内蒙古索伦地区中二叠统哲斯组砂岩段粒度分析与对比

摘要

Suolun Middle Permian Zhesi group subaqueous fan is divided to fan,middle fan and inner fan subfacies in the Inner Mongolia area.The deposition of the underwater fan is mainly supported by matrix.There are far source deposition,braided channel deposition,the channel filling and main channel filling.From bottom to top of sandstone,we have found that the content of matrix increases,the size turns from fine to coarse,the selectivity gets bad,the standard deviation increases and the frequency curve decreases.The cumulative curve of probability is from the middle-low slope to the high slope of two sections,which indicates that the sand body is formed in the process of sea water accunulation and the energy of the water increases gradually.The projected area of the freedman discrete distribution map is an underwater gravity flow region.CM image of the underwater fan is characterized by a long strip gravity flow parallel to the C =M line.%内蒙古索伦地区中二叠统哲斯组水下扇主要划分出外扇、中扇和内扇等沉积亚相.水下扇沉积多为杂基支撑,自下而上展现出远源沉积、辫状沟道、沟道间到主沟道充填等沉积微相,杂基呈现逐渐增多的趋势.粒径表现为自下而上由细变粗的反粒序特征,沉积物分选变差,标准偏差递增,频率曲线尖度减小.概率累计曲线由较高斜度两段式逐步过渡为中—低斜度两段式,说明砂岩体是在海水退积过程中形成,其间水介质能量逐渐增强.弗里德曼离散分布图投射区域为水下重力流区域,水下扇CM图像表现为与C=M线平行的长条状重力流沉积特征.