华北板块东南缘徐淮推覆-褶皱带的物理模拟

徐淮地区发育一系列推覆-褶皱带,以皇藏峪背斜为界,区域剖面分为具有明显构造差异的东部、西部构造带,其中东部构造带样式主要表现为斜歪褶皱,西部构造带为一系列逆冲推覆构造,构造变形强烈。采用物理模拟手段对徐淮推覆-褶皱带构造的控制因素进行实验研究,选取硅胶、微玻璃珠模拟不同性质滑脱层,石英砂模拟沉积脆性盖层,改变盖层与基底摩擦力、滑脱层深度变化等控制因素。模拟结果表明,剖面上滑脱层性质及深度变化控制区域剖面构造的强弱变化。皇藏峪背斜以东主要以新元古界青白口系泥灰岩充当滑脱层,滑脱层深度大,构造样式主要表现为斜歪褶皱;皇藏峪背斜以西则以寒武系页岩为滑脱层,滑脱层深度小,构造样式主要表现为逆冲推覆构造。

Physical modeling of Xu-Huai thrust-fold belt on the southeastern margin of North China Block

Xu-Huai area has developed a series of thrust-fold belts. The regional section is divided into eastern and western tectonic zones with obvious structural differences:the eastern tectonic belt mainly shows the characteristics of inclined fold, and the western tectonic belt mainly shows the characteristics of a series of thrusts in style. In this paper, the authors studied Xu-Huai thrust-fold belt with the physical modeling method, selected silica gel and micro glass beads to simulate different decollement properties, selected quartz sand to simulate sedimentary brittle cover layer, and changed basal control factors such as friction and decollement depth. The modeling results show that the properties of decollement along the section and the depth change control the regional structural defor-mation. To the east of Huang-Cang valley anticline, main decollement is Upper Proterozoic marl of deep burial depth, and the main tectonic style is characterized by inclined fold; to the west of Huang-Cangvalley anticline, Cambrian shale serves as the decollement, and the decollement is of small depth, with the tectonic style characterized by a series of thrusts.