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Questions tagged [sedimentology]

Sedimentology encompasses the study of modern sediments such as sand, mud, and clay, and the processes that result in their deposition.

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Is there any significance of lacustrine gastropoda fossils regarding paleoenviroment interpretation?

How to interpret lots of gastropoda fossils seen in lacustrine marls? Do they indicate any paleoenvironment conditions? Depth, temperature, chemistry, ph?
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How do I plot Troels-Smith lithological symbols in R?

I'm trying to plot lithological data using the Troels-Smith scheme. I have tried psimpoll but as I only have lithological data I cannot create a main input file which is required. I also do not have ...
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A few questions about the morphology and sediment dynamics of Wissant Bay (France)

Could someone please explain what exactly is shown on the following image? I have a few questions such as: How did the 'Banc à la Ligne' come about? (I know it has something to do with the fact that ...
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Assessing graded bedding in metamorphosed pelitic sediments

I have the following image of metasedimentary outcrop from a Proterozoic continental rift-fill sequence: The middle layer has a pelitic composition and contains abundant cordierite porphyroblasts (...
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How do you interpret Oxygen Isotope changes?

In a paper I am reading, the authors note "large (5-7%) negative shifts in the oxygen isotopic composition of geologic proxy materials" (Davis 2008, pg. 102) in several regional basins. This is then ...
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What are these basal rip up clasts in North Dakota?

Ther's an graph that appears that the KT asteroid turned the rocks into rubble 3000 km away, else there was a rain of big rocks from the sky. What are the rip up clasts and what is the way they were ...
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How much climate history can be reconstructed using marine sediment cores?

Today I learnt in college that marine sediments can be used to reconstruct the climate up to 500 million years back. I find that number very strange because in another class we learnt that the ocean ...
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How do we detect floods?

How do we know that there was a flood at a certain place at a certain time. For example if there was a flood in place A 200 years ago. How could we detect it?
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170 views

Geological feature - what is it?

Hello, We were walking in Bundoran in Donegal County, Ireland today and we encountered the geological feature shown in the picture (from above from cliffs and from very close up at beach level). We ...
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What caused this waterfall to have rounded formations?

This is at Bua Tong Waterfalls in Chiang Mai, Thailand. Tried to find scientific information about this waterfall, but google turns up only travellers' vague guesses, suggesting calcium carbonate ...
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In an Earth-like planet with no history of carbon-based life forms, would there be limestone?

The extent of my understanding of limestone is about what Wikipedia says at the very top of the page: Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such ...
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Where can I find papers on the geology of the Wastach Range in Utah

I am looking for papers on the stratigraphy, geochronology and/or compositional make up of the Wastach Range and its formations. I prefer a broad overview paper and I can't seem to find one. Any help ...
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Is there sand in Antarctica?

There's a song "Blizzard's Never Seen the Desert's Sand". Given Antarctica is a desert, someone questioned the title's validity. BUT is there sand in Antarctica? I'd imagine yes as it's a pretty ...
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How much does sea level rise due to sediment deposition?

There has been a lot of noise in the news in the last few days because Congressman Mo Brooks from Alabama claimed that erosion played a role in rising sea levels. Quoting from Science magazine: ...
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How are the Scala dei Turchi staircases formed?

The Scala dei Turchi i (Italian: "Stair of the Turks") is a rocky cliff on the coast of Realmonte in Italy: https://en.wikipedia.org/wiki/Scala_dei_Turchi#/media/File:Scala_dei_Turchi_panorama.jpg ...
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How are sand blocks formed?

My son asked me at the beach how are "sand stones" formed. These are the solid (but fragile) sand conglomerates which you can hold in your hand and which crumble to sand once pressed. I tried some ...
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Presence of cross stratified conglomerates in fan deltas

Why are cross stratified conglomerates found in deposits of fan deltas? I know that fan deltas are alluvial fans that deposit directly into the sea, hence they are poorly sorted.But could not ...
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How are chenier ridges and strand plains formed at wave dominated coastlines?

In the attached image, we can see chenier ridges and strand plains. How are they formed and what is the involvement of rip and longshore currents in their formation?
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What are the differences between alluvial, eluvial and colluvial deposits? [duplicate]

There's always confusion and disagreement when these terms are mentioned. Need to be sure of their exact meanings.
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Inorganic Limestone and Inorganic Gypsum

I read that limestone is made from the compaction of marine animals' bones. But, I am unable to find out why limestone could not have been produced from calcium occurring naturally (5th most abundant ...
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Is this a conglomerate type sedimentary rock? [closed]

This is my first attempt at studying geology. A year ago I found this stunning rock in the Maumee River here in Northwest Ohio. The rock is very smooth in texture, measures approx 2 cm, and was ...
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Geology: facies v. formations

Can someone please explain the difference between sedimentary facies and formations?
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What is the difference between Saprolite and Regolith?

Saprolite and Regolith both imply loose material, is one a subset of the other how can I differentiate them ?
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Are fossil fuels really formed from fossils?

