浅表生改造均有重要意义。本文在简述了龙羊峡谷形成史之后，通过分析树木年轮法、植物孢粉法、同位素法等所获取的资料，总结了更新世以来龙羊峡地区气候演变特征。分析认为龙羊峡地区更新世以来气候以旱寒为主，这种气候特征对于拉西瓦水电站坝区花岗岩风化作用的影响主要存在于两个方面：温度变化及由此带来的冰劈作用。

CHARACTERISTICS OF THE CLIMATIC DEVELOPMENT IN LONGYANGXIA GORGE AREA SINCE PLEISTOCENE AND ITS INFLUENCE TO WEATHERING OF LAXIWA DAM-SITE GRANITE

Longyangxia Gorge is the hydro-power bonanza section of up-stream of Yellow River, and Laxiwa Hydro-power station is located in the down-stream of Longyangxia Gorge. It is important to study its climatic development characteristics since pleistocene for probing into natural environment development and epigenetic reformation evolutionary process of rock mass of the large-scale hydroelectric project district. The paper firstly introduces the geological history of Longyangxia Gorge area. The climatic development characteristics since pleistocene are described by analyzing data which are obtained by dendro-chronology method, plant pollen spore method and isotope method. The climatic characteristics since pleistocene is mainly dry and cold according to the data. The climatic influence on Laxiwa dam-site granite lies in two aspects: one is from temperature variation; the other from frost action.