Cardboard Model Analysis and Interpretation Activity 10.5 Name: Course/Section:
ID: 116351 • Letter: C
Question
Cardboard Model Analysis and Interpretation Activity 10.5 Name: Course/Section: Date: Tear Cardboard Models 1-6 from the back of your lab manual Cut and fold theas noted in red on e od Cardboard Model 1 This model shows Ordovician (O, green), Silurian (S, tan), Devn (D, gay,Mississippian (M, light brown). Pennsylvanian (yellow),nd Permian (P, peach) formations striking due north and dipping 24 to the west Provided are a complete geologic map on the top of the diagram and three of the four vertical cross-sections (south, cast, and west sides of the block diagram) . Finalize Cardboard Mode as follows. First construct the vertical cross-section on the north side of the block so it shows the formations and their orientations (strike and dip). On the map, draw a strike and dip symbol on the Mississippian sandstone that dips 24 to the west (see Figs. 10.2 and 10.4 for the strike-and-dip symbol) 2. Explain the sequence of events that led to the existence of the formations and the relationships that now exist among them in this block diagram B Cardboard Model 2 This model is slighdy more complicated than the previous one. The geologic map is complete, but only two of the cross-sections are available. Letters A-G indicate ages from oldest (A) to youngest G) 1. Finalize Cardboard Model 2 as follows. First complete the nrth and east sides of the block. Notice that the rock units define a fold. This fold is an anticline because the fold closes upward and the oldest formation (A) is toward the axial surface of the fold (Figs. 10.14 and 10.15). It is an upright horizontal fold because its axial surface is vertical and its axis is horizontal. On the geologic map, dra strike-and-dip symbols to indicate the orientations of formation E (gray formation) at points I, II II d IV. On the map a the op of e mo, draw the proper symbol along the axis of the fold (Fig. 10.4) 2. How do the strikes at all four locations compare with each other? 3. How does the dip direction at points I and II compare with the dip direction at points III and IV In yr ansuer, include ihe dip direction at ail four points Cardboard Model 3 This cardboard model has a complete geologic map. However, only one side and part of another are complete. Letters A-E are ages from oldest (A) to youngest (E) 1. Finalize Cardboard Model 3 as follows. Complete the remaining two-and-one-half sides of this model using as guides the geologic map on top of the block and the one-and-one-half completed sides. On the map, draw strike-and-dip symbols showing the orientation of formation Cat points I II, III and IV. On the map at the top of model, draw the proper symbol along the axis of the fold (Fig. 10.4) 2. How do the strikes of all four locations compare with each other? 3. How does the dip direction (of formation C) at points I and II compare with the dip direction at points III and IV? Include the dip direction at all four points in your answer 4. Is this fold plunging or horizontal? 5. Is it an anticline or a syncline 6. On te basis of this example, how much variation is there in the strike at all points in a horizontal fold? 289Explanation / Answer
Cardboard 1:
2. The beds must have been formed by normal sediment deposition starting from Ordovician followed by Silurian, Devonian, Mississippian, Pennsylvanian and Permian age beds. The eastern side of the whole sequence is then uplifted thereby forming a dipping angle of 24 degrees due west.
Cardboard 2:
2. The strikes of all the beds are parallel to each other.
3.The dipping directions at points I and II due west whereas dip direction at point III and IV are due east the limbs are pointed away from each other.
Cardboard 3:
2. The strikes of all the four location are directed towards the north. thus they are parallel to each other.
3. At the point, I dip direction is due East. At point II as well, the dip is due East. At point III the dip is due west and similarly, at point IV the dip is due west. both the limbs are pointed towards each other.
4. No, the fold is neither plunging nor horizontal. It is non-plunging and vertical.
5. It is a syncline.
6. In a horizontal fold, the strike at all points will be pointed at the same direction.
Cardboard 4
2. the dip directions of all the shown points in cardboard 4 are due northwest and northeast, however, in cardboard 3 they were dipping due east and west. the strike of the beds in cardboard 3 was due north but in cardboard 4, the strike is due north but cardboard 4 shows a plunging fold.
Cardboard 5
2. the syncline is plunging North with a plunging angle of 33.6 degrees.
Cardboard 6
2. the sequence is a reverse fault. the evidence for such a conclusion is that the hanging wall is resting upon the foot wall with its beds at a higher elevation than that of the footwall. moreover thinning of central strata in hanging wall suggests that it has moved up.
3. the contact between A and B units would produce slickensides with pointed towards the dip of the fault.
4.no, the same offset of dipping contacts cannot be produced by a strike-slip fault. strike-slip fault can only produce horizontal offset.