The Formation Mechanism of the Lakes in Jinjiang City , Fujian
详细信息
- 责任者：Xu Qihao (Earthquake Administration of Guangdong Province ; Guangzhou 510070 ; China) ; Shi Jiansheng
- 刊名：Seismology and Geology
- 出版年：2012
- 卷期：34(1)
- 关键词：堰塞湖 ; barrier lakes ; 福建 ; Fujian Province
- 页码：p.110-128
- 图表：9 illus., 1 table, 36 refs.
- 分类号：1400
- issnNo：ISSN0253-4967
- isbnNo：CN11-2192/P
摘要
On the basis of field investigation of the Qiangang Lake,Longhu Lake,Huihu Lake,and Bingzhou Lake in Jinjiang City of Fujian Province,and analysis of sedimentary facies and micro-palaeontology of drill cores,especially the analysis of the cores from 78 bore holes in Longhu Lake and along its banks,the distribution of eluvial-deluvial formations and late Pleistocene sediments was obtained,then,the environment of the depression and the palaeo-river developed in the depression before the formation of the lakes was analyzed,and finally,the four above-mentioned lakes were inferred to be earthquakedammed lakes formed in late Holocene.The evidences are as follows:1) The four lakes spread linearly along the hidden Yakou-bingzhou fault(which controls the northwest boundary of Shenhuwan graben.2) All are fresh water lakes developed in the depression consisting of Epipleistocene gravel-bearing sandy clay and eluvial-deluvial deposits;paleo-rivers are found existing in the depression before the formation of the lakes.3) The bottom of the paleo-river channel in the lower reaches is about 3 meters higher than that in the upper reaches in the Longhu Lake depression.4) The earliest age of lake facies deposits of Qiangang Lake and Lonhu Lake is about 2.4ka BP by 14C dating of drilling cores,and it is inferred that the two lakes were formed in about 2400a BP,an age being possibly in the time range of the late Holocene strong paleo-earthquake that caused the paleo-forest to be buried more deeply on the sea floor of Shenhuwan Bay.The above lakes are inferred to be earthquake-dammed lakes resulting from the titling and upwarping of the northwest block of Yakou-bingzhou fault in this earthquake,which blocked the rivers and created the lakes.The dams were widened and elevated due to aggradation at the lake dams and filling in the graben after the formation of the lakes,and connected the graben deposits into one mass of roughly the same height,thus,damming the outflow of the lakes.This is an important reason for the lakes to develop continuously and remain up to now.
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