广西滨海地貌特征及砂矿形成的研究

COASTAL PLACER DEPOSITS AND GEOMORPHOLOGICAL FEATURES IN GUANGXI PROVINCE

广西滨海地貌,大体以饮州犀牛脚为界,东部以侵蚀一堆积的砂质夷平岸为主;西部则主要是微弱充填的曲折溺谷湾岸。滨海地貌与砂矿有直接关系。不同的地貌类型形成的砂矿床有所区别,一般砂矿床主要产于砂质海岸、沙坝—泻湖海岸、三角洲海岸内。生物海岸、泥质海岸不成矿。砂矿成矿与地貌形态相联的有海积的、冲积的、残积的、浅海的及混合的几种类型。砂矿的形成与富集多受地貌形态的控制。不同的地貌形态,砂矿富集的部位不一样,一般在沙堤的根部、海滩的高潮线附近、沿岸沙堤的上中部、水下沙坝的顶部和向海坡的上部,以及冲积平原的边缘地貌部位,容易形成砂矿和富集。区内滨海砂矿极其丰富,主要有北海白虎头玻璃石英砂矿床、江平澫尾锆石—钛铁砂矿床、巫头金红石—锆石砂矿床等。沿岸不同的砂矿种类与沉积物的粒级有不同的选择。钛铁砂矿产在中细砂—中粗砂中;玻璃石英砂矿产于中细至中粗级沉积物中。

This paper studies the relation between coastal placer deposits and geomorphological features in guangxi Province. The placer deposits are mainly formed in sandy coasts, bar lagoons and deltas. Their formation and enrichment processes and their distributions are investigated, and the relation between placer types and sediments characteristics is analysed. Coastal placer deposits are rich in the investigation area, such as the placer deposit of quartz sand found in Bai-hutou, Beihai, and that of zircon-iron ore in Manwei, Jiangping and that of rutile-zircon in Watou. Different kinds of placer deposits are accumulated in sediments of different grain sizes Zircon-iron-placer is found in medium fine to medium coarse sands, and the quartz sand is better in middle fine-middle coarse sediments.