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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13
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1answer
133 views

Does the heating of the oceans due to greenhouse effect negate the acidification due to increased CO2 levels?

As I understand, the dissolving of carbon dioxide leads to increased acidification of the oceans, and thus increased atmospheric CO2 levels would lead to more dissolution in the oceans and thus ...
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8 views

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 ...
3
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1answer
46 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?
8
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1answer
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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 ...
6
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2answers
561 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 ...
7
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1answer
452 views

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?
3
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2answers
119 views

Is there a risk with putting out smouldering underground coal reserves? [closed]

According to this Discovery News video about Centralia Pennsylvania and other underground coal fires, there are many smouldering underground coal reserves making the land above it uninhabitable to ...
6
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2answers
253 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 ...
4
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1answer
69 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 ...
3
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1answer
35 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, ...
8
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1answer
425 views

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 ...
6
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1answer
220 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 ...
4
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1answer
90 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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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 ...
13
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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
134 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
35 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 ...
3
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4answers
156 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%". ...
8
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1answer
76 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
145 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 ...
1
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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 ...
4
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1answer
79 views

Employment of Volcanologists and Petrologists

What industries or government departments hire volcanologists and igneous petrologists/geochemists in the United States?
6
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2answers
213 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 ...
5
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1answer
155 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 ...
2
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2answers
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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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4answers
16k views

What was the first rock in the rock cycle?

I am an undergraduate student but I am a tutor at a High School, and one student asked me. Attempting to explain the rock cycle "if one rock turns into the other then which came first" my gut is ...
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2answers
62 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 ...
4
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2answers
550 views

Looking for a complete table of minerals for a database

I am building an open source spatial geochemical/geological observational database for mineral exploration. I need to fill the mineral lookup table. Where can I find a complete list of all minerals ...
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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 ...
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0answers
21 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?
5
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1answer
189 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 ...
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3answers
1k views

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:...
4
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1answer
1k views

Does ground-to-cloud lightning create crystals as well?

I've read that cloud-to-ground lightning can create fulgurites. Does ground-to-cloud lightning also create crystals within the earth as it surges through the minerals?
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1answer
48 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 ...
33
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5answers
6k views

How and why did the oceans form on Earth but not on other planets?

Earth is the only planet in our solar system that has copious amounts of water on it. Where did this water come from and why is there so much water on Earth compared to every other planet in the ...
0
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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 ...
2
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1answer
41 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 ...
0
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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 ...
26
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4answers
11k views

What is the origin of the dominant atmospheric nitrogen content in Earth's atmosphere?

Comparing the atmospheric compositions of Earth with our nearest neighbours: As the table shows, the Earth's atmospheric nitrogen concentration is 78%, compared to 3.8% for Venus and 2.7% for Mars ...
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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
59 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
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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 ...
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0answers
79 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 ...
19
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3answers
2k views

Why does Earth have abundant oxygen in the atmosphere?

Because of photosynthesis, obviously. But then it's not actually that obvious after all, because photosynthesis is mostly balanced by respiration. We can summarise the processes of photosynthesis ...
22
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2answers
2k views

Peak phosphorus - what are the sinks?

The minable phosphorus reserves are limited. Where is the mined phosphoprus landing, what are the global phosphorus sinks? I would assume that most phosphorus is used for fertilizer and ultimately ...
8
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1answer
163 views

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 ...
1
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1answer
148 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 ...
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0answers
18 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 ...
33
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3answers
14k views

Why is Earth's age given by dating meteorites rather than its own rocks?

Reading a course on Precambrian, I read that: Earth Age (around 4.5 billion years) is dated thanks to the meteorites hitting Earth during its formation rather than the inner materials composing the ...

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