Carbonate Petrography

Carbonate petrography is the study of limestones, dolomites and associated deposits under optical or electron microscopes greatly enhances field studies or core observations and can provide a frame of reference for geochemical studies.

25 strangest Geologic Formations on Earth

The strangest formations on Earth.

What causes Earthquake?

Of these various reasons, faulting related to plate movements is by far the most significant. In other words, most earthquakes are due to slip on faults.

The Geologic Column

As stated earlier, no one locality on Earth provides a complete record of our planet’s history, because stratigraphic columns can contain unconformities. But by correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a composite stratigraphic column, called the geologic column, that represents the entirety of Earth history.

Folds and Foliations

Geometry of Folds Imagine a carpet lying flat on the floor. Push on one end of the carpet, and it will wrinkle or contort into a series of wavelike curves. Stresses developed during mountain building can similarly warp or bend bedding and foliation (or other planar features) in rock. The result a curve in the shape of a rock layer is called a fold.

The Importance of "Dirty" Rivers

Complex river systems are the foundation of much of what we have to enjoy here on this planet. They support wildlife populations, provide soil nutrients, and so much more. Humans have had a profound impact on river systems, however, changes in current practices and increased focus on restoring rivers to their natural status can make a major difference in our lives. 

Image Source: pixabay.com

 

Think of your local river. The place you take a walk when you’re looking for solitude or comfort in nature. The place you take your children fishing. Or perhaps where you go when you’re looking for relief from the brutal summer heat.

Chances are, that the river that you love for all the nature it brings into your life really isn’t all that natural. In fact, the majority of the river systems in our world today have been significantly altered by humans whether we recognize the changes we have made throughout history or not. A vast number of our river systems have been greatly simplified — they aren’t as messy or complex as they really should be.

Though in many ways these changes have produced some benefit for people at some point in time, they are catching up with us. Simplified rivers are not as resilient and the ecological damage we have inadvertently caused could come back to haunt us within our lifetimes. Small changes in our habits and priorities could lead to greater changes that will benefit our river ecology and could just save us all.

Complex Rivers

When we think of a complex, natural, healthy river, we are really talking about one of the greatest natural feats of engineering available in the world. These rivers have ebbs and flows that the foundations of the surrounding ecosystems are built around. They have variability in pitch and depth that creates homes for numerous species that our society depends upon. 

These complex rivers collect and move sediment across a landscape. For instance, seasonal flooding refreshes the floodplains with minerals and nutrients brought down by the river from mountain erosion and decomposing substances. This influx of sediment is critical for the long-term growth and survival of native vegetation and forms the basis of the food chain that all animals are part of.

Finally, a complex river is one that is resilient. It — and the surrounding habitats it supports — are able to recover from unexpected natural events and thrive after a short period. Many experts believe that healthy rivers and surrounding ecosystems are absolutely critical to our ability to deal with climate change. Basically, the more healthy, intact natural areas we have, the better our chances are in the long-run.

Human Impacts

Once humans entered the equation things began to change. Typically that which benefited us in the short-term negatively impacted the entire ecosystem (including future generations of humans) in the long-term. For instance, dams and overfishing have powered many of our cities and made many people rich selling food, but they have altered the geomorphology of streams, ruined quality habitat, and caused populations we could be sustainably harvesting today to crash.

Many dams built back in the day are reaching a point where they are requiring more and more maintenance to keep up. Many of them are a collecting point for sediment, which hinders the sediment renewal cycle in floodplains downstream and leads to decreases in soil and vegetation health. Furthermore, the sediment causes wear and tear on the dams and must be monitored regularly.

It may come as a shock with all of the environmental regulations that have been put in place since the 1960s, but one study conducted in 2013 found that nearly half of America’s rivers were still too polluted to be healthy for people, let alone the ecosystems they originally supported. The current administration has worked diligently to roll back numerous environmental regulations, so it can only be assumed that these rivers and possibly more will remain too polluted.

