"Why I left Electrical Engineering and choose Geology?" with Rana Faizan

About author: Rana Faizan is currently in his third year of under graduation in Applied Geology at Institute of Geology at University of the Punjab in Lahore, Pakistan. He is interested in Petroleum Geology, Structural Geology, Sedimentology and Tectonics.         
  

When I was studying in the 8^th grade, my father had a wish to make me an Electrical Engineer. Honestly speaking at that time I have no idea about my future goals and even I didn’t knew anything about Electrical Engineering.

One day I was in my class, my teacher gave us a lecture on future planning which really inspired me to think about future aims. This was the first time I started thinking about my future goals. I reached home and asked my father about this concern. He advised me to choose Electrical Engineering in future and told me that this is his dream about me. At that time, I was not familiar with the Geology. Days were passed and I completed my 10^th grade exams with good percentage and took admission in 11^th grade (pre-engineering), and I started study hard to fulfill my parent’s dream.

Then a day come, my father was sharing his university life experiences with me and this was the first time I heard about Geology because his hostel mates were Geology students. My father told me about the geology field work experience that his friends shared with him. And his friend is currently settled in Canada and working as a Geologist. He told me about some more people and some of them are now my professors.

These all things sums up and gave me inspiration about geology, I searched about geology on internet and I found it an interesting field as geologists ruin tourism in their daily life. They can work in natural resource companies, environmental consulting companies, government agencies, non-profit organizations, and universities. Many geologists do field work at least part of the time. Others spend their time in laboratories, classrooms or offices. All geologists prepare reports, do calculations and use computers. I found that geology is a practical and professional field, all sciences and engineering required geology work in some disciplines. Another thing is the study of mountains, different rocks, minerals, structures and more over their observations in field with naked eye is so interesting. Moreover thin section study and geological mapping was another cause that inspired me to pursue my career in this field.

Due to all these things, I mentally prepared myself to choose geology in future but my father wanted me to become an engineer.

After few months, I completed my 12^th grade with good percentage and I applied for electrical engineering as per my father’s wish. And I also applied for geology as per my wish. Unfortunately, I didn’t get admission in any geology institute and get admission in electrical engineering. My parents were very happy because their wish was near to fulfill at that time but I was not so happy because I wanted admission in geology. Then unwillingly, I have to study the electrical engineering. This was little bit interesting subject for me especially circuits. I liked working on C++ programming. I completed my first semester with good CGPA and got 2^nd position but still I wasn’t satisfied in this field. 

Next year, when I was studying 2^nd semester in engineering, the admissions in geology get opened and again I tried to get admission in this field but my parents, relatives and friends even my engineering professors advised me that I should not leave this field (engineering) now because that decision would effected my future and one year of my study would be wasted. I listened to my heart voice and applied for admission and I was surprised to know that I got admission in geology. I left engineering and join geology field. My friends and professors of engineering institute asked me again not to leave this field. I still remembered, I simply told them that I don’t want high marks, I want to fulfil my interests so that I can give my 100% in that work. I thought what if I done electrical engineering with good percentages and get job. But what if I am not satisfied with my decision then what is the benefit of that job? Geology may not give me highly paid jobs easily as I could find in electrical engineering but I would definitely find peace and satisfaction in geology.

Me (left) discussing geological map of Pakistan with my class mate (right).
Photo © Rana Faizan 

Describing about Salt Range (Sub-Himalayas) model
Photo © Rana Faizan 

Now, I’m studying geology and I am fully satisfied with my decision. I have completed my two and half years of bachelor’s degree with three field works and I have learnt many things about geology. I found all things as same as I imagined, when I was in 12^th grade. This was my dream that one day I will become a geologist and will study from the same institute from my father’s friends have studied. Everyone has its own interest. Some like engineering, some like medical and some go for other. My purpose here is not to degrade anyone especially electrical engineering students, no doubt it is also a good field as technology is becoming a need of everyone. So, I have an advice for everyone, always listen to your own decisions and do not bother what other say.

