华北新生代断陷盆地边缘的山麓断裂与盆缘主干断裂的比较分析——以内蒙古临河断陷盆地为例
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摘要
华北西部许多第四系隐伏的断陷盆地,经人工地震探测发现在盆地边缘存在生长性主干大断裂。于大断裂附近隆起的山麓露头区,有时出露新活动断裂,二者性质似乎"相同"、产状近于平行。隐伏的主干大断裂发育的最晚时代(时代上限)与山麓活动断裂的形成时代接近,因此被认为是同一断裂系,其差异仅仅是出露与隐伏的不同。为此以内蒙古临河断陷盆地为例进行了实地野外观察与地震反射剖面解释,认为隐伏的主干断裂是自下向上发育的生长断裂,是地壳运动的产物,而山麓露头的活动断裂则是自上向下滑落,断裂的形成倾向于(主要)是重力因素。二者本质上毫无关系,不是一个断裂系,不能依据山麓活动断裂的特征来推导隐伏断裂的性状与活动性。
In many Quaternary buried down-faulted basins in the west of North China,the growth main faults located at the basin margins have been found by the artificial earthquake exploration.At the piedmont outcrop area uplifted near the main faults,the newly active faults sometimes will outcrop,with seemingly "same" characteristics and approximately parallel occurrence.The latest development time(upper limit) of buried main faults is close to the formation time of piedmont active faults.They are believed to be the same fault system,and the difference is just the outcrop or bury.Therefore,taking Linhe Down-aulted Basin,Inner Mongolia as an example,we carried out the field observation and seismic reflection profile interpretation.The results indicate that the buried main faults are growth faults developed from bottom and resulted from crustal movement.Meanwhile,the active faults of piedmont outcrop are formed by slide from up to bottom,seeming to be formed by gravity.They have nothing to do with each other in nature and are not the same fault system,so that the characteristics and activity of the buried faults cannot be deduced from the characteristics of piedmont active faults.
In many Quaternary buried down-faulted basins in the west of North China,the growth main faults located at the basin margins have been found by the artificial earthquake exploration.At the piedmont outcrop area uplifted near the main faults,the newly active faults sometimes will outcrop,with seemingly "same" characteristics and approximately parallel occurrence.The latest development time(upper limit) of buried main faults is close to the formation time of piedmont active faults.They are believed to be the same fault system,and the difference is just the outcrop or bury.Therefore,taking Linhe Down-aulted Basin,Inner Mongolia as an example,we carried out the field observation and seismic reflection profile interpretation.The results indicate that the buried main faults are growth faults developed from bottom and resulted from crustal movement.Meanwhile,the active faults of piedmont outcrop are formed by slide from up to bottom,seeming to be formed by gravity.They have nothing to do with each other in nature and are not the same fault system,so that the characteristics and activity of the buried faults cannot be deduced from the characteristics of piedmont active faults.
引文
[1]内蒙古自治区地质矿产局.内蒙古自治区区域地质志[M].北京:地质出版社,1991.
[2]杨承先.活动断裂鉴别中常见的假象与误解[G]∥地壳构造与地壳应力文集(4).北京:地震出版社,1990.
[3]马杏垣.重力作用与构造运动[M].北京:地震出版社,1989.
[2]杨承先.活动断裂鉴别中常见的假象与误解[G]∥地壳构造与地壳应力文集(4).北京:地震出版社,1990.
[3]马杏垣.重力作用与构造运动[M].北京:地震出版社,1989.
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