Hypotheses on the bottom dropping out in the Nanaimo: It was a shallow basin in a ribbon continent Island group when it docked but then the outboard bits continued to move N leaving a marine margin behind. Then quite a bit later the outboard stuff is smeared further North as the N part of Greater Siletzia barrels through. I'm wondering if any significant stash of the contentious PCZ's show up way North in one of the convergent jumbles.
Thank you Nick and Erin! What a. treat to have Erin back! What a lovely lady and so smart too! I appreciate the generosity of you, and all your guests and their willingness to share all this knowledge with us. I consider these "Alphabet Series" to be one of the best things happening on the planet at this time. Keep up the good work. Miss Donaghy I look forward to your future appearances. Your enthusiasm is as infectious as your smile! Have a great day Nick and Erin!
For the record, if you have VU meter, set the gain on the input signal to -10db max. That way the output won't be so hot and you won't be driving your circuits (too much current). Those circuits are on the client, meaning the user has to set their volume to 1, instead 7 or 10.
Funny coincidence. I saw the crazy movie 2012 last night, right between the Saturday and Sunday Baja to DC shows. They moved all the continents in just a few days.
Wow this episode was so much better than I thought it would be. Erin truly is a superstar and I was glued to the whole conversation until the end. Thank you so much Nick for making all this possible!
I think what’s important about the Yakutat research is that it presents a complex transportation model that can help explain the transportation of another body at a different time, i.e., the movements potentially defining what is being called “Baja BC”. The Yakutat model demonstrates that a number of influences happen along a complex transportation route over time, all of which must be identified and interpreted for their impact on the actual path that body might have taken in the course of its journey. In other words, transportation of a major body may or may not happen steadily and progressively and, instead, may happen in stops and starts, ups and downs, and with various influences impacting its path - particularly in a broad region like the one on which this course is focused, with all the intersections of moving plates and junctions (east and west subduction, slab breakage / dipping / and realignment), major tectonic activity, and many other influences. The very fact that gradual and directional movement of some of these bodies can actually be detected and analyzed, just adds to the impetus of trying to make sense of this massively complex and complicated region for us mere mortals.
A great episode, as always with Erin Donaghy. She is a wonderful guest, always willing to share her knowledge, her work, and honest in her answers, how difficult the questions may be. Thank you Nick to allow us to benefit from those conversations.
Interesting. I'm endlessly fascinated by the technical details underpinning the various lab analyses being utilized. I'm eagerly awaiting the paleomag folks and their portion of the discussion. Thank-you Nick and Erin for a well spent hour and fifty.
Great program! Thanks Nick and Erin! I don’t understand all the details, but I get the big picture- thanks! Great to hear about your field work and writing Erin and how much thought and work you’re putting into these questions. Thanks too for all the contributors in the live chat! ⭐⭐⭐
Excellent episode. Erin is tremendously impressive! It has been interesting following her progress on her PhD the past two years. The University that hires her on their faculty after she finishes her PhD will be very lucky (and wise). She is the face of what geology will look like in the future.
Great program. I keep trying to imagine what global forces could cause so much translation of pieces of the west coast northward. It’s a simplistic view but I keep imagining some force like possibly the Pacific Plate rotating counterclockwise like a buzz saw as the North American Plate pushes westward against it shearing accreted bits off to the north. Over time that force causing the movement seems to move northward to Alaska and even tug the land in western Washington and Oregon to rotate slightly clockwise for a time.
Hey Erin, you are a PhD candidate. Did you notice the array of professional heavyweights Nick included you with in his Baja BC juggernaut? WOOO! Impressive. 👍😎❗️💯
"If an opinion contrary to your own makes you angry, that is a sign that you are subconsciously aware of having no good reason for thinking as you do. If some one maintains that two and two are five, or that Iceland is on the equator, you should feel pity rather than anger, unless you know so little of arithmetic or geography that his opinion shakes your own contrary conviction. The most savage controversies are those about matters as to which there is no good evidence either way. Persecution is used in theology, not in arithmetic, because in arithmetic there is knowledge, but in theology there is only opinion. So whenever you find yourself getting angry about a difference of opinion, be on your guard; you will probably find, on examination, that your belief is going beyond what the evidence warrants."
