摘要
在岩芯观察和沉积相分析基础上,利用粒度分析资料对东营凹陷北部陡坡带盐22块沙四上亚段近岸水下扇砂砾岩体的粒度概率累积曲线进行了研究。研究表明,该地区近岸水下扇砂砾岩中的粒度概率累积曲线主要包括:"上拱弧形"、"简单一段式"、"准牵引流型"等3种基本类型和"近似上拱弧形"、"台阶状多段式"、"低斜率两段式"、"低斜率三段式或多段式"等4种主要过渡类型。内扇亚相以泥石流(碎屑流)沉积作用为特点,其粒度概率累积曲线主要为"宽缓上拱弧形";中扇亚相以碎屑流和颗粒流沉积作用为主,辫状沟道微相中下部的粒度概率累积曲线以"近似上拱弧形"为主,顶部砂岩表现为"准牵引流型";外扇亚相发育牵引流和颗粒流沉积,粒度概率累积曲线为"低斜率滚动—跳跃—悬浮三段式"、"一跳一悬夹过渡三段式"和"较高斜率上拱弧形"。总体上,从内扇到外扇亚相,随流体性质由泥石流(碎屑流)向牵引流逐渐演化,粒度概率累积曲线会依次出现"宽缓上拱弧形"、"较高斜率上拱弧形"、"简单一段悬浮式"、"低斜率滚动—跳跃—悬浮三段式"或"一跳一悬夹过渡段三段式",相邻典型曲线间有复杂的过渡类型。
On the basis of observation of cores,facies analysis and grain size analysis of 226 samples from 3 core wells,the probability cumulative grain size curves features of sandy conglomerate of the upper Es4 in Yan22 block Dongying Depression are summarized,the relationships between the probability cumulative grain size curves types and the hydrodynamic conditions are studied.Conclusions are gained as follows：（1） The relationships between the probability cumulative grain size curves shapes and the hydrodynamic conditions or fluid property are found.The research shows that the grains size curves of the nearshore subaqueous fan have the characteristics of coarse-grained,wide-range and low-slope,can be classified into 3 basic patterns（e.g.＂uphill arched arc＂ pattern,one segment pattern and ＂quasi drag flow＂ pattern） and 4 transitional patterns.The ＂uphill arched arc＂ pattern represents debris flow deposition,one segment pattern represents turbidity deposition,the transitional patterns represent the deposition of transitional fluid property.（2） The composition characteristics of probability cumulative grain size curve patterns vary with the change of micro-facies or sub-facies.Inner fan of the nearshore subaqueous fan,made up of thick sandy conglomerate with mixed fabrics of main channel,is typical of ＂broadly uphill arched arc＂ pattern,that represents debris flow deposition.Middle fan mainly has two kinds of deposition： debris flow deposition and drag flow deposition.The curve type of the lower-middle part,made up of thick coarse sandstone with massive bedding,is ＂approximate uphill arched arc＂ pattern.And the upper part,made up of parallel bedding,are ＂one bouncing population-one suspension population sections-transitional zone ＂ pattern and ＂ one rolling population-one bouncing population-one suspension population＂ tri-segment pattern.Outer fan has three types of curve patterns,such as ＂low slope tri-segment＂ pattern,＂one bouncing population-one suspension population se
出处
《沉积学报》
CAS
CSCD
北大核心
2011年第5期815-824,共10页
Acta Sedimentologica Sinica
基金
山东省自然科学基金项目(编号:2009ZRA05059)资助
关键词
近岸水下扇
砂砾岩
粒度概率累积曲线
沙四上亚段
东营凹陷
nearshore subaqueous fan； sandy conglomerate； probability cumulative grain size curve； the upper 4th member of Shahejie formation； Dongying Depression
