Siletzia Fireworks in the Pacific Northwest

thank you thanks everybody for coming this is a lecture entitled Celestia fireworks in the Pacific Northwest now let me explain Pacific Northwest that's us Ellensburg Washington that's where you're seated right now great Celestia some of you have heard of but I need to elaborate and fireworks that could mean about anything and so I need to Define that as well but there is a gimmick there is a plan and it involves not so much Celestia itself but the fireworks the effects the after effects the result of adding a huge exotic terrain the last one to come in silencia which was a major land grab for the Pacific Northwest and many of those fireworks whatever they happen to be are right here in the Pacific Northwest and you know many of those places you just didn't plug it into this Regional story so that is the plan tonight it's going to get fancy but I think we should start with something very simple do you mind something very simple nice and tidy from geology 101 land he goes to a map of the Pacific Northwest right here here we are in Ellensburg Eastern Washington is separated from Western Washington by a mountain range called the Cascades it's not just Washington that Cascade and curtain as it's called culturally is a geologic entity it's where our beautiful famous strata volcanoes in the Pacific Northwest reside and there's all sorts of strata volcanoes lined up in this beautiful line yes I'm talking about Rainier in Saint Helens and Adams and Baker and Glacier Peak and down here in California Lassen And Shasta if you want to do Oregon we can do hood and three sisters in Crater Lake okay this is pretty basic and this is nice and tidy the Cascade volcanic Arc why does it exist there's an oceanic trench offshore there's an oceanic plate in its most simple way in geology 101 land that's moving west to east it's called the Juan de Fuca plate and as long as we have subduction of the wand if you could plate we're generating magmas into this Cascade volcanic Arc we're good the Cascade Arc is younger than 44 million years old so in other words we've had this line of strata volcanoes for 44 million years and I do not mean that Mount Rainier has been standing for 44 million years instead I mean that there has been strata volcano eruptions for 44 million years each individual cone lives for about 2 million years before it goes away so there's all sorts of ghost volcanoes in this line but we're still in a nice tidy line of volcanoes that's not the topic tonight and Celestia was a volcano but it Celestia is not one of these volcanoes in the Cascades and so for the first time tonight we introduced the idea that we have to go older than 44 million years ago and generally we need to go east of the Cascades that's us you are here and we want to look for volcanoes and other things that are east of the Cascades that are older than 44 million years ago and our number tonight I guess our two numbers tonight entire lecture tonight is confined between 55 million years ago and 44 million years ago that's our time window tonight Celestia and its fireworks we still don't know what that is but that's the story okay well what was Celestia well it was a huge Oceanic plateau Oceanic Plateau it was a volcano out in the water it was out here and it was a monster Oceanic Plateau is an incredible pile of flood Basalt that was built quickly 55 million years ago so you're like I'm already confused I thought we were going to look to the east of the Cascades and now you're out in the water well there's a relationship be patient with me please so the formation of Celestia off the coast of the Pacific Northwest 55 million years ago was an incredible pile of flood basalts mostly underwater but occasionally it did get high enough to get out of the water and it'd actually be an island and you're like wow really we used to have an island off the coast of Southern Oregon and Northern California yes well we don't have it anymore it's not out there anymore you would have heard about it probably so what happened to it it got added to the edge of the Pacific Northwest it's the last exotic terrain to add the volume of this flood Basalt in celexia was huge I've already said that but how huge is huge well we do have flood basalts here in the desert and they're still here they're way younger than 44 million years ago they're 16 million years old that's the German chocolate cake the Columbia River of basalts three miles thick if you drill through those flood basalts those myosin 16 million year old Continental flood basalts here but if we go out to the solezia story that's 17 cakes that's 17 times the volume of our flood basalts it was a monster 17 times the volume of basaltic material created pretty quickly 55 million years ago out in the water well if it's not out there anymore and it's 17 times the volume of our normal German chocolate cake we should be able to find it then right that's a lot of basalt yes everything west of the Cascades on this map is mostly Celestia basalt not all but most the surface and the subsurface there's a lot of Celestia that used to be out here and got added it got added 50 million years ago keeping up with the dates 55 we make the thing 50 million years ago we add either with North America drifting out to it or so let's you being set towards us or maybe a combination of both doesn't even matter it's here but if that still doesn't seem right that this acreage is this acres is this right here more than 17 times the volume of the German chocolate