Nick, you asked about viewers reading your papers. Maybe I’m more egalitarian than most but I believe those papers are meant for me AND you! In fact, I opened a drop box just for your Geo papers and dutifully dl them when you put them up. I like marking them up on my iPad. Oh, and BTW. …. Pls consider forgiving yourself for an undergrad 2.5. No need to blurt out to those two dudes for comic relief. Today you ARE a respected academic, even if those shoes are uncomfortable to you. I respect you and look up to your knowledge and desire to connect even if you are the foil. And FWIW, I’m a retired academic holding a PhD.
This was packed with information that has to be thought about. One thought. Could the conflict in distance travelled be explained by either the shape of both of the terranes or a possible split prior to collision. Were they longer on the N-S axis or were there two of more islands formed due to prior splits by a fault or plate boundary movement prior to as well as after collision. 2. Can we reconstruct the shape of the terrances at or prior to the collisions.
Have been having trouble visualizing the amount of movement, so my best estimate: Movement of Nanaimo, BC for the Nanaimo Basin & Peak of Mt Stuart for the Mt Stuart Batholith 900 to 1000 km: Nanaimo Basin moved from Redd Bluff/Dunsmuir CA area; Mt Stuart Batholith moved from Sacramento/Chico CA area 2000 to 2600 km: Nanaimo Basin moved from Ensenada/Ciudad Obregon, Mex area; Mt Stuart Batholith moved from Desemboque/Los Michos, Mex area About 3000 km per paleomag: Nanaimo Basin moved from Culiacan (or about La Paz), Mex area; Mt Stuart Batholith moved from Mazatlán, Mex area Remember! Current locations and projected locations DO NOT account for other geologic changes (ie, Basin-and-Range Extension, Baja California rifting, etc). These are approximate and only give a sense of the magnitude of the movement.
But your base profile doesn’t reverse engineer the NA conveyance from the ENE @90MA. Baja was much further Northeast of its present @30 deg. latitude; the territory that far South @90MA was @Guatemala.
When you say why not have the erosion that fills the Nanimo basin come from the CPC, what about the quartzite spuds in the conglomerate? Don’t they have to come from further east?
Zombie my butt! Very interesting parallels. Obvious differences but the sub oceanic, re-emergence and interpretation of transport pattern between the nanimo and today’s subject is intriguing!
I wish you would have asked Erin to do a pro/con on several DZ dating procedures. Dr. Link, in last LS, seemed to fine tune metamorphic DZ to igneous DZ. Semantics? Chemical ablation, Erin suggested, potentially is more accurate for dating DZ.
Could the previous occurrence of clockwise rotation (that Basil said was ~85 Ma to 45 Ma) combined with the transform / strike-slip northward translation of INS be part of the cause of the Nenimo dropping (transtension)? And possibly be part of the reason Siletzia's drop was sooner, since the clockwise rotation was still occurring at the time it accreted (along with the Straight Creek fault getting going)? Interesting thought you had about the PC'ers coming from the CPC❣💡 I don't think it's completely out of the question. I was thinking that if the PC'ers came from Idaho, perhaps the initial transfer was from Idaho to IMS (post accretion) as IMS moved southward and then the PC'ers got moved farther westward to INS once it accreted and the uplift of the Rockies started. 😵💫 💞 Very interesting❣ 💕
Nick if it turns out that this 3,000 km movement did not happen and the signatures used to determine it did. What does that mean for the rest of the questions we have around the globe and the assumptions we have made using these data? Does that in fact misalign and bring into question many things we've previously considered fact?
Great stream Nick & Friends ! Frome earlier within this episode ; *but need to make a LOC Correction to : HORNE LAKE via CHRIS YORATH : WHERE TERRANES COLLIDE: GEOLOGY OF WESTERN CANADA. Wondering where he would be on your SCALE @NICKZENTER in this day & age ? @Avana Vana
If you need an analogy for the Yakutat/Siletzia thing you could call it an Oreo cookie. The 2 basaltic cookies and all the stuff scooped up between them is the creme.
