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Lecture 11


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Kerogen is the ... part of sedimentary organic matter. Difficult to characterize but likely a heterogeneous, complex polymeric structure.
[Back]


insoluble

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Lecture 11 - Marcador

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Lecture 11 - Detalles

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Another pathway, aside from the selective preservation pathways, is geopolymerization, what does this entail ?
Functional molecules can react under de influence of light and oxygen (oxidative polymerization, jetification) or sulfide (vulcanization) to form geological polymers (“Geopolymerization”)
What is kerogen?
The insoluble part of the organic matter (90%), likely largely consisting of polymers -> makes oils
What was the speculative view of kerogen structure (early 80’s)
They are lipids but random polymerization of low molecular weight compounds: “Geopolymerization” leading to non-extractable material. Happens in geosphere, after death of organism, something is catalysing this process.
What 3 types of analyses may be performed on kerogen?
Elemental analysis, solid state spectroscopic analysis, chemical analysis through flash pyrolisis
With elemental analysis we mean?
Simply a count of elemental ratios of H/C and O/C -> know potential to create oil and the basics of where it is coming from
Solid state nmr can give us information on...
Functional groups, relies on spin resoncance of 13C and how it is affected by its neighbours. It gives an overall average
Chemical analysis may be performed if we use smaller fractions of the kerogen polymers, how could we get these?
Flash pyrolisis, thermal depolymerisation which makes the polymer fall apart and can now be analysis with Gc/Ms
The biopolymer algaenan was proof that...
It was ot only through geopolymerization that these kerogens were formed, because the algaenan was also making up the algal cell walls of life eustihmatophytes (biomarker = long chain diols). So selective preservation of algaenan
What is algaenan
Polymer (insolublle) from outside of cell wall (mainly green algae such as eustigmatophytes and botryococcus braunii) that is very resistant to degradation. Structure of longchain diol monomers connected through ester and ether bonds.
Why is this (algaeanan) selective preservation?
Only a few algae make these cell walls and are able to survive for millions of years -> Green algae! (not diatoms and haptophytes so their cell walls will not accumulate and preserve over time)
What is cutin?
It is a hydrolysable polymer present in the leaf and stem cuticles of plants. they contain labile (weak) esterbonds (know because upon hydrolysis they released ester (C16/18) bonded hydroxy fatty acids). Mainly longchain fatty acids and alcohols.
What is cutan ?
Insoluble, non-hydrolysable, aliphatic biopolymer of plant cuticles. It is very resistant to degradation and cant be destroyed throuhg simple hydrolisis. It is mainly found in CAM plants (drought adapted) and formed a hydrophic cuticle layer (aliphatic = hydrophobic, long alkanes and alkene, Cs and Hs)
What is sporopollenin
Polymer in spores and pollen walls, a biopolymer consisting of p-coumaric acid and some ferulic acid building blocks
Sporopollin looks like lignin, what is lignin?
Lignin is an insoluble biopolymer occurring in higher plants. In particular wood consists of lignin and cellulose
Why do lignin and sporopollenin look alike?
Pathway for lignin and sporopollenin are close to each other, slightly different monomers, but the biosynthetic pathways are very closely related -> similar buildingblocks
Geopolymerisation ooccurs in the ...
Natural environment after cell death
Natural vulcanisation is a type of gepolymerisatio, what doesit entail?
It relies on the intra- versus intermolecular incorporation of sulphur to make polymers
Oxidative polymerization is another type of geopolymerization , what does it entail?
Forming “geopolymers” from unsaturated lipids during diagenesis under influence of light and oxygen
What is jetification
Polymerization of a polyme, oxidative “polymerization” of fossil lignin upon exposure to oxygen (cross polymerization)