Jamie MacDonald: Mount Persis Volcanics

[@leslie3832]

This was a fabulous interview. I love hearing Jamie talk. He’s so good at explaining difficult melts etc. thanks for having him. Learned a lot

[@deborahferguson1163]

Agree!!!

[@inqwit1]

This was awesome. I could almost follow what Jamie was saying.

[@adamchaffee6536]

Jamie is fun and funny, and what a knack for explaining things simply! And this is meant to be a compliment to Nick for giving us more like him. Thank you.

[@mikelouis9389]

The Pacific northwest is infinitely complex and thus, attracts the best geologists. Fantastic interview!

[@joannekellam191]

Fabulous convo with Jamie! He’s a real treat to listen to, so engaging and knowledgeable!

[@kenmunozatmmrrailroad6853]

THIS WAS EXCELLENT Nick; he's as descriptive and easy to understand as you. Hopefully back again in the future!

[@amacuro]

Ok Jamie has become my new favorite guest. He likes to explain the basics, which is SOOOOO helpful!!! Thank you Jamie!! You gotta visit us more! Thanks for having Jamie, Nick, that was so interesting.

[@garypaull9382]

What a ride! So much in this interview. I had no idea Persis spanned upwards of 10 million years. Glad to see Fuller Mtn make an appearance!

[@hjumper8238]

As the fog I face slowly begins to clear, my feeling of understanding comforts my mind. Thank you, Nick and Jamie! Now I get to watch the next live broadcast N, Early Days of Cascades.

[@charleymitchell5461]

Thanks to PBS, KSPS- Spokane for letting me find you years ago. Always great.

[@jonathanblubaugh5049]

As always thank you for presenting Dr. MacDonald again. Home run, Nick. 🏆🏆

[@_Michiel_]

I love Jamie. He is só knowledgeable, has a knack of explaining complex subjects in understandable language without talking down and adds so many interesting details! I guess we all learnt a lot today! Thank you Jamie and Nick! ❤

[@elainejones5109]

“Partially melted mantle makes mafic magma.” Great mnemonic!

[@robmagee100]

Oooo… fascinating discussion and mineralogy! Really enjoyed this. For a moment I had the feeling that I grasped how “paraluminous” minerals form in those particular environments. Ok, I heard Garnet, and I’m easily distracted by pretty, sparkly things… Still, it’s important as part of the complex interactions that were and are building our Pacific Northwest.

[@OkkiePepernoot]

What a great conversation! Very, very enjoyable and informative! Thank you, gentlemen!

[@PlayNowWorkLater]

Jamie is fantastic! I love the chemistry between you and him throughout this video. Thank you Nick. Hope to see more of Nick and Jamie videos in the future

[@MellnikMary]

Thanks Jamie! And Nick. So much enrichment in my life.

[@lorrainewaters6189]

This is absolutely great! I am still trying to figure out adakites, and he is really helping. I gotta make dinner, so I'll be sure to watch the rest later. To get us exposed to more of these geologists is a true gift that you offer, Nick. thanks again

[@kaywischkaemper4259]

So fired up to see the video with Jamie MacDonald. His GSA 2003 field trip guide of the Ingalls Ophiolite was so great to do when i visited you in 2023. You guys really had a great KZbin talking about the conditions for the presence of various rocks like the aluminum rich magmas and the Kay’rocks.

[@chayachaya420]

Wonderful discussion! So helpful in understanding adakites and the formation of igneous rocks in general. Thank you, Jamie and Nick!

[@vugmeister918]

As a mineral collector, I absolutely loved listening to this. The Persis Andesites are host to fabulous calcite and quartz crystals, zeolites, as well as petrified wood and jasper.

[@dancooper8551]

Great interview! Put Jamie on your go to geochem list.

[@donnparis137]

Great video! May be my favorite of this recent series.

[@judischarns4509]

Great interview! I hope to hear from him some more in the future.

[@grandparocky]

Thanks so much for your input Jamie!

[@raenbow66]

I always enjoy Jamie. It's great to see you both. I feel like I could follow and understand this discussion. Thank you very much.

[@kban77]

He speaks well

[@ryanmarshall8758]

The melting mantle due to volatiles/flux description was eye opening for me. Good speaker Mr MacDonald

[@ryanmarshall8758]

+slab subduction angle effects moving the volcanics geographicly💡

[@yukigatlin9358]

That was very interesting!😃✨I got sucked in as Jamie spoke, thanks!!😆💞💛

[@wiregold8930]

At least they didn't find peraluminous rocks on Chuginadak ... although Chuginadakite sounds like a heck of a drinking game.

