ABSTRACT
This paper presents the results from simulation of seven types of geological structures by use of mathematical and physical methods. Curvilinear equations for plume and rib marks are derived. From mathematical simulation, the theoretical values of plume fringe angle for monoplume structure and half-plume structure are 72° and 81°, respectively. Different plume and rib structures are achieved from physical models. Measurement values of plume fringe angle from physical models and natural rocks are statistically identical with the theoretical values. Experiments are performed for ductile shear zones by use of Chen's grid method. The finite shear strain in the model is similar to that in natural shear zones. In simulation of chess-board structures (or conjugate fractures), the clay models are adopted to examine the effect of material behavior, mean stress and sustained loading on conjugate shear angle, respectively. The results from simulation of epsilon-type structure by use of superposition principle, finite element method, photoelastic method and in-plane moiré method indicate that a large plate sustained by two nuclear columns and loaded by unidirectional body forces is an ideal model for this type of structure. It is concluded from the simulation of uninucleus-type torsional structures by use of the stress function method, finite element method, brittle coating and bubble method that the nearer to the nuclear column, the greater the values of the principal stresses, maximum shear stress and differential ture strain, and that these values decrease rapidly with the increase in distance away from the center of the nuclear columns. In particular, the experiment by the bubble method indicates that the distortion mainly takes place near the nuclear column and that nearly only rigid rotation takes place far from it. At the same time, the Weissenberg effect is observed in the bubble method experiment. The binucleus-type torsional structure is a new kind of structural type presented by the first author. It is characterized by two nuclear columns which distinguish it from uninucleus-type torsional structures. Analytic method in viscoelasticity, tissue paper method, clay model, shadow moiré method are adopted in the simulation of this type of structure. It is shown by both mathematical and physical simulation that torsional movement around two nuclear columns can produce s-shape, reversed s- shape, elliptic arc, hyperbolic and turbine-like structures. The simulation of India-Eurasia collision come to the conclusion that the inversion of Tan-Lu faults and Red River fault, the clockwise rotation of Southeast Asia may be the result of the collision.
