Great to hear how Erin’s research is progressing and evolving. Incredibly interesting! It gives all of us a bit of insight to how complex and difficult it would be to earn a PhD in a field like Geology. Erin’s approach to analyze sediments to determine what happened with Siletsia and the Yakatak is such a clever line of inquiry. She does a super job explaining her research in an understandable way and has a tremendous mastery of the material. Nick please continue allow us to track Erin’s research journey through more videos with her as time goes on!
Thank you Nick, keep these coming! It's so difficult to have access to these fascinating people and you make us feel like we are in that room with you guys.
This is brilliant!! Thank you. My father often pointed out wave cut sandstone bluffs under pumice layers all over southern Oregon as well as fossils in the Klamath Mts.
@Skydaddy Myth-Busters I've only been introduced to the idea of accreted terranes since I found Prof. Zentner on here. I hope to learn about the extent of the Columbia Embayment as well. I've also learned I've dwelt on Mazama ash my entire life.
Excellent interview, Nick and Erin. So exciting to hear the follow-up research to all the work you’ve shared with us in 101 and 351. So glad to hear about current research results. Keep it coming. You make it all make sense and make it so interesting Thank you so much.
Thank you Erin. What a great chat. Geology + geography. I had to look up most of the conversation and was able to learn a lot…@7:53,(Detrital sedimentary rocks, also called clastic sedimentary rocks, are composed of rock fragments that have been weathered from pre-existing rocks.)
Received this video in my suggested video feed. Didn’t look at the channel name. Started watching, because I love geology, especially Washington geology, and said to myself “I know the sound of that voice, is that Nick I hear?!!!” Super excited to see a video on Washington geology but one with Nick, my favorite geologist, this is icing on the cake!! ❤️❤️❤️
Since I aint no geologist, most of what the lady said were French to me, but for some reason the stories that she told were captivating. Good job proffesor for getting her to talk 👍
I love deep marine deposits because they are so extreme and sexy, so to imagine this deep water basin forming rapidly off the new coast of the PNW. And then being exhumed by the convergence of the Farallon/Kula plates for us to see and touch. Really cool stuff!
WOW!!! .. very interesting!!! I'm going to forward this to my sister ... she lives in the "Oly Pen" (at the water's edge) .... I've been there several times visiting her -- when I visit, we do a lot of driving around which made this even more fascinating. I have told my sister a little about what I have been learning from your video presentations -- she has been quite surprised to hear some of what I have told her... she knew a little about her area, but not much. Thanks so much for these very educational videos!
You can tell Erin is extremely passionate about the work she is doing, it really shows in the way she presents her data. I am completely in the dark ages when it comes to geology but I find myself extremely interested in her explanations and finding that she does a great job at explaining the data.
There is hope ! This young woman is an example ,of some of the greatest minds, out there ! What energy , and pride she haves in her work ! I see mini successes in her long career . thank you Nick for introducing her to us
Hello and what a delight to see how Erin Donaghy has grown in her field of studies! You certainly picked a winner when you first interviewed her along with her advisor, Mike Eddy in 2020; impressive!
Thanks, Erin and Nick, for a great poster session! Def a blue ribbon science fair presentation! In some ways, easier to understand than using slides and maps. Sometimes size matters..... teehee.
I really love Erin, she's so brilliant and she is such a great teacher or Lecturer and you can tell that she really knows her work. And I can't leave out Michael Eddy who works with her to the Dynamite team
That's another chunk of information to fit into the puzzle. My fondness for Geology might be based on never knowing for certain what ages, depositional patterns, subsequent movement, etc resulted in what's before us. Ha! Fascinating. And, I was just in the same Olympics areas 2 weeks ago, with Marli's book. I really appreciate your interviews and videos! 👍❣
Thank you Nick, thanks to your site this meteorologist actually understood this discussion. Lol.. When I was a grad student I did a poster session, it was a blast.
Really good job explaining the poster and tying it back in with Nicks questions Erin! Hope to see more of your work in reference to Nicks topics, it seems like there is data and evidence that may tie right into many of his favorite topics and talking points. Would love to see animations to help visualize the ideas you guys are thinking about in terms of timing, location, and the mechanics required to allow those series of events to work.