cake in Eastern Washington does this help when selexia got added 50 million years ago it was all here the oceanic plateau but shortly after it docked it broke in half and the Western half of that Oceanic plateau started heading north and it's still heading north today it's up in Southeast Alaska and it is still subducting and accreting to Southwest Alaska Southeast Alaska Southern Alaska that's the yakitat terrain so there's the missing half of this giant Oceanic plateau so in a way I'm done talking about selexia itself half here and half up in Alaska that's not the focus the focus of the fireworks but I hope you get the sense of this now that the size of this thing was enormous and so the effect of adding such large material to our map it's not just going to kiss the shore it's going to plow in it's going to create all sorts of problems or fireworks or excitement what might those look like and where can you go find some of those guys oh my God the energy is so great in the room like I I don't know if you've ever taught in a room before but like it's like a vibrating silence as opposed to like aha silence it's a good silence so thank you all right um no I'm going to keep this you know what I'm going to keep this improv improvisation number four already let me just use some colored chalk and verbally while I'm drawing give you a sense of the fireworks that don't make any sense if we just think of volcanoes being a line like we do with the Cascades so now I am talking about fireworks between 55 and 44 million years ago ready here we go oh we got magmas uh oh watch this we have plutons between 55 and 44 million years ago I'm kind of exaggerating but not really some of them are beneath the German chocolate cake today but just play along with me if you like these are granites these are high silica plutonic rocks magma chamber rocks and there are occasionally some volcanic remains from those old systems but these are eocene plutons red blue chalk I'm going to make some blue kind of squarish things these aren't magmas these are metamorphic core complexes these are places where metamorphic rock was at 20 kilometers depth high temperatures and high pressures and then oh I don't know between 55 and 45 million years ago this metamorphic rock starts Rising quickly and coming to the surface it shouldn't be up here it should be way down but a geologic elevator brought it up that's what each of these blue squares represent these are the fireworks I'm going to explain why I'm using the phrase fireworks in just a second I got another color chalk I got orange I don't know I'll use green oh boy messy gonna have to check the stage full of chalk here in the middle of all of this the red magmas and the blue squared metamorphic core complexes these Turtles Rising with these slippery shells and having these upper plates Sliding Away there are places where there are sand boxes sedimentary bases with floors that are dropping out so the blue are rising areas the green dotted areas are places where the floor is dropping so we have this going on at the same time these are Sandstone basins essentially deep Sandstone basins with some volcanic ash tephries recording some old volcanic events and finally this is orange I don't know if it looks like orange to you there are faults strike slip faults and each of these faults has motion to the Northwest on the west side of the fault each strikes that fault is doing this and generating earthquakes none of these things were here before solexia arrived these are the Celestia fireworks it's not Celestia it's the fireworks that have responded to that impact why am I saying firework well you've been to a fireworks show what's the experience it's dark is it dark enough are they going to start is it dark enough I can't I don't think I start and then the men over in the parking lot there's a one-two punch there's set the fire Arc off in the parking lot and then the firework happens different colors the fool is Celestia arriving and roughly at the same time and slightly delayed after is all of this stuff going on Inland but it's not in a line this isn't a volcanic Arc this is this abduction story this isn't a simple ocean plate diving how do we explain all this stuff and if you're getting a little impatient these are things like the liberty gold just north of Ellensburg the Tiana way feeder dikes the Golden Horn basileth up in the North Cascades the granite of Grand Coulee Dam the Kamloops Magnus the Ross Lake fault Zone the Leavenworth fault Zone the metamorphic car complex is up in the shoe swab the North Cascades Highway the uplift there these are places we know but typically are presented in little bite-sized nuggets a little factoid here a little factoid there I'm not into that I'm into Regional stories and I get particularly charged if I can take something local and put it into something big especially if there's questions about why it all happened and tectonic models that we might have and we do I wouldn't waste your time if we wouldn't have a tectonic mop okay let's do this I think I'm going to pick up the pace now um after bumping my microphone and give you a little bit more visuals but I want this to be fast so the red splotches are plutons okay and we don't know why they're coming up and we know that there's a lot of them and they stretch all the way back to Wyoming they switch all the way back to the Dakotas this is not just Washington but I want to do this inside profile so here comes our magma down below it's hot why is it forming question