a) List the sequence of geologic events recorded by relationships on the map. b)
ID: 286709 • Letter: A
Question
a) List the sequence of geologic events recorded by relationships on the map.
b) Determine the orientation of i) the fault; ii) contacts in the hanging wall of the fault; iii) the contact in the footwall of the fault; iv) the contact between the basalt flow and sedimentary rocks. Be specific.
c) What type of fault is it? Be as specific as possible
Jsh Tb North s 500 m Jsh Jis Tb Tertiary basalt flow Keg Cretaceous conglomerate EKSS Cretaceous sandstone Jurassic limestone Tb Jsh Jurassic shale Rs Triassic limestone Jsh fault Js s JisExplanation / Answer
a) By careful observation of the given map, the geological event sequence can be interpreted. The events are from older to younger (bottom to top) numbered as 1-5 are as follows :
5.Deposition of Tb
4.Erosion after deposition of Kcg (unconformity)
3.Faulting
2.Folding of the rock groups
1.Deposition of JIs, Jhs,RIs, Kss, Kcg
b) i. It is clearly seen that the fault is an inclined fault. The rock groups are dipping towards west determined from the strike lines of the rock groups. The fault is also dipping westwards.
ii. Towards the dipping side the hanging wall is found. Therefore, JIs, Jsh side is the hanging wall side.
iii.The right side block of the fault consisting of Kss, Kcg is the footwall.
iv. The contact between the basalt flow and sedimentary rock is an unconformity. As the basalt flow is horizontal and below the unconformity the rock groups showing folding and faulting, so the unconformity is angular unconformity.
c) The older rock group is found towards the younger direction. So the fault must be a reverse fault.
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