四川盆地东北部二叠系层序发育的动力学分析  

SEQUENCE DYNAMICS OF THE PERMIAN SYSTEM IN NORTHEASTERN SICHUAN BASIN

作　　者：李凤杰[1] 刘琪[1] 刘殿鹤[1] 刘犟[1] 

机构地区：[1]成都理工大学沉积地质研究院,四川成都610059

出　　处：《地层学杂志》2010年第1期35-42,共8页Journal of Stratigraphy

基　　金：国家重大专项"中西部前陆盆地构造地质与沉积储层特征"(No.2008ZX05003-001)资助

摘　　要：运用可容空间分析法,在野外剖面岩性、岩相厚度和旋回变化分析的基础上,对川东北地区宣汉县渡口镇羊鼓洞二叠系剖面的旋回层序进行研究,识别出3种类型5种亚类型的高频旋回层序类型,并将剖面中栖霞组、茅口组以及吴家坪组下部划分为118个高频旋回层序。根据测井曲线的旋回变化,将普光4井的长兴组划分出49个高频旋回层序,据此运用Fischer图解绘制了二叠系可容空间变化曲线。将可容空间变化曲线与相对海平面升降曲线之间进行对比发现,二者之间存在着良好的对应关系。采测井曲线的频谱分析,对研究区长兴组进行了米兰科维奇沉积周期进行研究,结果表明:长兴组中广泛地保存着124,44.89,35.11,21.16和17.72ka的米兰科维奇沉积周期;地层中的沉积旋回主要受古气候变化的控制,偏心率、地轴倾角和岁差周期引起的地层旋回厚度变化范围分别为:12.47—13.74m,3.56—5.21m,1.78—2.41m,其中受偏心率周期的影响最大。在构造活动相对较弱的川东北二叠系中,层序发育的动力学因素主要为相对海平面的变化和气候变化两个方面。相对海平面的变化主要是三级层序的控制因素,而气候变化则是高频层序旋回的主要动力。On the basis of thickness and cycle change of lithology and lithofacies of field profile, and guided by accommodation theory, we analyzed the cycle sequences of the Permian System at the Yanggudong profile in Dukou Town, Xuanhan County, Northeastern Sichuan Basin. Three types, five subtypes and 118 high-frequency sequence cycles are recognized in the Chihsia Formation, Maokou Formation and upper Wujiaping Formation. And based on cycle change of logging curve of well Puguang 4, 49 high-frequency sequence cycles are identified in the Changhsing Formation. The curve of accommodation change is drawn by using the cycle analysis technique of Fischer Plot. There is a very well correlation between the accommodation and sea level curves. To identify the Milankovitch cycle in the Permian Changhsing Formation in Northeastern Sichuan Basin, the logging curves were analyzed with frequency spectral techniques. The resuits reveal that the Changhsing Formation shows Milankovitch sedimentary cycles of 124,44.89,35.11, 21.16 and 17. 72ka. The sedimentary cycles are controlled by palaeoclimate, which is related to the eccentricity cycles, obliquity cycles and precession cycles. The thickness of sedimentary cycles corresponding to the eccentricity cycles, obliquity cycles, and precession cycles is 12.47-13.74m, 3.56-5.21m, and 1. 78-2.41m respectively. Among the three controlling factors, eccentricity cycles have a more important effect on the Changhsing Formation. Dynamics factors of sequence development were mainly relative sea level change and climate change in Northeastern Sichuan Basin where tectonic activity was relative weak. Relative sea level change was the major controlling factor for the development of third-order squences, whereas climate change was important in the development of higher frequency cycles.

关 键 词：可容空间变化 Fischer图解 米兰科维奇旋回层序 二叠系 川东北 四川 

分 类 号：P534.46[天文地球—古生物学与地层学] P539.2[天文地球—地质学]