Metamorphism of Pelitic Rocks: Barrovian Zones vs Metamorphic Facies vs Bathozones | GEO GIRL

Metamorphosed shales and claystones contain mineral assemblages with various amounts of Na, K, Ca, Mg, Fe, Al, Ti, Si, & water. With increased temperature and pressure passed the point of diagenesis, but before the point of melting, the original clay minerals transform into higher T and P polymorphs (minerals stable at higher temperatures & pressures). For examples, montmorillonite is replaced by chlorite and illite with low grade zeolite metamorphism, and illite is replaced by muscovite in the greenschist facies, slightly higher grade metamorphism. These mineralogical transitions are made possible by the increase in energy provided by heat which overcomes the activation energy of these chemical reactions.
Barrovian zones (temperature and pressure zones where specific minerals appear) include the chlorite, muscovite, biotite, garnet, staurolite, kyanite, & sillimanite zones each defined by the first appearance of that mineral. These metapelitic mineral assemblages can also be categorized by bathozones or pressure ranges. Remember, metamorphic facies, barrovian zones, and bathozones are all different but are all dependent on pressure & temperature and are often used for a similar purpose (to group common mineral assemblages).
References & helpful resources:
Essentials of Igneous Petrology by Ronald and Carol Frost: amzn.to/37Zs9AL
Earth Materials by Cornelis Klein and Anthony Philpotts: amzn.to/3z5sCxe
Atlas of Metamorphic Minerals under Thin Section: www.earth.ox.ac.uk/~oesis/atl...
Thin Section Rotation + Labeled Hand Specimens Website: www.virtualmicroscope.org/col... (just pick a collection, pick a rock sample, and it will show you hand sample pictures, thin sections, and tell you the mineral assemblage)
Thin Section Atlas Book (in color): amzn.to/3HYsrrj
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!)
0:00 Pelitic protoliths & composition
1:48 Metamorphic grade determines minerals present
4:02 Why minerals transform with increasing T & P
5:46 Barrovian metamorphism & zones
6:24 Biotite zone
7:49 Garnet zone
9:00 Staurolite & Kyanite zones
10:06 Sillimanite zone
11:01 Metamorphic facies vs zones
14:00 Mineral assemblages depend on P, T, & chemistry
14:55 Bathozones
16:41 Relating Bathozones to PT diagrams
18:02 Related videos & references
Hey there, Earth enthusiast! Check my favorite Earth-friendly products:
Bamboo toilet paper: shrsl.com/3cvku
Bamboo paper towels: shrsl.com/3cvkw
Compostable tableware: shrsl.com/3cvkz
Compostable trash bags: shrsl.com/3cvl0
Bamboo cutlery + straw! : shrsl.com/3cwfl
Eco-Friendly Tote (great for grocery shopping!): shrsl.com/3cwfp
Reusable straws + cleaning brushes (my fav!): shrsl.com/3cwft
Eco-friendly laundry detergent: shrsl.com/3cwgo
Directly offset your carbon footprint with Wren: shrsl.com/3d0t2
(Just click link, press get started, take the free C footprint quiz, then choose how much you want to reduce your footprint by donating to the C sequestration projects they're funding!)
Non-textbook books I recommend:
Oxygen by D. Canfield: amzn.to/3gffbCL
Brief history of Earth by A. Knoll: amzn.to/3w3hC1I
Life on young planet by A. Knoll: amzn.to/2RBMpny
Some assembly required by N. Shubin: amzn.to/3w1Ezm2
Your inner fish by N. Shubin: amzn.to/3cpw3Wb
Oxygen by N. Lane: amzn.to/3z4FgwZ
Alien Oceans by K. Hand: amzn.to/3clMx1l
Life's Engines: amzn.to/3w1Nhke
Tools I use as a geologist/teacher/student:
Geology field notebook: amzn.to/3lb6dJf
Geology rock hammer: amzn.to/3DZw8MA
Geological compass: amzn.to/3hfbdLu
Geological hand lens: amzn.to/3jXysM5
Camera: amzn.to/3l6fGRT
Carbon-neutral pencil bag: shrsl.com/3cvjv
Carbon-neutral backpack: shrsl.com/3cvkc
Disclaimer: Links included in this description might be affiliate links. If you purchase a product or service with the links that I provide I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel so I can continue to provide you with free content each week! And as always, let me know your topic suggestions in the comments down below!

