论文部分内容阅读
本文对南京菊花台一带的雨花台砾石层,进行了岩組和岩相的綜合分析。研究結果表明:雨花台砾石层是一种古代的冲积层,属於河流相的粗碎屑沉积物。单向的韻律性斜层理的发育,及大多数砾石a軸呈逆水流方向傾斜(平均傾角10°±)的特征,乃其重要的成因标誌。旋迴多阶构造的出現,表明該砾石层至少形成于两次升降运动的情况下,並且是在总的下陷环境中形成。砾石在空間上具有明显規律性的方位,以“枞向”方位为主,有“横向”和“斜向”方位的复合;砾石呈空間迭置的形式存在。岩组和岩相分析的結果同样証实,該区砾石层形成吋古河流运动的方向是自西南向东北(NE15—60°),水流的速度可能为0.8—1.6米/秒。对砾石成份、粒度、形态特征詳細研究的結果,可以认为部分砾石可能是再生砾石,即由更古老的砾岩經冲刷搬运和再沉积而成。由於90％以上的砾石为坚硬的硅貭岩石,同时砾石的园度和分选性也比較好,因此,实用經济价值也很大。
In this paper, a comprehensive analysis of lithofacies and lithofacies has been carried out on the Yuhuatai gravel layer in the Dahuatai area of Nanjing. The results show that the Yuhuatai gravel layer is an ancient alluvial layer belonging to coarse clastic sediments of river facies. The development of unidirectional rhythmic oblique bedding and the character of most gravel a-axis inclined to the direction of counterflow (average dip angle 10 ° ±) are the important genetic markers. The occurrence of a cyclic multi-stage formation indicates that the gravel layer was formed at least during two lifting movements and was formed in a total subsidence environment. The gravel has obvious regular orientation in space, which is mainly composed of “fir-shaped” orientation and composite of “horizontal” and “diagonal” orientation. The gravel exists in a spatial overlapping manner. The rock group and lithofacies analysis also confirmed that the direction of the paleo-river flow from the gravel layer is from southwest to northeast (NE15-60 °), and the velocity of the water flow may be 0.8-1.6 m / s. A detailed examination of gravel composition, grain size, and morphological characteristics suggests that some of the gravels may be reclaimed gravel, ie, washed and redeposited by older conglomerates. As more than 90% of the gravel is hard silicon rock, gravel and garden grade and sorting is also relatively good, so the practical economic value is also great.