Structural Geology: Fill in the blank sides of the block diagrams below (questio
ID: 112439 • Letter: S
Question
Structural Geology: Fill in the blank sides of the block diagrams below (questions 5-16) by extending the contacts between the lettered units. The letters correspond to different age stratigraphic units and are defined in attached Table 1. Use different colors for the different units to help you work out the structure. Draw in symbols on the top surfaces of the blocks to indicate the bed orientations (i.e. strike and dip directions) and presence of any structures (i.e. folds or fault symbols). Also answer questions below the diagrams.
) What is this structure? 6) What is this structure? 11) What is this structure? 12) What is this structure? 7) What is this structure? 8) What is this fold's 13) What is this structure? 14) What is this structure? 9) What is this fold's geometry? 10) What is this structure? 15) What is this structure? 16) What is this structure?Explanation / Answer
S=Silurian, D= Devonian, M=Mississippian
5) So, we can see that the fold has younger rock formation in the core(Mississippian), so it is an anticlinal fold, and it also the opening upward so it is a synformal fold. So, overall it is a Synformal-Anticlinal fold.
6) The fold has older rock formation(Silurian) in the core(so, synclinal) and opening downward(so, antiformal). so the fold is an Antiformal-synclinal fold.
7) As the cross-section indicates its an effect of shearing, a shear structure. But the shearing is not so strong. If we have the surface extension then it will look like a scarp or escarpment.
8) In the cross-section, we can see, Silurian is in the middle or at the core. and both sides of it we have D and M, which are younger than S. So firstly it is a Synclinal fold. Secondly, both the limbs( either side of S) has the same dip amount(so, homoclinal fold). Thirdly, the fold has an inclined axial plane(so, an inclined fold). So, overall it is a Synclinal-inclined homocline fold.
9) Antiformal open fold.
10) Plunging Synformal fold.
11) Normal fault.
12) Reverse fault.
13) Listric fault(curve fault surface).
14) Dome.
15) Synclinal fold.
16) Basin.