摘要
本文讨论了砂屑岩综合结构系数与沉积环境分析的实例。 这里介绍的测定砂屑岩结构成熟度的方法是在显微薄片粒度分析基础上提出的,其中包括了成熟度、分选性、颗粒圆度和岩石的杂基等多种因素。综合结构系数可按下式求得: T=(SoΦPo)/(PΦC) 因为圆度是在显微镜下的薄片中求得,因而总是比实际投影的易反映其棱角而降低了圆度,所以采用了[p02+(R-A)2]0-5来校正颗粒的圆度,于是得出了发展的综合结构系数Td:Td=SoΦ[P02+(R-A)2]0.5/(PΦC)多数情况下Td和T很接近,只是颗粒圆度非常好时才拉大差距,因此,Td可用来检验超成熟度的砂岩。 本文提出了四种成熟度阶段:不成熟的(T<10);次成熟的(T=10-40);成熟的(T=40-100);超成熟的(T或Td>100)。
The comprehensive textural coefficient of arenaceous rocks can be used for analysis of sedimentary environments. A formula for defining the textural maturity of arenaceous rooks is put forward based on microscopic grain-size analysis in thin sections.The aim that we proposed this formula is to establish a numerical relationship between sorting and roundness of grains as well as matrix content and maturity of rocks. The comprehensive textural coefficient can be obtained according to the following formula: T=(S_0ΦP_0)/(PΦC)Since the roundness of a grain is determined under a petrographic microscope, it is always smaller in thin section. The projecting of a grain often reflects its angular coners and grain roundness is corrected by (P_0~2+(R-A)~2)^(0.5) The developed comprehensive textural coefficient Td is thus Td=S_0Φ (P_0~2+(R-A)~2)^(0.5)/(PΦC)In most cases Td is similar to T. When grains are very well rounded, Td is more useful for checking the supermature sandstone.Four maturity stages are divided, i. e. immature(T<10), submature (T=10—40), mature (T=40—100), and supermature (T or Td>100).The usage of the comprehensive textural coefficient is illustrated by some examples in this paper.
出处
《岩石矿物学杂志》
CAS
CSCD
1991年第3期210-220,共11页
Acta Petrologica et Mineralogica
关键词
砂屑岩
结构系数
沉积环境
comprehensive textural coefficient
arenaceous rocks
analysis of sedimentary environments
