1 / 13

Folds analysis techniques

Folds analysis techniques. Goal : To apply some of the basic geometric techniques for analyzing folds and refolded folds. 1. Foliation bedding intersections. Three cases for overturned fold: Bedding upright, dipping more shallowly than foliation

Download Presentation

Folds analysis techniques

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. Folds analysis techniques Goal: To apply some of the basic geometric techniques for analyzing folds and refolded folds.

  2. 1. Foliation bedding intersections Three cases for overturned fold: • Bedding upright, dipping more shallowly than foliation • Bedding overturned dipping more steeply than foliation • Bedding highly oblique to foliation

  3. Note that for cylindrical folds, bedding-foliation intersection lineation lies close to fold hinge.

  4. 2. π-axes and β-axes Define fold axis using measurements of bedding from around the fold Plot on stereonet

  5. π-girdle: best-fit girdle to poles to beddingπ-axis: pole to π-girdle

  6. Finding π-axes 1. Plot poles to bedding 2. Find best-fit great circle

  7. β-axis: defined by intersections of bedding planes plotted on net

  8. 050°, 80°-SE 350°, 44°-NE 088°, 72°-NW Use both π-axis and β-axis methods Find a fold axis using these bedding measurements

  9. 3. Refolded folds

  10. Refolded folds recognition • Can often be found in outcrop • Regional patterns in facing direction • Interference patterns

  11. Interpret these maps: Draw in F1 and F2 axes and indicate plunge directions

  12. Steps to interpret maps • Draw two lines representing fold axes. Which one is refolded? • Identify pattern of younger and older rocks. e.g. youngest on outside • Is the hook/boomerang shape a syncline or anticline? • Decide what kind of fold refolded the first fold.

More Related