mark we're going to try to address especially with the visuals we'll get that magma to the surface and I would love to draw you Mount Rainier right now but I'm not going to because the chemistry of these magmas and other indicators by the way most of these magmas most of these red blotches have gold and silver associated with them gold and silver why still don't know that answer but many of the gold and silver deposits in the Pacific Northwest are tied to this swarm of Celestia fireworks what I want to draw for you is this aren't you glad you came I don't want to draw a cone I don't want to draw a shield volcano I want to draw a bimoto volcanism system I want to draw a super volcanic explosion creating rhyolite and I want to have effusive Basalt coming out at the same time bimodal two different opposite types of lavas coming out of the ground in the same system that is the general story with much of this story here in these volcanic centers super volcano scenes much more work needs to be done on that but for instance the Golden Horn baffle lith up in the North Cascades produced a bunch of volcanic ash Mike Eddy and Aaron Donaghey think they have those ashes in the chum stick Basin right over by Leavenworth they have precise timing matches between the magma and the deposits from more than 45 million years ago pretty impressive and I think it's just the start I think there's going to be a lot more detail geochronology work with these eocene magmas and these eocene volcanic deposits to put that together but I said it was going to be quick let's keep that on the board where's Bijou here the blue are the places where we have a geologic elevator going up and when I was in graduate school in the 1980s this was the Hot Topic these metamorphic core complexes and these Detachment faults and the idea is that you have metamorphic rock that should be down deep with a brittle over plate or upper plate that's going to be slid away and so these blue things are the result of major uplift why why is this uplift happening so quickly at each of those blue squares the Valhalla the shushwap there's one in Republic all of these places where we're sliding the upper plate away sedimentary rock and we're lifting this slippery metamorphic material when you drive North Cascades Highway the next time you're driving right through one of these metamorphic core complexes this gadget nice the SWAT cane nice the Chelan migma type by Lake Chelan that's what we're talking about and that's just one of many of these is the lecture working for you I hope that you're not only kind of following here but you're like why I don't go there must be some sort of explanation for this well there's attempts it's coming a model is coming doesn't have to be the right model but so models have been published recently this is all brand new work what color was the sand right green so at the same time we're doing this geologic lifting we're also dropping the floor of these sedimentary basins most famously for me the one that's been studied to death and I'm pointing over to Highway 2 between Wenatchee and Leavenworth that's the jumpstick sedimentary base The shaston Pinnacles all those beautiful Sandstone outcroppings that's what I'm talking about and yes within the chum stick are these Tufts I've made some videos on them and those chuffs at least one of them may be more than one of them are coming from known volcanic centers during this time pretty close to home but the boundary I don't even know what color I used or orange the boundary are the strike slip faults so instead of these sedimentary basins being in a true sandbox where you're just pulling the crust open and all the sand is coming in from the uplifting elevators on opposite side we need to add the idea that these sedimentary basins these sandboxes are bounded by strike slip faults and we are wrenching the crust like this we're still opening it this is called trans tension and I'm laying all this out in detail so that our model is going to come in and save the day and explain why all of this is happening at the same time but we're opening torquing the crust and all this sediment is falling in and there are many of these archaic Sandstone sedimentary basins throughout the region okay we know Celestia we know the fireworks can we get to a model please I can try a little bit with the chalkboards but I think the visuals are really going to do the work for us so The Germ of this lecture came in 2019 and I went to a geology conference in Portland a GSA sectional meeting and there was a geologist named Jeff Tepper who was standing at a poster and that's one way to present your new scientific work and I will always remember that session and I never left usually when you visit a poster you make some Chit Chat and you kind of pretend like you're reading some text and then you move on but I was just like reading just I I hogged the thing for like an hour and a half I think Jeff's like get this guy out of here but he was talking about my state and Jeff Tepper has a long teaching history at University of Puget Sound in Tacoma and over the last 25 years Jeff Tepper has taken seniors undergraduate students and taken them to different eocene plutons and lava flows and they've sampled and they've gone back to the lab and they've gotten high precision geochemistry and high Precision uranium-led dates and so really in the last generation mainly through Jeff tepper's work each of these eocene plutons have been studied very carefully that there was an age progression that there