三肇凹陷T11反射层断层构造成因机制的定量研究

The quantitative study of structure genetic mechanism about T11 reflecting layer fault in the Sanzhao sag of Songliao Basin

为了对三肇凹陷T11反射层断层成因机制做出符合实际地质理论解释，本文鉴于前人各种非构造成因观点所存在的问题，从构造变形层间剪切力、断层线面密度关系、与国外哈默费斯特盆地典型的非构造成因多边断层解释特征对比3方面，对其成因机制做了定量分析。研究结果认为：1）T11反射层断层为构造成因机制，是姚家组一段泥包砂地层结构受到上覆载荷作用构造变形时，在其泥岩层界面或层内优先发生层间滑动产生的内部作用力一层间剪切力所形成的切层断层和层内变形断层；2）从断层线面密度关系计算结果来看，二者存在密切相关性，断层线密度越大面密度越大，这与构造成因断层空间分布规律相一致；3）与哈默费斯特盆地的对比得出，T11反射层断层展布存在近南北向和东西向优势方位，其次是北北东向和北北西向，仅在几个鼻状构造带内发育走向随机的小断层，这些内部走向相对多方位的小断层实际上是由波状起伏的层间滑动断层及其伴生构造所形成的一种特殊构造现象。

In order to interpret the genetic mechanism of fault in T11 reflecting layer of Sanzhao sag and confirm the actual geological theory, this paper reviewed the previous problems of various views which regard fault as non-structural origin. Then quantitative analysis of its origin mechanism is based on the following factors： The interlaminar shear stress during the period of structural deformation, the relationship of fault line and areal density and the comparison with features of polygonal fault with non-structural origin in foreign Hammerfest Basin. Comprehensive study shows that the mechanism of fault in T11 reflecting layer is tectonic genesis. It is the fault that cutting layers or deformation in layers formed by the internal forces-interlaminar shear stress in the mudstone layer interface or layers preferred interlayer sliding, as the deformation of mud- sand stratum in Yaojia Formation was happened during the loading effect of upper rock. From the calculation result, there is a close correlation between fault line and areal density, the greater the fault line density, the greater the areal density, this is consistent with the spatial distribution law of structural origin fault. Compared with the interpretation features of polygonal fault with non-structural origin in Hammerfest Basin, the faults in T11 reflecting layer mainly distribute near SN and EW direction, then are the NNE and NNW direction and the faults with random strike only distribute in a few nose structure zones. These small faults with random strike are special structure phenomena, which actually formed by the interlaminar gliding faults with undulation and its associated structure.