I see a hundred thousand+ square mile archipelago/plateau formed by the Yellowstone Hotspot on a spreading ridge similar to Iceland, but at Cape Mendocino; then separated much more slowly into two 50,000 square mile terranes and transported by individual narrow (think East Pacific Rise size) Northwesterly spreading ridge offsets; much like SoCal’s Salinian and Franciscan Terranes are being transported the same way, Northwest via the East Pacific Rise offsets. The Yakutat Terrane was on a Northwesterly spreading ridge offset outboard of Siletzia on another slower offset. Siletzia was captured by the North American Continental drift as Yakutat continued Northwest relatively quickly, grazing the continent until finally becoming captured in Alaska. The mass of these collisions, and the relatively NW orientation and SW drift of the NA plate jammed the former Northerly motion of the Pacific plate and changed its motion to Northwest. Btw, for what it’s worth, I am convinced that mantle upwelling driving their spreading ridges continue on for tens of millions of years after their ridges and crustal plates were subducted by Continental Drift and continue their divergent activity with the continent- Basin and Range Province and Baja, among others worldwide.
Erin, What you are doing and the knowledge you are teasing out of the ground, blows me away! Erin, do you have a continents tattoo? Thanks Nick, very informative! When is the Nick from Alaska series?
Perhaps siletzia was formed from the Yellowstone hot spot, from a double triple junction possibly, siletzia got so big and heavy that it got pushed by the hotspots plume, forcing siletzia north, into Vancouver island, it’s downward super subduction would be enhanced by the hotspots plume and its sheer weight, now there is the evidence at Copper Bottom mine of orogenic copper adjacent to the Clearwater River in the center of the Olympic peninsula. Within 3miles there are exposures of slate highly folded with quartz intrusions. Now I’m getting a better bead on why lake Ozette is 310 ft below sea level and Lake Crescent is 44 ft below sea level.
Wow. Erin should have her Phd after generating this poster and her oral discussion. Thanks Nick for capturing this poster session. What a great poster.
If only it were so straightforward! She will have to write a pretty large thesis and then defend it in her viva ... but judging from the quality of her Masters she should be fine.
That's really a brain twist to hear "Yellowstone hot spot" which might be in "Oregon" and realize all of the pieces are in different places, not where we see them across Puget Sound from Seattle. I'd need an animation of the plates moving and a million year clock spinning to come close to getting this.
Go and watch Nick's exotic terranes A to Z series and his geology 351 class. It's a lot of videos, but it's worth it. The accretion of Siletzia is discussed in a fair bit of detail in both video series. The A to Z series is aimed more at a lay audience, as his geology 351 class is a lecture course (and indeed field trips) for advanced undergraduate students. I had no problem following both, but I do have a considerable science background myself. However essentially it's a reinterpretation of the start of the Yellowstone hotspot. Hotspots are traditionally viewed as starting with a plume head coming to the surface which is the most vigorous part of the hotspot's life. For Yellowstone the interpretation had been that the plume head coming to the surface was the Columbia River Basalt Group with successive rhyolitic supereruptions forming a track to the modern location of the hotspot. That would take it back 16 Ma. One of the problem with this interpretation is that for a hotspot plume head igneous province the CRBG is actually pretty anaemic. It's a small large igneous province in the grand scheme of things and is actually an outlier in that respect. A more current interpretation is that the plume head of the Yellowstone hotspot was actually the emplacement of Siletzia which would take the hotspot back well over 50 Ma. The location of Siletzia's formation supports this interpretation as does the fact that a track of hotspot volcanism has been found heading across Oregon. The Crooked River Caldera is one such example and there are other indications of an unusual amount of heat being present in the mantle of the area via eruption of rocks called adakites. Normally with subduction zone volcanism water is driven off the subducting plate at depth and acts as a flux for continental crust above to melt it, thus producing the classic intermediate and felsic magmas and lavas of continental arc volcanoes. Where adakites are seen it's a sign that the mantle itself has melted somewhat. This is due to an extra source of heat and might be due to a hotspot, slab rollback or subduction of a spreading ridge. Siletzia fits as being the plumehead emplacement as it is a good deal larger than the CRBG. The CRBG is now theorised to have come about because the track of the hotspot reached the suture point between the oldest of the exotic terranes accreted onto North America during its active margin phase of the last 200 Ma and the craton. At that suture are faults, thus providing a weakness in the crust for material to come up through and producing the CRBG. That explains the location and orientation of the fissures which produced the 300 lava flows of the CRBG.
