九龙江口一岩心的重矿物组合

Characteristics of heavy minerals in a core from Jiulongjiang Estuary

本文详细地分析了九龙江口SD0 3岩心中自生矿物的成因 ,推断河口区在约1 0ka ,B .P .中历经了河流沉积、湖泊沉积和河口海湾沉积三种沉积环境 .在沉积环境演化过程中共形成了 1 0种重矿物组合 .

The composition of heavy minerals in medium and fine sands of surface sediment is compicated Among over 59 species, the principal ones are magnetite, gregorite, haematite, limnite, leucoxene. biotite, allochite and andalusite. All of them belong to terrigenous detrital minerals except some to authigenic minerals such as pyrite, siderite. Among them most are silicates and secondary are oxides and hydroxide.In total abundance of heavy minerals oxide minerals account for the most (average 46%) and silicates the second (average 40%). In the relative abundance of heavy minerals, the abundant area (64.74% at maximum) is mainly in nearshore areas where wind waves and tidal currents are strong such as the mouth of Xunjiang Bay and nearshore area south to Xiamen Island. The content decreases from west to east in south to the mouth of Jiulong River and the mouth of Out Port of Xiamen.According to the change of heavy minerals and abundance of major minerals and by taking into account the bottom sediment, 11 zones in two types have been divided which are closely related to their mother rock, hydraulic factor and chemical environment of deposition.