5 Alaska

 Alaska

Alaska apparently began as the tip of an Asian peninsula.  Asia's move north swung the peninsula like a whip, pulling out Korea.  Japan and Kamchatka were flung off, trailing trenches.  As Alaska spun away from Asia, it laid down a trench with a small eddy from the turbulence.  North America was near the end of its run when Alaska hit and merged with it, raising mountains throughout Alaska.

 

The ideas for the formation of the features of the Bering Sea are quite different in Plate Tectonics versus Shock Dynamics.  The Bering Sea is bounded by Kamchatka, Siberia, Alaska, and the 3000 km-long Aleutian Ridge.  It contains two curious ridges; the Shirshov Ridge and Bowers Ridge.  The Shirshov Ridge extends south from Siberia, is linear, 700 km long, up to 130 km wide, and narrows at the southern end.  The west slope is steep, mostly 25 - 30 degrees but up to 40 degrees, while the east slope is gentle (7 - 10 degrees).1  The "structure of the Shirshov Ridge most probably is a chaotic piling up of tectonic slabs of the crust of an ancient oceanic basin."3  The facts "indicate intense tectonization of the basement bedrock in the Shirshov Ridge, common in structures developed by considerable horizontal compression."3,1  Yet it was also once part of the edge (margin) of a continent, and was "torn away"4 from the continent.  Bowers Ridge is an uplifted arc 700 km long.  It is considered a volcanic ridge, although there is no current volcanism, there are no earthquakes (aseismic), and there is no evidence of subduction (remnant slab and trench).2  Along the north and east side is some slightly deformed sediment, then a mild dip (Bowers Trough) buried in sediment, and beyond that a small (90 meters high, 12 - 20 km wide) rise, Bowers Swell.

In the Plate Tectonics view, the uncertainty over the origin of the Shirshov Ridge is reflected by its having been labeled an ancient spreading center, a microcontinent, an uplifted piece of ocean floor, and the remains of an island arc.1  Researchers seem to have settled on the notion that it was formed by compression and then rifted off of Kamchatka.4  Regarding Bowers Ridge, the thinking is that it formed either before or at the same time (about 60 million years ago) as the Aleutian Ridge.  Either it was 'rafted' into the Bering Sea on a piece of another oceanic plate, or it formed in the Bering Sea.  Either it was a fragment of an oceanic subduction arc or it was formed along a transform fault.  In any case, elements related to its origin seem to have fallen away long ago.  What has researchers perplexed is the deformed sediment at the base of Bowers Ridge, and the origin of Bowers Swell.  Both indicate slight compression in the relatively recent past, although as mentioned the ridge is aseismic and lacks evidence of subduction, plus it is separated from block rotation in the Aleutian Ridge.2

Consequently, some have surmised that the pressure may come from the motion of Siberia and Alaska pushing on the Aleutian Basin.  However, "such motion is not evident in seismicity data for the Bering Sea, perhaps because the motion may be slow and limited and the seismic events may be below the threshold of detection in the world seismic network."2

As you can see, researchers have treated the Shirshov and Bowers Ridges as different and unrelated.  But there is reason to think their origins are related.  You may already have noticed the tiny curved line connecting the two.


From National Geophysical Data Center - Global Seafloor Topography from
Satellite Altimetry (updated Nov. 1997) by Walter H.F. Smith and David T. Sandwell

The Shock Dynamics account begins with the counterclockwise rotation of Asia.

Alaska began as the end of the Siberian peninsula.  As Asia started north, inertia held back Alaska and it rammed Kamchatka.  This pinched oceanic crust between Alaska and Kamchatka, providing the compression found in the Shirshov Ridge.  As Asia continued north, the peninsula swung outward, tearing away the Shirshov Ridge and laying down the arc of the Aleutian Ridge.  Eventually Alaska separated from the peninsula and collided with North America.

The connecting line (in black above) between the Shirshov and Bowers Ridges shows what happened.  A piece of the southern tip of Shirshov Ridge was pulled off and dragged along with the Aleutian Ridge.  The fluidized oceanic crust in the basin opening behind Alaska resisted the motion of the piece, and a turbulent backflowing eddy resulted.  Thus light compression is on the out-thrown (east and north) side of the eddy, Bowers Ridge.  That this turbulent feature 'froze' in place is consistent with the apparent Bingham fluid (temporarily fluidizes under stress) nature of the crust.  Decide for yourself whether the Plate Tectonics or Shock Dynamics scenarios for the Bering Sea provide the clearest explanation.