@@davidpnewton Wow, nice summary. Nick's website has the .pdfs of the papers available for the 251 class and the linked SiletziaYHS, Wells (2014) paper addresses the current understanding of these ideas in detail.
I have often wondered how big the river was that the Puget Sound replaced as it was dug out and removed by the ice sheets. Never really hear much about it.
Great interview. Following modern technical data will help sort out timelines, hopefully. Might get confusing, until things are sorted out. Is International Space Station LiDAR being used for geology education & research? LiDAR can utilize layers to remove vegetation for geology.
Just a thought, If Siletzia is being push on to the West Coast and then the Western, say, third(Yakatat) got transferred north, would not the remaining Siletzia subside to the West and the Eastward pressure is removed?
This was very interesting, it would have been fun to attend, but at least they offered the online meeting, and it was cheaper than a plane ticket across the country! Regarding the coarsening-westward trend and the ridge migration theory-I find this very confusing because on one hand there is massive thermal subsidence recorded in the evolution of these sediments (e.g. Iceland would be a few km under the sea surface if it wasn’t thermally supported)-how is it possible to both have thermal subsidence of enough magnitude to form basically exclusive deep sea sediments, but then sediments that shallow westwards, offshore, to basically Boulder breccia? Very confusing without having really looked deeply into it, probably even more confusing if I were to look into it more…. Another thing is the clasts of these conglomerates that coarsen westward, if they were in fact shallowing in facies due to a migrating ridge creating a topographic high, should basically just be clasts of MOR basalt, but instead the rich variety of clasts described seems much more connected to the inboard terrane wreck source (as Erin described it, a proximal fluvial system from those terrane pictured) than to any theoretical source from a migrating ridge. Unless the idea is that the ridge is still subducting and it is now thermally supporting sediments in some part of the basin? I’m confused because Siletzia is supposed to have been actually formed on the ridge-is the idea that after accretion, a new ridge, different from the one that separated Siletzia/Yakutat, forms to the south of now-accreted Siletzia and then migrates northward? What about the Chugach rocks or any other rocks that may have migrated with Yakutat, and could have been a source from the west and are now no longer there? Has there been any geochem on the “younger” volcanics that interfinger with the sediments above Siletzia? I am curious if they are OIB or WPB, and have a hotspot affinity, or calc-alklaline and represent re-establishment of the arc after accretion, or something else entirely, forearc basalts or something related to a slab window forming from ridge subduction. Thanks!
I wonder if when rock cools and solidifies and thus crystallizes does it expand in volume like water does when it forms ice? Could that be a factor in uplifting?
Water is pretty much unique in expanding when it crystalises. It's all down to the hydrogen bonds between the water molecules making a very open crystal structure with lots of space in between the molecules in comparison to most solids. If you think about it, solidifying is losing kinetic energy compared to being liquid. In fluids such as liquids and gases individual molecules are free to move around with respect to each other. In solids the individual molecules certainly vibrate and rotate but generally do not translate with respect to each other. On the microscopic scale temperature is molecular kinetic energy, so the higher the temperature, the faster molecules move.
@@davidpnewton very well explained. Water is unique in terms of expanding when going solid. One thing i'd add is that going from hot solid to cool solid, when you have such a gigantic mass, you have a lot of weight gained through increasing density. When Siletzia gains density due to cooling, it sinks more into the plastic-like asthenosphere below it. That's why you lay flat on thin ice. You don't want to concentrate your weight on one area because it would push down more, even though you haven't gained any weight.
I interpreted what she said to mean that after the docking of Siletzia the terrain subsided below sea-level and was inundated with the salt water from the pacific ocean. In that scenario the alluvial fan/turbidites would be caused by a basin/basins draining into the depression and nearshore turbidity currents.
@@BlGGESTBROTHER I just connect turbidites to abyssal canyons, like off the mouth of the Columbia or the Grays harbor. I suppose all you need is sediment and an slope to run down.