Polluted and unhealthy rivers also pose a more direct impact on our health. For example, different forms of human-caused pollution in rivers can lead to the growth of different bacterias that can make people seriously ill. It is one of many ways that diseases of the future could evolve to pandemic level proportions.

Contributed by Indiana Lee: Indiana Lee is a  journalist from the Pacific Northwest with a passion for covering workplace issues, environmental protection, social justice, and more. When she is not writing you can find her deep in the mountains with her two dogs. Follow her work on Contently, or reach her at indianaleewrites@gmail.com

Top 5 Little Known Geological Jobs in 2020


Image: Unsplash 

In these uncertain times, Science, technology, engineering, and mathematics (STEM) fields are all the rage among job seekers looking for stable and timeless careers. In fact, employment in science and engineering occupations was expected to grow by 18.7% between 2010 and 2020, across all STEM fields. While jobs in the physical sciences aren’t growing as rapidly as computer and mathematical scientist occupations, plenty of opportunities exist for those who hold a geology degree.

While many laymen might think geology is just the study of rocks, geologists know that the field has much more to offer, and prospective job seekers with an interest in the Earth’s composition have numerous sub-disciplines to choose from. Some geological jobs allow you to explore outer space while others keep you firmly rooted on Earth, creating maps or studying the topography of glaciers. Let’s explore five little-known geological jobs that promote a greater understanding of Earth and its history.

1. Astrogeologist

Humanity has long looked to the stars for inspiration, and today’s innovators are working hard to make space tourism a reality. Astrogeologists are among the hard-working professionals who keep the dream of space exploration alive. It’s likely that Richard Branson has at least one astrogeologist on his payroll at Virgin Galactic, a spaceflight company founded in 2004.

Interestingly, however, astrogeology doesn’t have a direct connection to spaceflight per se. Instead, those within the discipline of astrogeology study the growth and evolution of celestial bodies including planets, asteroids, comets, and moons. Astrogeology is also known as planetary geology, and trained astrogeologists may create planetary maps, conduct the remote sensing of celestial surfaces, and more.

2. Cartographer

Astrogeology has much in common with cartography, as both disciplines involve exploration and are deeply rooted in human history. Cartographers are responsible for making maps and ensuring their precision. Whether those maps are in paper or digital form, accuracy is essential to a cartographer’s job.

Cartographers should hold at least a bachelor’s degree in mathematics, according to Maryville University. Further, “a combination of experience and/or further education in cartography, geology, or civil engineering” is vital for map-making professionals. And make no mistake: The competition is fierce in the realm of cartography, which is ranked No. 4 in the U.S. News and World Report’s list of best engineering jobs.

3. Glaciologist

Climate change is directly linked to geology, as the negative effects of the phenomenon become increasingly apparent. It’s no secret that the Earth’s glaciers are melting at a rapid rate, and glaciologists are on the front lines of the phenomenon. Glaciologists study the formation and movement of glaciers, both arctic and alpine, as well as ice caps and sheets.

While collaboration with other glaciologists and professionals is part of the job, plenty of solo work is involved. Furthermore, a glaciologist’s office is often in a remote location, and jackets are always required outdoors.

4. Petroleum Geologist

If you’re interested in exploring coastlines and cultivating sustainability, you may be interested in working as a petroleum geologist, arguably the occupation least involved with actual rocks on this list. But make no mistake, this dynamic and lucrative occupation is still firmly rooted in STEM and in the field of geology.

Petroleum geologists work to determine the location and amount of combustible fuel in a particular area. The job toes the line between land and sea, and the job requirements are a bit more intensive than in some other geological disciplines. Generally speaking, a master’s degree is preferred for all prospective petroleum geologist candidates, along with appropriate certification such as the Certification for Petroleum Geology (CPG).

