库车再生前陆逆冲带造山运动时间、断层滑移速率的厘定及其意义

Megascopic pyrolysis characteristics of organic matter samples related to the occurrence of immature and low mature oils

塔里木盆地北缘的库车再生前陆逆冲造山带发育生长断层相关褶皱。根据ShowJH和SuppeJ等提出的生长断层相关褶皱模型,对该逆冲造山带的运动时间进行探讨。在地震剖面中识别出典型的生长地层和生长三角。生长地层的连续性表明,自中新世吉迪克组沉积期至今,该造山带一直处于运动速率和强度递增的活动状态,而侏罗纪至早第三纪处于较稳定的构造背景中;利用生长地层确定断层滑移的时间为晚第三纪至第四纪,反映了由北向南台阶状逆断层的依次扩展和主逆冲断裂带的转换,以及主活动带由山前向盆地不断扩展,沉积、沉降中心随之向南迁移。根据生长三角计算出的各阶段断层滑移速率,吉迪克组沉积期(距今25Ma)为0.10～0.71mm/a,康村组沉积期(距今16.9Ma)为0.13～0.40mm/a,库车组沉积期为0.76～2.11mm/a,西域组沉积期(距今2.5Ma)为1.33mm/a。库车再生前陆逆冲带的中生界烃源岩主排烃期受其所在构造带的构造运动开始时间的控制,该逆冲带构造圈闭的形成和油气运移都与断层相关褶皱作用相伴随,油气聚集发生于晚第三纪至第四纪,且北部较早、南部较晚,最靠近北缘山前的东风背斜带为吉迪克组沉积期,北部背斜带为康村组沉积期,南部背斜带为西域组沉积期。图2表1参8(王孝陵摘)

Two types of sample (taken from the resins and peribles of the immature mudstones in 6 wells of 5 districts, which are considered as predecessor of resins and suberins of modern high plant) and a part of reference samples (containing normal organic matters) are pyrolysed at a constant rate of temperature increase under similar conditions. Rate of hydrocarbon generation vs. temperature curves are obtained. With these and the chemical dynamic behavior of all types of organic matter closely related to the immature and low mature oils (including original organic materials, soluble organic materials, sulphur rich organic materials, and organic materials modified by microbes) are dealt with quantitatively. Results of megascopic pyrolytic characteristics and the quantitative chemical dynamic analyses of these samples show that: although the occurrence and accumulation enrichment of immature and low mature oils are related to a number of different geological factors and conditions, under relatively low thermodynamic stresses organic matters related to immature and low mature oils do be matured to generate hydrocarbons. This not only shows the reasonability of the close relationship of these samples with the occurrence and accumulation of immature and low mature oils, but shows that the generation of immature and low mature oil may be a process of chemical reaction under certain thermodynamic conditions and low mature and only, the process of hydrocarbon generation requires a thermodynamic stress condition lower than that under which normal organic matter may generate mature oil.