小秦岭地质构造新认识

A NEW IDEA OF GEOLOGICAL TECTONICS IN THE X1AOQ1NLING REGION

本文初步厘定了小秦岭区域构造格局及其动力学背景。将小秦岭划分为两个次级构造单元,北部基底岩系上隆区(太华台拱)及南部盖层沉积区(金堆-卢氏台凹)。北侧紧邻渭河断凹。两者之间为一套古老糜棱岩代表的韧性剪切带所分隔。自中、新生代以来,该区处于伸展构造环境,中南部(金堆-卢氏台凹)、北部(渭河断凹)为多期拆离构造,中部(太华台拱)抬升,形成了“拆离-变质杂岩核”构造,该构造控制着本区的金矿。

A study on the gold deposit and ductile shear zone in the Xiaoqinling region has raised the curtain on the study of multi-level and multi-stage development and evolution of tectonics in the region. This paper preliminarily defines the regional tectonic framework and the dynamic setting for its formation and evolution.According to the regional tectonic characteristics, two secondary tectonic units may be distinguished in the Xiaoqinling region: the upwarping area of the basement rock series (Taihua platform arch) in the north and the sedimentary cover area (Jingdui-Lushi platform hollow in the south; to its north is the Weihe fault depression. The Weihe fault depression and the sedimentary cover area are seperated from the upwarping area by ductile shear zones displayed by paleomylonites.Since the Mesozoic and Cenozoic, an extensional environment prevailed in the region: the south and north parts underwent multi-phase detachment and the middle part was upwarped and exposed gradually, forming a detachment-metamor-phic core complex structure, which has controlled gold deposits in the Xiaoqinling region.