辽东早元古造山带隆滑构造初析

PRELIMINARY ANALYSIS ON UPLIFT BEDDING DELAMINATION STRUCTURE OF THE PALAEOPROTEROZOIC OROGENIC BELT IN LIAODONG PENINSULA

辽东早元古代裂谷带内的隆滑构造是在吕梁造山前期伸展体制下的第一幕变形期间形成的。本区隆滑构造的内核隆起部位大致与中南岩基空间分布一致，由同构造侵位的二长花岗岩（辽吉花岗岩）组成，在裂谷带西区和东区，辽吉花岗岩皆顺基底与盖层之间的接合面呈席状侵位。由于辽吉花岗岩局部隆起，引起外壳内多层滑脱型韧性剪切带（简称韧变带）及流褶层的形成，在递进变形过程中流褶层会发生尖灭。因变形分解作用，在形成韧变带及流褶层的同时，也形成一些巨型透镜体，它们为弱变形域或未变形域，其内原生构造保存完整。对流褶层内流动褶皱的倒向及拉伸线理的统计，结果进一步表明中南岩基为辽河群内隆滑构造的隆起部位。现今东区和西区的穹形构造是初始席状侵位的叠加性构造，即在吕梁运动期间收缩体制下，辽吉花岗岩仍呈塑性并向背斜部位聚集，呈底辟式重就位；第三幕构造形迹横跨叠加于第二幕构造形迹之上，从而最终使辽吉花岗岩有规律地分布于穹形构造核部。

While Laiodong palaeorift was still in the tectonic setting of pre orogenic extension during the first stage of Lüliang movement, uplift bedding delamination structure formed. It is shown that, from structural observation and analysis, the position of local uplift was the same as that of Central southern batholith. Core of uplift bedding delamination structure consists of syntectonic monzonitic granite (so called LiaoJi granite) emplacing as sheet along the contact plane between cover and basement in Western and Eastern structural provinces. The local uplift resulted in the multilayered delamination of ductile shearing and the rheid fold layers in cover. Pinch out of rheid fold layers could happen during progressive shearing. Some large scale structual lenticles, in which primary sedimentary structures have been well presserved, formed by deformation partitioning coeval with the bedding ductile shear belts and rheid fold layers. It is further shown that, from the statistics of stretching lineations and the direction indicators of B type rheid fold, the initial uplift was located in Central southern batholith. Some present day dome shaped structures were formed by shortening at the later stages of Lüliang movement while. LiaoJi granite was still plastic to move toward the cores of anticlinoria and re emplaced in diapir. So LiaoJi granites regularly distributed in the cores of dome shaped structures.