地质学基础 地质构造.ppt

Chapter 4 Geological Structure 第四章 地质构造 §2-1 geological time and Chronological scale地质年代与地质年代表 一、Geological Time Geological time is a method of ordering and measuring past events. The ordering of events uses a group of observational methods known as: 1 Absolute dating methods(绝对年代法) 2 Relative dating methods（相对年代法） conformity （整合接触关系） ①②③④⑤⑥⑦⑧⑨●??◆?◇▼????★ 五 、地质构造在地质图中的表现形式 断层切割褶皱后在地 质图中的表现规律 3 the classification of folding (1) According to the Orientation of axial plane The orientation of the axial plane relative to the horizontal together with the orientation of fold limbs翼部 allow subdivision into upright (axial plane vertical, limbs symmetric), overturned (axial plane moderately inclined, one limb overturned), or recumbent 平卧的(axial plane near horizontal, one limb inverted). Upright 直立的 Inclined 倾斜的 Overturned 倒转的 Recumbent 平卧的 （2）according to pivot location state Horizontal fold Inclined fold （3）According to the tightness of folding The tighness of folds can be described as open (limbs dip gently), tight (limbs dip steeply) or isoclinal (limbs are parallel). 四 、Fracturing structure断裂构造 Fault 断层 Jointing节理 Fracturing structure （Fragile rock 脆性岩石） Fracture plane 1 Jointing节理 （1） The definition of Jointing Joints are discontinuities on which there has been little or no displacement in shear (in contrast to faults). Joints are ubiquitous (普遍存在的)in igneous, metamorphic and sedimentary rocks. They are evidence of brittle failure of the rock mass at some stage in the deformation history. ◆ joints in igneous rock Joints in igneous rocks are often associated with the tensile stresses generated by shrinkage as the rock cools. The joints form normal (at right angles) to the cooling surface. The margins of lava flows, sills（岩床）, dykes （岩墙）and plutons（侵入体） commonly form the cooling surfaces. （2） the formation of joints 岩浆岩中的节理构造 ◆ Joints caused by crust movement a: Joints in Compressive Stress Fields