[@sharonseal9150]

What fun! I love these nice lively geology discussions and getting to know new geologists. The synergy is palpable when two minds meet to tackle an idea. Looking forward to where the alphabet is taking us nex, and learning new things! Thanks Nick and Jamie.

[@Steviepinhead]

Sensational stuff! Possibly worth creating a table of the different kind of melts and the suspected scenarios that relate to each: ridge, arc, subducting ridge, hotspot, etc.

[@xwiick]

Thanks for all the hard work on these videos!

[@davec9244]

thank you both good job!

[@ms_khoff]

This video was incredibly engaging, interesting, and informative. I learned a lot! Thank you, both.

[@jonathanblubaugh5049]

Fine. Mt. Persis volcanics 36-47MA. The subduction of the spreading center will naturally lead to a widening slab window, maybe faster than usual due to Kula/Resurrection northward sprint. Asthenospheric melting due to decompression is admitted. Thus the real question is how can NTM magma or Adakite genesis distinguished between spreading center subduction, a slab window, or slab breakoff?

[@cyndikarp3368]

Jamie talk left me wanting to know more. He reviewed complex formations and transition to help solve complexities.

[@pmgn8444]

Thanks Jamie and Nick. Very interesting as always. Ah yes, thought I've in WA for the last 30+ years, I lived in central FL in the late 70s to late 80s. So I understand Jamie's definition of 'cold.' I still laugh at it, but I understand it! 😁

[@JoshExmoor]

The Mt. Persis volcanics have intrigued me ever since I found the Maltby quadrant map which shows that essentially all of Lord Hill Regional Park near Monroe is exposed Persis rock including several visible dikes. This rock is easily viewed for those willing to walk around the park, but also visible from HWY 522 just east of the Snohomish river crossing on the north side of the road. It seems fairly unusual to have volcanic deposits this far west and the fact that they're so exposed in an area where glacial till is the norm also opens up some questions. I'd hoped to email you some photos in advance of you covering this topic, but I haven't had time to get out there this week and I'm thinking you'll probably beat me to the punch.

[@susanwymer6912]

Finally, I have a better understanding of adakites and the relationship to the mantle and the plates! Thank you, Jamie! So in summation we have a melange of magma types as time goes forward. Could one say that?????

[@jonathanblubaugh5049]

33:56 OK. so the slab angle is changing back an forth based on the surface expression of the arc. could that be due to folding of the lower slab as it makes ribbon candy? Or is that not relevant because Cascadia hugs the continental margin? or are we still too shallow and brittle?

[@montejarvis]

great interview! doesn't seem possible that as the ridge subducts it would continue to produce signatures of a ridge subduction as it goes on, while other areas like hanson lakes would have a slab beneath it. in otherwords both slab and no slab would be right next to each other and that window would last until the ridge stopped ridging.

[@charlesflorian1758]

Two in one day, Thanks May have to watch replay. Woke to freezing fog this morning. Tri-Cites roads were a mess.

[@KSparks80]

Thx, Nick.

[@kban77]

Can the slab window just simply be a spreading ridge which also implies transform boundary parts as well. Divereg-transform-diveregw-etc

[@janetcollins1129]

"that guy " great guest :) thk u

[@Dragrath1]

The Mendocino triple Junction hmm does Lassen Peak have any of this Adakite chemistry? I did find that the Clear Lake volcanic field has Adakites soo I guess its a question of how far from the trench do the Adakites from the slab window reach? For the arc migration I can't help but think of Camp's Yellowstone hot spot slab break and associated rollback Shoshonite huh that is what Vesuvius and Campei Flegrei's primitive melts appear to be I think those typically come from oceanic arcs typically right? Do we know why those settings tend to produce alkaline and more specifically potassium rich alkaline melts?

[@ms_khoff]

Jamie, don’t feel bad-I wear layers or sweatshirts anytime it is cooler than 70-deg F (I am in Belvedere, CA and went to college in FL at ERAU) 😎

[@kban77]

How does this compare to volcanic patterns in places like, indonesia for example?

[@montanawardog]

Well, we get two extra credit conversations today!!

[@ssgtmole8610]

"Melt a mafic magma" - sounds like a tongue twister. 😅

[@williamwood9948]

"Flux"! Damn, this is good coffee!

[@lauram9478]

❤❤

[@guytowers9236]

Wow, a petrologic nerd. Jamie has a Tesla level infatuation with rock formation that rubs off, I think I just had a 301 level class in rock chemistry

[@BLSKYZ]

So true! I felt the same and I haven’t taken geology coarses!

[@johnplong3644]

What 2 videos in one day?? I haven’t even watched the first one with Erin Donaghy