Absolute Dating / Radiometric Dating / Geochronology / Dating rocks with isotopes | GEO GIRL

[@GEOGIRL]

Lol I realize I pronounced tritium wrong haha, my bad. The content of the video is still good tho! Hope you guys find it helpful ;)

[@gabeesp9654]

It's ok it is

[@gabeesp9654]

Seems like a great job

[@GEOGIRL]

@@gabeesp9654 Thanks so much!

[@gabeesp9654]

@@GEOGIRL sure thing

[@PacificEagle_official]

I found this channel 2 days ago and so far I have watched 50-60 videos. You explained things very well 👌!!!

[@GEOGIRL]

Thank you so much for the support and for watching so many videos haha! I am so glad you have been enjoying them :D

[@jensphiliphohmann1876]

About 05:30 And one element in the decay chain of Uranium is gaseous, so some of the stuff can get lost.

[@dharmareyes]

So nice video! You explained it very simple and you keep the audience very motivated during the video =)

[@GEOGIRL]

Thanks so much for the comment, I am so glad you thought so! :D

[@koyou33]

Hey. Cheers for reply. I just looked at th pic above with th 3 rocks which shows th ratio changing but th amount staying same. Had I saw this pic initially I wouldn't have asked th Q. I used th term 10g because that's wat u had in th video 10g,5g,2.5g, Ratio is ratio weather weight or number. I get th atomic weight change but my Q was regarding ratio.th pic above is 100% self explanatory and shud replace th 10g,5g,etc weight pic so others who skip th cover pic like me won't b confused. Or show matching weight ratio to balance total 50/50,25/75,12.5,87.5. Wish I had seen th cover pic th first time. Spent more time writing than watching th video lol. At least I will never forget now. Cheers

[@jjnoguera]

Simple, conciso y exactamente explicado. Con pocas palabras he aprendido mucho.

[@GEOGIRL]

So glad to hear that, thanks so much for the sweet comment! :)

[@SMAA373]

True Passion.

[@qwerty-lu3wd]

thank you for this video :)))

[@GEOGIRL]

Of course, so glad you liked it! :D

[@Vanda-sv5vr]

Thanks for this! Love your videos

[@GEOGIRL]

No problem, so glad you've found them helpful and/or entertaining! ;)

[@PepsiMagt]

Aren't the Argon and Potassium swapped at the 7 minutes ish mark? Regards

[@AztroNut66]

Not swapped but, she placed text at the bottom of the screen correcting this mistake 6:44

[@RichardLewisCaldwell]

I have never heard anybody explain the OBVIOUS question: How do you know the parent rock contained pure uranium with no daughters? After all, the rock formed millions to billions of years after the uranium was formed in a supernova or whatever.

[@GEOGIRL]

Actually I am working on a video answering this exact question right now! I hope to have it out in the coming few weeks! :D I hope it will answer your questions :)

[@markgamache6377]

How does a rock start with 100% parent element and not a mixture of parent and daughter?

[@GEOGIRL]

Great question! As for the parent isotopes, they are 'reset' during melting because the energy is being provided to the system, compared to being released from the system over time after cooling. That's why we have to be careful with materials that have undergone metamorphosis. We are dating the metamorphism not the original formation of that rock. As for the daughter isotopes, we can tell the difference between radiogenic (coming from radioactive decay) and non-radiogenic isotopes for most systems, for example, lead(Pb)207 is the radiogenic product of Uranium(U) decay, but Pb204 is a primordial nucleus, meaning it did not come from decay, so we make sure to measure which isotopes are radiogenic and which are not and take the ones that are not out of the equation. :)

[@markgamache6377]

@@GEOGIRL thanks for the detailed answer. The lead 204 vs 207 is fascinating. Lead 204 was formed in stars directly and 207 as a result of decay. Amazing and very helpful!

[@gregoswald7723]

@@GEOGIRL I have watched several videos and read several articles on radiometric decay and I have not found a clear explanation about how the rock's parent isotope is 'reset' during melting. Please help me understand this, if you can. Let's say, A rock has 50% parent isotope and 50% daughter. You apply heat and pressure and time to metamorphosis(ize?) the rock into a 'reset' rock. If the rock is 'reset' how does that happen? I get that the 50% parent can become the new 100%. But then, 100% of the daughter would have to leave for the daughter to become 0%. Where does the daughter go? How do you know all of it has gone? Why doesn't the parent also leave? How long does this 'reset' take? If, in the above example, due to only partial metamorphosis, the rock is only partially 'reset,' and only half of the daughter left, that would leave the ratio at: 75% parent, 25% daughter. The rock would now appear to be much younger. It appears to have only gone through about 0.41 half-lives. Example 2: If I take a 1 billion year old rock, put it in a furnace and melt it (lava), then plunge it into water. Let's say, this process took 1 hour. Would the new rock be 'reset'? If yes, then what is the You said, _As for the parent isotopes, they are 'reset' during melting because the energy is being provided to the system, compared to being released from the system over time after cooling._ What is the 'energy is being provided'? Heat? As I understand it, heat does not affect the rate of decay. This would be a great video all by itself. I have not been able to find any that adequately explain this 'reset' process.