5. Geomorphologist

The Earth is made up of countless components, some of which can change the very nature of our planet’s surface. The study of the way in which the Earth’s surface is morphed and altered by oceans, rivers, air, mountains, and beyond is called geomorphology. Typically, geomorphologists specialize in a single area such as sand, rivers, or rock as well as mineral formations.

Information gathered by geomorphologists is used in a variety of applications such as healthcare. Minerals and rocks aren’t always as innocuous as they seem. Asbestos, for example, is a naturally occurring silicate mineral commonly used in construction materials. It’s also extremely dangerous, and prolonged exposure to asbestos fibers can cause cancer including an aggressive lung cancer known as mesothelioma.

Geomorphologists are integral to the mesothelioma prevention process by continuing to study the forms and processes of asbestos. Searching for mineral-based alternatives and regularly assessing asbestos risks at job sites may also be part of the job of a trained geomorphologist.

Final Thoughts

Studying rock formations is just the beginning for today’s geologists. Workers in the versatile discipline of geology might head to Antarctica to study glaciers, observe and map out a changing coastline, or help plan a major oil pipeline. No matter the geologic field you hope to specialize in, a strong background in STEM subjects can help you stand out. 


Contributed by Indiana Lee: Indiana Lee is a  journalist from the Pacific Northwest with a passion for covering workplace issues, environmental protection, social justice, and more. When she is not writing you can find her deep in the mountains with her two dogs. Follow her work on Contently, or reach her at indianaleewrites@gmail.com

The Science of Gemstones [Guest Article]

Gemmology, also known as the science of gemstones, is the study of precious gemstones. It mainly focuses on identifying gemstones, confirming its authenticity, evaluating the quality, determining the origin, and disclosing the treatment used for the gemstone. A major part of it requires distinguishing between natural gemstones and synthetic counterparts and imitations. Earlier it was difficult to identify synthetic crystals but that is not much of a problem these days. Gemmologists also find out the treatment used for gemstones as it directly influences the price of a gemstone. In most cases, original gemstones undergo physical and chemical treatment to enhance the aesthetic appeal.


Origins of Some Famous Gemstones

Gemmologists have a set of skills to identify where exactly the gemstone was mined from. Gemstones usually have certain characteristics typical of the origin. Many consumers also have a special preference for gemstones belonging to a particular origin. for example, Blue sapphire from Kashmir, Rubies from Burma, Emerald from Columbia have always been in great demand. Such gemstones cost comparatively more than similar gemstones from other localities.

 Kashmir sapphires are valued as they contain the best specimens. These gemstones are seen to have an excellent cornflower blue tint. Most describe the hue as ‘blue velvet’. While some Burmese and Ceylonese sapphires also come relatively close in quality, only the Kashmir Sapphire continues to rule the Sapphire World. 

Difference Between Synthetic and Natural Gemstones

Classification of gemstones is necessary when dealing with them. Natural gemstones are the ones that grow naturally in nature over the years. On the other hand, "Synthetic" gemstones are those which exactly mimic natural gemstones but are created by man in a laboratory. They possess the same physical, chemical, and optical properties as the natural gemstone. The most common of these are synthetic Diamonds, Synthetic Sapphires, and synthetic Quartz. A layman can not identify the difference between synthetic and natural gemstone. Then comes the “Imitation gemstones” which basically have a similar appearance as the original gemstones. For example, blue glass, polystyrene, or zirconia. The most popular impression of a diamond is zirconia (synthetic ZrO2). Zirconia cannot be easily distinguished from a diamond in the same shape.

How to check the quality and related certifications

Gemstones are not only used for Jewelry purposes but also for their astrological benefit and healing properties. It is crucial to be assured of the authenticity of the gemstone to avoid any negative impact. Many dealers trade fake gemstones in the market to maximize profit. One should be aware of the tricks used by such dears to dupe their customers. It is always desirable to get a gemstone from a reputed seller who is happy to answer all your queries with utmost honesty. There is no better way than to invest your hard-earned money in a real, lab certified gemstone as it ensures the best value for your money. When buying a rare and expensive gemstone that too of a popular origin, one should be extra cautious and must look for certificates issued by the reputed gem labs like IGI, GTL, GIA, GRS, etc.