Hydrocarbons have been found in great abundance elsewhere in the solar system where there is unlikely to be evidence for life past or present. No fossils involved. Petroleum and natural gas wells ...
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Rock ID: hard, smooth, found on hill south of Nashville [closed]

Could use help identifying this rock. It's face has some variation in color which ranges from cream to caramel. (Some variation could be from different exposure to the weather.) The rock face is ...
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Formation of petrified trees

In my book, I came across this question: Give reason why formation of petrified tress is considered as a degradation and a sedimentation action of the underground water. My book explains that ...
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What is this vein-bearing rock? [closed]

This rock was found in Indiana, USA. It is large, egg-shaped and measures approximately 75 cm by 15 cm (2.5' by 0.5'). It is non magnetic. What could it be that caused those lines?
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The grains of the parabolic dunes

My text book says that parabolic dunes consist of consolidated limestone grains, but I wondered if they have sand grains too, so I googled this issue and found that they consist of sands, but I am ...
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Deposition in epioceanic areas

I found allochthonous (I don´t know the 2 locations) fined grained carbonate sediment in Ammonitico Rosso, which is possibly mudstone in the South Iberian Peninsule, specifically in Carcabuey (Córdoba)...
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What are these oblong shaped rocks called, with pigment inside? [closed]

There are these rocks we have -- not too common, usually find them in loads of small rocks, very seldom at random. They are perfectly oblong, and sort of smooth, but not quite as smooth as a river ...
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A sedimentary rock with only minerals

In my text book I came across this multiple-choice question A sedimentary rock consists of only minerals and lacks fossils, it could be classified as: i) a clastic sedimentary rock ii) a ...
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What are the differences in terms of appearance between sandstone and limestone?

On the field, I find it very difficult to differentiate the two types of rocks just by looking at them.I know that you should do some analysis of the sample before any conclusions. But, for example in ...
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How can we estimate the amount of sediment that traveled downstream during the California flood?

It's amazing how much water traveled down the slopes of California during the first two months of rain/flooding of 2017. Since the amount of water was far greater than anything in recent history, ...
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Do you have any informations about fossil-rich cherts from Scandinavia?

Me and some of my friends have found many rocks similar to these in central Europe - we believe that it is fossil-rich chert that originally comes from Scandinavia. There are many interesting fossils ...
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What, exactly, is angle of repose, and where is it in this image?

I'm a little mystified by "angle of repose" and the relationship to deposition and transport. In the following image, I detect 2 different angles of repose for the same material. How can this be? ...
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Does the existence of limestone nodules in a clay soil horizon indicate a limestone bedrock?

A profile (clay soil) was excavated to a depth of 100 cm in the north of Tunisia. We have found limestone nodules, colluvium and alluvium. What I would like to know is the nature of the bedrock of ...
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Do any rivers deposit sediment in their deltas fast enough to counteract sea level rise?

Assume a 1m per century sea level rise. Looking at a topographic map it quicly becomes clear that Bengal, the Netherlands, the lower Mississippi, South American Mesopotamia, etc will all soon be ...
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90 views

Dolomite in deep-water environment

Is it possible that dolomitization occur in deep-water environment? If it possible, how?
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538 views

Sedimentology (Particle size distribution parameters)

The Inclusive graphic standard deviation (sorting) value of this claystone sample is negative (-1.29). Is this right to be considered as very well sorting ? However, the bivariate plots of ...
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191 views

What is meant by Monte-carlo simulation? (would like an elaborated answer with some references) [closed]

I have come up with simulations which involves monte-carlo method that I am not fully aware of. I would be very happy if someone can help me with some references to read and learn.
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How should core-rim detrital zircon ages be reported in a sedimentary provenance study?

I understand this might be drifting into the black hole of subjectivity but I would like to know if anyone knows if there is a generally accepted practice. If one has a detrital zircon with a core age ...
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How this sedimentary rock is made?

Apologies in advance for a beginners question. Different rock types make me curious and recently went to an area where interesting sedimentary rock is all over. As the area is on the coast, sea has ...
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Large scale structures in the Sahara – what are they?

In Google Earth we can see some very clear lines in the Sahara. In the screenshot below you can clearly see these lines starting at the top going southward, then gently curving westward towards the ...
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What is the best way to mount white mica separates?

I have detrital mica separates that I would like to mount in EpoThin resin for microprobe analysis and I would simply like to know the best method for mounting them. With zircons you can mount on ...
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Would you see a correlation between detrital zircon age and grain shape?

If one was to quantify the shape (particularly roundness) of detrital zircon grains, would there be a correlation between the age of the detrital zircon grains and their shape? For example, if the ...
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What is the maximum grain size of a sediment that can be point counted using a standard thin section?

Point counting is an extremely useful tool for determining the composition of a clastic sedimentary rock. It is also very useful in provenance studies to determine the sediment source of a sedimentary ...
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Waves on sandy beach separating differently-sized rocks?

I recently went to a beach, and I noticed that the sand seemed to have a few distinct regions. I'm wondering what would cause this, and how it works. One region is the part of the beach which is ...
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What factors bring sand into or out of the beach?

I like to walk my dog along a beach, but in medium to high tide, there is no beach at all, as the water reaches the bluffs. The thing is, the height of the sand seems to vary drastically as well. ...
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Specific Chemical Composition of Nero Marquina Marble

I'm looking to understand the chemical composition of the Spanish Nero Marquina Stone. Specifically, are the white veins of different composition than the black? We are design studio pursuing work in ...
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What is the earliest sedimentation we know of?

Did large-scale sedimentation occur in any great amount during or soon after the Hadean/Archean period? Or did it only start later, because of the intense geological activity?