Selfie at Harno River, Abbottabad, Pakistan.
Photo © Rana Faizan 

Had a rainy fieldwork at Indus River, Pakistan
Photo © Rana Faizan 

I still remember a quote:

                    "Think 100 times before you take a decision,

But once that decision is taken, stand by it as one man."

We have a lot of hidden potential that we don’t know. And if we know then we don’t utilize it because we fear what people would say. More than that there is our own voice shouting inside that you can do this. What if we stop listening to those voices and listen only to our heart.

I have observed many geological things during field work and some pictures below are describing about the beauty of geology. I have many pictures related to rocks, minerals, structures and other features. Some beautiful pictures are given below:

Hammering slates
Photo © Rana Faizan 

Plunging anticline fold observed during fieldwork.
Photo © Rana Faizan

 

Enjoying fieldwork after mapping sedimentary area
Photo © Rana Faizan 

Note: This article is originally written and contributed by Rana Faizan. You can also contribute your article by sending us at geologylearn@gmail.com. We would love to share your field experiences with our readers. See guidelines here.

Fault anatomy

Fault anatomy

Faults drawn on seismic or geologic sections are usually portrayed as single lines of even thickness. In detail, however, faults are rarely simple surfaces or zones of constant thickness. In fact, most faults are complex structures consisting of a number of structural elements that may be hard to predict. Because of the variations in expression along, as well as between, faults, it is not easy to come up with a simple and general description of a fault. In most cases it makes sense to distinguish between the central fault core or slip surface and the surrounding volume of brittlely deformed wallrock known as the fault damage zone, as illustrated in Figure 8.10.

Simplified anatomy of fault.

The fault core can vary from a simple slip surface with a less than millimeter-thick cataclastic zone through a zone of several slip surfaces to an intensely sheared zone up to several meters wide where only remnants of the primary rock structures are preserved. In crystalline rocks, the fault core can consist of practically non-cohesive fault gouge, where clay minerals have formed at the expense of feldspar and other primary minerals. In other cases, hard and flinty cataclasites constitute the fault core, particularly for faults formed in the lower part of the brittle upper crust. Various types of breccias, cohesive or non-cohesive, are also found in fault cores. In extreme cases, friction causes crystalline rocks to melt locally and temporarily, creating a glassy fault rock known as pseudotachylyte. The classification of fault rocks is shown in heading below.
In soft, sedimentary rocks, fault cores typically consist of non-cohesive smeared-out layers. In some cases, soft layers such as clay and silt may be smeared out to a continuous membrane which, if continuous in three dimensions, may greatly reduce the ability of fluids to cross the fault. In general, the thickness of the fault core shows a positive increase with fault throw, although variations are great even along a single fault within the same lithology. 

The damage zone is characterized by a density of brittle deformation structures that is higher than the background level. It envelops the fault core, which means that it is found in the tip zone as well as on each side of the core. Structures that are found in the damage zone include deformation bands, shear fractures, tensile fractures and stylolites, and Figure below shows an example of how such small-scale structures (deformation bands) only occur close to the fault core, in this case defining a footwall damage zone width of around 15 meters.

Damage zone in the footwall to a normal fault with 150–200 m throw. The footwall damage zone is characterized by a frequency diagram with data collected along the profile line. A fault lens is seen in the upper part of the fault. Entrada Sandstone near Moab, Utah.

The width of the damage zone can vary from layer to layer, but, as with the fault core, there is a positive correlation between fault displacement and damage zone thickness (Figure below a). Logarithmic diagrams such as shown in Figure below are widely used in fault analysis, and straight lines in such diagrams indicate a constant relation between the two plotted parameters. In particular, for data that plot along one of the straight lines in this figure, the ratio between fault displacement D and damage zone thickness DT is the same for any fault size, and the distance between adjacent lines in this figure represents one order of magnitude. Much of the data in Figure below a plot around or above the line D=DT, meaning that the fault displacement is close to or somewhat larger than the damage zone thickness, at least for faults with displacements up to 100 meters. We could use this diagram to estimate throw from damage zone width or vice versa, but the large spread of data (over two orders of magnitude) gives a highly significant uncertainty. 