@@swirvinbirds1971 yes, a river flowing into the basin from the south would supply sediment. That's something you cay test for in the samples. Didn't she say something about matches with the San Juan island deposits? At 15:51
Great to hear how Erin’s research is progressing and evolving. Incredibly interesting! It gives all of us a bit of insight to how complex and difficult it would be to earn a PhD in a field like Geology. Erin’s approach to analyze sediments to determine what happened with Siletsia and the Yakatak is such a clever line of inquiry. She does a super job explaining her research in an understandable way and has a tremendous mastery of the material. Nick please continue allow us to track Erin’s research journey through more videos with her as time goes on!
Thank you Professor Zentner and thank Erin for sharing her time with us.
Thank you Nick, keep these coming! It's so difficult to have access to these fascinating people and you make us feel like we are in that room with you guys.
This is brilliant!! Thank you. My father often pointed out wave cut sandstone bluffs under pumice layers all over southern Oregon as well as fossils in the Klamath Mts.
@Skydaddy Myth-Busters I've only been introduced to the idea of accreted terranes since I found Prof. Zentner on here. I hope to learn about the extent of the Columbia Embayment as well. I've also learned I've dwelt on Mazama ash my entire life.
Thanks for recording, mc'ing and posting this Professor. This is cutting edge research. Very interesting.
Excellent interview, Nick and Erin. So exciting to hear the follow-up research to all the work you’ve shared with us in 101 and 351. So glad to hear about current research results. Keep it coming. You make it all make sense and make it so interesting Thank you so much.
Thank you Erin. What a great chat. Geology + geography. I had to look up most of the conversation and was able to learn a lot…@7:53,(Detrital sedimentary rocks, also called clastic sedimentary rocks, are composed of rock fragments that have been weathered from pre-existing rocks.)
Erin's diagrams and the overall poster design are fantastic.
Collect enough data to shake and bake your hypothesis... Thank you for sharing it in an on the spot video with Nick... we love it!
Received this video in my suggested video feed. Didn’t look at the channel name. Started watching, because I love geology, especially Washington geology, and said to myself “I know the sound of that voice, is that Nick I hear?!!!” Super excited to see a video on Washington geology but one with Nick, my favorite geologist, this is icing on the cake!! ❤️❤️❤️
Since I aint no geologist, most of what the lady said were French to me, but for some reason the stories that she told were captivating. Good job proffesor for getting her to talk 👍
I'm not fluent in Geology, but I am beginning to learn alot at the latter stage of my life. Interesting presentation.
And we can repeat watch to understand more. For free. Can you believe it??
So interesting and thought provoking especially the docking and then subsidence in such a short timeframe. Fascinating.
I love deep marine deposits because they are so extreme and sexy, so to imagine this deep water basin forming rapidly off the new coast of the PNW. And then being exhumed by the convergence of the Farallon/Kula plates for us to see and touch. Really cool stuff!
WOW!!! .. very interesting!!! I'm going to forward this to my sister ... she lives in the "Oly Pen" (at the water's edge) .... I've been there several times visiting her -- when I visit, we do a lot of driving around which made this even more fascinating. I have told my sister a little about what I have been learning from your video presentations -- she has been quite surprised to hear some of what I have told her... she knew a little about her area, but not much. Thanks so much for these very educational videos!
You can tell Erin is extremely passionate about the work she is doing, it really shows in the way she presents her data. I am completely in the dark ages when it comes to geology but I find myself extremely interested in her explanations and finding that she does a great job at explaining the data.
There is hope ! This young woman is an example ,of some of the greatest minds, out there ! What energy , and pride she haves in her work ! I see mini successes in her long career . thank you Nick for introducing her to us
As a Purdue geologist from the early 80's, it was great to hear Erin's research findings! TY?
Erin is such a fine geologist and explains things so well. Thanks for sharing, Nick.
I need more posters and poster talks.. thanks Nick (and Erin)
Wow that was a lot of new information to take in. I cant wait for you to break it down slowly! Thanks. I need to listen again!
Stunning stuff from a fascinating region. Thank you Erin and Nick for sharing.
