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 are ionic bonds considered the "dominant" type in minerals?
I'm just starting out in geology and I keep reading that ionic bonds predominate among minerals. However, the majority of minerals are silicates and the silicate ion has covalent bonds, so they ...
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What is the reason that some elastic constants are negative?
In this table of elastic constants, indices m = 1 and n = 4 result in negative values. What could the reason be?
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Estimation of rare earth elements in the SUAC complex
I am currently competing in a case study competition a part of which has asked us to estimate the amount of Nd, Pr, and Dy in the SUAC complex (Sung Valley Ultramafic-Alkaline-Carbonatite) in electric ...
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Interpretation of Phanerozoic CO2 levels graph
I used to talk with a family friend who often sent me links to Nobel Prize winners, claiming that climate change is a myth.
Last week, we had a disagreement over a link referencing a Nobel Prize ...
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Co variance of isotopes in geochemical amplications
I recently heard that the d98Mo isotope is not different from the d238U isotope in redox processes e.g. in black shale events. But I can't find any evidence except the figure from Zhang et al. ...
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If the universe (and our galaxy) has about twice as many oxygen atoms as carbon ones, why does Earth have 300 times as many oxygen atoms as carbon?
A (relatively) recent 'Sky & Telescope' magazine feature story mentioned how little carbon the Earth has, and how some scientists' models predict we should somehow have even less....
So I looked ...
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Can $\ce{CaCO3}$ shells contribute to $\ce{CO2}$ emissions in volcanoes within subduction zones?
CaCO3 dissolves below the Carbonate Compensation Depth (CCD).
However, this paper suggests that some CaCO3 can exist below the CCD.
My question arises from a discussion in this answer.
The question is ...
user28185
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Is it possible that the rainbow sand dunes in Death Valley, California were formed by some massive mining in the ancient past? [closed]
I know there is a mainstream answer that thinks the rainbow sand dunes they be explained geologically... I just want to know if it's possible to form those colors and those dunes from mining? And if ...
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Does granite and basalt behave differently in different atmospheric pressures?
We all know that the oxygen levels increase and decrease as well as the temperature, so I believe it's safe to assume atmospheric pressure changes as well... And since granite and basalt are formed ...
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Why does calcium occur together with felsic rocks and magnesium with mafic rocks if calcium is denser than magnesium?
Felsic rocks contain a lot of sodium, potassium and calcium (and a great deal of aluminum), while mafic rocks consist of a lot of magnesium with iron....
Why is this?
Why is magnesium (z=12) in the ...
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How do I convert an element measurement to oxides?
So, I did some measurements in ICP-OES and the results were given to me in elemets. However, I need to convert the results to oxides. After some googling I found out that I need to use simple ...
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Why is NaCl so hyper abundant in the ocean?
Why is sodium chloride far and away the most abundant salt dissolved in ocean water? Its two constituent ions do have a very high frequency in the crust of the earth, but they are far from the most ...
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Reason for finding low boron levels in clayey soil with high organic matter?
I've read from various University Extension sites (e.g., here and here) that boron levels would be deficient in sandy soils with low organic matter.
This would suggest that boron levels would be ...
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Causes of high calcium levels in sandy alluvial soils
When soil calcium is high: High levels of soil calcium may be expected when there is substantial calcium carbonate bedrock from which the soil has weathered. Calcium levels can be high in agricultural ...
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Searching for Geochemical Threshold for PTE's of Spain
Where can I find a table with the geochemical threshold for potentially toxic elements in the soils of Spain? I only have seen a decree with organic compounds for Spain.
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Why does decreasing surface alkalinity increase surface pCO2?
According to Takahashi et al. (1993), pCO2 (partial pressure of CO2) in the surface ocean changes due to 4 surface variables: temperature, salinity, total carbon (dissolved inorganic carbon, DIC) and ...
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Under which conditions would you see the MOST lake effect precipitation?
It's well known that the Great Lakes produce large amounts of precipitation in the Fall. When cold polar air moves over the lakes it causes large amounts of relatively warm moist air to rise, ...
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Why is there gold in the earth's crust?
I would naively assume that when the earth was formed and still molten, all the heavy stuff such as gold would have sunk to the centre, so almost nothing would remain in the earth's crust where humans ...
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What oxidised the soil on Mars?
What exactly was it in the ancient Martian atmosphere that made it red? Was it water, molecular oxygen or something else?
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Help me find a certain type of crystallographic notation
I was looking through wikipedia a few weeks ago while half asleep, reading articles about rocks and their chemical compositions. I then came across a certain crystallographic notation which I had not ...
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Why is silver found mainly in lead
Apparently according to the Parkes Process silver is 3000 times more soluble in zinc than in lead. So why is it that most silver is obtained from galena?
Edit:
“ Silver mainly occurs as a contaminant ...
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Calculate original volatile content of a degassed mineral
A lunar apatite sample has a relatively low OH content of 5 ppm, but a an elevated D𝛿 of 11,000‰ (vs. SMOW). Assuming that water had an original figure of around -100‰ or so, how do I estimate the ...
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Is experience abroad important for your career?
