南郑梁山地区第三系狮子山组及其成因

Shizishan Formation and Genesis of the Tertiary System in Liangshan Region, Nanzheng County

梁山地区第三系狮子山砾岩是一套以泥石流沉积为特征的连续沉积,与下伏地层为不整合接触,笔者将其命名为狮子山组。狮子山组的扇积物以筛状沉积和泥石流沉积最为典型,它们分别构成了冲积扇的扇根、扇中和扇端。三者互相叠覆,形成了向上变细的退积型正旋回层序。狮子山组沉积时,梁山地区处于燕山运动后形成的山前地带,地势南高北低,物源来自南面。古气候条件为半干旱气候。

Shizishan conglomerate of the Tertiary System in Liangshan region is a suite continuous sedimentary series, the characteristics of which is debris slide. It is in discordant contacts with the underlying strata. It was named Shizishan Formation. The fan deposit of the Shizishan Formation is typical of sieve and debris slide deposits. They formed fanroot, midfan and fanend respectively. These three parts overlapped eachother and formed normal cycle sequence which is upward fining retrograding sequece. When Shizishan Formation is deposited, Liangshan region is in the mountain front formed after Yanshanian movement. The terrain is higher in the sonth and lower in the north. The provenance is located in the south. The paleoclimate is semiarid.