Pricing Factors of Gemstones

Before choosing a gemstone, it is necessary to know how a minor variation in quality, size, or origin can bring a huge variation in the gemstone price. Color, clarity, cut and carat weight are some of the key price grading factors. If you are planning to buy a gemstone for astrological use, it is important to ensure that the gemstone is natural and free from any sort of treatment (heating, chemical treatment, dying, etc.). Selecting a gemstone from a reputed origin is one good way to ensure quality.

Where does energy in U.S come from? [Guest Article]

From burning firewood to using electricity from renewable sources, the home energy landscape has drastically changed over the last 150 years. This article and infographic explore the history of energy use and what the sustainable future may look like.

We no longer have to gather firewood for our wood-burning stoves to keep us warm at night, but there are a variety of energy sources used in each home. Most homes in the U.S. run on either electricity or natural gas, or a combination of both, but homeowners may also employ solar panels or even residential wind-powered solutions too. 


Looking at the charts below, you can see that energy consumption has grown significantly each year and in 2018, it hit an all-time high. However, you’ll notice some changes in the way we use each energy source. Coal is the only energy source below that has suffered a decline and renewable energy has recently surpassed nuclear energy. As new technologies are developed, we are finding new ways to meet the increased energy demand. The future of energy consumption will look very different than it does today.

home energy use infographic


Where does energy in US come from?
By no surprise, oil has been the largest and most popular source of energy. Since the 1950s, oil and natural gas were used to heat homes. Now in 2020, you know that petroleum is used for many other reasons and industries, from powering our cars to packaging products in plastic. 

Although coal was another popular source of energy, it has been on the decline for the last few decades. It’s less efficient than other sources and negatively impacts the environment. To answer that problem, the U.S. has been investing in renewable energy sources. Wind, solar, and geothermal energy are proving to be great resources for a clean future.

Are renewables the future?
Although only 11% of U.S. energy production comes from renewable sources, it is expected to grow. Solar, wind, and geothermal technology energy are three of the top sources for renewable energy. Among those, wind is the fastest growing and judging from the production map, it has wide geographic potential as well. Geothermal energy, which uses underground temperatures to transfer energy, is becoming a popular alternative for home heating and cooling. Of course, residential solar panels are gaining wide adoption as well. As renewable energy options become more available, the energy consumption landscape is likely to move toward a more sustainable future. 

This infographic from The Zebra walks through the history of energy use, where energy is produced, and what the future of energy may look like.
Author bio: Amanda Tallent is a writer who covers everything from business to lifestyle. She creates content to help people live more informed and confident lives. 
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Factors Controlling the Shape of a River Delta

What is a Delta?
A delta is an accumulation of sediments at the mouth of a river that may consist of a network of distributary channels, wetlands, bars, tidal flats, natural levees and beaches that typically shift from on location to another. Delta shape is dependent of dominant current conditions where the mouth of the river: tide-, sea wave-, and storm-dominated.

Lena River Delta, Siberia.
Factors that control the shape of a River Delta? 


River deltas around the world are very different. The shape of a river delta is controlled by a variety of factors including:
• the volume of river discharge.
• the volume of sediment being deposited in a delta region.
• vegetation cover in delta regions capable of trapping sediments.
• tidal range conditions where the river enters the ocean.
• storm-related climate and oceanographic conditions.
• coastal geography (mountains or plains) in coastal regions.
• human activity is now a dominant factor influencing the shape of river deltas.

Yellow River Delta, China
Nile River Delta, Egypt.
River deltas like the Amazon and Indus Rivers discharge into the ocean where a high tidal range influence flow into and out of the mouth of the rivers. Some river delta region are highly effected by erosion effects of storms and high wave energy. Infrequent but intense superstorms impact the shape of deltas and shoreline, such as the impact of hurricanes on the Gulf Coast.