was an age progression of these plutons and therefore of these volcanoes as well this ain't no Cascade Arc we don't have a line we have as age progression that these plutons are forming 52 million years old and we're having potentially super volcanic explosions up in the panel of Idaho there's a thought and then 51 50 49 48 47 46 45 44 were sweeping somehow we're having some igneous activities Sweeping in a weird Direction and this must have something to do with Celestia do you have an idea like how would you explain this and if these are not subduction zone magnets which they are clearly not geochemically and otherwise why are we even getting Magnus coming to the surface well I'll give you a teaser right now the geochem says that these are mental derived magnets that hot mantle is surging to the surface faster and quicker and more efficiently than they should and they're heating up the crust a lot faster there's a deeper hot mantle Source that's just accelerating the mantle uh accelerating the melting and we're getting this weird pattern now there's not an obvious plate tectonic model that comes to mind to ultimately explain this let alone this and this is like a four ring circus going on simultaneously how you're supposed to come up with one plate tectonic explanation for all of it well I don't know maybe I'm building it up too much maybe I'll share the model and you're like I don't think I even see it and that might very well be true but the data is there now and it's up to as many geologists as possible to weigh in on this story I'm going to just try this verbally and then I think we are switching to the slides but I'm going to try to do that no I'm going to do it this way I'm not going to do it verbally are you kidding me I'm not doing it verbally here is the tectonic model keep all these on the board I'm just going to stay over here hope that's okay there goes nothing what happens If instead of a big tectonic plate that's subducting like we had with the Cascades What If instead we take a spreading Ridge a spreading Center like the Mid-Atlantic Bridge but we're in the East Pacific Rise we're in the East Pacific Ocean at this time we're talking about tonight and what happens if you subduct a ridge what happens if you subduct a divergent plate boundary what does that look like what it's basically a place where hot material hot mantle is coming up and generating new seafloor crust but what happens if you have a continent encroach that scene and I don't know excuse me oh God Mike I got to get the mop after this and what happens if you have an oceanic Plateau did you forget about it straddling that seafloor spreading Center instead of that Oceanic Plateau out in the middle of an ocean plate that's maybe what you were thinking I'm not sure what if half of the ocean the oceanic Plateau was on one ocean plate going this direction we lost our arrows and what happened if the other side is on another plate it's straddling two oceanic plates and what happens if North America then starts encroaching into the whole scene is it possible that the North American continent as it encroaches on top of that seafloor spreading Center is some sort of slab window where up here we still have an ocean plate and it's abducting beneath British Columbia between 55 and 45 million years ago right we're not talking about today we're talking about back then the eocene and maybe down here we still have an ocean plate being generated and that's subducting nicely to the South but what what happens in here we we're subducting nothing we're subducting the boundary and possibly that slab window that place where we're not subducting an actual plate is basically a big old hole where we can get hot mantle shallower levels than we would otherwise expect and if I then take my red colors does that help us see why the Chien away lavas in many other lavas in this window work with this pattern you're like maybe but like how's that explain the geologic elevator going up I'll wait for that how does that explain the the the strike slip Falls how does that explain the sedimentary basis well give us give the slides a chance but this kind of going back and forth between detailed field data and big picture thinking is to me some of the funnest geology that we have it's not just taking a local story it's thinking regionally and especially at a time when 30 years ago I was taught about the Chalice magmas when I went to school in Pocatello but they were called The Chalice Ark and it was assumed that those magmas of the Idaho batholith that were of this age not all the Idaho baffles at this age but some of it is eoceneh and the absarakas and many of these other eocene magnets I was taught that they were subduction generated and maybe some are still thinking that but this kind of new data and this kind of synthesis of all these different kinds of things help us see that this is a regional story that is not a subduction story if you want a subduction story it's a subduction of a boundary as opposed to a subduction of a plate that's my best attempt but I got one more thing I want to do before we go to the slides you're waiting I think for why we go 52 aren't you to 44. be nice if the model suggested that and this is Jeff tepper's model the guy standing at the poster trying to get rid of me he wasn't he was he was very I knew him before and so it was nice tried not to hog the time this model is promising to me we'll see how long it lasts but it's been published now so I'm happy to share it with you he has a slab rollback