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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Why is calcium so much more abundant in/on Earth's crust (and oceans) than it is elsewhere? (relatively speaking…)
Inside the entire Earth as a whole, and throughout our Solar System and galaxy, etc., magnesium is at least 14 times (or more) as common as calcium, atom-per-atom.
But, on Earth's crust and oceans, ...
3
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2answers
26 views
Calculating/estimating volatiles based on other representative samples
I am currently working on a set of geochemical data representing calc-alkaline igneous intrusions from central Canada. The samples were analyzed in ~2013-2014. These samples have been tested for LOI ...
2
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1answer
60 views
Stratigraphy of limestone applied to the Great Pyramid of Giza
The Great Pyramid of Giza is made from blocks of limestone quarried from the Giza plateau. The pyramid is composed up of about 200 layers, with individual blocks varying in thickness from 20 to 60 ...
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1answer
42 views
Question Concerning Meteorite Ejecta Travel
I was researching more into the studies done by Kjaer and his team ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235527/ ) concerning the hypothesis about the Younger Dryas impact crater named ...
4
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3answers
97 views
How much does the gravitational and magnetic fields of a planet effect the chemistry in it?
It is known that the earth has a magnetic field and gravitational field around it, I wish to ask to what degree is the chemistry on the planet is influenced by these fields? How would the chemical ...
2
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1answer
60 views
Are there any sulphides, sulphates, carbonates that cannot be dissolved by aqua regia?
I was looking into these specific minerals: arsenopyrite, pyrite, chalcopyrite, barite, calcite, dolomite. I investigate issues with tellurides not showing expected gold concentrations.
There is gold ...
6
votes
2answers
90 views
Will the sea get saltier forever?
The sea wasn't always salty. It's been getting saltier over millions of years as minerals dissolve.
Is there a natural limit to this process, or the will the sea keep getting saltier forever?
Is there ...
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2answers
74 views
How abundant is high purity silica?
Silicon is often touted as the second most abundant element in the Earth's crust. However, this can be misleading when looking at the abundance of high purity silica needed for manufacturing ...
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0answers
19 views
Why REE concentration in a melt due to fractional melting is less than in a melt of same source rock due to batch melting?
I plotted this ree data for batch melting and fractional melting for the same source. From the plot we can see that the melt due to fractional melting is more depleted in REE than the melt due to ...
4
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1answer
54 views
Phosphate in the oceans, does it tend to bond with sodium?
Phosphate has a major role in biology and the biosphere. In its "abiotic" form, floating around in the oceans, lets say marine oceans to be specific, does it tend to be in the Na3PO4 form? ...
4
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1answer
82 views
Relation between molecular mass and retention of a gas on a planet
An Introduction to Our Dynamic Planet under section 2.4 "The origins of the atmosphere and hydrosphere"(Page 80) says on the topic of gases escaping from our atmosphere as:
Different gases ...
4
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1answer
173 views
Why is the concentration of highly siderophile elements so uniform in the mantle?
The plot above is about the concentration of siderophile elements in the terrestrial mantle.
From the logarithmic plot, we can deduce that the concentration of highly siderophile elements is quite ...
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Why we compare the oxygen fugacity of magma ocean with IW, FMQ or any other buffer?
e.g., Nitrogen solubility as high as near 25 ppm in forsterite, pyroxene, and garnet have been reported in an
experimental study in the 1.5–3.0 GPa range with the
oxygen fugacity controlled at those ...
4
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1answer
89 views
Are the precious metals (silver, gold, platinum) present everywhere throughout the Earth's crust at least in the trace quantities?
Do some rocks, soils, sands or waters exist that contain fewer than one atom of gold per cubic meter or tonne of their mass?
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2answers
574 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 ...
3
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1answer
42 views
Is CO2 in the Pacific Ocean depleted or enriched in Carbon-13 compared to the Atlantic, and why?