@@jasonhuntley9927 No. Any spreading ridge at that kind of time would be fairly perpendicular to the coast. Remember we're not talking about the East Pacific Rise as the spreading ridge at this time. We're talking about the spreading ridge between the Farallon and Kula plates as the spreading ridge in question. The East Pacific Rise was still well offshore at this time. It was only at about 30 Ma that it began to be overriden by North America, hence the creation of the San Andreas further south. I'm not sure when the triple junction between the Pacific, Farallon and Kula plates went under North America, but that would have been a trigger point for some fairly fundamental realignment.
@@davidpnewton IMHO, the subducted paleo spreading ridges at question can be traced to the extended and rifted crust from SW NA, and NM to Michigan and beyond respectively. A great circle can be reverse engineered connecting the Baja-EPR to the Explorer/JDF/Queen Charlotte through these paleo divergent zones. The SAF is not alone, it and it’s sister faults are part of the EPR’s offsets. Mojave is over a Triple Junction. Since the JDF is conveying to the ESE, it and the Farallon had to have accommodated the Kula/Resurrection with Arc subduction zones which created the Exotic Terranes in the first place. Sincerely, “Lunatic Fringe”
@@davidpnewton I respectfully disagree with your first assumption. Look at the NNE-SSW orientation of the JDF-Pacific spreading ridge, it still contributed to the Yakutat Terrane migration into Alaska even though its subduction was oblique. Indeed, this orientation would allow more movement before NA entrapment if the Terrane was closer to NA.
Sorry I didnt get a chance to watch this video live . After mulling over your 5 steps , I was wondering if the ghost forests provide us with a example of the uplifting and subsequent subsiding of the terrain over a long period of time . With each insular terrain colliding the cycle would repeat itself further and further west from the original North American craton. We just can`t see it buried under the chocolate cake.
You know that the you can follow the Hawaiian hot spot all across the pacific. I think the Yellow stone hot spot has something to do with the super terrains.
Nobody seems to be articulating the concept of “trans-tensional basins. Is the Nanaimo a trans-tensional basin? If the “contact” between the accreting terrane and the continental cratonic, or previously accreted terrane is OBLIQUE, then, depending on the geometry of the junction, “trans-pression” may create uplift, and trans-tension may cause rapid basin development along different segments of the same right lateral boundary. It does not need to be an either/or choice. If we look along the current active margin we see basins in the Sea of Cortez, the Salton Sink, Death Valley, San Francisco Bay and perhaps Walker Lake. Not sure if there is an easy way to distinguish between the Basin and Range faulting of the collapse of the Nevado-plano, but the presence of right lateral faulting could be the dividing line. San Francisco Bay is a basin bounded by the San Andreas and Hayward Faults, but there are significant blocks of uplift of Franciscan accretionary wedge sediments north of the Golden Gate all the way to the triple point at Arcata, and south all the way to the Channel Islands. Is there a distinction to be seen in the Coast Ranges that may have uplift due to reverse faulting that then transitioned to right lateral faulting with the subduction of the Farallon spreading axis? Perhaps this is transition that could be contemporary with the “shutting off” of the Sierra Nevada batholith. The CPC may also be a record of the period when accretion transitioned to right lateral motion, shutting down arc volcanism. It may not be a matter of “hit and run” with suddenly changing plate and terrane vectors, but a gradual transition of vectors from frontal accretion to right lateral displacement.
Hey! I need to put this in context with the younger dryas. I just realized this transit (however far) is happening around the time of the mass extinction event 65 million years ago. Could a massive asteroid impact set some weird geology in motion?
Not on topic but you did say unconformity? There's been major unconformities. The question is if we were to figure out some of the Dynamics and causes of the unconformities the understanding you're trying to reach might be obvious? As we know there's been huge changes without any obvious initial energy input.?! Except the obvious! Would I guess my question be if I was to ask a little bit of interstellar power help with some of these equations?