model and so Jeff says yeah there's maybe a spreading Ridge out there yeah there's so let's see out there for sure and the impact of selexia with North America is definitely part of their story he's talking to us now through his scientific paper but Jeff says I think I have an idea that maybe tomography can support in other words looking for slabs that are down below and Jeff says what if this was all part of the same big oceanic plate and what if we break the plate what if we break it off from the rest of the subducted ocean plate about 55 million years ago under Montana and how about the oceanic plate between these two blue lines starts to sag s to go down towards hell and to do that we need to not only break it away from the rest of this monster plate under Montana but we need to tear it up here at the Canadian border and down here at the end should have this line down here down here at the Oregon California line and Jeff says now just follow me here if you can follow this to explain this 52 to 44 age progression we have hot mantle under the plate my blue arms now I'm now the the oceanic plate okay you're looking side view with me but you're looking map view on the map that's convenient map view on the map break the plate in Montana 55 million years ago tear it on both sides break it free that's over here and that's over here there's hot mantle under my arms but how are we going to get the hot mantle to the surface we roll the plate down and what's coming around my fingertips hot mantle hot mantles coming up around my fingertips 52 in the panhandle of Idaho 51 50 49 48 47 in other words we have an age progression of these magmas as we continue to lower the drawbridge and allow the hot mantle to generate melts working Northeast to Southwest you kind of seeing it hope so and if you want a crescendo we're going to break the freaking thing again at 50 million years ago so this thing that is not only broken once to start rolling back breaks again somebody Patrick get a saw get me aren't cut my biceps please we'll now have this thing fall because there's a whole generation of magmas bimodal volcanic magmas in central Washington including the tianue basalts rhyolites and basalts that appear to be from this second break off let's see if these visuals can help I'm confident that they can not only with the models with other things well let's start simply just like we were at the beginning of our talk today this is not our Celestia story this is our well-behaved simple Oceanic versus continental plate boundary to create the Cascade volcanic Arc and we can take this picture and go back 44 million years Jeff Tepper is confident that the beginning of our known Cascade volcanic Arc 44 that's the magic number but tonight we are earlier than 44 million years ago well here's Tanya Atwater Santa Barbara and she's showing us what well she's showing us a subducting spreading Ridge that's encouraging and this is on a loop and this I think this animation is 20 years old at least maybe 30. I don't know but with her expertise in reconstructing ocean plates in the Pacific Basin and she's the expert on that she's one of the most famous geologists we have she's showing this subducting spreading Ridge so Jeff Tepper didn't dream it up there's many geologists who've come up with this concept okay well what did you have in mind from the chalkboard is this kind of what you had in mind this is a classic picture of a slab window when you subduct a spreading Ridge underneath the continent and The Wider you get this Gap the more you're getting our eocene-like Magnus our fireworks magnets that we've been talking about today another diagram showing the same thing slab window maybe A New Concept to most here tonight it's an interesting concept and perhaps we have a classic example of it in the eocene here in the Pacific Northwest okay we get it there's a third one my God all right but yes now we're talking about the fact that we're leaking this hot mantle up through that window all right well we're feeling comfortable hopefully now we can make sense of maps like this so this is roughly 50 million years ago when we docked the oceanic plateau half of its Celestia stays with us the other half is yakitat and it's about to make its Journey to the north and if you're curious about that story I think that's another lecture coming this very bright student Aaron Donaghey who I've been making videos with over the last few years she's a student of Michael Eddy at Purdue University that's her PhD dissertation matching geology from Celestia with the geology of yakitat she's been hop skipping and jumping between Southeast Alaska and the Olympic Peninsula to make those cases so I'm particularly excited to follow through on that but for now we just need cartoons like this until Aaron finishes her work where can I find this Alexia Bedrock well you can find it in Roseburg Oregon in Corvallis and so let's River and Tillamook all those colors in red all those colors in blue they're all part of this greater solezia and the places where we don't have bright colors is where Celestia is in the subsurface there's a lot of basalt that was originally offshore today hurricane Ridge Road is a is a nice classic place to visit that Celestia bus alt including pillows within it but I like this diagram from Robert Hildebrand saying if you go west of Seattle that's the Celestia accretion story if you go east of silencia here's the fireworks and just a portion of it the North Cascades and this is a new way to think of the North