[@dennis_mihaylov]

Thank you very much!

[@brucewinningham4959]

One question please. Since Radioactive Materials are Unstable, how can we rely on their Trustworthiness for Radiometric Dating? It appears to me the More Unstable a material, such as a rock would be, the less Predictable (Unreliable) it's Half Life would be.

[@zinobi]

Disclaimer, I haven't studded this for 10+ years, and I wasn't very good at it even then. You are actually partially right! The reason it usually works is that there are many billions of atoms and the quantum-effects even out over that amount. Yes, they really really do over a few thousand years and a many billion molecules we have probabilities in the same ranges as the odds that your hand would just phase through a table the next time you lean against it. However, I seem to recall that as you get down to really small amounts of a parent isotope the error bars gets wider, not only because it gets harder to detect but also because the quantum uncertainty effects become more of an issue.

[@koyou33]

hey.so,when u start with 10g of parent , do the daughter isotopes replace the parent and u always still have 10g of isotopes but in different ratio,eg 100% parent changes to 50/50 (still 10g)?.then 25/75(still 10g) ,then 12.5/87.5 .so u can tell in this example its 3 half lives due to the ratio of parent to daughter?but u still have 10g? is that what u mean? if so,its unclear as u dont clarify and the diagram shows the weight going down ,10g,5,2.5,1.25 as if the entire weight halves each time .i think,if what im saying is right that is,that the diagram shud maybe have stayed at 10g each half life but showed the replacemant daughter isotopes replacing the parent.the diagram makes it seem as if the original 10g is dissapearing 50% at a time,hence your self anserwed Q "how do u know how much parent u started with".and u say just compare the parent to daughter.it seemed like th weight was halving each time which made it confusing .showing the replacment daughter ratio would have made it 100% understandable.and all this is only matters if im right about it.untill u reply and say im right "thanks to this video lesson" i dont know for sure let me know if ive got it .im new to isotope lives,.cheers

[@GEOGIRL]

So yes and no, you always have the same total 'number' of isotopes as the parent decays into the daughter (AKA: if you have 10 total C14 parent isotopes at the beginning, then 1 half life goes by, you still have 10 total isotopes, but now it's 5 C14 and 5N14 isotopes). But it's not necessarily correct to say the same regarding the mass of the isotopes present because what equals 10g of C14 is slightly different that what equals 10g of N14 because different isotopes have different masses. Now, sometimes this mass difference is a negligible and you would be right that the total parent + daughter isotope mass stays the same, but sometimes the mass difference is much larger like for uranium (U) to lead (Pb) decay, which is why we rely of isotope ratio, not total mass to track isotope decay. That is why the graph was only plotting the parent isotope C14 and the mass was going down with each half life. And that is also why I included the figure to the right showing the total numbe of isotopes remaining the same. Hope that helps! :D

[@zinobi]

Wait, but how do we know the initial conditions for various elements? For carbon14 we have various calibration curves, but how about Argon -Argon dating or Led-Uranium?

[@zinobi]

Ah, a friend of mine explained: > Because the amount of Pb present in zircon when it forms is negligible on account of its extreme incompatibility (DPb < 10− 6; Watson et al., 1997), the correction for common Pb (the “- 20xPb” terms) is often insignificant.

[@96sam26]

Fantastic!

[@ThrashmIO]

I did the harder way for nothing. =\ The equation for halving every 5730 years: 1/2^(age/5730) = contentRatio Rearranged to solve for age: age = 5730 * log2(contentRatio)/log2(1/2) Plug in the value: age = 5730 * log2(0.03125)/log2(1/2) age = 5730 * -5/-1 age = 28650

[@gokul7585]

Thank you....

[@DavidFMayerPhD]

You missed out on positron decay, resulting from these isotopes. carbon-11, nitrogen-13, oxygen-15, fluorine-18, copper-64, gallium-68, bromine-78, rubidium-82, yttrium-86, zirconium-89, sodium-22, aluminium-26, potassium-40, strontium-83, and iodine-124

[@MarAwanaDISPOCO.]

I love absolutely 💯 😅

[@meesalikeu]

cool - now i dont have to spend half my life understanding dating. waka waka. 😂

[@KerriEverlasting]

Right. I'm 100% sure I understand none of this! 😂 prolly have to go watch a few more isotopes lol

[@meesalikeu]

just remember alpha decay goes to smaller number on top, beta to larger on bottom & beta capture to same on top -

[@meesalikeu]

also first make sure its a igneous or magma/lava rock, not sedimentary or metamorphic rock.

[@MarAwanaDISPOCO.]

We're just magnetic fields, That can Inhabit things

[@RM-yw6xe]

tritium tri-tee-uhm

[@GEOGIRL]

I know, this is one of those moments early in my channel that I wish I could erase lol 😅but then again I guess I can look back at it to see how far I've come haha

[@RM-yw6xe]

@@GEOGIRL I appreciate your content more because you're human. Keep it up.

[@MarAwanaDISPOCO.]

So your single 😉

[@DOCB-op1qc]

you can analyze my carbon content any day.