1. Baranov, B.V., I.A. Basov, P.A. Gladkikh, A.A. Zabolotnikov, V.P. Zinkevich, M.K. Ivanov, V.V. Kepezhinskas, G.B. Rudnik, N.V. Tsukanov, O.A. Shmidt. 1984. The Bedrock of the Shirshov Ridge (Bering Sea). Oceanology, Vol. 24, No. 6, pp. 703-706.

2. Marlow, Michael S., Alan K. Cooper, Shawn V. Dadisman, Eric L. Geist, Paul R. Carlson. 1990. Bowers Swell: Evidence for a zone of compressive deformation concentric with Bowers Ridge, Bering Sea. Marine and Petroleum Geology, Vol. 7, November, pp. 398-408.

3. Neprochnov, Yu.P., V.V. Sedov, L.R. Merklin, V.P. Zinkevich, O.V. Levchenko, B.V. Baranov, G.B. Rudnik. 1985. Tectonics of the Shirshov Ridge, Bering Sea. Geotectonics, Vol. 19, No. 3, pp. 194-206.

4. Shipilov, E.V., A.Yu. Yunov, Yu.I. Svistunov. 1990. Marine Geology - A Model of the Structure and Formation of Aseismic Elevations on the Ocean Floors. Oceanology, Vol. 30, No. 2, pp. 193-196.

This simple demonstration illustrates the turbulence.  A drop of colored cream is placed at the joint of two wooden paddles in a shallow pan of water.  The vertical paddle represents the Shirshov Ridge.

Pulling the horizontal paddle to the right represents fluidized crust drawn behind Alaska.

Larger scale flow is shown in this computer model of the escape of water under a newly opened sluice gate:

   

   
From: Harlow, Francis H., John P. Shannon, J. Eddie Welch. 3 September 1965. Liquid Waves by Computer.
Science, Vol. 149, No. 3688, pp. 1092-1093

   

As with all accoustically fluidized crustal features in the Shock Dynamics model, once the fluidizing energy falls below a threshold level, the crust "freezes" in place.

The fact that both Bowers Ridge and New Hebrides-Hunter Ridge (in presentation 13, next page) can be simulated with fluid turbulence is powerful support for the Shock Dynamics model, especially when compared to the flimsy Plate Tectonics explanations.

If there is any doubt that Alaska slammed into North America along the path of the Aleutian Ridge, take a look at this topographic map.

The whole southern half is arched upward.  The seismic map below gives us an idea of where the suture line is between Alaska and North America.  It follows the extended curve of the Aleutian Ridge.  Shallow seismic waves under central Alaska show that the lithosphere is stretched along this curve (along-strike anisotropy)1, as we would expect if Alaska swung east into North America.
1. Christensen, Douglas H., Geoffrey A. Abers. 2010. Seismic anisotropy under central Alaska from SKS splitting observations. Journal of Geophysical Research, Vol. 115, B04315, pp. 1-12.


Seismicity of Alaska: 1975 - 1995

The polar dinosaur test

We can test Plate Tectonics and Shock Dynamics with fossils found near the North and South Poles.



Some of the North Slope dinosaurs

North Pole:
In a PBS NOVA television program "Arctic Dinosaurs", that aired October 7, 2008, the producers brought together specialists in several fields to investigate dinosaur fossils on the north coast of Alaska (the Liscomb bone bed by the Colville River on the North Slope).  They uncovered a variety of dinosaur fossils.  A member of the team, British paleobotanist Robert Spicer, had been studying the many types of plant fossils found in this area since 1976
1.  He used a global statistical model to determine very precisely the average temperature of this area when the dinosaurs lived there, which the researchers believe was 70 million years ago.

What did Spicer conclude?  That when the plants lived there the average temperature was about 42°F, which is 30 degrees warmer than it is today.  Paleoichnologist Stephen T. Hasiotis studies fossil tracks of birds, insects, and worms.  He described the ancient scene this way: "Picture yourself standing on this lake shoreline.  It's warm sunny; there are herds of duck-billed dinosaurs and other kinds of plant-eating dinosaurs along the lake, eating vegetation like horsetails, gingkoes, the flowering plants; an abundance of flying insects and crawling insects are on the shoreline, in the water; Theropod dinosaurs... are hunting these plant-eating dinosaurs."4  Hans-Dieter Sues of the Smithsonian Institution added, in "the good times of the year, when it was not dark and cool, it probably would have been very similar to what we now see in the southeastern United States, with lots of conifers, lots of flowering plants.  In fact, the Late Cretaceous, except for the dinosaurs, would not have been an unfamiliar environment to us."4  This fits the Shock Dynamics model exactly, which says that Alaska began far to the south, about the latitude of Maryland, USA, before it was flung north by the impact event (see the pictures and video at the top of the page).