[@GEOGIRL]

Hey guys, sorry I forgot to mention when I moved onto the Barrovian zones that I was starting with biotite because I had already gone over the appearance of chlorite and muscovite earlier in the video when I introduced facies. Also, I accidentally forgot to list the muscovite zone when I was saying them, but it is listed in the figure, so just don't forget that is also zone ;) Lastly, if you'd like to see more pictures of how these metamorphic minerals and rocks look in thin sections & hand sample, I've linked some resources in the description! ;)

[@jadefinchscene5644]

I am going to watch this a few times. very information packed. great job. exactly the kind of information i thrive on.

[@GEOGIRL]

So glad you found this info helpful! ;)

[@mayureshjoshi4075]

your videos are a great way to study a new topic. I get the overall idea of the topic from the video then it becomes easier to understand them while reading a book.

[@geoscilove6609]

Great video as always. You.re doing an amazing job contentwise and delivery. Waiting for the next set of videos on this playlist..

[@geoscilove6609]

request for making for making videos on the metamorphism of calcareous and basic rocks too. Thank you in advance.

[@GEOGIRL]

@@geoscilove6609 Oh great! I was wondering if anyone would want a video about the metamorphism of carbonates, good to know! ;D

[@GEOGIRL]

@@geoscilove6609 Yay! Hope you like it ;)

[@JoesFirewoodVideos]

Time to check this masterpiece out. I ❤️ GEO GIRL

[@Fr33_X]

We just had our final in metamorphic rocks in my petrology class. If I only I had this video a week before ❤️

[@GEOGIRL]

Oh no! Well I am sure you did great in any case!! ;)

[@larsfredriksson3108]

Whether a reaction is spontaneous or not is not governed by the enthalpy ΔH nor the 'inner' energy ΔU of a reaction but of the Gibbs free energy ΔG. The standard value of the Gibbs free energy, i.e. ΔGº can by calculated from the standard enthalpies of formation ΔHº and the standard entropy ΔSº, by the formula ΔGº=ΔHº - TΔSº. Then, whether a reaction is spontaneous or not is governed by ΔG which is calculated by using the relation ΔG=ΔGº+RT ln Q where Q is the reaction coordinate. At equilibrium Q=K and ΔG is by definition 0 and hence ΔGº=-RTln K and thus ΔG=RT ln (Q/K). For non-equilibrium reactions (where |ΔGº| is larger than about 10kJ/mol) then it may be safe to assume spontaneity if ΔGº

[@GEOGIRL]

Wow thanks for sharing this! I try not to go in depth into the thermodynamics in my videos like this because that's where people drop off haha! But I am so glad that you shared this here in the comments, this will help a lot of people understand the chemistry behind the mineral transitions better :)

[@georgestewart9001]

i like this video alot andthis is the very best video i have seen about minerals good video

[@GEOGIRL]

So glad you found this video helpful/informative! Thanks for the comment ;D

[@ketuzsl5521]

Finally the video I have been waiting.. 👍

[@GEOGIRL]

Glad to hear it, hope you enjoyed it ;)

[@Adam-nf8lo]

You are the best, keep it up..👍

[@GEOGIRL]

Thank you! ;D

[@Smilo-the-Sabertooth]

Thank you very much for continuing to increase my knowledge with another interesting topic and outstanding video. I always feel more and more educated after watching every incredibly fascinating video that you make. As usual, it’s always such a tremendous pleasure for me to learn with someone as beautifully gifted and intelligent as you my favorite teacher. 😊❤😉👍

[@GEOGIRL]

Thanks so much my friend! As always, you make my day so much better with your incredibly supportive comments ;D

[@Smilo-the-Sabertooth]

@@GEOGIRL You're very welcome my friend. 😉You’re videos never disappoint because you always make the best content. 😊 You’re absolutely amazing Rachel. And I also really love your shirt. ❤👍

[@GEOGIRL]

@@Smilo-the-Sabertooth Haha thank you! I love this shirt too, I am a sucker for clothing items that say the word happy right on them lol

[@Smilo-the-Sabertooth]

@@GEOGIRL You’re welcome. An admirably stylish way of expressing your positive emotions, and no emotion is more positive than feeling happy.

