岩浆物理过程对钾质煌斑岩岩相特征的控制机制  

THE CONTROL OF PHYSICAL PROCESSES OF MAGMA ON THE CHARACTERISTICS OF PETROGRAPHY OF POTASSIC-LAMPROPHYRE

作　　者：舒小辛[1] 

机构地区：[1]同济大学海洋地质系

出　　处：《地球科学（中国地质大学学报）》1995年第6期689-692,共4页Earth Science-Journal of China University of Geosciences

基　　金：国家教委博士导师基金;国家自然科学基金

摘　　要：沿扬子地台西缘分布的橄辉云煌岩和白榴橄辉云煌岩在成分上相似，但岩相差异很大，两者的区别主要在于前者含橄榄岩包体，斑晶和基质金云母稳定，基质中有透长石存在，后者则无橄榄岩包体，斑晶金云母分解呈黑褐色，基质有白榴石及他形新鲜金云母，经对两种岩石的岩浆物理特征计算及分析，结果表明：造成这种差异的主要原因是两种岩浆的密度差异大，造成上升速度不一样。从而引起岩浆在上升过程中所含挥发分发生散失的程度有差异，造成ＰＨ２ｏ的变化，而这正是控制金云母、透长石及白榴石稳定性及变化的主要物理参数。The O1-Cpx-lamprophre and Le-O1-Cpx-lamprophre form the westrn border of Yangtze platform are very similar in composition bue quite different in petrography.The main discrepancy is that,the former contains peridotite xenoliths,with stable phlologopites both ,in porphyritic crystals and matrix and sanidines in the later has no xenoliths ,with unstable black phlologopites as porphyritic crystals but stable oncs and leucites in the matrix .The results of analyses and calculations of physical properties of the two types of rocks show that the main factors causing the differents in petrography between them are as follow:the densities of two magmas are quite difrerent.This will causedifferent ascent velocities and then different diffusion rates of volatile in magma. The change of the pH2o in magmas during their ascenting triggers the changes of the stability of phlologopite,leucite and sanidine.

关 键 词：钾质煌斑岩 岩相 岩浆物理过程 岩浆密度 

分 类 号：P588.13[天文地球—岩石学]