Zircon analysis methodology clearly needs work. Zircons are "forever", and contain lot more information than just the age of the core. Bulk methods like chemical etching allow more precise measurement of the age of the core, but discard potentially valuable information in the outer layers. Trace element analysis also needs to be included. Thorium and hafnium data is a start, but there can be much more detailed history of the outer crust of the crystal. Blasting the whole crystal with a NdYAG laser is fast, but only yields average for the whole crystal. More gentle ablation with a pulsed UV laser or electron beam microprobe would provide details about the crust and internal layers of the crystal.
Awesome presentation, thank you Erin & Nick!
Think Nick just wanted to have a pleasent conversation today after being talked at a lot yesterday.
VERY GNEISS ERIN AND NICK
Hypotheses on the bottom dropping out in the Nanaimo: It was a shallow basin in a ribbon continent Island group when it docked but then the outboard bits continued to move N leaving a marine margin behind. Then quite a bit later the outboard stuff is smeared further North as the N part of Greater Siletzia barrels through. I'm wondering if any significant stash of the contentious PCZ's show up way North in one of the convergent jumbles.
I remembered! Hi from New Jersey
What a great series. Going to binge re watch on Christmas, to think further.
Keep it up Nick. Love from Ireland.
Thanks Erin, is good to see her again🙏🙏🙏
Impressive description of the zircon testing Erin! I learned a ton.
😘WOW, awesome job, Erin, you are always pleasant to listen to!💗 A lot to think about..., thanks, Nick!💚💫
That WAS a great show! Really enjoyed it!
Thank you Nick and Erin! What a. treat to have Erin back! What a lovely lady and so smart too! I appreciate the generosity of you, and all your guests and their willingness to share all this knowledge with us. I consider these "Alphabet Series" to be one of the best things happening on the planet at this time. Keep up the good work. Miss Donaghy I look forward to your future appearances. Your enthusiasm is as infectious as your smile! Have a great day Nick and Erin!
So how often do you say to a male presenter “what a handsome gent and so smart too!”
When are you going to get late April 2024? And pls give us an overview of the reasons for postgrad geology and where its going, ok?
Erin, you are a spectacular young woman!
“You have no idea what you’re doing.” I love this high-wire act!! Thanks Nick
Great information. Thank you Nick and Erin!
I was doing coastal geology at Cape Yakutat in 1970.
For the record, if you have VU meter, set the gain on the input signal to -10db max. That way the output won't be so hot and you won't be driving your circuits (too much current). Those circuits are on the client, meaning the user has to set their volume to 1, instead 7 or 10.
Thank you Nick. Thank you Erin! A great discussion, as always. Good luck! 👍
Funny coincidence. I saw the crazy movie 2012 last night, right between the Saturday and Sunday Baja to DC shows. They moved all the continents in just a few days.
Wow this episode was so much better than I thought it would be. Erin truly is a superstar and I was glued to the whole conversation until the end. Thank you so much Nick for making all this possible!
It didn't leave me confused about things unlike yesterday's video.
Ditto! Erin was great!
I think what’s important about the Yakutat research is that it presents a complex transportation model that can help explain the transportation of another body at a different time, i.e., the movements potentially defining what is being called “Baja BC”. The Yakutat model demonstrates that a number of influences happen along a complex transportation route over time, all of which must be identified and interpreted for their impact on the actual path that body might have taken in the course of its journey. In other words, transportation of a major body may or may not happen steadily and progressively and, instead, may happen in stops and starts, ups and downs, and with various influences impacting its path - particularly in a broad region like the one on which this course is focused, with all the intersections of moving plates and junctions (east and west subduction, slab breakage / dipping / and realignment), major tectonic activity, and many other influences. The very fact that gradual and directional movement of some of these bodies can actually be detected and analyzed, just adds to the impetus of trying to make sense of this massively complex and complicated region for us mere mortals.
A great episode, as always with Erin Donaghy. She is a wonderful guest, always willing to share her knowledge, her work, and honest in her answers, how difficult the questions may be. Thank you Nick to allow us to benefit from those conversations.
Interesting. I'm endlessly fascinated by the technical details underpinning the various lab analyses being utilized.
