华北板块南缘中段中上三叠统软沉积变形构造的发现及其地质意义

豫西地区中上三叠统主要出露在济源、义马、伊川和南召一带。印支期秦岭造山运动控制和影响着邻区中上三叠统盆地属性和沉积地层展布。通过观察研究区野外露头剖面,发现中上三叠统发育一系列典型的软沉积变形构造,包括液化底辟、枕状构造、液化柱、液化卷曲变形、负载、球-枕、火焰状构造、液化角砾岩。这些软沉积变形在垂向上表现出明显的复现性,在侧向上表现为沿地层连续展布,表明该时期研究区内地层受到频繁强烈的地震影响。通过对这些软沉积现象的识别和形成机制解释,判定其触发因素为秦岭造山过程中伴生的地震。区内地层中震积岩的存在即是对秦岭造山过程中构造活动的响应。

Discovery of the Soft-sediment Deformation Structure in the Middle-Upper Triassic Sequence of the Middle Segment of Southern North China Plate Margin and Its Geological Significance

The Middle-Upper Triassic sequences in western Henan are mainly exposed at Jiyuan,Yima,Yichuan and Nanzhao.The Qinling orogenic movement controls the properties of the Middle-Upper Triassic basins in the region and the development of Indosinian sedimentary sequences.Outcrop and profile geological characteristics of the study area show,a series of typical soft-sediment deformation structures in the Middle-Upper Triassic sequences,including liquefied diapir,pillow structure,pillar,liquefied convolute,ball-and-pillow,flame-and-load structures,and liquefied breccias.These soft-sediment deformations structures show obvious reproducibility in vertical direction and lateral continuous.It is indicated that the local stratigraphy was affected by frequent and intense seismic activities during this period.By identifying these soft-sediment deformation features and determining its formation mechanism,it is revealed that the triggering factor is the earthquakes related to the Qinling orogeny.The existence of seismite in the local stratigraphy is likely a response to the Qinling orogenic movement.