张风艳, 孟翊. 长江口北支表层沉积物重矿物分布和磁学特征[J]. 海洋地质与第四纪地质, 2011, 31(1): 31-41. DOI: 10.3724/SP.J.1140.2011.01031
引用本文: 张风艳, 孟翊. 长江口北支表层沉积物重矿物分布和磁学特征[J]. 海洋地质与第四纪地质, 2011, 31(1): 31-41. DOI: 10.3724/SP.J.1140.2011.01031
ZHANG Fengyan, MENG Yi. HEAVY MINERAL DISTRIBUTION AND MAGNETIC CHARACTERISTICS OF SURFACE SEDIMENTS IN THE NORTH BRANCH OF THE CHANGJIANG RIVER[J]. Marine Geology & Quaternary Geology, 2011, 31(1): 31-41. DOI: 10.3724/SP.J.1140.2011.01031
Citation: ZHANG Fengyan, MENG Yi. HEAVY MINERAL DISTRIBUTION AND MAGNETIC CHARACTERISTICS OF SURFACE SEDIMENTS IN THE NORTH BRANCH OF THE CHANGJIANG RIVER[J]. Marine Geology & Quaternary Geology, 2011, 31(1): 31-41. DOI: 10.3724/SP.J.1140.2011.01031

长江口北支表层沉积物重矿物分布和磁学特征

HEAVY MINERAL DISTRIBUTION AND MAGNETIC CHARACTERISTICS OF SURFACE SEDIMENTS IN THE NORTH BRANCH OF THE CHANGJIANG RIVER

  • 摘要: 分析了长江口北支表层沉积物的重矿物分布,结合磁参数和粒度特征,探讨其在各沉积动力分区的分布特点及控制因素。研究表明:研究区重矿物以角闪石和绿帘石组合为主,其次为云母类和磁铁矿等。其中浅滩和潮流脊处水动力较强,沉积物颗粒较粗,重矿物以片状矿物-稳定矿物组合占优势,磁性参数相对较低;汊道和潮汐通道处水动力相对较弱,沉积物以细颗粒的黏土质粉砂为主,重矿物以角闪石-黑色金属矿物-碳酸盐矿物为特征,磁性矿物多集中于此且含量较高,对应的磁学参数也呈现高值。北支的重矿物组合分布和磁性参数均与长江口其他区域具同源关系,表明北支表层沉积物主要来源于长江流域。总之,北支的重矿物组合分布和磁性特征受制于研究区的水动力强弱、沉积物类型、泥沙来源及搬运方式。

     

    Abstract: Based on data from the surface sediments obtained from the north branch of the Changjiang River, this paper deals with the distribution of heavy minerals, the spatial variations of sediment magnetic properties and their controlling factors. Results indicate that hornblende and epidote dominate in heavy minerals in the research area, followed by mica and magnetite, but mineral assemblages vary in different sedimentary dynamic zones. The mica-stable mineral assemblage mainly occurs in sandspits and tidal sands,where, under strong hydrodynamic conditions, coarse sediments prevail and magnetic parameters, such as Xarm、Xfd%、Xarm/Xl and Xarm/SIRM are relatively low. The assemblage of hornblende-magnetite-carbonate is mainly distributed in river channels and tidal inlets, where hydrodynamic condition is relatively low and fine sediments, such as clayey silt, dominate, and as the result, magnetic parameters of Xarm、Xfd%、Xarm/Xl and Xarm/SIRM are quite high. Data suggest that the sediments in the north branch of the Changjiang River are mainly from the Changjiang River drainage. The distribution of heavy minerals and magnetic parameters are controlled by hydrodynamics, sediment types, source rocks and sediment transportation.

     

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