Magnetic Properties and Relevant Minerals of Late Cenozoic Sediments in the Yangtze River Delta and Their Implications

详细信息   

• 责任者：Wang Zhanghua (State Key Laboratory for Estuarine and Coastal Research ; East China Normal University) ; Zhang Dan
• 刊名：Geology in China
• 出版年：2008
• 卷期：35(4)
• 关键词：磁性矿物 ; magnetic minerals ; 沉积物 ; sediments ; 长江三角洲 ; Yangtze River Dalta
• 页码：p.670-682
• 图表：6 illus., 1 table, 17 refs.
• 分类号：0803
• issnNo：ISSN1000-3657
• isbnNo：CN11-1167/P

摘要

The grain-size analysis and magnetic property measurements of Late Cenozoic sediments of borehole SG7 in the Yangtze delta plain have revealed the evolution of dominant magnetic minerals with time and coupling effects of neotectonic movement, climate and sea level changes on the sediment provenance and depositional environment. The results demonstrate that strong and weak magnetic properties alternated with the highest signal of the whole profile during the Pliocene. Dominant magnetic minerals are magnetite, maghemite, goethite, and pyrite indicating a warm/humid climate and an intermontane lacustrine environment in the area and that the sediments were mainly derived from the weathering product of the Bailonggang basalt in the surrounding areas. During the early part of the early Pleistocene, magnetic signals were weakest of the borehole, with magnetite predominating. This implies that the material sources changed due to tectonic subsidence, i.e. the material sources were mainly iron-poor intermediate-acid hypabyssal rocks and extrusive rocks.