Indus River Delta, Pakistan

Human activity is responsible for the irregular shape of the Birdfoot Delta on the Mississippi River created by the constant dredging to keep shipping channels clear. The construction of dams and diversion of water out of the Colorado River has essentially shut of the supply of water and sediment to the Colorado River Delta in the Gulf of California.

The Mississippi Birdfoot Delta is largely controlled by Human activities
Changes to Mississippi River Delta over the last 4000 years ago.
A river no more. Very little water makes it to the Colorado River Delta




Thanks to Dr. Phil Stoffer for assisting in publishing this article.

Designing Buildings to Reduce the Impact of Earthquakes

Earthquakes rip through our cities, with seismic waves that tear down our buildings and take away lives in the process. Just two years ago, in September of 2017, a 7.1 earthquake thundered throughout Mexico City and killed nearly 230 people.


The main cause of damage isn’t from the earthquake but from the collapsing structures. Historical and pre-earthquake safe buildings are not equipped to shield themselves from these natural disasters, leading to loss of lives and immense costs.
How Earthquakes Wreak Havok
On average, collapsing buildings cause $2.1 billion in damage and 10,000 deaths a year. Let’s analyze how earthquakes damage manmade structures.

The shockwaves from earthquakes force horizontal pressure on buildings. Without the right structure to divert this energy away from the building, they collapse—killing the people inside of them. That’s because buildings are unable to handle side forces. Although they’re able to handle vertical forces, earthquakes attack the core of the building. The horizontal forces strike the columns, floors, beams, and connectors that hold them together—rupturing support frames.



How to Make a Building Earthquake-Proof
There are many methods that engineers use to make structures more earthquake-proof, they make improvements to the foundation, structure, material flexibility as well as preventing waves from hitting the buildings. Let’s examine the methods used to help buildings resist this deadly force. For a visualization of how these methods work check out the visuals at earthquake-proof visual by BigRentz.


1. Build A Flexible Foundation
One way to prevent seismic waves from traveling throughout a building is to use flexible pads made of steel and rubber to hold the building's foundation. In this manner, the pads “lift” the building above ground and absorb the earthquakes’ shocks.

2. Damping

Engineers also use shock absorbers (similar to the ones you find in cars) for earthquake resistant buildings. These fixtures help reduce the magnitude felt from the shockwaves for the building. They’re also responsible for slowing down the life-threatening movement when buildings sway after a quake.

To accomplish this, geological engineers use:
  • Vibrational Control Devices
By placing dampers between a column and a beam at each building level, they use pistons and oil to convert the motion into heat. The heat absorbs the shocks felt from the earthquake.
  • Pendulum Power
This method is used primarily in skyscrapers. Engineers use a large weight and hydraulics that move opposite of the earthquake’s motion to help reduce the effects of any seismic shocks that hit the building. 3. Shield Buildings from Vibrations
Concrete and plastic rings are built underneath three feet beneath the building in expanding rings. These rings are sometimes called, “seismic invisibility cloaks” because they keep waves from reaching the building. These rings channel shockwaves so that they move to the outer circles and divert away from the building. 4. Reinforce the Building’s Structure
Shear walls and cross braces help shift earthquake movement away to the foundation. Horizontal frames are also useful, as they redistribute forces to the building’s columns and walls. Lastly, moment-resisting frames help keep joints rigid, simultaneously allowing the structure to bend for safety. 5. Use Resistant Materials
It’s vital to note that the building materials you use have a huge effect on a building’s stability. Two of the best materials for earthquake-resistance are structural steel and wood. There are also innovative materials that are being incorporated into structures like bamboo and memory alloy (flexible but returns to its shape easily).

With the right geological engineering practices, we can make cities safer from unpredictable earthquakes. Many cities have implemented earthquake-safe codes and requirements for new construction. Although making structures completely earthquake-proof is difficult to achieve—the goal is to keep buildings standing tall and people inside them safe.

