A waste of time? What rot. This superb blog, including the sniping, is going to be hugely useful, for decades. I am trying to rethink the plte tectonics model of Holmes (1928, Transactions, Geological Society of Glasgow 1929) et al, only at this geo stuff 40 years, a nanosecond in geotime, so still immensely confused as yet. So ta, one and all.

Peter Ravenscroft

Geologist. Oz

which I find most interesting. what is the dateing of the underwater meandering of the river located under the sea surface? How old could that be? Another question and I am assuming it is some type of error in the drawing figure 17 what are those parallel lines ( dimple looking things running up and down to the left side of the drawing. Is that real?

That can’t possible be real unless it is very VERY large in which case the thought of subduction in this zone is totally not important as it is a very small effect.

Sorry to irritate any one, I am not a scientist, but are those parallel lines ( submerged ) ( not the obvious wrinkles cause by the pacific thing going under the coast )

those dimples lined up in two parallel lines. ……. this is interesting. please email me if you have an inkling on this.

Stephanie R
http://www.memphissigncompany.com

or info@memphissigncompany.com

Interestingly, there was a recent paper in Science about “mantle wind” affecting upwellings at hotspots and kill the “hotspot reference frame” [John Tarduno et al, The Bent Hawaiian-Emperor Hotspot Track: Inheriting the Mantle Wind (2009) Science, 50, p324.]. It would be interesting to check if hotspots remain stationary in case of an asymmetrical planetary growth (just an hypothesis). Maxlow already made a remarkable work showing that poles apparent wander is well explained by such an asymmetrical growth (http://tinyurl.com/kklg6y).

Anyway, as you guess, I read mantleplumes.org on a regular basis. In my opinion, the plume controversy could lead to the kind of crisis triggering Kuhnian revolutions, especially because diapirism is the main mechanism by which the mass is redistributed toward the surface during planetary growth. Yes, convection is crucial, but that is a “one way” convection (advection toward the surface without return flow).

Andrew says : Doglioni does not cite evidence that trenches are stretching apart, does he?

What a strange idea? Why would a trench be stretching apart? Or did you refer to flexural faulting of the oceanic crust (evident on some seismic profiles)?
No, an active margin is about overthrusting, not stretching. Except eventually during eduction, that to my knowledge, do not currently takes place.

Andrew says: It is a provocative paper, and I thank you for the link. But seeing it as bolstering Earth and universal expansion is just living in a contrarian’s mirror-land.

One more time, I do not cite this paper as a support to earth expansion, but to illustrate that, contrary to common belief, geophysics is not mature yet.

Andrew says: That can be fun–I used to enjoy it in the mid-1970s after reading Carey–but most of us give it up. You’re grasping at straws and looking only for confirmatory evidence.

Actually, everywhere I look, I see evidences that either do not falsify planetary growth and plate tectonics, or falsify plate tectonics and support planetary growth. Thus, I logically conclude that planetary growth is the valid theory.

Andrew, please forget any prejudice and look carefully at the pictures of the moons I posted a couple of message above. Dare you tell me that the most logical explanation for their apparence is not that they did experience an important inner growth?

Look at the older brownish upper terrains of ganymede (http://ciclops.org/media/mr/2007/3628_9052_1.jpg). No objective scientist who examines this image could reasonably doubt that Ganymede has massively inflated from its deep interior, causing its old dark crust to pull part as the globe expands. A new lighter coloured crust is being emplaced between older, darker crustal shards. The entire surface of ganymede illustrates tensional pull-apart rifting with global extensional chasms and multiple dilatational contiguous rift systems.
Actually, in a first article about ganymede’s surface, Prockter mentioned that the surface was likely the result of a massive inner growth. Evidently, Prockter abandoned the hypothesis because it sounds so odd at first sight. However, with the hindsight, it is expected that other bodies should grow if Earth is growing, because there is no reason to believe that Earth is a special planet. The good news is that comparing planets/moons lead to the conclusion that most telluric planets have experienced, or are experiencing a significant growth. It follows that planetary growth theory is also a much better theory than plate tectonics, because it provides a universal framework for a wider range of data.

Well, sorry to digress… Hope I don’t get too much boring…

It is a provocative paper, and I thank you for the link. But seeing it as bolstering Earth and universal expansion is just living in a contrarian’s mirror-land. That can be fun–I used to enjoy it in the mid-1970s after reading Carey–but most of us give it up. You’re grasping at straws and looking only for confirmatory evidence.

Doglioni et al do not say that there are no shear zones with some lithosphere below another lithosphere, they put forward arguments to show that the mechanism by which a lithosphere is *plunging* into the mantle is not on firm ground. The issue is that none of the data used to classically describe subduction (sismology and geochemistry) allow to determine the absolute displacement of a slab: Is the oceanic lithosphere actively plunging into the mantle, or is it passive, being overthrusted by lithosphere laterally spreading away from an upwelling center?
Curiously not many people tried to address this simple question, simply because everybody always assumed that the slab can only be plunging. But it is far from obvious, and on the contrary, there are plenty of evidence supporting the second hypothesis (I cited a few above).

Sometimes ago, I read a treatrise discussing this point. It is written by a geologist, Andrew Kruger: http://www.lulu.com/content/421591.
I do not agree with all his ideas, but he has pretty good evidence (lot of geological data) supporting overthrusting vs underthrusting.

This make a huge difference, because while de subduction concept allows to destroy thousand kilometers of oceanic lithosphere, the overhtrusting interpretation can’t. Of course, there is a significant amount of old crust that get buried/destroyed in the process, but not more than a few hundred kilometers.
For example, look at this figure I made using GMT, representing the philippine sea and age of seafloor (isochrons each 5 Ma): http://tinyurl.com/ny4d56

It appears that successive episodes of seafloor emplacement destroyed part of old pacific crust (150 Ma or so) bit by bit. But the amount of new ocean crust that formed in the backarcs can only be equal or larger that the amount of ocean crust that got destroyed, not smaller. All things considered, surface is created at these zones, not destroyed.

By the way, look at the region of the Banda arc with the new crust forming at the center (bottom of the figure). Here, the arc makes a full 180 degrees turn. That is easily conceivable as a rising diapir which margins are spreading outward. But how would you conceive that ocean crust is coming from all directions over 180 degrees to sink below the arc? It just does not make any sense. Scalera makes the same comment for the mediterranean sea where direction of subduction are improbable (see figure 10.5 in this paper http://tinyurl.com/l77ub8).

Another point I wanted to mention. In a message above, I cited the Heide salt dome as an analogy to what happens at active margins. I scanned the figure from Holmes book: http://tinyurl.com/mvzk2n
Carey suggested that a WBZ is equivalent to the shear zone between the rising salt diapir and the sequence on the right. In this context, rapid exhumation of UHP rocks is easily explained as a layer carried along the rising diapir. No need to invent weird channels where UHP rocks are creeping upstream along a descending slab…

I’m sure that if you do your own research, you’ll find a lot that can be easily explained using the planetary growth paradigm.
And keep in mind that this is a universal phenomenon, while plate tectonics is not. The surface features of moons like Ganymede (http://tinyurl.com/n8e7ma), Ariel (http://tinyurl.com/lcveeo), Miranda (http://tinyurl.com/kmgp2v), dramatically show the effect of a large inner growth.

I know that it sounds completely crazy, but I remind you that all scientific revolutions sounds crazy at first.
Actually, one of my favorite quote is from Arthur Schopenhauer:
“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. ”

Regards.