Cascades probably is a showcase for eocene fireworks eocene effects of the Celestia accretion okay we're Pros now I think we've got it and you'll notice tonight I have backed off of the Yellowstone hotspot story and I did that five six seven years ago in one of these downtown events it was a lecture called Yellowstone hot spot and Liberty gold I think that was the title and there's still thought about the Yellowstone mantle plume creating silencia and then North America drifting over the top of that mantle plume and it's now in Wyoming but I'm choosing to go a completely different angle here tonight what is new to us tonight are Concepts like this so let's say that so let's see offshore Oceanic plateau and let's say it is being brought into us that's fine what happens when you first dock such a monster oceanic plate the thought is you clog the trench it's too big to just go down the tubes and so we're going to take our ocean crust that was subducted which used to be between Celestia and the coast and we're going to tear it and we're going to break it that's what pepper was talking about right so if you were missing the connection between Celestia docking and all of this crazy stuff maybe you're starting to see it with some of these cartoons so this is India colliding with Asia also courtesy of Atwater but I just want to show you how again if we close an ocean Basin between two massive pieces of crust we're going to snap off that ocean plate we're going to tear it we're gonna we're gonna fail it we're gonna we're gonna cut it off and we're gonna get hot mantle to Surge to the surface this is slab failure essentially we're not rolling back in here that's the only thing we would need if we want to show this as truly so let's you with Jeff tepper's model but otherwise I like it to show us about failing that Ocean's lab here's gender Johnson doing an animation with Anita grunder and a portion of it showing Celestia docking let's keep our eye on the oceanic plate uh oh there we go we're going to fail it we're going to have it break off and we're not showing here but we could a bunch of Magnus coming up and we could also show the rollback which again is tepper's idea not necessarily from this animation this is on a loop of course please notice uh that the position of the trench is going to suddenly shift West because we're adding this huge Gumdrop this huge chocolate Gumdrop right there and what do we do we set up the Cascade Arc at 44. we're starting with all these animations like we were just doing with the chalkboard so I thought I just kind of get us to these animations quickly as opposed to forgetting about them this one's maybe less sexy to look at but there's a lot of good stuff in it this is from Ray Wells who is really the Godfather of thinking about all things solexia and did much of the work I'll play it and try to narrate this starts 55 million years ago the capital S is solesia the capital Y is yakitat that's the one that's going to go up to Alaska Ray has different ages of ocean crust in this kind of herky-jerky animation and he's also emphasizing the Yellowstone hotspot which today is let's get it there for yeah okay good back so he's got a fixed Yellowstone Hot Spot creating this Oceanic Plateau out in the water and then North America is going to cross over the top of it and that same Yellowstone manto plume is going to be in Wyoming but more apropos for us tonight that's French is we have two different shades of green and I think what Ray is showing us is that the light green is when we have these things on the move and when they're dark green they're a moose on our windshield and so the light green there's the yakitat doing its northward journey to that's the Western half of this massive Oceanic plateau we'll do it one more time you're probably noticing a bunch of stuff that I'm not noticing and you might notice that Rafe for whatever reason doesn't want Celestia and yakitet as one big hunk like is pleasing to me and then we cut it in half we will see what the new researchers decide they want to do but again that's mostly Michael Eddy and Aaron Donaghey from Purdue University keep your eyes open for their work coming in the next five years well this is not the first time this has happened that we've run into one of these massive Oceanic plateaus if we go back 170 million years ago there was an oceanic Plateau that had Cache Creek limestones on top of it that got added and cut in half Dock and slice if we jump to 100 million years ago there's the carmutian flood basalts that make a majority of the Vancouver Island area part of rangelia that was docked and sliced so there's a this is a repeat offender this is many of these geologic chapters are not brand new it's kind of fun to see multiple generations of this story so yes tonight we're only focusing on 50 million years ago and the last major Collision but we had two other major collisions that severely impact the geology of Washington and that means that if you go to the north casc gauge and start looking at granites they're of different generations and they tell of different collisional stories and I'm not saying that all those granites are from slab failure and extension like we're talking about tonight but I am saying that the usine ones are if you know the railroad Creek pluton the Duncan Hill pluton the golden pluton and the Cooper Mountain pluton those are all eocene plutons that are beautifully in our slab window and not subduction generated magnets and by the way you need extension during that