基于颗粒离散元计算架构建立单矿物石英岩的颗粒簇模型(grain based model,GBM),以石英岩微裂纹发展规律为约束优化矿物模型的弹性模量及其边界强度参数,开展热-固耦合下石英岩的高温损伤及强度劣化细观机理研究,获得以下结论:(1)优化矿物弹性模量及其边界强度参数后可很好地再现石英岩高温作用下微裂纹演化规律:首先从石英晶粒边界萌生,逐渐扩展至晶粒内部,最终形成裂纹网络。(2)单轴压缩模拟中石英岩弹性模量随温度的升高总体上呈现出先增大后减小的趋势,泊松比表现为先减小后增大,且泊松比较弹性模量对热损伤表现出更高的敏感性。(3)随着温度的升高,石英岩单轴压缩过程中微裂纹的离散性增加,破坏模式从多斜面剪切破坏逐渐转变为无明显宏观裂纹的分散式拉伸(劈裂)破坏。(4)岩石的力学强度劣化规律与其本身的致密性及矿物成分、含量密切相关,与花岗岩相比石英岩热损伤温度阈值高,约为200℃。(5)3种不同石英含量的岩石的热损伤结果表明:矿物边界和力学强度较低的矿物内部首先发生热破裂,矿物之间的镶嵌结构对石英矿物的热损伤有抑制作用。
云南个旧的锡多金属矿床是世界上众多超大型矿床之一,其中包含马拉格、松高、卡房、松树脚和老厂等矿田。白云山碱性岩体分布于花岗质杂岩体北部的白云山林场一带,主要由碱性正长岩和霞石正长岩组成。本文对白云山霞石正长岩进行全岩元素含量分析,并且利用电子探针对岩石中的长石、霞石和辉石单矿物进行了元素含量分析。全岩元素含量分析结果说明白云山霞石正长岩为硅不饱和超钾质碱性岩,岩体起源于不均一的富集地幔源区,在成岩过程中可能发生富镁铁质矿物和少量长石的分离结晶作用。岩石中含少量辉石,电子探针分析结果表明辉石的组成结构单一,均为霓辉石。利用巴尔特二长地质温度计进行计算,得到长石结晶温度约为385.53℃左右,代表了岩石形成的最低温度。电子探针元素含量分析表明霞石符合采矿指标,可对其进行开采利用。The Gejiu tin polymetallic ore deposits in Yunnan are among the world’s significant megadeposits, encompassing mining fields such as Malage, Songgao, Kafa, Songshujiao, and Lao Chang. The Baiyun Mountain alkaline rock mass is situated in the Baiyun Mountain Forest Farm area, north of the granitic complex, predominantly consisting of alkali feldspar granite and nepheline syenite. This study presents a comprehensive whole-rock geochemical analysis of the nepheline syenite from Baiyun Mountain, complemented by electron microprobe analysis of the feldspars, nepheline, and pyroxenes within the rock samples. The geochemical findings suggest that the nepheline syenite is a peralkaline rock characterized by silica deficiency and ultrapotassic affinity, likely derived from a heterogeneously enriched mantle source. Fractional crystallization of mafic minerals and minor feldspar may have occurred during the petrogenesis of the rock mass. The rocks contain a few of pyroxenes, and the electron microprobe data show these pyroxenes have a uniform comp