Hello and what a delight to see how Erin Donaghy has grown in her field of studies! You certainly picked a winner when you first interviewed her along with her advisor, Mike Eddy in 2020; impressive!
Thanks, Erin and Nick, for a great poster session! Def a blue ribbon science fair presentation! In some ways, easier to understand than using slides and maps. Sometimes size matters..... teehee.
We need more geologists in this world. They give us humans in the nicest way possible an insight how insignificant we are actually.
Wow so much information to absorb. Thanks Erin and Nick.
I really love Erin, she's so brilliant and she is such a great teacher or Lecturer and you can tell that she really knows her work. And I can't leave out Michael Eddy who works with her to the Dynamite team
That's another chunk of information to fit into the puzzle. My fondness for Geology might be based on never knowing for certain what ages, depositional patterns, subsequent movement, etc resulted in what's before us. Ha! Fascinating. And, I was just in the same Olympics areas 2 weeks ago, with Marli's book. I really appreciate your interviews and videos! 👍❣
Thank you Nick, thanks to your site this meteorologist actually understood this discussion. Lol.. When I was a grad student I did a poster session, it was a blast.
Thank you for sharing this video Nick.
Thank you Nick. Good luck Erin. 👍
Really good job explaining the poster and tying it back in with Nicks questions Erin!
Hope to see more of your work in reference to Nicks topics, it seems like there is data and evidence that may tie right into many of his favorite topics and talking points.
Would love to see animations to help visualize the ideas you guys are thinking about in terms of timing, location, and the mechanics required to allow those series of events to work.
Thanks Erin ! Thanks Nick! 🥰
Nick...thank you.So cool to listen to E.D.'s "summer " work.
It is great to see the work evolving “on the Fly” as it is being interpreted.
*THANKS, ERIN!* You too, Brother Zinger.
I see a hundred thousand+ square mile archipelago/plateau formed by the Yellowstone Hotspot on a spreading ridge similar to Iceland, but at Cape Mendocino; then separated much more slowly into two 50,000 square mile terranes and transported by individual narrow (think East Pacific Rise size) Northwesterly spreading ridge offsets; much like SoCal’s Salinian and Franciscan Terranes are being transported the same way, Northwest via the East Pacific Rise offsets.
The Yakutat Terrane was on a Northwesterly spreading ridge offset outboard of Siletzia on another slower offset. Siletzia was captured by the North American Continental drift as Yakutat continued Northwest relatively quickly, grazing the continent until finally becoming captured in Alaska. The mass of these collisions, and the relatively NW orientation and SW drift of the NA plate jammed the former Northerly motion of the Pacific plate and changed its motion to Northwest.
Btw, for what it’s worth, I am convinced that mantle upwelling driving their spreading ridges continue on for tens of millions of years after their ridges and crustal plates were subducted by Continental Drift and continue their divergent activity with the continent- Basin and Range Province and Baja, among others worldwide.
Thank you for this. Clarifies the relationship between Yakutat and Silezia that I’d found troubling
This stuff is awesome! I am so interested in learning more about all of this! Thank you so much for sharing all of this fantastic information!
Awesome stuff. Great job Erin!
Great to be first to view your presentation. Richard fromHuntington Beach, CA
Thankyou, most informative. MORE PLEASE!
Thank you, professor 🙏
Fascinating, thanks Nick
It would be interesting to know if Erin used or plans to use USGS LIDAR data to plan further trips to the Olympic Peninsula.
Thanks again for sharing. Pretty amazing work.
Nice! Thanks Nick.
Liked these videos at the convention center
Thanks Erin, the West Coast ring of fire is very interesting, and beautiful too. Good luck on funding $.
Great interview, Nick. Erin, you too. A real pleasure to listen to.
And your photobomb fellow lol, nice moment.
Excellent! Yeah, Erin!
❤️❤️❤️ super cool presentation and information Erin!! Thank you
Amazing. Loved this.
Erin, What you are doing and the knowledge you are teasing out of the ground, blows me away! Erin, do you have a continents tattoo? Thanks Nick, very informative! When is the Nick from Alaska series?
loved the fade out too...
So interesting thanks for the work .
