Questions tagged [geochemistry]

The science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems.

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What makes the conditions at the core/mantle boundary ideal for aluminum to combine with other elements besides oxygen?

Recently, steinhardite was accepted as a new mineral by the International Mineralogical Association. It's quite an interesting story in its own right. There's an interesting article in New Scientist ...
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Did an impact crater influence the formation of uranium deposits in South Australia?

As a supplementary question Did an impact crater cause the formation of the gas fields in north eastern South Australia . South Australia is a well documented uranium province. Could an impact crater, ...
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Predicting volcanic eruptions by experimentally proven volatile outgassing observations

In the abstract for the article Forecasting Etna eruptions by real-time observation of volcanic gas composition (Aiuppa et al. 2007), the authors assert that real time monitoring of volcanic volatiles,...
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How do archaeologists address time dilation when analyzing carbon dating results?

It is a proven fact that the gravitational force exerted upon an object directly affects that objects experience of time; the greater the gravity, the slower time passes, and visa versa. While the ...
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Are there minerals which are not been found on earth but which are still possible to exist?

On Earth we find many kind of minerals, a lot of them are silicates. How much different kind of minerals would there be on Earth? But are there Fe minerals found in meteorites which do no occur on ...
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Is oxygen the most abundant element on Earth?

When I was in school, I was taught that we need oxygen to breathe, but it actually constitutes only a small fraction of the atmospheric composition, and that nitrogen constituted the largest fraction ...
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Magma resultant from group 1 and group 2 elements?

I was recently speaking with a geology professor over lunch at a university who has a theory that I've never heard before. His postulation was quite compelling and I was hoping to do a little digging ...
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What is the concentration of silver in tap or freshwater in the United kingdom

Can anyone tell me the concentration of silver in uncontaminated water ways, or treated tap water in the united kingdom? sources would be desirable too
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637 views

Why does Australia have extensive uranium ore deposits?

According to the World Nuclear Energy page about Australia's uranium deposits, the continent's known uranium resources are the world's largest – 31% of the world total. Of which In 2013 ...
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Release mechanism for methane clathrate at the PETM

The Paleocene-Eocene Thermal Maximum (PETM) is a well-studied warming event near the Paleocene-Eocene boundary. It is characterized by its extreme warming rate: from onset to recovery the event lasted ...
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What is the white coating “patina” we often see on deposited chalcedony/agate?

Me and some of my friends were wondering what exactly is the white coating we can see on chalcedony that has been deposited by a river during quartenary (and so the original material is damaged and ...
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Most corrosive seawater areas in world

I am looking for any studies or maps detailing the average salinity and temperature for areas of the Earth's oceans. As an extra if anyone has data or maps on areas with large amounts of in-trained ...
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Melting basalt on the lunar surface - what would the resulting material be like?

The idea is to melt the fine-grain portion of basalt regolith using a large Fresnel lens, and let it cool to a solid. The lens would track along a tamped bed of material leaving a molten puddle ...
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Identifying serpentinite reworked during high-T metamorphism

What kind of mineralogy results when a serpentinite is reworked during high-T or UHT metamorphism? I am envisaging a possible scenario where an obducted ophiolite terrane is buried and metamorphised ...
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Why are the Little Colorado River and Havasu Creek blue?

In Grand Canyon there are two side streams that carry heavy carbonate loads and deposit travertine along their lengths. The Little Colorado and Havasu Creek both rise from springs a few miles above ...
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What controls the acidity of the ocean?

I have learned that: coral reefs are made up mostly of calcium carbonate coral reefs are mainly distributed in the tropical zone The calcium carbonate will be decomposed in the reaction as ...
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The different types of plagioclase

The fractions of albite $\ce{NaAlSi_3O_8}$ and anorthite $\ce{CaAl_2Si_2O_8}$, which I call $\ce{Ab}$ and $\ce{An}$ in the following list, present in a plagioclase are often used to define it in the ...
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725 views

Oxygen isotope ratio and Glaciers

The question is basically: During the Cretaceous there were no continental ice sheets. The ratio of O-18/O-16 in sea water was: a) Higher than today b) Lower than today The answer ...
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571 views

Non-invasive techniques to find rock composition

If we had access to a totally new kind of rock (maybe a new meteorite), is it possible to tell what the rock is composed of without touching it / drilling into it? I'm thinking of something like ...
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Where can fluorite be found on Long Island, New York?

