金沙江金坪子堆积体地貌过程与稳定性研究

对金沙江乌东德河谷及临近河谷进行了详细的野外调查,对河谷中的金坪子堆积体不同部位进行钻孔、竖井、平硐勘探作业并取样,室内进行TL测年和重矿成分分析,运用地貌学、沉积学和年代学进行综合研究,获得了金坪子堆积体地貌过程和稳定性的初步认识,金坪子堆积体地貌过程可分为乌东德峡谷的贯通与老金沙江金坪子深槽的形成、老金沙江金坪子深槽被充填过程、金沙江改道和现代金沙江的发育3个阶段,金坪子堆积体形成于197±9.70~86.61±7.36KaB·P,是乌东德河谷地貌发育过程中的残留堆积体,属于老金沙江深潭岩壁的崩坡积物与金沙江流水带来的冲积物填充古深槽而成,堆积体深嵌在古深槽槽底基岩中,堆积体比较稳定不会影响乌东德水电站的选址。

GEOMORPHOLOGIC EVOLUTION AND STABILITY OF JINPINGZI DEBRIS DEPOSITS AT WUDONGDE VALLEY OF JINSHA RIVER

Based on the field investigation in Wudongde valley of the Jingshajiang River, and comparative analysis of available data from drills, silos and galleries in the different parts of the Jinpingzi debris deposits of the Wudongde valley, the basic features and original types of the debris deposits were investigated. Geomorphological, sedimentological and chronological analyses of debris deposits infilling the Jinpingzi reaches of Wudongde valley, are used to elucidate the geomorphologic evolution and stability of debris deposits. Thermoluminescence (TL) dating provides a temporal frame for the process of the river incision and fluvial sedimentation in the past. The samples in the bottom and in the top of the deposits give the TL ages of ca.197±9.70 KaB·P. and 86.61±7.36 KaB·P., respectively, implying that the forming of the deposits took about 110 Ka. The Jinpingzi debris deposits were not due to landslides They were formed during three different phases of the geomorphic process of the river and formed thick layers of alluvia and collapsed cumuli. The Jinpingzi debris deposts are in a stable condition and would not affect the selection of the site for Wudongde hydropower station.