and the the metamorphic core complexes are also a direct result of massive amounts of crustal extension but if we go back to the earliest generations of magmas exposed in the North Cascades that's not an eocene story that's not a slab window story Mount Stuart black Peak 10 Peak six figure Jack seven finger jack those are granites that have paleomag telling us that they came from the south remember that so to get some photos from Backcountry Gary Paul from the North Cascades it's it boils down to some simple approaches oh oh you're saying oh the slab window gold and silver may be tied to this oh black pink twice as old totally different chapter totally different story that's what some of us can do now with enough geology background to get a little bit more out of these mountain scenes and these places that have granites that are right up next to each other are not the same age not the same chemistry and not the same story this is my favorite photograph of the Golden Horn basilis Liberty Bell if you know it better that way Washington Pass one of my favorite areas in Washington thank you Gary for the photographs and Mike Eddy Again part of this research team is starting to see that the Golden Horn which is massive in volume is almost all exactly the same age and so one of his angles is how to create incredible flare-up of magma at the snap of a geologic finger and to him the Golden Horn is one of the best places to study this very quick magma generation story more coming on that from him in this photograph from Gary Paul we have the Golden Horn which I just got done talking about the Ross Lake which is an initiated strike slip fault at the same time and in the background this gadget nice one of our geologic elevators coming up so three of the four in the four ring circus are in this photograph and it doesn't hurt that it's a beautiful area besides so thanks to these three geologists who four years ago got a major National Science Foundation Grant and asked me to be their public Outreach person and so they've been the motivator for me to make videos and to learn what I've done and much of the learning I've done with you on the internet has been spurred by the work of these three plus our buddy Jeff Tepper who we haven't gotten to but we are almost to him couple quick photos from the geologic elevator the concept of the North Cascade this is a Daryl Collins slide this orange is just so weird it's like a black hole it doesn't match the geology both to the East and the west of the North Cascades in Washington why is it orange that's the place that popped up Suddenly as a metamorphic core complex and all of those volcanoes are gone probably a bunch of the plutonic rock is gone it eroded away as this thing rocketed to the surface Skagit nice SWAT cane nice Chelan nigmatite the metamorphic core compasses themselves the biggest one is up in British Columbia the shoe Schwab entire mountain ranges are part of these elevators going up it's hard to grasp the scale of much of this but then the fact that it repeats and repeats and repeats in that wedge that slab window really fun to plug it all into something bigger these are photos from Backcountry Eric Cole up in British Columbia metamorphic core complexes metamorphic rocks high temperature high pressure metamorphic rocks that have no business being up here they should be way down there's a map of the shoe swap Crossing down into Northern Washington all right we got it from many of these scientific papers Bob Miller and Friends they're plotting with beautiful colors between 60 and 40 million years ago all of this happening simultaneously so you need High Precision dating techniques to keep track of things and so his example is looking at folds Inland from the impact of solexia the swak formation north of Ellensburg is intentionally folded as a direct result of docking Celestia but these grobans as well these down this is the only photo I think I have of a sedimentary Basin with this strike slip fault on both sides we're looking South there's a friend Mount Stewart you're sitting in an auditorium just on the other side of that Skyline so wenatchee's off to our left but those sandboxes those chewacam sandboxes would not be there without this idea this is the the chum stick sorry skip it skip it we don't need it even the strike clip even the straight Creek fall got started as Celestia are created you've heard it now but I'm trying to fill in a bunch of details to help you see so you look at a map of Washington like this looks familiar but think of all the geologic stories that are hidden in all those different shades and these stories are brand new from work that's been done in the last decade we're going to finish tonight with where this lecture got started pre-covered I was all set to go with this lecture and I had this Auditorium booked in April of 2020 didn't happen so here we are three years later finally getting a chance to share it with you all all spurred on by the work by Dr Jeff Tepper University of Puget Sound that was the poster where I hugged all the time and here are some of the maps from his original thought I just couldn't believe that he had a chance to survey all those red areas fireworks of volcanic rock yellow deep yellow eocene volcanics you see the Republic areas chock full of stuff and then the pale yellow is the Cascade volcanic Arc which is too young for our story tonight Jeff and many others are working with zircons that they pull out of these volcanic rocks and plutonic rocks to get very high Precision