盐城凹陷南洋次凹阜一段砂砾岩粒度特征研究

Glutenite Characteristics of the First Member of Funing Formation in Nanyang Sub-Sag, Yancheng Sag

盐城凹陷南洋次凹作为盐阜地区的重要勘探地区,在阜一段沉积环境的研究尚且存在争议,沉积环境研究的根本是沉积水动力条件,而粒度特征是分析判断沉积水动力条件的关键。在岩心观察的基础上,利用大量粒度特征分析资料,分析了盐城凹陷南洋次凹阜宁组一段砂砾岩C-M图、粒度概率累积曲线反映的沉积水动力条件,总结了研究区阜宁组阜一段辨状河三角洲前缘、扇三角洲前缘沉积水下分流河道微相的粒度概率累积曲线组合特征。C-M图表明该区阜一段牵引流与重力流并存,粒度概率累积曲线表明该区辨状河三角洲前缘水下分流河道微相有“两跳一悬式”;扇三角洲前缘水下分流河道微相有“一跳一悬两段式”、“一跳一悬夹过渡式”、“一滚一悬多跳式”以及“一跳多悬夹过渡式”。依据对研究区粒度特征的分析,为还原古沉积环境以及划分沉积相提供重要依据。

As an important exploration area in Yanfu area, the study of sedimentary environment in Nanyang sub-sag of Yancheng Sag is still controversial. The fundamental research of sedimentary environment is the sedimentary hydrodynamic conditions, and the grain size characteristics are the key to analyze and judge the sedimentary hydrodynamic conditions. On the basis of core observation, use a large number of granularity characteristics analysis data to analyze the glutenite concave funing group C-M figure of Yancheng sag of Nanyang time period and sedimentary hydrodynamic conditions reflected by grain size probability cumulative curves, summarize combination characteristics of grain size of cumulative probability curves of subaqueous distributary channel microfacies in the bian river delta front and fan delta front of the first of member Funing group in the research area. The C-M diagram shows that the traction flow and gravity flow coexist in the Fu1 section of this area, and the particle size probability accumulation curve shows that the subaqueous distributary channel microfacies in the delta front of the differentiating river in this area have “two jumps and one suspension”. The subaqueous distributary channel microfacies of fan delta front include “one-hop one-suspension two-section type”, “one-hop one-suspension transition type”, “one-roll one-suspension multi-jump type” and “one-hop multi-suspension transition type”. Based on the analysis of grain size characteristics of the study area, it provides an important basis for the reduction of paleo-sedimentary environment and the division of sedimentary facies.