中国地质大学：《构造地质学》课程PPT教学课件（英文版）Lecture 21 stress（3）

Review. 1. What is the orientation relationship between maximum shear stresses and principal stresses 2. What are trajectories of principal stresses

Review: 1.What is the orientation relationship between maximum shear stresses and principal stresses? 2.What are trajectories of principal stresses?

Stress Analysis for the formation of En echelon veins and of Vortex Structures

Stress Analysis for the Formation of En Echelon Veins and of Vortex Structures

Stress Analysis For The Formation Of En echelon veins

Stress Analysis For The Formation Of En Echelon Veins

En echelon quartz veins Observe the en echelon veins and examine the relationship among the en echelon extensional veins, the slaty cleavages and the straight shearing veins En echelon slaty cleavages are perpendicular to the en echelon quartz veins After J.G. Ramsay, 1967

En echelon quartz veins En echelon slaty cleavages are perpendicular to the en echelon quartz veins. After J.G.Ramsay, 1967 Observe the en echelon veins and examine the relationship among the en echelon extensional veins, the slaty cleavages and the straight shearing veins

En echelon veins

En echelon veins

Stress analysis Considering the equilibrium of an triangular plate element Set the coordinate systems as in the diagram. we have the equilibrium equations ∑Fa=0and∑F1=0

Considering the equilibrium of an triangular plate element Set the coordinate systems as in the diagram, we have the equilibrium equations: F =0 and FT =0 Stress analysis

A 0 Acoso T Asin e

 T

135 45

    135

Formation of the z En echelon veins 2 十 (After Wang, WX 2 1984) 十

 1  1  2  2 Formation of the En echelon veins (After Wang, W.X, 1984)

sigmoid en echelon veins 2 cm

Sigmoid en echelon veins