I'm just finishing my Bachelor's degree in Geochemistry at a German university and will soon start my Master's degree, but I've been wondering for a few weeks whether a stay abroad (1 semester or even ...
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What does fugacity mean in the context of geology?
I am reading about water in the Lunar mantle, however it mentions fugacity a lot. What does it mean in this context?
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Where is basalt in the Goldich dissolution series?
In relation to this experiment: https://www.remineralize.org/rem_publications/action-of-microorganisms-in-basalt-powder/
It is said that applying basalt rock dust to soil can improve soil fertility ...
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Kinetic or equilibrium fractionation from 2H and 18O in evaporation and condensation?
Is the isotope fractionation that occurs during evaporation of surface water equilibrium fractionation or kinetic fractionation? I mean, evaporation can be described by Rayleigh fractionation, but I ...
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What chemical or physical parameters altered during the usage of buffered versus unbuffered extractant for leachability of a soil or sediment?
Toxicity characteristic leaching procedure (TCLP) is an extraction method to simulate a soil or sediment leaching. The method employed two extraction fluids - one is a buffered
solution of acetic acid ...
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Is this kind of sediment location sampling on river acceptable?
Yesterday, we performed a sediment sampling along both sides of a river. On various research papers, it seems that they always made it successfully to perform the sampling at both left and right side ...
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Do scientists ever make rock vapor in a laboratory? If so, is it ever used to study planetary or lunar formation?
This answer to What is the nature of "rock vapor" in this description of the formation of the Moon? explains what "rock vapor" is and how scientists use the concept to understand ...
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How did hydrogen make its way into proto-Earth?
Background
I read (what I could understand of) this article in which authors Yuan and Steinle-Neumann "...use advanced quantum mechanical simulations on silicate and metallic melts showing that ...
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Taking into account the decay products of transuranic elements, are the world's uranium reserves growing or shrinking?
I was talking to a friend of mine who is an environmentalist like me but not a big fan of nuclear power and she told me it was not a good option in the long run because of the decay of uranium. Of ...
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How should we deal with geochemical anomalies in stream sediment?
We know that geochemical anomalies in stream sediment usually distributed along the drainage. Therefore, when we use stream sediment as the sampling medium and found an anomaly, we should trace the ...
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Reconstructing lake level from organic and magnetic sediment data
I would like to understand why any of the following conditions in a layer of a lacustrine sediment core appear to imply that the lake level was low at the relevant time:
low C/N ratio
low δ13C
low ...
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What are the compressive strengths of goethite and magnetite?
I am attempting to determine what the compressive strengths are of the minerals goethite and magnetite.
None of the research I did has proven to be fruitful. What I have found:
multiple studies ...
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What is the role of trace elements in magmatic crystallization?
I understand that trace element behavior in a system depends on whether they are compatible or not. But , if that question is asked in an examination , what could be the points that one should write ...
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Carbon emission from estuaries
I've heard that estuaries like Chesapeake Bay produce a lot of methane during anoxic conditions. Is there a chance of these estuaries emitting significant amounts of CH4 in the future (because of the ...
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Can geochemical anomalies of stream sediment samples be used directly for mapping targets?
We know that geochemical dispersion in stream sediment is much widespread, facilitating discovering mineral targets in a regional scale. However, we also know that there should be discrepancy in space ...
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convert mol/m2 to μg/m3 [duplicate]
Sentinel-5P satellite provides high-resolution data products on concentration levels for several atmospheric trace gases (NO2, SO2, O3, and others), which are measured in mol/m2 within the total or ...
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Why were Fe-oxides not usually used for finding skarn Fe ore deposits in geochemical exploration?
I found that Fe-oxides were usually not used for vectoring Fe mineral deposits of skarn type in geochemical exploration. As an indicator element, the common practice told us Fe-oxides should be the ...
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What is the electrical conductivity of a liquid Komatiite?
I am searching for previous work that has determined the electrical conductivity range for komatiites at the surface. Does anyone have some values or references?
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Do lead 206 and other daughter isotopes occur naturally?
I am reading studies about the age of the earth and U-238 to Pb-206 comes up a lot.
My question is:
In meteorites, or really anywhere, is lead 206 natural or does it always come from radioactive decay?...
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Do carbon dioxide hydrates exist in nature?
Do CO2 hydrates exist in nature? If so, how much carbon could they contain?
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Artifical Ore Genesis?
From my understanding, the formation of ores can be reduced to a simple three-step process of the removal of minerals from a source via some mechanism, the transportation of these minerals, and ...
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Spatially-explicit global database of parent rock chemistry?
As the title suggests, I am looking for the most reliable database(s) of parent-or bedrock chemistry, e.g. the concentration of nitrogen, phosphorus and some other metals (basically plant nutrients). ...
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How are we going to handle oxygen shortage problem arising due to massive usage of current fossil fuel combustion and future Hydrogen fuel cell tech?
This question is being redirected from the Chemistry Stack Exchange community.
The current corona pandemic has created a situation where in order to save lives, there is a huge huge requirement for ...
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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, ...
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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 ...
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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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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 ...
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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 ...
user21385