I'm eagerly awaiting the paleomag folks and their portion of the discussion. Thank-you Nick and Erin for a well spent hour and fifty.
Great program! Thanks Nick and Erin! I don’t understand all the details, but I get the big picture- thanks! Great to hear about your field work and writing Erin and how much thought and work you’re putting into these questions. Thanks too for all the contributors in the live chat! ⭐⭐⭐
Excellent episode. Erin is tremendously impressive! It has been interesting following her progress on her PhD the past two years. The University that hires her on their faculty after she finishes her PhD will be very lucky (and wise). She is the face of what geology will look like in the future.
Tofino is one of my favorite places! Long beach there is epic.
I had fun rewatching all the earlier Erin and Nik shows, worth looking up if you have not seen them.
Always enjoy time with Erin. Looking forward to being live with everyone Wednesday.
Great program. I keep trying to imagine what global forces could cause so much translation of pieces of the west coast northward. It’s a simplistic view but I keep imagining some force like possibly the Pacific Plate rotating counterclockwise like a buzz saw as the North American Plate pushes westward against it shearing accreted bits off to the north. Over time that force causing the movement seems to move northward to Alaska and even tug the land in western Washington and Oregon to rotate slightly clockwise for a time.
Another great video. Thanks Erin and Nick.
Thanks Erin and Nick!
I'm catching up as I had to bow out of the live stream.
Discussion was interesting. Most was over my head. So, enjoyed the diagrams andpitures.
Hey Erin, you are a PhD candidate. Did you notice the array of professional heavyweights Nick included you with in his Baja BC juggernaut?
WOOO! Impressive.
👍😎❗️💯
"If an opinion contrary to your own makes you angry, that is a sign that you are subconsciously aware of having no good reason for thinking as you do. If some one maintains that two and two are five, or that Iceland is on the equator, you should feel pity rather than anger, unless you know so little of arithmetic or geography that his opinion shakes your own contrary conviction.
The most savage controversies are those about matters as to which there is no good evidence either way. Persecution is used in theology, not in arithmetic, because in arithmetic there is knowledge, but in theology there is only opinion. So whenever you find yourself getting angry about a difference of opinion, be on your guard; you will probably find, on examination, that your belief is going beyond what the evidence warrants."
Bertrand Russell
Nick, you asked about viewers reading your papers. Maybe I’m more egalitarian than most but I believe those papers are meant for me AND you! In fact, I opened a drop box just for your Geo papers and dutifully dl them when you put them up. I like marking them up on my iPad.
Oh, and BTW. …. Pls consider forgiving yourself for an undergrad 2.5. No need to blurt out to those two dudes for comic relief. Today you ARE a respected academic, even if those shoes are uncomfortable to you. I respect you and look up to your knowledge and desire to connect even if you are the foil. And FWIW, I’m a retired academic holding a PhD.
This was packed with information that has to be thought about. One thought.
Could the conflict in distance travelled be explained by either the shape of both of the terranes or a possible split prior to collision. Were they longer on the N-S axis or were there two of more islands formed due to prior splits by a fault or plate boundary movement prior to as well as after collision.
2. Can we reconstruct the shape of the terrances at or prior to the collisions.
Have been having trouble visualizing the amount of movement, so my best estimate:
Movement of Nanaimo, BC for the Nanaimo Basin & Peak of Mt Stuart for the Mt Stuart Batholith
900 to 1000 km: Nanaimo Basin moved from Redd Bluff/Dunsmuir CA area; Mt Stuart Batholith moved from Sacramento/Chico CA area
2000 to 2600 km: Nanaimo Basin moved from Ensenada/Ciudad Obregon, Mex area; Mt Stuart Batholith moved from Desemboque/Los Michos, Mex area
About 3000 km per paleomag: Nanaimo Basin moved from Culiacan (or about La Paz), Mex area; Mt Stuart Batholith moved from Mazatlán, Mex area
Remember! Current locations and projected locations DO NOT account for other geologic changes (ie, Basin-and-Range Extension, Baja California rifting, etc). These are approximate and only give a sense of the magnitude of the movement.
Wow! Thanks for doing the math!
