Stable Sulfur Isotopes & Paleoclimate / Paleobiology Proxies | GEO GIRL

[@sginoakley]

Thanks

[@GEOGIRL]

Thank you! Glad you enjoyed it ;)

[@nalonda3319]

This helped so much, I'm very new to earth science in general, and while I'm looking through books, a lot of it just goes over my head. This perfectly explained so many of my doubts and thank you for being so lucid and simplistic with your explanations ❤

[@GEOGIRL]

So glad you found this video helpful! Your comment made my day, that is my whole goal. :D

[@ahmedel-sayed8717]

Good job

[@lethargogpeterson4083]

Thank you for including the whole equation for the delta per mill notation, even though you made it essentially optional. I was wondering.

[@EddieS95]

Keep it up, this was super high quality

[@GEOGIRL]

So glad you found it helpful! Thanks for the encouragement ;D

[@gwyer23]

Super helpful video! Been having a hard time to understand MIF and your video nailed it! Also a small clarification - @4:39 you mentioned SRB "eats" sulfate. Based on my readings, my impression was they "breathe" sulfate? And I wonder if eating is the assimilatory SR and breathing is the dissimilatory SR? My microbio is not very strong and I often get lost in terminologies and what they imply. I'd appreciate if you have any thoughts on this part. Thanks!

[@GEOGIRL]

You are absolutely right! I often use the terms 'eat' sulfate and 'poop out' sulfide when describing it to students to decrease the amount of jargon so it's a bit more understandable, but you are technically right that it is kind of their equivalent of O2 for us in their metabolic pathway. ;) The easiest way to understand assimilatory vs dissimilatory pathways is assimilatory ones end up converting the compound (in this case sulfate) to organic material (in this case cysteine I think), so they assimilate it into their biomass, whereas, dissimilatory pathways just convert the compound to something else (in this case sulfide) and release it to the environment rather than assimilating it. So I think you are spot on by saying that for assimilatory microbes it is more like eating, whereas for dissimilatory ones it is more like breathing! ;)

[@gwyer23]

@@GEOGIRL Cool! I appreciate it. Kudos to the great work you're doing here with this channel.

[@funfrolics6114]

Superb, a public thumbs up to you.

[@GEOGIRL]

Thanks so much! Glad you enjoyed it ;D

[@funfrolics6114]

@@GEOGIRL a few lines I learned, added to my PhD thesis.

[@koksalan75]

Great video thank you...One question...if the ♤S34 value is -20, then that could correspond to many different times, correct? It could be ~2 Ga or 1.5 Ga or 0.7 Ga or 0.4 Ga... right?

[@loganwashere24]

I think I’ve been taught the opposite: when lots of sulfate is available, fractionation is less pronounced and even is driven down into negative d34S. Then we compared this to carbon isotope excursion (in Cretaceous for example) to show that there was a lot of oxygen and thus sulfate available in the ocean. Is this right?

[@GeologiadaTerra]

This was very helpful, thanks!

[@libraryofpangea7018]

Palynology also studies NPPs or non pollen- palynomorphs. Such as fungal spores.

[@Vra_fanl]

Thanks for your explanation. Could you please share the reference regarding the diagram @9:09?

[@stevengill1736]

It's totally thiodelic! Cheers...

[@blockchainasaservice7496]

Geo Girl you are amazing at what you do & your explanation. I’d love to introduce you to some amazing science friends with RTG. I’d be curious as to know if the mass matters for the nutritional value of plant substances.

[@GEOGIRL]

Thank you so much! It would be so nice of you to share it with your science friends! :D What is RTG? I am actually not sure about whether mass affects the value of plant substances, I'll have to look into that!

[@pablofarias3265]

Thank you! Very well explained! :) Now I need to know how to apply these principles to mineral systems ($). Thanks!

[@GEOGIRL]

Thanks for the comment, I am glad it was helpful to you! :)

[@pablofarias3265]

@@GEOGIRL I would add the references from where you took the graphs and figures. Cheers!

[@GEOGIRL]

@@pablofarias3265 They are always in my descriptions!👍🏼 enjoy!

[@dont_know_who]

Best wishes from India👏👍

[@taofikjasalesmana3235]

So interesting, its very helped so much. However I'm still confused how to distinguish the δ34S of sulfide from sulfate-reducing bacteria or from disproportionation of magmatic sulfur dioxide in dormant volcanic lake sediment? Thank you so much...

[@GEOGIRL]

So, to my understanding, SO2 disproportionates into elemental sulfur (S) and sulfate (SO42-) in hydrothermal systems, and during this processes the S isotopes fractionate. However, bacterial sulfate reduction produces sulfide (S2-). So if you are analyzing a rock for S isotope composition, the first step to distinguishing these two fractionation processes is to consider the composition of your sample. If it is a sulfide (e.g., sedimentary pyrite) the bacteria likely had a strong influence. If it is elemental sulfur from a hydrothermal environment, abiotic SO2 disproportionation was likely the cause of S isotope fractionation. The other thing to look for is hydrothermal alteration. For example, say it is a sulfide, but it's been hydrothermally altered, in this case, the S isotope composition would no longer represent the pure bacterial signal, instead is represents a combination of bacterial and alteration fractionation effects. So it really depends on what kind of sample you are looking at, I hope that makes sense ;)

[@taofikjasalesmana3235]

@@GEOGIRL Thank you, very enlightening explanation. However, what if the sample used is sulfide that dissolved in water? I'm still having a hard understanding how to distinguish the source of this sulfide, because if I look at the reference, the δ34S sulfide from the bacteria and magma can overlap each other. Thanks..

[@oliverweeweepie3132]

So interesting

[@dont_know_who]

Kinda helpful👏

[@wolfmann5160]

What would happen if we shifted the graph (time ~ 12:32) to the left 1500 units. Instead of millions of years, we consider it thousands of years. We know that massive amounts of rain would consume great amounts of carbon dioxide and release oxygen. So, the Great Oxidation Event would coincide with one massive deluge. With all the pressure of water on the surface, you have massive erosion. Since water cavities now exist in the depths of the earth because of a major shift in the lithosphere, we have much more water on the surface and the Earth's crust is not quite broken up yet. The emptiness within creates fissures in the lithosphere and over 1 to 2 centuries, this develops further until the lithosphere is divided into plates. The water recedes and earthquakes shift our plates; while, in the meantime magma starts to flow along these boundaries at a tumultuous rate. Plates move and smash into each other, creating mountains that were once just land covered by water. The uplifting of land causes massive runoff, creating great crevices in the surface of the Earth. What if?

[@rickkwitkoski1976]

ANY evidence of this? What you have is pure speculation, UNLIKE what she presents. "That which is asserted with evidence can be dismissed without evidence." - Christopher Hitchens

[@Anuchan]

Did you just dis isotope scientists? Shame!