Fascinating!😳🤩
And the drink word for this video is: proximal. 😉😁
Brilliant.
Perhaps siletzia was formed from the Yellowstone hot spot, from a double triple junction possibly, siletzia got so big and heavy that it got pushed by the hotspots plume, forcing siletzia north, into Vancouver island, it’s downward super subduction would be enhanced by the hotspots plume and its sheer weight, now there is the evidence at Copper Bottom mine of orogenic copper adjacent to the Clearwater River in the center of the Olympic peninsula. Within 3miles there are exposures of slate highly folded with quartz intrusions. Now I’m getting a better bead on why lake Ozette is 310 ft below sea level and Lake Crescent is 44 ft below sea level.
My backyard, my daily view. Would love to have a copy of that poster to study it more and gain a better understanding of the strata under my feet.
Agree! Would buy a copy if available!
Wow. Erin should have her Phd after generating this poster and her oral discussion. Thanks Nick for capturing this poster session. What a great poster.
If only it were so straightforward! She will have to write a pretty large thesis and then defend it in her viva ... but judging from the quality of her Masters she should be fine.
That's really a brain twist to hear "Yellowstone hot spot" which might be in "Oregon" and realize all of the pieces are in different places, not where we see them across Puget Sound from Seattle.
I'd need an animation of the plates moving and a million year clock spinning to come close to getting this.
Go and watch Nick's exotic terranes A to Z series and his geology 351 class. It's a lot of videos, but it's worth it. The accretion of Siletzia is discussed in a fair bit of detail in both video series. The A to Z series is aimed more at a lay audience, as his geology 351 class is a lecture course (and indeed field trips) for advanced undergraduate students. I had no problem following both, but I do have a considerable science background myself.
However essentially it's a reinterpretation of the start of the Yellowstone hotspot. Hotspots are traditionally viewed as starting with a plume head coming to the surface which is the most vigorous part of the hotspot's life. For Yellowstone the interpretation had been that the plume head coming to the surface was the Columbia River Basalt Group with successive rhyolitic supereruptions forming a track to the modern location of the hotspot. That would take it back 16 Ma.
One of the problem with this interpretation is that for a hotspot plume head igneous province the CRBG is actually pretty anaemic. It's a small large igneous province in the grand scheme of things and is actually an outlier in that respect. A more current interpretation is that the plume head of the Yellowstone hotspot was actually the emplacement of Siletzia which would take the hotspot back well over 50 Ma. The location of Siletzia's formation supports this interpretation as does the fact that a track of hotspot volcanism has been found heading across Oregon. The Crooked River Caldera is one such example and there are other indications of an unusual amount of heat being present in the mantle of the area via eruption of rocks called adakites. Normally with subduction zone volcanism water is driven off the subducting plate at depth and acts as a flux for continental crust above to melt it, thus producing the classic intermediate and felsic magmas and lavas of continental arc volcanoes. Where adakites are seen it's a sign that the mantle itself has melted somewhat. This is due to an extra source of heat and might be due to a hotspot, slab rollback or subduction of a spreading ridge.
Siletzia fits as being the plumehead emplacement as it is a good deal larger than the CRBG. The CRBG is now theorised to have come about because the track of the hotspot reached the suture point between the oldest of the exotic terranes accreted onto North America during its active margin phase of the last 200 Ma and the craton. At that suture are faults, thus providing a weakness in the crust for material to come up through and producing the CRBG. That explains the location and orientation of the fissures which produced the 300 lava flows of the CRBG.
@@davidpnewton Wow, nice summary. Nick's website has the .pdfs of the papers available for the 251 class and the linked SiletziaYHS, Wells (2014) paper addresses the current understanding of these ideas in detail.
Sorry Nick, I was marvelling at the quality of the gym-floor .... :)
Future Dr Erin will be a great teacher too.
I have often wondered how big the river was that the Puget Sound replaced as it was dug out and removed by the ice sheets. Never really hear much about it.
Great interview. Following modern technical data will help sort out timelines, hopefully. Might get confusing, until things are sorted out. Is International Space Station LiDAR being used for geology education & research? LiDAR can utilize layers to remove vegetation for geology.
👍🏼, impressive to the max.
