三门峡-宝丰控煤逆冲断裂构造带地球化学分析

Geochemical Analysis of Sanmenxia-Baofeng Coal-Controlling Thrust-Fault Tectonic Zone

三门峡-宝丰控煤逆冲断裂构造带是华北板块南部NW向延展的巨型逆冲断裂构造带的一部分。构造地球化学分析表明:从外围原岩到断裂带中心,w(Fe2O3)逐渐增大,w(FeO)逐渐减小,说明逆冲断裂构造带经历了封闭性还原环境系统到相对开放性氧化环境系统的变化过程;各种化学成分的质量分数(SiO2、Al2O3、Fe2O3、MgO、CaO、FeO、灼失量以及TiO2、K2O、Na2O等)呈现有规律的递增、递减或峰值变化,说明逆冲断裂构造带是挤压应力作用下形成的压性断裂,而且处于演化阶段的晚期;动热变质强度在南、北两支逆冲断裂带存在差异:南支强烈,导致新生应力矿物的形成,为断裂的远距离相对逆冲运动增添了塑性润滑层;北支相对较弱,新生应力矿物少。

The Sanmenxia-Baofeng（south-west Henan） coal-controlling thrust-faulted tectonic zone is one segment of the giant NW-strike coal-controlling thrust-faulted tectonic zone in the southern part of North China Plate, The analysis of tectonic geochemistry indicates that the content of Fe2O3 increases and the content of FeO decreases gradually from the outside to the center part of the faulted zone reveals the evolutional process from enclosed reduction to relatively open oxidation system. In the meantime, the contents of SiO2, AlO3, Fe2O3, MgO, CaO, FeO, TiO2, H2O and CO2 increase or decrease gradually from the outside to the center part of the faulted zone, and the contents of Na2O, K2O indicate change wavelike. All of these confirm that the thrust-faulted zone is compressive and in later fault evolution stage. Moreover, a different intensity of dynamothermal metamorphism occurred in south and north thrust-faulted branches. The south one was intense and resulted in the formation of neogenic stress minerals which provided plastic lubricating layer for long-distance thrusting gliding. The north one was relatively gentle with rare stress mineral.