摘要
报道了云南大具盆地北部金沙江下渡口西岸的2层早更新世金沙江砾石层,它们分别位于盆地底部的冲、洪积砾石层的底部。该砾石层的砾石分选与磨圆很好,局部被钙质胶结,成分复杂,大部分为本地所无,表明其应为金沙江长距离搬运而来。该砾石层的钙质胶结物和钙质砂层2个样品的ESR年龄测定结果分别为1950±230kaBP和1770±160kaBP,属早更新世。对比其上游四川德格含下更新统汪布顶组哺乳动物群的金沙江第五级阶地砾石层和下游四川攀枝花金沙江沿岸伏于中、晚上新世湖相沉积昔格达组之下的分选与磨圆良好、成分复杂的河流相砾石层,表明在早更新世甚至上新世时期,金沙江已经贯通。
This paper reports two beds of early Pleistocene gravels on the western bank of the lower ferry of the Jiinsha River in the northern Daju basin, Yunnan. They are located at the base of a thick alluvial and proluvial gravel bed at the bottom of the basin. The gravels in the gravel bed are well sorted and rounded and partly cemented by calcareous materials, and their components are very complicated, most of which are absent in the study area, indicating that they were transported over a long distance by the Jinsha River. The ESR. dates of two samples of calcareous cements and sands from the lower bed of gravels are 1950±230 kaBP and 1770±160 kaBP respectively, indicating an early Pleistocene age. The gravel bed is correlated with the gravel bed in the fifth terrace of the Jinsha River containing the mammal fauna of the early Pleistocene Wangbuding Formation at Wangbuding, Dega County, Sichuan Province, in the upper reaches of the river and the bed of alluvial wellsorted and -rounded gravels of complex composition underlain by the middle-late Pliocene lacustrine Xigeda Formation at Panzhihua City, Sichuan, in the lower reaches. The results show that all the sections of the Jinsha River had been joined up and become into a long river by the early Pleistocene and even the Phocene.
出处
《地质通报》
CAS
CSCD
北大核心
2006年第12期1381-1386,共6页
Geological Bulletin of China
基金
中国地质调查局国土资源调查项目<滇藏铁路沿线地壳稳定性调查评价>(编号1212010541404)资助
关键词
云南大具盆地
早更新世
金沙江砾石层
ESR年龄测定
金沙江河谷发育
Daju basin, Yunnan
early Pleistocene
gravels of the Jinsha River
ESR dating
development of the Jinsha River valley
作者简介
赵希涛（1940-），男，研究员，从事地貌与第四纪地质学研究。E-mail：xiao_zhao@sina．com
