CAJ | 학술논문

本文通过采用有限差分法(FLAC)对”侏罗山式”褶皱进行数值模拟发现,层间粘聚力差异和上覆压力是控制隔档式褶皱、隔槽式褶皱样式的主要因素,即层间的能干性差异和埋深的控制.当地层在埋深较浅时,层间能干性差异对褶皱样式起主控作用,能干性差异小时出现隔槽式褶皱,差异大时出现隔档式褶皱.随着埋深加大,压力逐渐起主要作用,这时仅出现隔槽式褶皱.川东东带褶皱地层总体上层间能干性差异小,因而盖层的深部与浅部皆出现隔槽式褶皱,与模拟结果一致.西带褶皱地层总体层间能干性差异大,因而浅部出现隔档式褶皱.而其深部的下古生界地层主要受上覆压力控制,根据模拟推测应为隔槽式褶皱.
본문통과채용유한차분법(FLAC)대”주라산식”습추진행수치모의발현,층간점취력차이화상복압력시공제격당식습추、격조식습추양식적주요인소,즉층간적능간성차이화매심적공제.당지층재매심교천시,층간능간성차이대습추양식기주공작용,능간성차이소시출현격조식습추,차이대시출현격당식습추.수착매심가대,압력축점기주요작용,저시부출현격조식습추.천동동대습추지층총체상층간능간성차이소,인이개층적심부여천부개출현격조식습추,여모의결과일치.서대습추지층총체층간능간성차이대,인이천부출현격당식습추.이기심부적하고생계지층주요수상복압력공제,근거모의추측응위격조식습추.
Numerical modeling of Jura-type (detachment) folds by using the finite-different code FLAC shows that interlayer cohesion contrasts and overlying confining pressures are key factors for development of comb-like and trough-like folds, indicating controlling by interlayer competence contrast and burial depth. When folded strata are in shallow levels, interlayer competence contrast plays an important role in fold styles. Lower interlayer competence contrast will produce trough-like folds whereas higher interlayer competence contrast will lead to comb-like folds. As the depth increases, the pressure gradually plays a major important role and higher overlying pressures will cause trough-like folds only. Lower interlayer competence contrast in the folded strata in the eastern part of the eastern Sichuan fold belt results in trough-like folds both in shallower and deeper levels of the cover, which are consistent with our numerical modeling results. Higher interlayer competence contrast in the western folded strata causes comb-like folds in the shallower levels. However, the fold style in the deeper,lower Paleozoic cover strata in the western belt are mainly controlled by overlying pressures, and the developed fold style should be trough-like folds according to the numerical modeling results.