Today, the Liscomb bone bed is on a latitude of about 70°N, 1,500 miles from the North Pole.  Temperatures there can drop to minus 60°F.  According to Plate Tectonics, 70 million years ago it was even closer to the North Pole, only 350 miles from it at nearly 85°N, where there is total darkness for 120 days each year.

Footprints from a herd of Hadrosaur dinosaurs found in the Upper Cretaceous Cantwell Formation in the Alaska Range, Denali National Park, Alaska, preclude the possibility that they migrated far away for the winter.  It is the largest tracksite known this far north.  According to the researchers, "Caribou migration distances are often mentioned as possible analogs for distances that hadrosaurids might have been capable of achieving as they traveled from high latitudes to the temperate latitudes for warmer climes."3  Yet even "these hypothesized migration distances are inadequate to have taken the hadrosaurids out of the northern polar region."3  "These animals, however, did not migrate significant distances to lower latitudes during the winter, based on 1) a bio-mechanical argument from hadrosaurid bones found in northern Alaska2... and 2) evidence from this new tracksite for very young juvenile hadrosaurids in the herd that would have been incapable of making such a long journey."3  They "therefore lived in high latitudes year round".3

South Pole
Fossil plants in Cretaceous rocks in southeastern Australia and New Zealand are of ferns, trees, and mosses in a swampy environment.

Here are a few examples


 Ginkgoites


 Gleicheniaceae


 Araucarian


 Bennettitales


Podocarps 


Pentoxylales 


 Osmundaceae


Sphenopsids


Lycopods 


Bryophytes 

They were abundant enough to feed plant-eating dinosaurs such as


Hypsilophodontids 


Ankylosaur 


Serendipaceratops 


Diluvicursor 

and there were enough of those to feed carnivorous dinosaurs such as


Abelisauridae 


Timimus 

There are fossils of these dinosaurs, as well as fossil mayflies, water beetles, wasps, ants, fleas, flies, spiders, earthworms, and horseshoe crabs.

Where was southeastern Australia when these early Cretaceous fossils were buried?

Plate Tectonics theory says it was near the South Pole, about 75° South


The fossils were found near the red dots on the map
From: http://home.alphalink.com.au/~dannj/ecenvir.htm

where for 50 days straight every year it is totally dark.

 

Plate Tectonics places southeastern Australia there for not just 10 years, or 100 years, or 1000 years, but for 40 million years – between about 140 and 100 million years ago.  The Early Cretaceous fossils are assigned dates from 115 to 105 million years ago, but clearly the plants, animals, insects, and environment must have been well-established before that.

This is how 75° South looks now, in daylight

The situation has puzzled paleontologists for many years, and they have offered several ideas within the Plate Tectonics framework:

1)  Did higher levels of CO2 in the atmosphere produce global warming that warmed the South Pole?

This chart shows calculated CO2 levels in parts-per-million-by-volume (ppmv) for a portion of the geologic column.  Today, it is about 400 ppmv.  Between 115 and 105 million years ago (blue lines) it wasn’t much higher, except for a spike at 114 million years ago.  So atmospheric CO2 would not have had much affect.


From (annotation added): Retallack, Gregory J. July 2009. Greenhouse crises of the past 300 million years. Geological Society of America Bulletin, Vol. 121, No. 9-10, pp. 1441-1455 DOI: 10.1130/B26341.1

2)  Did the dinosaurs migrate to higher latitudes before winter?

"…dinosaurs living at the poles would have to pass through 30° of latitude, about 2000 miles or 3200 km, in order to avoid the total darkness of a polar winter; in other words, a seasonal migration of 6400 km.  No terrestrial animal achieves such distances today."5  Large portions of Australia were also covered by water.

While big dinosaurs such as Abelisauridae with long strides could conceivably make long seasonal migrations, at enormous energy costs, smaller polar dinosaurs, including ankylosaurs and hypsilophodontids, appear unable (based on biomechanics or absolute size) to migrate long distances.5  For example, "the odd gait… limited range of motion and stocky leg design contribute to the inefficient mechanics of the leg"5 of ankylosaurs.