[@jakujaks9413]

Thank you for uploading a new video, I will learn it tomorrow

[@GEOGIRL]

Sounds great, I hope you enjoy it! ;)

[@jaredmeeks4491]

So does Asbestos to Tigerseye fit in this category?

[@TheRexisFern]

A personal question. What's the most difficult part of learning in your field? I feel like the amount of names/materials we have make it hard to grasp things without going over it a hundred times. And the interactions each mineral or element has with the different temps, pressures, and chemical reactions with each other... it can feel overwhelming to learn sometimes!

[@GEOGIRL]

You are absolutely right, it is very hard to remember all the terms, definitions, and jargon sometimes haha! But I guess at some point when you are emersed in the field like I am you hear the terms so often that it becomes second nature. However, as an undergrad taking these courses and hearing these for the first time, I had a really difficult time remembering everything, it took a lot of note cards lol! The thing I will say is that I feel like some of the repetitive terminology is a little annoying, when we have 2 to 3 terns that mean the same thing that gets confusing🤣 To answer your original question, I think the most difficult part for me was learning that in geoscience there isn't always a right answer. When you are looking at an outcrop there are often multiple possibilities of what depositional environment it represents. It isn't 2+2 =4, so you really have to be open in your intperpretation and consider all reasonable possibilities. I have a brain that wants a single answer, so that was difficult for me at first ;)

[@TheRexisFern]

@@GEOGIRL I appreciate the time and effort you put in to share the things you learn and love. The more we all work and share, the better our systems are and the quality of what we do grows exponentially. I hope you feel proud for the things you do and create! They have taught, inspired, and brought smiles to me. Thank you.

[@GEOGIRL]

@@TheRexisFern oh my gosh, you just made my day, thank you so much for the kind words and support! It means the world to me, and I am so glad that my content has helped you!

[@ramchauhan5238]

Very nice video... And so so so so beautiful.. your look.. Very cute your T-shirt..

[@GEOGIRL]

Thank you ;)

[@ramchauhan5238]

@@GEOGIRL most welcome..🙃🙃

[@fromkorriban7369]

its very good video !

[@GEOGIRL]

So glad you liked it ;D

[@fromkorriban7369]

​@@GEOGIRL its was like i was return in my student time )

[@ramchauhan5238]

Really.. your look is so beautiful and cute

[@princeshukla7661]

Ohhh hello geo girl

[@GEOGIRL]

Haha, hello! ;D

[@princeshukla7661]

@@GEOGIRL thanks again for replying me

[@princeshukla7661]

Beautiful tshirt

[@GEOGIRL]

Thank you ;) I am starting to get the feeling you like all my shirts haha

[@princeshukla7661]

@@GEOGIRL pleasure to me :^) and thankyou

[@dblcheesebgr9243]

Isn’t that high grade blueschist from that show Breaking Bad?

[@GEOGIRL]

No idea, I never watched that show.. Do they reference blueschist facies?? haha

[@dblcheesebgr9243]

@@GEOGIRLWithin the constraints of temperature, pressure and crystallization. Yes, yes they do..

[@GEOGIRL]

@@dblcheesebgr9243 Ahh, maybe I have to watch it then ;)

[@princeshukla7661]

Love from INDIA

[@GEOGIRL]

[@princeshukla7661]

@@GEOGIRL always love and support

[@ramchauhan5238]

Plz..give me.. your T-shirt..😅😅🙃🙂...post it in India...

[@GEOGIRL]

🤣😂

[@ramchauhan5238]

@@GEOGIRL 😅😅😇