But your base profile doesn’t reverse engineer the NA conveyance from the ENE @90MA. Baja was much further Northeast of its present @30 deg. latitude; the territory that far South @90MA was @Guatemala.
When you say why not have the erosion that fills the Nanimo basin come from the CPC, what about the quartzite spuds in the conglomerate? Don’t they have to come from further east?
Time management! How do you find the time to do all of this? thank you and thank you Dr. Erin Donaghy, that haves a good ring to it. ALL stay safe
She's not doctor yet. Still a PhD student, although reasonably late in the program, so will hopefully get her doctorate fairly soon.
@@davidpnewton jest practicing for the time being thank you
Zombie my butt!
Very interesting parallels.
Obvious differences but the sub oceanic, re-emergence and interpretation of transport pattern between the nanimo and today’s subject is intriguing!
I wish you would have asked Erin to do a pro/con on several DZ dating procedures. Dr. Link, in last LS, seemed to fine tune metamorphic DZ to igneous DZ. Semantics? Chemical ablation, Erin suggested, potentially is more accurate for dating DZ.
Could the previous occurrence of clockwise rotation (that Basil said was ~85 Ma to 45 Ma) combined with the transform / strike-slip northward translation of INS be part of the cause of the Nenimo dropping (transtension)? And possibly be part of the reason Siletzia's drop was sooner, since the clockwise rotation was still occurring at the time it accreted (along with the Straight Creek fault getting going)?
Interesting thought you had about the PC'ers coming from the CPC❣💡 I don't think it's completely out of the question.
I was thinking that if the PC'ers came from Idaho, perhaps the initial transfer was from Idaho to IMS (post accretion) as IMS moved southward and then the PC'ers got moved farther westward to INS once it accreted and the uplift of the Rockies started. 😵💫
💞 Very interesting❣ 💕
Nick if it turns out that this 3,000 km movement did not happen and the signatures used to determine it did. What does that mean for the rest of the questions we have around the globe and the assumptions we have made using these data? Does that in fact misalign and bring into question many things we've previously considered fact?
Great stream Nick & Friends ! Frome earlier within this episode ; *but need to make a LOC Correction to : HORNE LAKE via CHRIS YORATH : WHERE TERRANES COLLIDE: GEOLOGY OF WESTERN CANADA. Wondering where he would be on your SCALE @NICKZENTER in this day & age ? @Avana Vana
Will podcasts return this year?
My family is from the same part of Italy.
Coast Plutonic Complex!! This is great NIck.
If you need an analogy for the Yakutat/Siletzia thing you could call it an Oreo cookie. The 2 basaltic cookies and all the stuff scooped up between them is the creme.
My live stream question was: Good morning Erin, why does Mike need to establish a migrating spreading ridge?
Wouldn’t a spreading ridge result in the bottom dropping out?
@@jasonhuntley9927 No.
Any spreading ridge at that kind of time would be fairly perpendicular to the coast. Remember we're not talking about the East Pacific Rise as the spreading ridge at this time. We're talking about the spreading ridge between the Farallon and Kula plates as the spreading ridge in question. The East Pacific Rise was still well offshore at this time. It was only at about 30 Ma that it began to be overriden by North America, hence the creation of the San Andreas further south. I'm not sure when the triple junction between the Pacific, Farallon and Kula plates went under North America, but that would have been a trigger point for some fairly fundamental realignment.
@@davidpnewton IMHO, the subducted paleo spreading ridges at question can be traced to the extended and rifted crust from SW NA, and NM to Michigan and beyond respectively. A great circle can be reverse engineered connecting the Baja-EPR to the Explorer/JDF/Queen Charlotte through these paleo divergent zones. The SAF is not alone, it and it’s sister faults are part of the EPR’s offsets. Mojave is over a Triple Junction.
Since the JDF is conveying to the ESE, it and the Farallon had to have accommodated the Kula/Resurrection with Arc subduction zones which created the Exotic Terranes in the first place.
