Questions tagged [geochemistry]
The science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems.
197
questions
12
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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
votes
1answer
117 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 ...
0
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0answers
33 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 ...
8
votes
1answer
71 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 ...
3
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1answer
141 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
votes
2answers
208 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 ...
3
votes
4answers
111 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
votes
2answers
121 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 ...
1
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0answers
26 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 ...
1
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2answers
56 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 ...
1
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0answers
20 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?
-1
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1answer
47 views
Can someone please help me figure out what this rock/mineral is? [closed]
Inside of the rock there is some type of fossil and it looks like a tiny tooth. Whatever this is, it's very interesting and doesn't make any markings when drawn with. It is white and yellow, almost ...
4
votes
1answer
70 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 ...
0
votes
1answer
46 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 ...
0
votes
1answer
62 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?
5
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2answers
112 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
40 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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0answers
14 views
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
58 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 ...
0
votes
1answer
73 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 ...
1
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0answers
75 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 ...
1
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0answers
17 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 ...
1
vote
1answer
132 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 ...
4
votes
1answer
202 views
Why Earth's outer core does not 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
votes
1answer
127 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 ...
3
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0answers
165 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 ...
1
vote
1answer
61 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 ...
5
votes
1answer
153 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 ...
14
votes
3answers
11k views
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
votes
0answers
37 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 ...
2
votes
0answers
22 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
votes
1answer
108 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
votes
1answer
61 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 ...
1
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1answer
93 views
What kind of purple stone is this? [closed]
I found this stone and I do not know what type of stone is this?
6
votes
1answer
101 views
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 ...
2
votes
1answer
68 views
The magnetite is in which type of magma
In which type of magma can I find magnetite? Peraluminous or peralkaline? I've been looking and the peraluminous magma have a lot of oxides so I thought it would be reduced magma so it would have ...
1
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0answers
19 views
Do living things have a magnetic field capable of any level of solar protection?
I understand how anything with an electrical current have a magnetic field including living things. Would a densely populated rain forest or jungle have enough combined magnetic field among the living ...
2
votes
1answer
944 views
What exactly are enantiotropic and monotropic polymorphic transitions?
Recently, I've been studying the subject of polymorphism and met two important concepts, the monotropic and enantiotropic polymorphic transition types. However, I can't really seem to grasp the ...
1
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1answer
130 views
What other graphical methods can be used to represent weathering?
Context:
For one of my reports I have taken samples of a rock from an adjacent creek. I have done XRD analysis to get compositions of calcium, potassium and aluminium.
My question:
I know about ...
4
votes
1answer
77 views
Employment of Volcanologists and Petrologists
What industries or government departments hire volcanologists and igneous petrologists/geochemists in the United States?
2
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2answers
2k views
Melting point of minerals
Looking at this website, I can see the melting point of the following minerals: http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/meltrock.html
Apparently at a temperature of 1200 °C, all the ...
0
votes
2answers
124 views
What does 5,000,000 tonnes of CO2 look like?
Reading a news article Probe after Gorgon releases millions of tonnes of greenhouse gas, I am confused. CO2 is a gas, right? Gases are not very dense, right? So what does 5MT of the stuff look like?...
6
votes
1answer
210 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 ...
5
votes
1answer
176 views
What are the cubic formations found inside Larimar gemstones?
I recently noticed what appears to be common cubic formations just beneath the surface of Pectolite (Larimar) gemstones. They quite resemble transparent sugar sprinkles. Each formation isn't perfectly ...
3
votes
0answers
55 views
Sulfate reduction
I read a document in which the authors stated "Sulfate and sulfide ( bisulfide and dihydrogen sulfide) both exist within a system just in varying proportions, and aqueous speciation is dependent on Eh/...
7
votes
1answer
532 views
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 ...
3
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0answers
65 views
Reason for higher content of Iodine and Copper than Iron in Seawater?
Does mineral weight contribute to the prevalence of minerals in seawater?
Why is there five times more copper in seawater than Iron?
Why is there 4000 times more strontium in seawather than Iron, ...
3
votes
2answers
88 views
Iron-nickel phase in pallasite meteorites
I have recently been learning and researching about meteorite types and classification. Pallasites are mainly composed of a 'solid-solution' of olivine crystals and an iron-nickel alloy. My question ...
8
votes
1answer
344 views
Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes?
When pondering the hypothesis of the Iron catastrophe, that seem to be widely accepted nowadays. It surprises me that currently the crust still contain a significant amount of Iron (5.6% in weight).
...
5
votes
1answer
236 views
Difference between pyrite oxidation and dissolution
I've seen papers use oxidation and dissolution of pyrite. Are these two processes the same? I was always under the impression that pyrite does not dissolve easily. What is the difference between ...
