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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How are Mauna Loa $\ce{CO2}$ monthly trends computed?

The problem I am trying to figure out how $\ce{CO2}$ concentration trends are computed in the data provided by the Earth Systems Research Laboratory Mauna Loa Observatory. The data contains monthly ...
Dima Chubarov's user avatar
10 votes
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95 views

Predicting volcanic eruptions by experimentally proven volatile outgassing observations

In the abstract for the article Forecasting Etna eruptions by real-time observation of volcanic gas composition (Aiuppa et al. 2007), the authors assert that real time monitoring of volcanic volatiles,...
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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 ...
Fred's user avatar
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Chloride and evaporation

I have a layered aquifer with water that contains high concentrations of calcium and sulfate (~400 mg/L Ca2+, ~1300 mg/L SO42-), at 50 cm below ground surface (bgs), 250 cm bgs and 300 cm bgs. The ...
Henry's user avatar
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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 ...
Victor1995's user avatar
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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 ...
tunar's user avatar
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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 ...
zachery moïse's user avatar
5 votes
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What causes a change in composition from basanite to nephelinite?

Can the change in composition from basanite to nephelinite (i.e. increasing alkalis with decreasing SiO2) be explained in terms of fractional crystallisation, or only by a decreasing degree of partial ...
Leticia's user avatar
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What reactions change seawater composition in hydrothermal systems?

Reactions in ocean floor hydrothermal systems are a significant contributor to the mass balance of several major elements in the oceans, in particular magnesium, calcium, sodium, potassium and sulfate....
bon's user avatar
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Can humidity changes induce stacking-sequence changes?

My understanding is that some minerals with layered crystal structures will reversibly absorb water with changes in humidity. Are there any minerals where this reversible absorption leads to a ...
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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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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 ...
theforestecologist's user avatar
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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 ...
Weiss's user avatar
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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 ...
làntèrn's user avatar
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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?
thehungrygraduate's user avatar
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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/...
Don's user avatar
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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, ...
bandybabboon's user avatar
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Dolomite and calcite precipitation

In an engineered wetland, there is groundwater flow from an aquifer with a chemical composition that is rich in magnesium, calcium and sulfate. We are finding that the aquifer is consistently ...
Henry's user avatar
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Does perchlorate(rocket fuel) and jet fuel make the salt and ground water near Cape Canaveral dangerous?

I've gotten into paddle surfing and I'm looking for a place to live and surf. I've been looking at an buying a condo in Cocoa Beach because of it’s proximity to Orlando and Cocoa’s decent but ...
BryanWheelock's user avatar
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Does each volcano have a fingerprint?

Thinking about arc volcanism in a region, and there are two neighboring composite volcanoes 50 km apart from each other. Do you expect any differences about their products (lavas, pyroclastic deposits)...
Muharrem Yavuz's user avatar
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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 ...
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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 ...
theforestecologist's user avatar
3 votes
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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 ...
孙雅杰's user avatar
3 votes
0 answers
36 views

Formation of dolomite

What are the kinetic barriers to dolomite precipitation? Does it precipitate out in solution as quickly as Calcite does?
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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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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, ...
user3501561's user avatar
2 votes
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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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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 ...
tunar's user avatar
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Can zircons be analysed by the (U+Th)/He after being ablated for analysis of U-Pb?

I have zircons that have been mounted in a resin block. They have been polished to approximately half way through the zircons (as is convention) and they have been ablated to attain the U-Pb or Pb-Pb ...
Ton's user avatar
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2 votes
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Inverse model problem

I have a dataset for river water, rain water and geology (main elements and trace elements). I want to apportion the contribution of geology to water chemistry using for that purpose a model. I was ...
Marlon Calispa's user avatar
1 vote
1 answer
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Does anyone know what the mineral of the year 2023 is?

I am collecting every mineral of the year since 2012, and I have not found anything on last year's mineral. Thank you.
Lalith_Aditya's user avatar
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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 ...
Vijay Arvind's user avatar
1 vote
0 answers
54 views

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. ...
Weiss's user avatar
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1 vote
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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 ...
paulina's user avatar
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1 vote
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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 ...
làntèrn's user avatar
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1 vote
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868 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 ...
Harry's user avatar
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1 vote
0 answers
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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 ...
Diksha's user avatar
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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 ...
Senna's user avatar
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1 vote
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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?
agn1496's user avatar
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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?
Jon's user avatar
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380 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 ...
Thorondor's user avatar
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1 vote
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28 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 ...
Thomas's user avatar
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1 vote
0 answers
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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 ...
Muze's user avatar
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1 vote
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Pyrite oxidation

How much pyrite has to be oxidized to produce a sulfate concentration of 15 mM? If the solution initially has a pH of 8, roughly what would the pH drop to if there is no buffering of acidity?
chrisuw92's user avatar
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1 vote
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182 views

Mass balance for calculating mantle composition

I've seen some problem sets given without answers / solutions regarding how to calculate the composition of the mantle given solar composition (and assuming the same would apply to the Earth). For ...
Harry B's user avatar
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1 vote
0 answers
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Weathering of silicates

I am trying to find a relationship between the silicate-rich rocks weathering products. For example I've found information regarding gabbro weathering in which, according the consulted source, in 100 ...
Marlon Calispa's user avatar
1 vote
0 answers
110 views

Dry deposition of the total sulfate deposition in forested region

Sulfate is one important inorganic aerosol in the atmosphere. It's subject to removal by two main mechanisms. Wet deposition which include rain/wash-out and cloud deposition. Dry deposition ...
Han Zhengzu's user avatar
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