Sincerely,
“Lunatic Fringe”
@@davidpnewton I respectfully disagree with your first assumption. Look at the NNE-SSW orientation of the JDF-Pacific spreading ridge, it still contributed to the Yakutat Terrane migration into Alaska even though its subduction was oblique. Indeed, this orientation would allow more movement before NA entrapment if the Terrane was closer to NA.
Sorry I didnt get a chance to watch this video live . After mulling over your 5 steps , I was wondering if the ghost forests provide us with a example of the uplifting and subsequent subsiding of the terrain over a long period of time . With each insular terrain colliding the cycle would repeat itself further and further west from the original North American craton. We just can`t see it buried under the chocolate cake.
You know that the you can follow the Hawaiian hot spot all across the pacific. I think the Yellow stone hot spot has something to do with the super terrains.
I am sorta wondering if faults left by movement of INS helped Yakutat move faster and help it split away from Siletzia?
Erin statement that the lazer eat away the younger halo to get a truer date is important to understanding what happened.
Nobody seems to be articulating the concept of “trans-tensional basins. Is the Nanaimo a trans-tensional basin? If the “contact” between the accreting terrane and the continental cratonic, or previously accreted terrane is OBLIQUE, then, depending on the geometry of the junction, “trans-pression” may create uplift, and trans-tension may cause rapid basin development along different segments of the same right lateral boundary. It does not need to be an either/or choice.
If we look along the current active margin we see basins in the Sea of Cortez, the Salton Sink, Death Valley, San Francisco Bay and perhaps Walker Lake. Not sure if there is an easy way to distinguish between the Basin and Range faulting of the collapse of the Nevado-plano, but the presence of right lateral faulting could be the dividing line.
San Francisco Bay is a basin bounded by the San Andreas and Hayward Faults, but there are significant blocks of uplift of Franciscan accretionary wedge sediments north of the Golden Gate all the way to the triple point at Arcata, and south all the way to the Channel Islands. Is there a distinction to be seen in the Coast Ranges that may have uplift due to reverse faulting that then transitioned to right lateral faulting with the subduction of the Farallon spreading axis? Perhaps this is transition that could be contemporary with the “shutting off” of the Sierra Nevada batholith.
The CPC may also be a record of the period when accretion transitioned to right lateral motion, shutting down arc volcanism. It may not be a matter of “hit and run” with suddenly changing plate and terrane vectors, but a gradual transition of vectors from frontal accretion to right lateral displacement.
What affect did 66 MA Yucatan Peninsula Asteroid Collision at have on plate tectonics? Did it make a change in east Pacific?
That’s what I want to know
@@robertrapine8791 It had to ring Earth's bell.
So the grains got cooked by the plutons?
Hey! I need to put this in context with the younger dryas. I just realized this transit (however far) is happening around the time of the mass extinction event 65 million years ago. Could a massive asteroid impact set some weird geology in motion?
Started at a 5. Now am at 2 with latest evidence presented. Let’s see where I end 😊
QUESTION: WAS THERE A SPEADING RIDGE AND/OR A HOTSPOT WHICH NORTH AMERICA OVERRAN DURING THE DOCKING OF INSULAR SIMILAR TO THE DOCKING OF SILETZIA?
Not on topic but you did say unconformity? There's been major unconformities. The question is if we were to figure out some of the Dynamics and causes of the unconformities the understanding you're trying to reach might be obvious? As we know there's been huge changes without any obvious initial energy input.?! Except the obvious! Would I guess my question be if I was to ask a little bit of interstellar power help with some of these equations?
Zircon analysis methodology clearly needs work. Zircons are "forever", and contain lot more
information than just the age of the core. Bulk methods like chemical etching allow more precise
measurement of the age of the core, but discard potentially valuable information in the outer layers.
Trace element analysis also needs to be included. Thorium and hafnium data is a start, but there can
be much more detailed history of the outer crust of the crystal.
Blasting the whole crystal with a NdYAG laser is fast, but only yields average for the whole crystal.
More gentle ablation with a pulsed UV laser or electron beam microprobe would provide details about
the crust and internal layers of the crystal.
detrital zircons? Who knew.
Zircon and sometimes garnet? dating----pls tell me about or direct me.
Thanks
Ps can you give me a small view into Baja BC