Syntectonic sedimentation analysis applied to the reconstructionof the thrusting deformation process: An example fromthe Mesozoic thrust tectonics in eastern Yanshan Orogenic Belt,south of Lingyuan City, western Liaoning Province
Syntectonic sedimentation analysis applied to the reconstructionof the thrusting deformation process: An example fromthe Mesozoic thrust tectonics in eastern Yanshan Orogenic Belt,south of Lingyuan City, western Liaoning Province
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发表时间：
2004
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通讯作者：
Zhang Chang-hou;Xu De-bin
中科院分区：
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作者：
Zhang Chang-hou;Xu De-bin
简要介绍了同构造沉积分析的思想和概念、研究方法及其对区域构造变形过程研究的潜在意义。通过对辽西凌源市南部晚侏罗世土城子组的构造变形和砾岩成分变化的研究，得出以下结论。(1)研究区同构造-同运动沉积作用始于跳积山组火山作用后。物源区不在盆地东侧，而是在同运动型沉积盆地--灯笼子盆地的西侧。邓厂子盆地并非如前人所认为的那样是一个向西冲断的前深沉积盆地。土城子组砾岩的变化指示了物源地层的倾斜正向序列的剥蚀和剥落序列。剥蚀作用到达中元古界集贤群雾迷山组上部。(2)位于牛营子-郭家店盆地与灯掌子半新盆地之间的中元古代长城群残片与东侧北票群的接触是一条向东向东南方向的大型逆冲断裂。而在西北侧，土城子组位于长城群遗迹之上，不整合。在长城群消失的老虎沟东南部地区，土城子组直接位于北票组之上。上述两个盆地之间的长城群遗迹被解释为在跳积山组火山活动之前的一次广泛的东-东南-东南向逆冲事件中形成的一个断裂带。(3)辽西凌源市南部的逆冲变形序列为：早侏罗世北票组(印支系)前开始向南逆冲，到跳积山组前东-东南向逆冲，条脊山组后逆冲伴生褶皱向东南，最后到早白垩世九佛塘组内局部逆冲变形结束。在研究区的东-东南-东东向逆冲褶皱过程中，盖层序列内的缩短率约为35%。
The ideas and concepts regarding to the analysis of syntectonic sedimentation are briefly introduced together with the investigation approaches and its potential implications to the research of regional tectonic deformation processes. It was studied that the tectonic deformations together with the conglomerate composition variation within the Late Jurassic Tuchengzi Formation in south of Lingyuan City, western Liaoning Province, the following conclusions are reached. (1) The syntectonic/synkinematic sedimentation in the research area was commenced after the volcanism of the Tiaojishan Formation. The provenance area was located to the west of the synkinematic sedimentary basin—Dengzhangzi Basin, instead of the east side of the basin. Dengzhangzi Basin was not a foredeep sedimentary basin of the westward thrusting as it was thought to be by previous investigators. Variations of the conglomerates within the Tuchengzi Formation indicate an erosion and unroofing sequence of the tilted normal sequence of the provenance strata. The erosion reached the upper part of the Wumishan Formation of the Mesoproterozoic Jixian Group. (2) The contacts between the relic slices of Mesoproterozoic Changcheng Group, lying between the Niuyingzi-Guojiadian Basin and the Dengzhangzi Bansin, and the Beipiao group to the east is a major east southeast-ward thrust fault. To the northwest side, however, the Tuchengzi Formation lies unconformably on top of the relics of Changcheng Group. In the area SE of Laohugou where the Changcheng Group disappeared, the Tuchengzi Formation lies directly on top of the Beipiao Formation. The relics of Changcheng Group between the two basins aforementioned is interpreted to be a klippe formed during an extensive east-south-east thrusting events of prior to the volcanic activity of Tiaojishan formation. (3) The thrusting deformation sequence in the south of Lingyuan City, western Liaoning Province, could be identified as follows: starting from a southward thrusting prior to the Early Jurassic Beipiao Formation (the Indosinian), then to the east-south-east ward thrusting before Tiaojishan Formation followed by a thrusting and associated folding with vergence to the southeast after Tiaojishan Formation, finally to the ending of contraction deformation with local thrusting deformation within the Early Cretaceous Jiufotang Formation. About 35% shortening within the covering sequence was achieved during the east-south-east thrusting and folding in the study area.