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。     

SEDIMENTARY PROPERTIES AND ENVIRONMENTAL VARIATIONS FROM CONTINENTAL SLOPE TO DEEP SEA PLAIN IN THE NORTHERN SOUTH CHINA SEA SINCE LATE PLEISTOCENE

The South China Sea is the westernmost marginal sea in the west Pacific Ocean. On thebasis of the analyses of sedimentary components, biofossils, oxygen-carbon isotopes and theirdatings in four seafloor cores which were collected from the deep sea plain to continentalslope in the northern South China Sea, the environmental variations were basically similarto other tropical ocean areas, and their cycle changes in about the ages of 40 ka and 20 kawere more apparent since the late Pleistocene. During the warm climates, the depositionrate on the continental slope was about 2.6 times as rapid as on the deep sea plain margin.The seafloor in the deep sea plain was below the CaCO_3 compensation depth. During thecold periods, however, the deposition rate on the deep sea plain margin was slightly quickerthan on the continental slope due to the sea level reduction on a larger scale and moresupply of the terrigenous clastics.     

南海北部大陆坡—深海平原晚更新世以来的沉积特征与环境变化

据南海北部深海平原与陆坡4个海底钻探岩芯样的物质成分、生物化石、氧与碳同位素分析及测年数据,该海区晚更新世以来的环境变化与其他热带洋区基本一致,其特点是约40ka与约20ka的周期变化表现更为突出。温暖时期,陆坡部位的沉积速率比深海平原边部约快2.6倍,深海平原海底位在碳酸盐补偿深度以下。寒冷时期因海面有较大幅度下降,深海平原边部沉积速率反比陆坡部位略快些,有更多陆源物质的补给。