Happy New Year (2019) from Learning Geology Team

Guest Blog: How Speleothems Are Used To Determine Past Climates?

About author: Alex Graham is an undergraduate student at University of Newcastle, Australia. He is interested in Geology as a whole but his major interests include fluvial processes, karst systems and ocean science. During his visit to New Zealand, he has obeserved the glow worms in Waitomo Caves and spelunking in Nikau Caves.

Speleothems, more commonly known as stalactites or stalagmites, consist of calcium carbonate (calcite or aragonite) crystals of various dimensions, ranging from just a few micrometers to several centimetres in length, which generally have their growth axis perpendicular to the growth surface. Speleothems are formed through the deposition of calcium carbonate minerals in karst systems, providing archives of information on past climates, vegetation types and hydrology, particularly groundwater and precipitation. However, they can also provide information on anthropogenic impacts, landscape evolution, volcanism and tectonic evolution in mineral deposits formed in cave systems.

Stalagmite Formation
Rainfall containing carbonic acid weathers the rock unit (generally either limestone or dolomite) and seeps into the cracks, forming caverns and karst systems. The groundwater, percolating through such cracks and caverns, also contains dissolved calcium bicarbonate. The dripping action of these groundwater droplets is the driving force behind the deposition of speleothems in caves.
Core drilling of an active stalagmite in Hang Chuot cave.
Speleothems are mainly studied as paleoclimate indicators, providing clues to past precipitation, temperature and vegetation changes over the past »500,000 years. Radioisotopic dating of speleothems is the primary method used by researchers to find annual variations in temperature. Carbon isotopes (d^13C) reflect C3/C4 plant compositions and plant productivity, where increased plant productivity may indicate greater amounts of rainfall and carbon dioxide absorption. Thus, a larger carbon absorption can be reflective of a greater atmospheric concentration of greenhouse gases. On the other hand, oxygen isotopes (d^8O) provide researchers with past rainfall temperatures and quantified levels of precipitation, both of which are used to determine the nature of past climates.


Stalactite and stalagmite growth rates also indicate the climatic variations in rainfall over time, with this variation directly influencing the growth of ring formations on speleothems. Closed ring formations are indicative of little rainfall or even drought, where-as wider spaced ring formations indicate periods of heavy rainfall or flooding. These ring formations thus enable researchers to potentially predict and model the occurrence of future climatic patterns, based off the atmospheric signals extrapolated from speleothems. Researchers also use Uranium –Thorium radioisotopic dating, to determine the age of speleothems in karst formations. Once the layers have been accurately dated, researchers record the level of variance in groundwater levels over the lifetime of the karst formation. Hydrogeologists specialise in such areas of quantitative research. As a result, speleothems are widely regarded as a crucial geological feature that provide useful information for researchers studying past climates, vegetation types and hydrology.


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10 of the Best Learning Geology Videos of 2017


Following are the best videos of 2017.
Some of the videos are part of our Live Virtual Field Tours project and Video Lecture Series while some videos were reposted by us.



1. Live from Kamokuna Ocean Entry, Big Island of Hawaii 

                                   
2. Live from Tucson Gem Show, Tucson, Arizona

                                            

3. The landslide of Maierato, Vibo Valentia, Calabria, Italy 






4. A double terminated Quartz being pulled from a pocket in the Alps. 





5. An incredible footage of a Flash flood





6. Live from Kaibab Limestone, South Rim, Grand Canyon



                                               

7. Earthquakes and the Richter scale with Fabiana from Geologia da Terra





8. Learn all about Actinolite with Chad keel



9. Soil Erosion 





10. Live from Mount Hood with Andrew Dunning of BetterGeology



Huge thanks to all who contribute videos to us and thanks to everyone for watching! :)

Want to contribute? Read guidelines here.

Basics of Basin Analysis



·         A sedimentary basin is an area in which sediments have accumulated during a particular time period at a significantly greater rate and to a significantly greater thickness than surrounding areas.

