古元古代拉伸构造模式──以胶北、辽东和吉南地区为例

EXTENSIONAL TECTONIC MODEL OF PALAEOPROTEROZOIC──AN EXAMPLE FROM NORTHERN SHANDONG PENINSULA,EASTERN LIAONING AND SOUTHERN JILIN AREAS

对胶北．辽东和吉南地区古元古代层状岩系第一系构造变形作的详细研究和综合分析，并以此为典型实例，提出了古元古代拉伸构造模式，即隆起一顺层分层滑脱构造模式。该模式由核部隆起和上部盖居及两者之间的拆离型韧性剪切带三部分组成。核部隆起常由岩浆隆起或基底隆起构成，上部盖层内发育有顺层分层滑脱构造体系，由底部主滑脱面和内部次级滑脱面、低级滑脱面及其间的流褶居和片理化带构成，靠近核部隆起的盖居表现为正向滑脱，而滑脱前缘则表现为反向滑脱，具有滑覆特征。该模式一般发生在大规模收缩造山作用之前，由于区域拉伸作用，导致壳下地任上隆，形成岩桨隆起或基底隆起，使上覆盖层岩系重力失稳，发生滑脱，内部横向构造置换强烈，形成透入性片理。

According to the detailed studies of the first episode structural deforma- tion of Palaeoproterozoic metamorphic sequences in northern Shandong Peninsula, east- ern Liaoning and southern Jilin areas . an extensional tectonic model of Palaeopro- terozoic, called uplift - clelaminated bedding slide model , has been put forward. The model consists of uplift core, cover and decollement zone between the core and cover. The uplift core is often a magma uplift or basement uplift. In the cover , there developed a delaminated bedding slide structure system which included the lowest main slide plane (decollement zone) and inner secondary slide planes and elementary slide planes as well as rheid fold layers and foliated zones between the slide planes. AII the slide planes in the cover have the characteristics of normal sliding near the core and reverse sliding in front area. The model occurred in extensional tectonic setting before large-scale contrac- tive orogeny. Regional extension resulted in mantle uplifting which in turn produced magma upwelling or made basement uplift , sequentially. The overlying cover sequences became unstable in gravity and began to slide. In the cover , the intensive transversal structure translposition produced penetrative foliations which were parallel to the region- al beddins. This model would be very useful to study the early structure evolution of Palaeoproterozoic not only in the eastern part of Northern China Plateform but also northern part of Korea Peninsula.