Due to thermohaline circulation, the Pacific water is more 'aged' so there is a higher amount of total dissolved inorganic carbon (e.g. CO2) in the deep Pacific when compared to the Atlantic. However, ...
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148 views
MATLAB - How to plot multiple timeseries (paleoclimate) with a common x axis and multiple stacked y axes?
I'm trying to create figures in MatLab and am a reasonably new user, I'm wondering if there is a good way to make plots that use a common x-axis and then vertically stacked and alternating y-axes as ...
14
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1answer
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Why don't iron meteorites on Mars rust or oxidize? Why are they shiny?
Wikipedia's WikiNews' 2005 article Mars Rover’s Basketball-Shaped Discovery Stirs Controversy says:
The surface of the meteorite was found to be remarkably free of corrosion. Researchers are as yet ...
6
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1answer
325 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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0answers
39 views
What are the favourable conditions for the formation of porphyry copper deposits?
Favourable condition for the formation of porphyry copper deposits is :
1. Extremely low oxygen fugacity in initial magma
2. High water content in initial magma
3. Crystallization of magama at deep ...
4
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1answer
102 views
The effect of CO2 concentration on the pH of the ocean
I'm confused about how increased $\ce{CO2}$ concentration in the atmosphere affects the pH of the ocean.
The increase in $\ce{CO2}$ concentration means the pH of the ocean will decrease (by several ...
8
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1answer
77 views
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 ...
4
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1answer
147 views
Has Earth's atmosphere lost mass throughout the geological ages due to biological $\small\sf{CO_2}$ fixation?
Stromatolites and other organisms have been storing $\small\sf{CO_2}$ in the form of $\small\sf{CaCO_3}$ throughout the geological ages, forming extensive limestone deposits scattered across Earth's ...
6
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2answers
222 views
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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4answers
381 views
Why is mass fraction always abbreviated wt% and not ma%?
In most geology papers, major elements chemical analyses are expressed as mass fraction of oxides, i.e. SiO$_2$ 64.2 wt%, K$_2$O 4.3 wt%, etc. The mass fraction unit is always abbreviated as "wt%". ...
2
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2answers
126 views
What is the history of atmospheric O₂ concentration?
(This is about O₂, not CO₂)
How did the concentration of oxygen change?
Over geologic time frames since plants began to produce it,
and during the time since the carbon dioxide increase caused by ...
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0answers
29 views
Why was the temperature change greater in higher latitudes than in lower latitudes during the Paleocene/Eocene thermal maximum?
In the "Plankton cooled a greenhouse", which is the article written by Birger Schmitz, it is stated that the subtropical regions became warmer during the PETM(Paleocene/Eocene Thermal Maximum) but the ...
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2answers
107 views
XRF analysis - recalculating results
For TAS diagram plot, one need to recalculate Major oxide data (NaO, K2O, SiO2).
Do one need to recalculate the ppms of Zr,Nb and Y and % of TiO2 for Zr/TiO2 vs Nb/Y diagram plotting for rock ...
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0answers
26 views
solubility of rare earth sulphides at different pH?
Will rare earth sulfides in soil be more soluble in aqueous solutions with lower pH? How can I know whether these sulfides will dissolve better at low or high pH or will it not be affected?
4
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1answer
118 views
Relationship Between Ratio of Atmospheric Gases and Ocean Gases
A version of this question was posted in Chemistry SE and Worldbuilding SE but I've been told it wasn't appropriate to either SE. I was told to give this SE a chance. If you think it doesn't belong on ...
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1answer
48 views
Possible and probable source of Curiosity Rover's $\small\sf{CH_4}$ detection on Mars
Past week, NASA announced Curiosity Rover measured 21 ppbv of $\small\sf{CH_4}$ on Mars.
This week, NASA's Curiosity Mars rover found a surprising result: the largest amount of methane ever ...
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1answer
67 views
How is the difference in crust and mantle composition explained?
