摘要
根据滇东南地区奥仑期沉积组合特征及其空间展布，永宁镇组中能识别出四个三级层序，九个高频层序。三级层序Ⅰ和Ⅱ及层序Ⅲ和Ⅳ分别代表盆地的两个不同的演化阶段。前者属盆地稳定阶段周期性海平面下降时期的层序组合；后者属基底断陷和周期性海平面上升复合作用的层序组合。据现有资料，奥仑期的相对海平面变化不但在中国南方有明显表现，在德国也有类似经历。显示出它具有一定的洲际可比性。分布于高频层序７至８的钙屑浊积岩，根据对其沉积组合、沉积旋回的叠置及区域展布特征分析，它们可以分为构造活动期钙屑浊积岩和构造平静期钙屑浊积岩两种组合类型。通过对构造平静期钙屑浊积岩形成机制的研究，认为它们属高水位期钙屑浊流扩散沉积作用，而不是低水位扇或低水位楔钙屑浊积岩。
third-order and 9 high-frequency depositional sequences can be distinguished in Yongningzhen Formation basing upon the features of the Olenekian sediment assemblages and their space distribution in SE Yunnan.Ⅰ-Ⅱand Ⅲ-Ⅳ of the thirdorder depositional sequence represent two diffdrent evolution stages of the basin. The former belongs to the sequence assemblage formed in the periodic fall of sea-level of the stable stage of the basin whereas the latter is that of the composite function of basement fault depression and periodic rise of sealevel.According to present data, the relative sea-level change of Olenekian is very clear in South China. And a similar process also took place in Germany. It indicates that this change is intercontinentally comparable in some aspects. The calcic turbidite in high-frequence depositional sequence 7-8 can be divided into two assemblage types,one formed in a tectonic active epoch and the other in a tectonic quiet epoch according to the analysis of the features in sediment assemblage,stacking pattern of sedimentary cycle and regional distribution. Basing upon the study of the formation mechanism of the latter,we believe it is formed by the sedimentation of calcarenaceous turbid flow diffusion in highstand,not the calcarenaceous turbidite of lowstand fan or wedge.
出处
《云南地质》
1995年第3期238-248,共11页
Yunnan Geology
