塔北隆起北部正断层的成因机制及地质意义

Genetic mechanism and geological significance of normal faults in northern North Tarim Uprift

塔里木盆地自中生代以来一直处于挤压构造背景,而塔北隆起北部正断层的出现却引起众多学者的关注.本文对塔北隆起北部正断层的成因机制进行了分析探讨.分析认为,根据正断层发育完全受基底古构造格架的控制,其成因源于再生前陆盆地挤压背景下基底构造活动对上覆构造层的影响,具体表现为:①基底受挤压强烈翘曲导致上覆脆性地层引张构造变形;②先存基底断块隐伏活动诱导上盘层系引起构造变形.得出正断层自西向东的持续发育随前陆盆地沉降中心的迁移而有规律性变化的结论.塔北隆起北部正断层的成因模式揭示了塔里木盆地北部基底—盖层统一构造变形的关系,对解释中国西北地区挤压构造背景下沉积盖层局部引张构造变形具有重要的地质意义.

Tarim Basin has been under the compressional tectonic setting since Mesozoic,therefore,the finding of the normal faults in northern North Tarim Uprift attracts the attention of many geoscholars.The genetic mechanism of the normal faults is discussed in this paper.It is held that the development of the normal faults is controlled by former basement framework,they originate from the effect of the basement movement on the overlying formation under the compressional background of foreland basin,and the development of the normal faults are completely controlled by the activity of basement,which behaves as follows:(1)the strong warpage of the basement because of being compressed leads to the extentional deformation of the overlying formation;(2)the concealed activity of former fault-blocks of the basement induces the deformation of the overlying formation,the consistent developing of the normal faults from west to east follows the variation of the subsidence center of Kuche generative foreland basin.The genetic mechanism of the normal faults reveals the united relationship of deformation of the basement and the overlying formation,which is of important geological significance to explaining the local extensional deformation of the overlying formation in North-west China under compressional background.