I'm interested in fluorite (Since Fluorine is my favorite element, and I wanted a sample of it, even if bonded, but I don't want to buy it; that would be no fun), and I'm curious if it can be found on ...
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Diamond at the core of Jupiter

Arthur C. Clarke, who correctly guessed there would be liquid water on Europa, posited a diamond core for Jupiter. Is this possible?
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456 views

What “g” would be needed to keep helium on Earth?

I know that helium is a very light and rare gas on Earth because Earths gravity is not strong enough to keep it. Instead, helium and hydrogen are rising through the atmosphere and escape into outer ...
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Acidity of rock

I read that the acidic character, or, better, persilicic character of a rock is determined by a content of more than $65\%\ \ce{SiO_2}$. A rock is defined, by the texts available to me, as ...
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How do hematite and magnetite form?

I want to understand the conditions under which hematite $\ce{Fe_2O_3}$ and magnetite $\ce{Fe_3O_4}$ form in nature. The linked Wikipedia articles explain various conditions under which they form, but ...
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Please help in understanding redox buffers

I'm trying to gain a firmer conceptual understanding of how redox buffers work in petrology, specifically how oxygen fugacity influences mineral crystallization. While I understand the mathematical ...
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906 views

What is the origin of the Laacher See caldera magma in Germany?

The Laacher See is a volcanic crater lake in Germany, with a diameter of 2 km (1.2 mi) in Rhineland-Palatinate area, approximately 24 km (15 mi) northwest of Koblenz and 37 km (23 mi) south of Bonn, ...
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Abiogenesis: Formation of Lipids from Montmorillonite

I have been really interested in scientific hypotheses regarding abiogenesis, particularly the lipid-world hypothesis. However, I could not find information on the chemical pathway that leads to the ...
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422 views

What fraction of Earth's crustal material survives the supercontinent cycle?

I know that things are not as simple, but for the sake of argument I'll assume a supercontinent cycle of $\sim$400 Myr periodicity is active on Earth. If that is the case, then my naive ...
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98 views

What is the geochemical source for the helium detected in deep Arctic explosive eruptions?

Recently, there has been explosive deep-ocean volcanism detected along the slowly-spreading Gakkel Ridge in the Arctic Ocean (see map below), according the National Geographic news article Arctic ...
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What ozone depleting chemicals can salt produce?

According to How Long Will Life Last On Earth, 250 million years ago Siberia underwent a large a prolonged period of volcanic activity. It has been speculated that large salt deposits that existed in ...
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Do different lavas have different volcanic volatiles associated with them?

This question was inspired by the question Predicting volcanic eruptions by experimentally proven volatile outgassing observations Depending on the type of volcano, three types of lava are released ...
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Are trends in crossplots of compositional data from different analyses valid?

Some geochemistry papers that I have read contain crossplots of compositional components that resulted from different analyses of a rock sample. For example, one is the percent volume of TiO2 versus ...
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Why is hydrogen formation in serpentinisation an exothermic reaction?

In the process of serpentinisation, protons act as oxidising agents for ferrous ions, which results in the production of dihydrogen gas. How is that possible? Dihydrogen being a strong reductor, I ...
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Recreating the rock cycle

I want to recreate the rock cycle using some item that can behave as a rock. The purpose of this is to get a point across to my students about how really there is a reason why the rock cycle is called ...
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Are all natural diamonds made of organic carbon material?

I've read that diamonds are created at a depth of about 180 km. By volcanic activity it comes above. But did plants and trees of 300 million years ago sink so deep? Or is it possible that inorganic ...
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Why doesn't the Earth's outer core dissolve into the mantle?