·         A low area on the Earth’s surface relative to surroundings e.g. deep ocean basin (5-10 km deep), intramontane basin (2-3 km a.s.l.)

·         Basins may be small (kms2) or large (106+ km2)

·         Basins may be simple or composite (sub-basins)

·         Basins may change in size & shape due to:
1.      erosion

2.      sedimentation
3.      tectonic activity
4.      eustatic sea-level changes
·         Basins may overlap each other in time

·         Controls on Basin Formation

1.      Accommodation Space,

a.       Space available for the accumulation of sediment
b.      T + E = S + W T=tectonic subsidence E= Eustatic sea level rise S=Rate of sedimentation W=increase in water depth
2.      Source of Sediment
a.       Topographic Controls
b.      Climate/Vegetation Controls
c.       Oceanographic Controls (Chemical/Biochemical Conditions)

·         The evolution of sedimentary basins may include:

1.      tectonic activity (initiation, termination)

2.      magmatic activity
3.      metamorphism
4.      as well as sedimentation
·         Axial elements of sedimentary basins:

1.      Basin axis is the lowest point on the basement surface

2.      Topographic axis is the lowest point on the depositional surface
3.      Depocentre is the point of thickest sediment accumulation

·         The driving mechanisms of subsidence are ultimately related to processes within the relatively rigid, cooled thermal boundary layer of the Earth known as the lithosphere. The lithosphere is composed of a number of tectonic plates that are in relative motion with one another. The relative motion produces deformation concentrated along plate boundaries which are of three basic types:

1.      Divergent boundaries form where new oceanic lithosphere is formed and plates diverge. These occur at the mid-ocean ridges.
2.      Convergent boundaries form where plates converge. One plate is usually subducted beneath the other at a convergent plate boundary. Convergent boundaries may be of different types, depending on the types of lithosphere involved. This result in a wide diversity of basin types formed at convergent boundaries.
3.      Transform boundaries form where plates move laterally past one another. These can be complex and are associated with a variety of basin types.

·         Many basins form at continental margins.
Using the plate tectonics paradigm, sedimentary basins have been classified principally in terms of the type of lithospheric substratum (continental, oceanic, transitional), the position with respect to a plate boundary (interplate, intraplate) and the type of plate margin (divergent, convergent, transform) closest to the basin.


·         Plate Tectonic Setting for Basin Formation

1.      Size and Shape of basin deposits, including the nature of the floor and flanks of the basin

2.      Type of Sedimentary infill
·         Rate of Subsidence/Infill

·         Depositional Systems
·         Provenance

·         Texture/Mineralogy maturity of strata

3.      Contemporaneous Structure and Syndepositional deformation

4.      Heat Flow, Subsidence History and Diagenesis

·         Interrelationship Between Tectonics - Paleoclimates - and Eustacy

1.      Anorogenic Areas------>

·         Climate and Eustacy Dominate

2.      Orogenic Areas--------->

Sedimentation responds to TectonismPlate Tectonics and Sedimentary Basin

   Types

SB = Suture Belt
RMP = Rifted margin prism
S C = Subduction complex
FTB = Fold and thrust belt
RA = Remnant arc
Wilson Cycle
 
about opening and closing of ocean basins and creation of continental crust.



Structural Controls on Sedimentary Systems in Basins Forming:

Stage 1: Capacity < Sediment

Fluvial sedimentation

Stage 2: Capacity = Sediment

Fluvial lacustrine Transition


Stage 3: Capacity > Sediment

Water Volume > excess capacity
Shallow-water lacustrine sedimentation


Stage 4: Capacity >> Sediment

Water volume = excess capacity
Deep-water lacustrine sedimentation


Stage 5: Capacity > Sediment

Water volume < excess capacity
Shallow-water lacustrine sedimentation     
Contributed by:

Rehan.A Farooqui
M.Sc Geology,,
University of Karachi.