准噶尔盆地车排子地区不整合结构对火山岩裂缝发育的影响

Effects of structural unconformity on development of volcanic rock fracture in Chepaizi area, Junggar Basin

关键词:  不整合结构  裂缝  火山岩  车排子地区  石炭系

Key words:  unconformity structure  fracture  volcanic rock  Chepaizi area  Carboniferous

摘要:

准噶尔盆地车排子地区石炭系火山岩储层裂缝发育，利用岩心、薄片、常规测井资料和成像测井资料，分析研究区不整合结构特征和各结构层的裂缝发育特征。结果表明，车排子地区石炭系顶面不整合各结构层发育，自上而下依次为不整合面之上的岩石、风化黏土层、水解层、淋滤层、崩解带Ⅰ、崩解带Ⅱ，不整合面下各结构层的裂缝发育特征具有明显差异，裂缝充填程度由低到高为淋滤层、水解层、崩解带Ⅰ、崩解带Ⅱ；裂缝发育由好到差为淋滤层、崩解带Ⅰ、崩解带Ⅱ、水解层；结构层内裂缝发育特征与火山岩岩性、风化淋滤作用和充填作用有关，玄武岩、安山玄武岩等裂缝发育程度较高的火山岩，在淋滤层和崩解带Ⅰ所占比例较大；淋滤层内，黏土化作用弱于风化淋滤作用，因此淋滤层裂缝发育程度最好。

Abstract:

The fractures of volcanic rock are studied in the Carboniferous Chepaizi area of Junggar Basin. Using drilling cores, thin section, conventional logging and image logging, the characteristics of the structural unconformity and the characterization of fracture in each structure are statistically analyzed. The results show that the structure of the Carboniferous top unconformity has a six-layer structure, which includes overlying rock, soil layer, hydrolysis zone, leached zone, broken-down zone Ⅰ, and broken-down zone Ⅱ from top to bottom. Under the unconformity, the characterization of the fractures in individual structures differs. The degree of fracture filling increases gradually from the leached zone, the hydrolysis zone, the broken-down zone Ⅰ, to the broken-down zone Ⅱ. The fracture development is the best in the leached zone, but downgrades gradually from the broken-down zone Ⅰ, the broken-down zone Ⅱ, to the hydrolysis zone, respectively. The characterization of the fractures in the structure is clearly related to volcanic rock, weathered leaching and argillazation. Basalt and andesitic basalt have well developed fractures, and account for a large proportion in the leached zone and the broken-down zone Ⅰ. Argillazation is less developed than weathered leaching in leached zone, where fractures are well developed.