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Faults “Faults” are one of the forms of secondary geological structures in addition to “folds” and they occur through the presence of a fracture in the rocks of the earth’s crust followed by a movement of one of the fractured blocks in relation to the other. This movement occurs at the level of the fault and in any A direction as a result of pressure or attraction forces, which leads to the lifting or lowering of rock masses, which may occur in the horizontal direction as a result of lateral displacement.
Fault parts “ Faults”
1- Fault line: It is the effect resulting from the intersection of the fault plane with the surface of the earth.
Fault Level:
It is the surface of the crack on which the displacement occurs, and it often shows some scratches and signs that indicate the direction of movement of the rock blocks. 3-
Displacement: is the amount of The horizontal distance between the two ends of the fractured blocks is measured in a horizontal plane.
4- Fault Throw: is the amount of vertical distance between i The fractured blocks are measured in a vertical plane. 5-
The angle of inclination of the fault:
It is the angle between the fault plane and the horizontal plane. 6-
Upper wall:
The rock mass at the top of the fault level.
7- Lower wall: The rock mass below the fault level.
Fault parts “faults” in nature
Types of Faults
Here are the types of faults “faults” in nature as follows:
1- Ordinary Fault
This fault arises by the influence of tensile forces, in which the slope is in the same direction Throw, i.e. the upper wall moves downward with respect to the fault plane.
2- Reverse fault
This type occurs as a result of compressive forces, in which the slope of the crack is in Reverses the direction of the throw, i.e. the upper wall moves down relative to the fault plane.
3- Vertical fault
in which the fault level is vertical, meaning that the angle of inclination of the fault becomes 90° and in the previous two types it was less than 2165° and therefore there is no displacement Horizontal.
4- Racket slip crack
The rock masses move in a horizontal direction with respect to the fault plane and therefore there is no vertical displacement.
5- Light fault
This type of fault occurs when the area is affected by tensile forces, which leads to the decline of a rocky mass in the area around it as a result of the vertical movement downward, forming a basin in the form of.
6- The prominent rift
The prominent rift is formed when the pressure forces prevail over the area, which leads to the rise of a rocky mass relative to its surroundings as a result of the vertical movement upwards.
The shape of the types of faults “faults”
Incompatibilities
It is an erosion surface that arises as a result of the interruption of sedimentation or the loss of part of it due to the lifting of the area and its rocks expose a period of time to the erosion process that leads to the erosion of part of the rocky succession and thus there becomes a missing time period during which no deposition occurred and thus the incompatibility surface is formed that represents this period that During which no geological events were recorded in this area, and usually a layer of conglomerates forms on top of this surface.
Incompatibility is divided into the following types:
1 – Angular Unconformity
Angular Unconformity is formed when the sedimentation discontinuation process is followed by tectonic activity that leads to uplifting the area and subjecting the rocky sequence to slope and erosion Part of it is due to erosion, and the surface on which the deposition will take place becomes intersected with the lower layers, and when it is immersed in sea water again, it will be deposited on this surface that has been stripped, a set of horizontal layers that differ from each other.
2- Do not agree with Nonconformity
This type is formed when a group of horizontal layers are deposited over igneous or metamorphic rocks, which indicates that there is a time period of geological history missing between each two groups.
3- Disconformity
This type is generated when two groups of sedimentary rocks with the same slope are separated by a disconformity surface.
4- Paraconformity
In which two groups of sedimentary layers of the same slope are formed, separated by an indistinct erosion surface parallel to the surfaces of these layers, and determining the missing time period involves investigating the fossil material of each stratigraphic sequence independently.
