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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4
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1answer
53 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? ...
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1answer
73 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 ...
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170 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
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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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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
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, ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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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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 ...
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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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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%". ...
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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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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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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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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?
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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 ...
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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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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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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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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 ...
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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?
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1answer
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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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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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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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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
166 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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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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1answer
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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 ...
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231 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 ...
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1answer
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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
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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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 ...
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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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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 ...
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1answer
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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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1answer
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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 ...
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1answer
114 views

What kind of purple stone is this? [closed]

I found this stone and I do not know what type of stone is this?
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1answer
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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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1answer
72 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 ...
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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 ...
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2answers
1k 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 ...
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1answer
133 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 ...
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Employment of Volcanologists and Petrologists

What industries or government departments hire volcanologists and igneous petrologists/geochemists in the United States?
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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 ...

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