We know that the composition of the crust is SiAl and SiMa and the one of mantle is mostly ophiolites, but why? Which are the geological processes that make this difference exist?
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2answers
114 views
Molten salt seas on the future Earth
As the sun gets brighter, the oceans are expected to evaporate by the next billion years or so (the vapor slowly gets stripped off into space). The salt, which is less dense than most rocks, will be ...
2
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1answer
43 views
Potassum-Argon Dating and Proportions of Daughter Products in Potassium 40 Decay Channel
So Potassium 40 decays in such a way that roughly 89% of it becomes Calcium 40 and 11% of it becomes Argon 40. When they list these figures are they implying that after 1 half-life, of the 50% of the ...
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Why is sulfate reduction less important in freshwater sediments?
Is this due to increased salinity reducing sulfate concentration or the production of marsh gas converting sulfate to hydrogen sulfide or something else?
2
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1answer
61 views
How does friction and radiolysis provide hydrogen for “unusual types of methane”?
The fascinating New York Times article Gas That Makes a Mountain Breathe Fire Is Turning Up Around the World talks about the Flames of Chimaera and the Deep Carbon Observatory:
And a series of ...
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1answer
80 views
Which are the mechanisms of the correlation between atmospheric carbon dioxid and global warming/cooling?
In the end of glacial periods there seems to be an increasing release of carbon dioxide as the global warming increase and at the end of these global warming periods the content of carbon dioxide in ...
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121 views
How much hydrogen can be extracted from the deep continental crust?
Far below the earth's surface, hydrogen gas is continuously produced through serpentinization. At least some fraction of this hydrogen remains trapped in the deep continental crust; indeed, Soviet ...
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0answers
20 views
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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1answer
213 views
How acidic waters make rocks disappear?
I was working on this science project.
I was on step 11, day. 4. Since day 2, I found out that my pH and the mass of the rock (limestone) stopped changing. This project should proves acidic water ...
6
votes
2answers
398 views
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 ...
2
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1answer
148 views
Why the “Mission to Earth’s core” proposal suggests using liquid iron instead of lead?
Nature communications article "Mission to Earth's core — a modest proposal", suggests placing a large volume of liquid iron in a crack and let it sink all the way to the Earth's core, carrying along a ...
4
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2answers
243 views
Where does molecular hydrogen in the atmosphere come from?
This figure from Wikipedia's Atmosphere of Earth shows a hydrogen fraction of 0.000055 percent by volume.
Question: Where does molecular hydrogen in the atmosphere come from?
Does this come directly ...
2
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2answers
101 views
Is weathering of rock a primary means of $\text{CO}_2$ scrubbing on primordial Earth?
I read somewhere that the reason Venus has a runaway greenhouse effect and Earth doesn't is because Venus failed to develop tectonic plates and instead formed a full tectonic plate enveloping the ...
6
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1answer
220 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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3answers
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Would oceans regenerate if removed?
On Earth, there is enough Hydrogen and Oxygen to make 13,88 million km$^3$ of water (calculation below). However, oceans contain only a tenth of that.
Clearly, most of the hydrogen must be stored in ...
2
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0answers
38 views
why igneous phosphate rocks contain less uranium than sedimentary rocks?
Sedimentary rock phosphates contain much higher concentrations of potentially hazardous elements (As, Cd, Cr,Pb, Se and U)than igneous rock phosphates. Why?
Is it because U concentration in magmatic ...
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0answers
26 views
Formation of Hematite on Mars via Perchlorates as an Oxidizer
Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity.
A comment to the answer to the question: How do hematite and magnetite form? states that ...
6
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1answer
114 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 ...
3
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1answer
97 views
Is it possible to form a diamond-sapphire hybrid?
I've been looking into diamonds recently and was made aware of diamond hybrids where diamond is grown on either a seed diamond or cubic zirconia. I was wondering if it would be possible to do ...
