Tag: convection

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The circular tectonic drift vectors of Anatolia

Steingrimur Thorbjarnarson

The tectonic drift of the Anatolian Plate is notably independent from its surroundings. While the Arabian Plate moves northward, similar to the African Plate, the Anatolian Plate exhibits a counterclockwise rotation. This motion can be examined through the lens of the convection rolls model to see whether it offers any additional insights. The outcome is striking and reveals two key points:

  1. The combined structure of convection rolls and plate boundaries appears to create the conditions for a central pivot point around which the Anatolian Plate rotates.
  2. If a fixed point within the convection model exerts a dominant influence on tectonic drift, then the convection rolls also offer a framework for understanding the subduction of the African Plate beneath the Eurasian Plate.

The map showing drift vectors can be found at:
https://www.tandfonline.com/doi/full/10.1080/19475705.2024.2446588#abstract

The most significant observation is that this central pivot lies near the 32nd parallel, precisely where two mantle upwelling lines intersect at approximately 32.1°E. Along this latitude, the convection roll system is aligned exactly north–south, making it a key structural feature, comparable in importance to the equator and the 64°N/S parallels. Interestingly, this location corresponds roughly to the eastern edge of the Nile River delta. It has previously been noted that the deltas of the world’s largest rivers—especially the Amazon at the equator—are situated at critical junctions within the convection rolls framework. https://magicmagma.com/2022/10/04/what-do-the-three-famous-rivers-amazon-nile-and-mississippi-have-in-common/

Given this fixed relationship between surface tectonics and mantle convection geometry, the concept of rollback requires reconsideration. In this case, the European continent appears to be drifting away from the latitude at which the African Plate subducts beneath it. Whether we interpret this as northward retreat of the African slab or northeastward drift of Europe, the geological consequences are functionally the same.

The side-view depiction of African Plate subduction shows how numerous geological features have developed over the last 35 million years, since subduction began. These reflect the continuing northeastward movement of the Eurasian Plate, while the northern edge of the African Plate descends beneath it.

This is from https://www.youtube.com/watch?v=cqK-CbuM3Eo

Just to clarify a bit what drives the tectonic drift anomaly of Anatolia, a particular bit of convection roll can be pointed out:

It can also be pointed out that most geothermal activity is found in this part of Turkey. Take a look at this map:

It is from https://www.researchgate.net/figure/Geothermal-map-of-Turkey-MTA-2021b_fig1_365230456

The red area in Western Turkey coincides with the convection roll taking part in driving the rotation of the local tectonic plate. This can explain the geothermal activity anomaly.

Note that the appearence of the aggregate of vectors of GPS drift measurements of the Anatolian Peninsula is not only circular, but also basicly from east to west. The mathematical precision of the drift can only be possible because of a very regular system of convection rolls underneath. The rolls following the drift are coupled to the layers above, the ones opposing are decoupled. Thereby the engine driving this interesting rotational drift of the plate can be explained thoroughly.

Just to clarify further how the convection rolls move the tectonic plate, this drawing is added:

The red areas provide force for the circle to move anti-clockwise in an almost circular way. As previously mentioned, the pivotal point is also a key point within the convection rolls system as a whole, due to the exact N-S alignment of convection rolls at the 32nd latitude.

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Why Convection Rolls of the Mantle Form a Regular Pattern

Steingrimur Thorbjarnarson

Convection rolls within the mantle have an adiabatic heat gradient, starting at the border between tectonic plate bottom and the layer below. Logically, the mantle must therefore as a whole be on the verge of being ductile and stagnant. A tectonic plate is 120 km thick, according to the defination that its lowermost border is where convection, or constant flow of mantle material, is found.

It has been found in laboratories, that if mantle material at this point (convecting but very close to becoming stagnant) does form convection rolls. As reality and experimental results are to be compared, especially if no other factors affecting real circumstances than used during experiment can be pointed out, inserting the outcome of experiment into known and measured circumstances is indeed a piece of work any scientist should undertake.

In this case it is easy, because the thickness of inner layers of Earth are known. Putting togherher the outcome of the experiments in laboratories, the logic of adiabadic thermal gradient, and knowledge about the depth of each layer, this is the outcome:

This is the basic picture of a section of convection rolls within the Earth. Inserting the results of experiments, fits exactly into measured environment.

Most people recognize the core, mantle and crust, and some might notice the Gutenberg layer, also known as the core-mantle boundary or CMB. This is a beginning of a study described in the book found here on this webpage. Reading that book is of course more difficult than reading this short post, and most people do certainly not have time enough to read it. It can be said here, though, that all the implications have been worked out, and how the convection rolls form a 3D system within the Earth is thereby fully understood. In turn, it enhances our overall understanding of geology.

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The Convection Rolls Model – How is it Derived?

Steingrimur Thorbjarnarson

The Convection Rolls Model has been used to explain a myriad of geological features. The starting point is easy to derive, because the layers of Earth have a regular pattern, and Rayleigh-Bénard type of convection rolls fit precisely into it.

Layers of Earth and Rayleigh-Bénard convection rolls inserted.

The convection rolls are affected by the rotation of the Earth, and the same proportions prevail farther north and south within the rotational plane. The height and width of the mantle convection rolls therefore adhere to the physics of Rayleigh-Bénard convection all over the globe.

Therefore, it was possible to derive the comprehensive or global convection rolls model, starting from the obvious match within the equatorial plane.

The match shown above is mathematical, to show that the intersection zones are really intersections between main layers. At equator, the convection rolls tend to be arranged directly above each other.

This drawing shows how the convection rolls are arranged directly above each other. It also shows secondary convection rolls within the lower mantle. The Lehmann layer of the core is omitted here. The system can then be traced northwards and southwards, and the global system derived, which is described here.

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The Eastern and Western Outposts of Icelandic Volcanoes – Snæfell and Snæfellsjökull

Steingrimur Thorbjarnarson

The two outposts of Icelandic volcanoes are both stratovolcanoes. They are outside the main volcanic zones, and do not fit with the most simplified version of Icelandic geology. One is too far to the west, the other too far to the east to match well with our most basic ideas about how Iceland is divided into its North American part and Eurasian part. The convection rolls model considered on this webpage is of course different, and according to the pattern emerging from the division lines between convection rolls, the positions become understandable. If there were no such reasons, such as convection rolls, the coincidence that those two mountains are exactly on the same latitude could not be explained. Of course it is easy just to ignore things like that, but these two volcanoes are both found on division lines between convection rolls, in a mirrored way.

It should also be mentioned that the distance from those two volcanoes to the main division line of the lower mantle, is exactly the same, when compared with the N-S axis of Hekla volcano. That means, of course, that the two Snæffells (Snæfellsjökull and Snæfell) are equidistant from Hekla. Such a coincidence can of course also be ignored, but according to this system of convection rolls, it is explainable, because Hekla does form on important crossings within the convection rolls division lines pattern. Different layers all have division lines under Hekla, four different convecting layers! The location of Hekla is therefore no coincidence, and the uppermost layer of mantle convection is upwelling underneath Hekla, making the location even more understandable. All over the world, countless similar patterns can be found, all in harmony with the convection rolls.

Snæfellsjökull, November 15th 2024.