济阳坳陷晚古生代—中生代构造演化特点

利用奥陶系和石炭系灰岩地层中的垂直缝合线构造,对济阳坳陷古生代古构造应力场进行的判别结果表明,自奥陶纪开始华北克拉通盆地就受到NNE—SSW向的水平挤压而整体抬升,在遭受长达140Ma的剥蚀作用后,即至晚古生代古构造应力场仍未发生改变。对地震剖面、断层活动特点以及火山活动的研究表明,晚三叠世济阳坳陷区挤压作用达到最强;早侏罗世—中侏罗世是构造转换过渡期;晚侏罗世开始以近南北向的伸展作用为特征,这是华北东部地区地幔柱上涌的结果。利用岩石薄片数据对晚古生代和中生代物源区性质和构造背景进行了判别。结果表明,石炭-二叠纪物源区性质为再旋回造山带和破裂岩浆弧;中生代物源区性质为再旋回造山带和岩浆弧,古老的基底陆块尚未遭受明显的剥蚀,说明济阳坳陷为活动大陆边缘陆相盆地。

Late Paleozoic-Mesozoic tectonic evolution features in Jiyang Depression

The Paleozoic tectonic stress field was reconstructed with the vertical stylolite structure found in the Ordovician and Carboniferous limestone. The identification of Paleozoic tectonic stress field showed that North China craton suffered the horizontal compression in the NNE-SSW direction and uplifted at the beginning of the Ordovician. Then it had suffered erosion for 140 Ma until the Late Paleozoic era. The analyses on the seismic section, the action rate of faults and the volcanic activity indicated that the squeezing action was the strongest in Late Triassic of Jiyang Depression, and the Early-Middle Jurassic was the tectonic transition period. In the Late Jurassic, Jiyang Depression was featured by the extension in the south-north direction, which resulted from the upwelling of mantle plume in the eastern region of North China. The provenance nature and tectonic setting from discrimination of the rock slice data in the Late Paleozoic and Mesozoic showed that the Permian-Carboniferous provenance was natured to the recycled orogen and dissected arc. The Mesozoic provenance was natured to the recycled orogen and magma arc. The ancient basement blocks in the Mesozoic suffered little erosion, which showed that Jiyang Depression was the terrestrial basin of active continental margin.