C 第一章 岩石和构造2-岩浆岩.pdf

昆明理工大学土木系 徐则民 2005/09/29 工程地质学 第三讲 1.2 岩石 根据成因，构成地壳的岩石可以分为岩浆岩、沉 积岩和变质岩三大类。 岩石循环 活动断裂（地震）主要分布板块边界上，有时也 受板块内部的超壳断裂控制的控制 全球板块构造略图 Cliff Erosion Devils Tower Wyoming The exposed rocks at Devils Tower National Monument are classified into two general types: igneous and sedimentary. The tower itself is composed of igneous rock formed by cooling and crystallization of once-molten materials. The rocks exposed around the tower are sedimentary-layers of shale, sandstone, silt stone, mud stone, gypsum, and limestone. They were formed by the consolidation of fragmented materials derived from other rocks or the accumulation of chemical precipitates that were deposited on the floors or near the shores of ancient seas. Devils Tower owes its impressive height to the differing rates of erosion of these two rock types-the soft sedimentary rocks have eroded more readily than the hard igneous rock. One of the most striking features of the tower is its polygonal columns, formed as the igneous mass slowly cooled and crystallized. Most of the columns are 5-sided, but some are 4-sided or 6-sided. Numerous cross-fractures in the upper part of the tower divide the columns into many small, irregularly-shaped blocks. [Photo credit: Michelle Flores, National Geophysical Data Center.] 颜色及成分变化构成的水平层理 西藏昌都, 2001/7/4 具有斜层理的第四系半胶结砾岩 金沙江水富段 Arizona has some of the most spectacular geology anywhere! The Grand Canyon, the worlds premier geologic locality, exposes 1.7 billion years of geologic history in its walls. The photograph to the left shows a beautiful view of the Grand Canyon, with its upper flat-lying layers of Paleozoic limestone, sandstone, and mudstone. From:/research/az_geology/az_geology.h tml Intensely foliated micaceous phyllites of the Malmesbury Group, Cogmans Kloof Pass 千枚 岩 http:// www. uct.ac. za/de pts/ge olsci/d lr/4da y2001 /index. html# 4day Phyllites of the Malmesbury Group forming the basement to the Table Mountain Group, Cogmans Kloof Pass h