1 / 12

Structural Geology

Structural Geology. Strike-slip fault System 010021-38 He Qi. Simple Shear --Reidel model. Fractures Generated During Strike-Slip Faulting. FIVE SETS OF Fractures. R shear Fractures R ’ shear Fractures P shear Fractures T tensional Fractures

love
Download Presentation

Structural Geology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Structural Geology Strike-slip fault System 010021-38 He Qi

  2. Simple Shear --Reidel model Fractures Generated During Strike-Slip Faulting

  3. FIVE SETS OFFractures • R shear Fractures • R’ shear Fractures • P shear Fractures • T tensional Fractures • Shear Fractures Parallel to main fault zone Ideal Model

  4. Arrangement of folds and faults in an ideal right-lateral strick-slip fault

  5. GEOMTRY OF STRIKE-SLIP FAULT ZONES Strick-slip faults often consist of a series of subparallel shear faults. There are two types: pinnate and en-echelon. Within large strick-slip fault zones ,subparallel faults are often arranged in a pinnate pattern, the en-echelon pattern being rare. In the pinnate arrangement the angle between the whole fault zone and that of the individual sub-parallelfault is less than 25˚,and the subparallel faults are shear or shear-plus-tensile fractures. In the en-echelon arrangement the so-called en-echelon angle is usually greater than 25˚,and the subparallel faults are tensional fractures.

  6. Overlappingbetween two subparallel faults is a common feature in both the pinnate and en-echelon arrangements. The pattern of overlapping consist of right steps and left steps. Theoretical analysis and model experiments would show that right steps occur in left-lateral fault zones and left steps in right-lateral fault zones, but some-times reverse overlapping. A ‘rock bridge’—the block between two overlapping subparallel faults—is an important unit within the fault zone that create compression or extension zones. Such as pull-apart area.

  7. Pull-apart basins Pull-apart basins formed in local extensional zones as a result of overlapping process.

  8. The deformation patterns in pull-apart areas are of four types. D is depth ,S is separtion, O is overlapping. (a). Single center, D>>O, S/O>=1. (b).Double center,D>>O,S and S/O<1. (c). Terminal extension type, D<O,S. (d). Combination.

  9. Two different kinds of evolution of strick-slip fault zones Basins are controlled by subparallel faults with large dip-slip componts. Normal faults developed at both ends of the basins. The thickness of sediments within the basins reaches750m. In the later stage of the basin’s history a series of shear faults with normal dip-slip components was generated in the interior of the basin. For a strick-slip fault zone with a compressional component normal to its general trend, the subparallel faults that bound the pull-apart basins will be linked through the formation of internal tensile shear faults, and the pull-apart basin will decrease in size until it disappears. For a strick-slip fault zone with a tensional component normal to its general trend, the adjacent rock bridges are enlarged and linked gradually ,so as to form a large pull-apart basin with more than one subsidence centers.

  10. Negative flower Positive flower Strike-slip faults are arranged in segment or sections that may jog or bend where they link together. Pull-apart basins form where strike-slip fault sections overlap at jogs. Flower structures form where there are bends in strike-slip faults.

  11. FLOWER STRUCTURE IN STRIKE-SLIP FAULTS Positive flower structure for uplift blocks Negative flower structure for depressed blocks

  12. THE END

More Related