It is well accepted that the outer core is made out of liquid iron and nickel, and as everything else it should tend to reach chemical equilibrium with its surrounding. In particular, I would expect ...
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181 views

How to convert mol/m^2 to total mass ( e.g gram, kg etc )?

I want to calculate the total $\rm{NO_2}$ amount in a year using satellite Sentinel-5p NO2 dataset. But the problem is sentinel satellite data stored in $\rm\frac{mol}{m^2}$ unit. But I have to ...
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111 views

If the study of “minerals” is covered by inorganic chemistry

I am wondering what field studies "minerals", such as the minerals in Wikipedia's list. I keep thinking that perhaps it would be covered in inorganic chemistry (list of inorganic compounds wiki), but ...
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Can you measure BOD/COD real time using any sensor?

There is a requirement to measure BOD/COD in a wastewater treatment plant in real time. Is it possible? And if so are there any sensors available in the market for it? COD: Chemical Oxygen Demand BOD:...
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712 views

What are the dominant elements that oxygen is bonded to on earth?

Elements are found in different minerals and chemical compounds on earth. Oxygen is dominantly found in silicate minerals which, aside from silica, contain other elements. One way of looking at the ...
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867 views

Plotting a mineral stability diagram

I'm trying to figure out how to plot the stability of 4 minerals — $\ce{CaCO3}$, $\ce{CaSO4}$, $\ce{CaMg(CO3)2}$, and $\ce{CaMg3(CO3)4}$ — with axes of $\mathrm{ln}\,a_{\ce{Mg^{+2}}}$ vs $\mathrm{ln}\,...
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What is the mechanism for deep-sea volcanism of the Gakkel Ridge in the Arctic?

Related to an earlier question, What is the geochemical source for the helium detected in deep Arctic explosive eruptions?, where it is stated in the linked article that there is evidence of explosive ...
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207 views

Does Xenon really covalently bond to oxygen within quartz?

Wikipedia's Xenon; occurrence and production says Within the Solar System, the nucleon fraction of xenon is $\small\mathsf{1.56 \times 10^{-8}}$, for an abundance of approximately one part in 630 ...
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What was the likely composition of Earth's early crust (how did crustal composition evolve)?

Was the first crust entirely mafic (oceanic) crust which was later distilled via volcanic arcs along subduction zones to make felsic rocks or did the earth start with bits of felsic crust? Are the ...
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96 views

What is the ratio of infra-red light absorbed by green house gases?

I know that some gases like CO2, N2O and CH4 absorb infra red radiation. What is the proportion or percentage of radiation absorbed by CO2 among all the gases?
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Considering the thin piece of material on the surface of Mars in the image below, is there anything like it on Earth?

The above is a magnified part of the original image below captured by the Curiosity rover on Mars on sol 1729 (June 17, 2017). From the added information with that raw image it can be estimated that ...
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Historically, how did the total amount of salt / NaCl on Earth develop?

After reading this question about the origin of NaCl on Earth, I'm wondering: How did the amount of NaCl develop historically? Is it a more or less linear growth until today? Was it such a linear ...
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221 views

Carbon's role in ocean acidification

This might seem like a basic question, but I'm a little confused about the effects on ocean acidification of different carbon compounds. I have heard that increased levels of carbon dioxide in the ...
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317 views

A simple formulation to calculate the sequence and rate of salt precipitation in a brine?

Is there a simple formulation to estimate the rate of salt precipitation in a brine given its ion concentrations and the evaporation rate? For example: if we know the concentrations of Cl−, Na+, Mg2+...
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398 views

Define components of mineral assemblage?

Given the a mineral assemblage with the minerals $$cp (\ce{CuFeS_2}), bn (\ce{Cu_5FeS_4}), cc (\ce{Cu_2S}), mt (\ce{Fe_3O_4}), py(\ce{FeS_2})$$ where cp, bn, mt are in contact, and py, cp, bn, cc are ...