A similar relationship exists between fault core thickness (CT) and fault displacement (Figure below b). This relationship is constrained by the straight lines D=1000CT and D-10CT, meaning that the fault core is statistically around 1/100 of the fault displacement for faults with displacements up to 100 meters.

(a) Damage zone thickness (DT) (one side of the fault) plotted against displacement (D) for faults in siliciclastic sedimentary rocks. (b) Similar plot for fault core thickness (CT). Note logarithmic axes. Data from several sources.

Layers are commonly deflected (folded) around faults, particularly in faulted sedimentary rocks. The classic term for this behavior is drag, which should be used as a purely descriptive or geometric term. The drag zone can be wider or narrower than the damage zone, and can be completely absent. The distinction between the damage zone and the drag zone is that drag is an expression of ductile fault-related strain, while the damage zone is by definition restricted to brittle deformation. They are both part of the total strain zone associated with faults. In general, soft rocks develop more drag than stiff rocks.

Fault rocks

When fault movements alter the original rock sufficiently it is turned into a brittle fault rock. There are several types of fault rocks, depending on lithology, confining pressure (depth), temperature, fluid pressure, kinematics etc. at the time of faulting. It is useful to distinguish between different types of fault rocks, and to separate them from mylonitic rocks formed in the plastic regime. Sibson (1977) suggested a classification based on his observation that brittle fault rocks are generally non-foliated, while mylonites are well foliated. He further made a distinction between cohesive and non-cohesive fault rocks. Further subclassification was done based on the relative amounts of large clasts and fine-grained matrix. Sibson’s classification is descriptive and works well if we also add that cataclastic fault rocks may show a foliation in some cases. Its relationship to microscopic deformation mechanism is also clear, since mylonites, which result from plastic deformation mechanisms, are clearly separated from cataclastic rocks in the lower part of the diagram. 

Fault breccia is an unconsolidated fault rock consisting of less than 30% matrix. If the matrix fragment ratio is higher, the rock is called a fault gouge. A fault gouge is thus a strongly ground down version of the original rock, but the term is sometimes also used for strongly reworked clay or shale in the core of faults in sedimentary sequences. These unconsolidated fault rocks form in the upper part of the brittle crust. They are conduits of fluid flow in non-porous rocks, but contribute to fault sealing in faulted porous rocks.

Pseudotachylyte consists of dark glass or microcrystalline, dense material. It forms by localized melting of the wall rock during frictional sliding. Pseudotachylyte can show injection veins into the sidewall, chilled margins, inclusions of the host rock and glass structures. It typically occurs as mm- to cm-wide zones that make sharp boundaries with the host rock. Pseudotachylytes form in the upper part of the crust, but can form at large crustal depths in dry parts of the lower crust. 

Crush breccias are characterised by their large fragments. They all have less than 10% matrix and are cohesive and hard rocks. The fragments are glued together by cement (typically quartz or calcite) and/or by microfragments of mineral that have been crushed during faulting.

Cataclasites are distinguished from crush breccias by their lower fragment–matrix ratio. The matrix consists of crushed and ground-down microfragments that form a cohesive and often flinty rock. It takes a certain temperature for the matrix to end up flinty, and most cataclasites are thought to form at 5km depth or more. 

Mylonites, which are not really fault rocks although loosely referred to as such by Sibson, are subdivided based on the amount of large, original grains and recrystallised matrix. Mylonites are well foliated and commonly also lineated and show abundant evidence of plastic deformation mechanisms rather than frictional sliding and grain crushing. They form at greater depths and temperatures than cataclasites and other fault rocks; above 300 C for quartz-rich rocks. The end-member of the mylonite series, blastomylonite, is a mylonite that has recrystallized after the deformation has ceased (postkinematic recrystallization). It therefore shows equant and strain-free grains of approximately equal size under the microscope, with the mylonitic foliation still preserved in hand samples.

Credits: Haakon Fossen (Structural Geology)