库车再生前陆逆冲带生长褶皱的倾斜剪切恢复

INCLINED-SHEAR RESTORATION OF GROWTH FOLDS IN KUQA REJUVENATION FORELAND THRUST BELT

去褶皱倾斜剪切恢复是褶皱作用的逆过程。利用生长地层可以恢复褶皱不同生长阶段的几何形态 ,建立一系列的不同时期褶皱的几何形态。分析褶皱翼长、褶皱翼倾角、轴面倾角的变化 ,可以得出褶皱生长机制 ,同时也用于判断对于地表地质、钻井资料以及地震剖面的解释是否正确。生长褶皱恢复过程中必须遵循地质平衡的准则 ,同时每一步恢复后的剖面在地质上应该是合理的。用倾斜剪切恢复技术对库车再生前陆逆冲带的生长褶皱进行了系统的恢复。恢复结果表明 ,米斯布拉克背斜是通过翼旋转发育的 ,发育过程中背斜顶部逐步少量地进入前翼 ;依奇克里克背斜是通过膝折带迁移的机制发育的 ,发育过程中翼倾角不变 ,翼长逐渐增加 ;大宛其背斜是通过翼旋转的机制生长的 ,生长过程中翼长几乎没有发生变化 ,前翼与向斜的水平地层之间的夹角逐渐减小。这说明库车再生前陆逆冲带是通过翼旋转和膝折带迁移两种机制变形的。褶皱的生长时间、生长机制与烃类的聚集有紧密的关系。

The Kuqa rejuvenation foreland thrust belt is one of the most important regions in the north flank of Tarim Basin for hydrocarbon exploration.The exploration results show that almost all hydrocarbon traps are anticlinal ones.Therefore,it becomes more important for researching on the evolution of folds in the Kuqa rejuvenation foreland thrust belt.Unfolding of inclined_shear restoration of growth folds is the anti_process of folding.Syntectonic sediments record clearly the detailed processes of folding and faulting.Therefore,the geometry of fold of every stage can be restored by analyzing the geometry of syntectonic growth strata.Then analyses on the changes of limb length,limb dip and axial surface dip can conclude the mechanics of the fold.Inclined_shear restoration techniques can be used to check the interpretations of seismic profiles,well data and surface geology.During inclined_shear restoration of growth fold,the restored profiles ought to be geologically reasonable.The inclined_shear restoration technique to process the growth folds that are interpreted on the seismic profiles was applied to restore the growth folds in the Kuqa rejuvenation foreland thrust belt systematically and carefully.The inclined_shear restoration results show that the Misibulake anticline was formed through limb rotation with limb increasing after starting before 24.5 million years.The Yiqikelike anticline through kink band migration with constant dip of limb and increasing limb length started before 16 9 million years.The Dawanqi anticline through limb rotation with constant limb length and increasing limb dip started before 3 1 million years.The Kuqa rejuvenation foreland thrust belt,including mechanics of fault_bend folding,fault_propagation folding and detachment folding,grows and propagates forward and southward by limb rotation and kink band migration in the Kuqa structure.The fold growth age is in accordance with timing of hydrocarbon generation and migration in Kuqa.The folds are ideal natural gas trap structures.