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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66 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, ...
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142 views

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 ...
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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 ...
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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 ...
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2answers
169 views

Is this why oceans are salty?

From noaa.gov's Ocean facts: Salt in the ocean comes from rocks on land. The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the ...
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1answer
134 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 ...
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1answer
52 views

Saharian calima dust, apart of Fe2O3 does contain FeO?

It is repeated often that Saharan calimas are fertilizing often Atlantic ocean. But I suppose that most of Saharan dust contains Fe2O3 and not FeO. Am I right?
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1answer
185 views

Ions & elements, which is the correct terminology to use when discussing chemical compounds in Earth Science?

Different textbooks use different terminologies when discussing the same chemical compounds, for example when discussing the minerals... Elements / Compounds Sulfide minerals consist of metallic ...
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1answer
563 views

Mixing equation for confluence of two rivers

How can I calculate the final concentration of two ions in a river after the confluence of two rivers? River 1 flows at $\small\sf{7000\ L/s}$, contains $\small\sf{500\ mg/L\ Mg,\ 1.1\ g/L\ Ca}$ ...
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2answers
124 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 ...
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1answer
52 views

Effect of reducing conditions on melting point

I've been reading a paper(*) looking at the deep carbon cycle and it mentions a key process that the authors refer to as "redox melting". According to the paper, reducing conditions increase the ...
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1answer
102 views

Dolomite in deep-water environment

Is it possible that dolomitization occur in deep-water environment? If it possible, how?
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1answer
95 views

Voronoi-like pattern in metal samples

What is this pattern in the samples' surface called and how/why is it formed? I remember having seen a similar pattern in galvanized sheets. Photos of metal samples from Wikimedia Commons (here and ...
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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 ...
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1answer
60 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 ...
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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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1answer
671 views

Gypsum saturation index

I did some geochemical modelling and found groundwater samples I have are saturated with respect to the mineral gypsum. I need some help with interpretation, more information is given below. The ...
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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 ...
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25 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 ...
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34 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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23 views

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 ...
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71 views

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 ...
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1answer
118 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
656 views

Crystallization path of diopside-wollastonite-silica systems

Can someone please explain to me (or give a source) how the crystallization diagram of the diopside-wollastonite-silica system looks. I am a new learner of geology and trying to learn ternary systems.
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2answers
130 views

Limitations on mineral precipitation from solution

If the solubility constant for a mineral is exceeded and, thermodynamically, a mineral is favored to precipitate in solution, are there any factors that may limit this from happening? Perhaps kinetics?...
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1answer
68 views

Elemental ratios in rocks and stream water

I have chemical analysis of one catchment which can be considered more or less homogeneous and also stream water analysis, I would like to know how elemental ratios (to Na for example) are related ...
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1answer
82 views

What negative side effects would occur if silicate mining were used to artificially lower atmospheric CO2 concentrations?

As one half of the naturally occurring Carbonate–silicate cycle, carbon dioxide is naturally removed from the atmosphere by the chemical reaction: CaSiO$_3$ + 2CO$_2$ + H$_2$O → Ca2+(aq) + 2HCO$_3$-(...
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290 views

Analyzing composition of a mineral using SEM

If I have a mineral in which I did a SEM analysis on and got the data (elements and their wt% with Std. Dev., MDL, atomic % oxide % and k ratio) how would I go about quantifying the sample's ...
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1answer
86 views

Would you see a correlation between detrital zircon age and grain shape?

If one was to quantify the shape (particularly roundness) of detrital zircon grains, would there be a correlation between the age of the detrital zircon grains and their shape? For example, if the ...
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1answer
176 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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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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2answers
710 views

Specific Chemical Composition of Nero Marquina Marble

I'm looking to understand the chemical composition of the Spanish Nero Marquina Stone. Specifically, are the white veins of different composition than the black? We are design studio pursuing work in ...
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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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2answers
73 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 ...
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24 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?
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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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87 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 ...
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19 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 ...
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2answers
93 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 ...
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20 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 ...
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46 views

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?
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148 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 ...
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47 views

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 ...
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52 views

What composition would the early cratons have? [closed]

I am trying to get into early-Earth geochemistry, and the cratons piqued my interest. They would need a very specific density to float, and the right heat resistance to not melt. What composition ...
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105 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 ...
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Are fossil fuels really formed from fossils?

Hydrocarbons have been found in great abundance elsewhere in the solar system where there is unlikely to be evidence for life past or present. No fossils involved. Petroleum and natural gas wells ...
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2answers
132 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?...
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1answer
76 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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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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58 views

calculation monocationic elements

How to calculate of the number of monocationic millimoles? If I have concentrations of: $SiO_2$, $TiO_2$, $K_2O$, $MgO$, $MnO$, $Na_2O$, etc. How can I get $Na^+$, $Mg^{2+}$, $Mn^{2+}$ ..? This is ...