dates and read Lewis over in Idaho sent this one to me just on his own using some colored pencils showed that these eocene igneous rocks both volcanic and orange and uh and plutonic in red are all through Idaho Montana and Wyoming as well it's not just a Washington story so I broke out the little colored pencils back in early 2020 getting ready for this Auditorium back then and just said where can I can I intersect places in Washington that at least I vaguely know with these places that are yielding these stories so I went switched from red to blue for some reason and there's the flood basalts covering up much of this to German chocolate cake is in the way of what we want to do here tonight but this is Saddle Rock looming above one Edge and when Tepper after that poster session says well it's covered but I want to get out and Sample a few more rocks if you've got an idea I said have you been to Wenatchee not much so I started coloring little cartoons of the plutons that I knew about looming above Wenatchee Washington and said maybe you'd want to come over and Sample so he did just he and I and he collected some samples from Saddle Rock and Castle Rock and other places Wenatchee Dome all right near Wenatchee Washington and he added them to his collection of eosine plutons and his ages from all those locations in Wenatchee 44 million years old right at the end of this lab rollback and right at the beginning of the Cascade volcanic Arc story so these familiar places in Wenatchee are the latest addition to his field data set some of these break-off rocks not only go in the Tiana way area but they head through the Cascades and you can even find some of these things on Western Washington Mount Pilchuck Bald Mountain mount persis they have the right age to go along with the tianue field feeder dikes and the tianoway story just north of Ellensburg so the intersection of this rollback story of the oceanic plate intersecting with the setting up of the earliest days of the Cascade Arc pretty fun about 44 million years ago so here's some Backcountry Gary photos from Western Washington near his house in Darrington that feed into this story tonight so not all these granites have the same stories to tell I think you knew that before you walked in this Auditorium some final brand new maps I talked to Jeff Tepper this morning and I said I got a few hours I got to get this thing ready for tonight and he said okay well we just got this paper published let me send you a few finished figures so this is a brand new figure coming from a paper that's coming out this year has not come out yet a little bit more professional look at the absurikas the Chalice the Montana Province the Kamloops magma is up in British Columbia all part of this story and here are these brand new maps from Jeff Tepper showing his sample sites in northeastern Washington not all of the miocene but the eocene ones yielded the rollback Story the age progression the Northeast to Southwest progression early maps from his poster more professional maps that have come out in the last year 52 51 working their way from Northeast to Southwest young to the Southwest indicating to him the leading edge of my arms drooping and the hot mantle Rising around my fingers to finish put it all together Jeff Tepper says here's his visualization I don't know if it's yours so let's you coming in filling the Colombian payment spreading Ridge offset by transformed fouls and a slab curtain is tomography that we do have a plate that's hanging vertically beneath Idaho so the idea of breaking the plate is not just an idea there is seismic tomography data underneath the Pacific Northwest to show and the green striped area is a a tear it's an opening where the hot mantle can surge to the surface you want it again block diagram same idea spreading Ridge subducting beneath Washington and Oregon docsoletsia break the slab once break it again roll the plate down almost like a tablecloth having its own momentum falling off the edge of your grandmother's table and a brand new figure that I haven't even looked at very carefully yet because it was sent to me three hours ago but this Southern Cascadia slab Northern cascadius lab Spencer fuston from Houston and others have found these broken slabs down below and Jeff is encouraged that it matches with his General models that he put together a few years ago and so dear viewers dear attendees that's just the latest in a series of geologic stories that all come from this wonderful Pacific Northwest we'll never run out of stories to talk about some of its old research involving Mount Stewart coming from Mexico some of its new research involving Mount Baker with the new person that we have in our geology department and everything in between going up to slate Peak you can keep going up to slate Peak and looking at these rocks and banging on them and getting new sets of data from places that have been already figured out quote unquote but we know that's not the end of the story and so this playground is nearby the geologists continue to crawl all over the place and you continue to come to these lectures to keep up on what's the latest thank you so much for coming to this one and all of these this spring thank you I love you and goodbye from Ellensburg Washington [Applause]

Channel: Nick Zentner

Views: 83,915

Keywords: Nick Zentner, Siletzia, Eocene geology, Straight Creek Fault, Challis magmas, Challis volcanics, Challis Arc

Id: nWS9XzW4BHs

Length: 56min 48sec (3408 seconds)

Published: Sun Apr 16 2023