近20年来中国古河道研究进展

近20年来,我国在嫩江大安古河道、莱州湾南岸平原古河道、长江南京以下段古河道及古深槽、海底古河道等区域的研究,获得了大量研究成果,深化了理论认识,拓展了应用领域。这些新成果与新认识进一步表明,中国各外流大河均有末次盛冰期埋藏古河道,该期古河流深切于末次冰期间冰阶的陆地及浅海大陆架,形成切割谷和谷底部的深槽,谷内堆积了末次盛冰期和早全新世的河流相滞留物质和粗颗粒物质,上部被中全新世海相、海陆交互相或陆相细粒物质覆盖,构成了埋深约20~50 m的浅埋古河道带。古河道中蕴藏着比较丰富的地下淡水,是洪冲积平原及浅海陆架地区的重要水源。

Progresses of palaeochannel studies in China in the past 20 years

The last 20 years have seen new progresses in palaeochannel studies in China, including the investigations on palaeochannels in Nenjiang Daan, palaeochannels in the plain south of Laizhou bay, and palaeochannels, deep ancient grooves and submarine palaeochannels in the Yangtze river downstream of Nanjing, and so on. As a result, a large number of achievements have been accomplished, and new theories proposed; the research achievements have found new applications as well. The new knowledge and new theories indicate that buried palaeochannels exist in all of large outflowing rivers in China since the LGM(Last Glacial Maximum). The palaeochannel runs deep into the stadial terrestrial and the sea bed of the continental shelf from the Last Glacial Epoch, forming a cutting valley with deep grooves at the bottom, stacked with fluvial carryover and coarse particulate material from the LGM and early Holocene. The upper part of the valley is covered with marine, paralic, and continental fine-grained material from the Holocene, which frames the shallow-buried palaeochannel with 20 m to 50 m depth. Palaeochannels are rich in underground water, and an important water source for the areas of alluvial plain and shallow continental shelf.