Just a thought, If Siletzia is being push on to the West Coast and then the Western, say, third(Yakatat) got transferred north, would not the remaining Siletzia subside to the West and the Eastward pressure is removed?
This was very interesting, it would have been fun to attend, but at least they offered the online meeting, and it was cheaper than a plane ticket across the country!
Regarding the coarsening-westward trend and the ridge migration theory-I find this very confusing because on one hand there is massive thermal subsidence recorded in the evolution of these sediments (e.g. Iceland would be a few km under the sea surface if it wasn’t thermally supported)-how is it possible to both have thermal subsidence of enough magnitude to form basically exclusive deep sea sediments, but then sediments that shallow westwards, offshore, to basically Boulder breccia? Very confusing without having really looked deeply into it, probably even more confusing if I were to look into it more….
Another thing is the clasts of these conglomerates that coarsen westward, if they were in fact shallowing in facies due to a migrating ridge creating a topographic high, should basically just be clasts of MOR basalt, but instead the rich variety of clasts described seems much more connected to the inboard terrane wreck source (as Erin described it, a proximal fluvial system from those terrane pictured) than to any theoretical source from a migrating ridge. Unless the idea is that the ridge is still subducting and it is now thermally supporting sediments in some part of the basin? I’m confused because Siletzia is supposed to have been actually formed on the ridge-is the idea that after accretion, a new ridge, different from the one that separated Siletzia/Yakutat, forms to the south of now-accreted Siletzia and then migrates northward? What about the Chugach rocks or any other rocks that may have migrated with Yakutat, and could have been a source from the west and are now no longer there?
Has there been any geochem on the “younger” volcanics that interfinger with the sediments above Siletzia? I am curious if they are OIB or WPB, and have a hotspot affinity, or calc-alklaline and represent re-establishment of the arc after accretion, or something else entirely, forearc basalts or something related to a slab window forming from ridge subduction.
Thanks!
Erin Donaghy Genius
I wish i was 1/100th as smart as Erin. What a mind!
I wonder if when rock cools and solidifies and thus crystallizes does it expand in volume like water does when it forms ice? Could that be a factor in uplifting?
Can you please ask her this?
Nick thanks for taking to the posters. Really enjoyed.
Hi Donna - rock cools/ solidifies and it shrinks ... hence all the jointing in igneous intrusions seen in quarries for instance.
Water is pretty much unique in expanding when it crystalises. It's all down to the hydrogen bonds between the water molecules making a very open crystal structure with lots of space in between the molecules in comparison to most solids.
If you think about it, solidifying is losing kinetic energy compared to being liquid. In fluids such as liquids and gases individual molecules are free to move around with respect to each other. In solids the individual molecules certainly vibrate and rotate but generally do not translate with respect to each other. On the microscopic scale temperature is molecular kinetic energy, so the higher the temperature, the faster molecules move.
@@davidpnewton very well explained. Water is unique in terms of expanding when going solid.
One thing i'd add is that going from hot solid to cool solid, when you have such a gigantic mass, you have a lot of weight gained through increasing density. When Siletzia gains density due to cooling, it sinks more into the plastic-like asthenosphere below it.
That's why you lay flat on thin ice. You don't want to concentrate your weight on one area because it would push down more, even though you haven't gained any weight.
A submarine alluvial fan? What river would that be, the Frasier?
I am unsure if it is related in any way but from what I understand the Puget Sound was a river valley before glaciation carved it out.
I interpreted what she said to mean that after the docking of Siletzia the terrain subsided below sea-level and was inundated with the salt water from the pacific ocean. In that scenario the alluvial fan/turbidites would be caused by a basin/basins draining into the depression and nearshore turbidity currents.
@@BlGGESTBROTHER I just connect turbidites to abyssal canyons, like off the mouth of the Columbia or the Grays harbor. I suppose all you need is sediment and an slope to run down.
@@swirvinbirds1971 yes, a river flowing into the basin from the south would supply sediment. That's something you cay test for in the samples. Didn't she say something about matches with the San Juan island deposits? At 15:51
did the sediment subside or did the sea rise?
Baja California rules !
!!!!!!
You could also work with the soil scientist that mapped the majority of the peninsula and knows it in great detail.