3) Did the dinosaurs evolve large eyes to see during the long, dark days of winter?

"Hysilophodonts are a group of small ornithischians that, while rare in the Northern Hemisphere, tend to dominate Austral [South] polar communities."5

"The enlarged optic lobes and expanded [eye] orbits found in the Australian hypsilophodont, Leallynosaura amicagraphica, suggest this animal had acute vision compared with its northern, low-latitude counterparts."5  Some researchers "argued this to be a possible adaptation to counter the long, dark polar winters."5

However, "small species and juveniles of larger taxa typically possess enlarged orbits and big brains in comparison with other cranial features…  Possession of these characters, therefore, does not necessarily mean vision was exceptional."5

4)  Did the dinosaurs hibernate to survive the cold, dark winters?

"During the Early Cretaceous, the state of Victoria, Australia, lay within the Antarctic Circle between the paleolatitudes of 75°S and 80°S."6

"The microstructures and cyclical growth exhibited by both ornithopods [hypsilophodontids] and theropods [Abelisauridae, Timimus] from the high paleolatitude of southeastern Australia resemble patterns observed in dinosaurs from lower paleolatitudes, indicating similarities in growth dynamics and physiology.  Although LAGs [Lines of Arrested Growth] can form as a result of the slowed metabolic processes experienced during hibernation, they are not microstructural features exclusive to hibernators."6

"…we suggest that the presence of growth marks [LAGs] alone cannot be used to support a hibernating behavior."6

And "no evident physiological modifications appear to be linked with the distribution of ankylosaurs and other non-avian dinosaurs at higher latitudes (>60°S)."7

So in Plate Tectonics, plants, plant-eating and meat-eating dinosaurs were on an isolated continent consisting of Antarctica, Australia, New Zealand, and the Chatham Islands all merged together near the South Pole, for 10 to 40 million years.  Yet there is no evidence for dinosaur hibernation, migration, or special adaptation to South Pole winters, nor for a CO2 hothouse environment.

Contrast that with Shock Dynamics, where southeast Australia began next to Africa at 23°S and moved to where it is today without going near the South Pole.

It is clear which theory passes the polar dinosaur test.

* * * * * * * *

1. Brouwers, E.M., W.A. Clemens,  R.A. Spicer. 12 May 1987. Dinosaurs on the north Slope, Alaska: high latitude, latest Cretaceous environments. Science, Vol. 237, pp. 1608-1610.

2. Fiorillo, A. R., R. A. Gangloff. 2001. The caribou migration model for Arctic hadrosaurs (Ornithischia: Dinosauria): A reassessment. Historical Biology, Vol. 15, pp. 323-334. Doi: 10.1080/0891296021000037327

3. Fiorillo, Anthony R., Stephen T. Hasiotis, Yoshitsugu Kobayashi. Published online 30 June 2014. Herd structure in Late Cretaceous polar dinosaurs: A remarkable new dinosaur tracksite, Denali National Park, Alaska, USA. Geology. Doi: 10.1130/G35740.1

4. Transcript of "Arctic Dinosaurs". October 7, 2008. NOVA on PBS. Online address: http://www.pbs.org/wgbh/nova/nature/arctic-dinosaurs.html

5. Bell, Phil R., Eric Snively. 2008. Polar dinosaurs on parade: a review of dinosaur migration. Alcheringa: An Australasian Journal of Palaeontology, Vol. 32, No. 3, pp. 271-284 DOI: 10.1080/03115510802096101

6. Woodward, Holly N., Thomas H. Rich, Anusuya Chinsamy, Patricia Vickers-Rich. 2011. Growth Dynamics of Australia’s Polar Dinosaurs. PLoS ONE, Vol 6, No. 8 e23339 DOI:10.1371/journal.pone.0023339

7. Cerda, Ignacio A., Zulma Gasparini, Rodolfo A. Coria, Leonardo Salgado, Marcelo Reguero, Denis Ponce, Romina Gonzalez, J. Marcos Jannello, Juan Moly. 2019. Paleobiological inferences for the Antarctic dinosaur Antarctopelta oliveroi (Ornithischia: Ankylosauria) based on bone histology of the holotype. Cretaceous Research, Vol. 103, 104171 16 pages, DOI: 10.1016/j.cretres.2019.07.001