GEOLOGIC STRUCTURES – Lab 4 Faults and Faulting In this lab you will examine som
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Question
GEOLOGIC STRUCTURES – Lab 4
Faults and Faulting
In this lab you will examine some structures using Google Earth. The goal is to identify the faults on the images. This is great practice for identifying them visually if you are out in the field or if you have other remote sensing images to work with.
Tectonism is ubiquitous on Earth, the fundamental process responsible for the terrains we find familiar. In this exercise, you will visit a series of locations where distinctive geologic structures are exposed by geologic processes. Your task will be to identify these structures as best you can.
Fig. 1. Google Earth image a transform fault in Montana
In Google Earth, use the coordinates below to locate a variety of structures. This week the structures of interest are all faults. There are normal faults, reverse faults, and strike-slip faults (right and left lateral). Inspect each fault and try to determine the sense of offset.
Note: In some instances, it may be helpful to increase the vertical exaggeration of the images. This can be changed in Google Earth by accessing ‘Tools’ from the main menu bar. Under the ‘Options’ function you will see ‘Elevation Exaggeration:’ in the lower left of the dialogue box. You can change the vertical exaggeration of the terrain model in Google Earth by typing 1, 2, or 3 (3 is the greatest vertical exaggeration, 1 is the least). ).
It can also be incredibly useful to change the camera angle and zoom in and out once you find the structure you are supposed to identify.
PART 1: The list of coordinates below will take you to various parts of the world to see examples of different types of geologic structures (faults). Examine each image and identify the type(s) of structure illustrated.
LATITUDE
LONGITUDE
ALTITUDE (km)
(camera height)
FAULT & OFFSET (e.g., “Reverse: upthrown on North side”, “Normal: East block dropped”, “left-lateral”, etc.
44.969228
-108.414814
10
35.528348
-117.336538
2
38.734632
-109.507026
3.5
35.442394
-117.686327
4
36.601581
-114.551509
1
36.500986
-111.714474
6
57.034394
-4.796493
320
PART 2: Tell me what the hardest part of identifying the faults was. Do you think you will be able to identify faults when you look at them in the future?
LATITUDE
LONGITUDE
ALTITUDE (km)
(camera height)
FAULT & OFFSET (e.g., “Reverse: upthrown on North side”, “Normal: East block dropped”, “left-lateral”, etc.
44.969228
-108.414814
10
35.528348
-117.336538
2
38.734632
-109.507026
3.5
35.442394
-117.686327
4
36.601581
-114.551509
1
36.500986
-111.714474
6
57.034394
-4.796493
320
Explanation / Answer
Part 1:
(i) The fault type in this location is a Stike Slip fault; Left Lateral strike slip fault
(ii) The fault type in htis location is a Strike Slip fault; Left Lateral strike slip fault
(iii) The fault type in this location is a Normal Fault; The Northern block is the hanging wall and the southern block is the footwall
(iv) The fault type in this location is a Strike Slip Fault; Left lateral strike slip fault
(v) The fault type in this location is a Strike Slip fault; Right Lateral strike slip fault
(vi) The fault type in this location is a Normal Fault; North western block has moved downward
(vii) The fault type in thsi location is a Strike Slip fault; Right Lateral strike slip fault
Part 2:
The hardest part of identifying faults is to identify the fault plane and fault trace in a given location. If we are able to identify the fault plane, it is relatively easy to identify the fault type. If we look in a satellite image of the location it is easier to find the fault plane. For strike slip fault, if we identify the geomorpholgy features of the area which has the offset and the mineralogy (using multi spectral of hyper spectral images), the offset would give conclusive proof that it was a continuous feature and is offsetted by the strike slip fault.
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