The Mirrored Oblique Rift Zones of Iceland – Reykjanes Oblique Rift Zone and Grimsey Oblique Rift

Similar oblique rift zones connect the Icelandic volcanic zones with the two mid-ocean ridges, Reykjanes Ridge and Kolbeinsey Ridge. When compared, the length of those two oblique zones appears to be exactly the same, and even the shape of them is alike. Considering that those areas have the same function, as they are reacting to similar effect of the tectonic drift, it is maybe not so strange. When compared to the convection rolls model, this picture emerges:

Identical (or mirrored) oblique rift zones

If put together, these zones form a triangle with three equal sides. The tilt of the triangle corresponds to the divisional vectors of tectonic drift in Iceland. The areas have the characteristics of both volcanic and seismic zones. Reykjanes Oblique Rift Zone is much better known, as it is largely found on land, but the part of it found offshore seems often to be neglected. Recently, more information has been gathered about the Grimsey Oblique Rift, often referred to as the Grimsey Lineament or the Grimsey Seismic Zone.

The end points of both oblique rift zones can be compared, as in the South, the main division line over Iceland is directly E-W oriented, whereas the end point in the North connects to a line directly N-S oriented. The other end points connects the zones with the regularly shaped mid-ocean ridges. The bending of the oblique zones takes place within the grid of polygons in a formidable way. Following the division between tectonic plates along the Reykjanes Ridge looks easy, as it follows one single line with a simple formula. Then is starts bending off the track, leading to the formation of Reykjanes Oblique Rift Zone. Then the E-W part takes over, with the South Iceland Seismic Zone and the East Volcanic Zone, respectively. Following the division along the eastern edge of the East Volcanic Zone leads us to the turning point at Kverkfjöll. Then we have a direct N-S line through the central axis of the North Volcanic Zone, all the way to the Öxarfjordur Bay, where a sharp turn is made for the Grímsey Oblique Rift. As has been dealt with in other posts, there are other faults of the Tjörnes Fracture Zone making the situation out of the north coast of Iceland more complicated, with a triple system of the Dalvik Lineament, Husavik-Flatey Lineament along with the Grímsey Lineament (here dealt with as Grímsey Oblique Rift Zone). From the end point, where a volcano called Storagrunn, the Zone is connected with Kolbeinsey Ridge, completing the main division line between the N-American Tectonic Plate and the Eurasian Tectonic Plate.

Some material about this subject is found here:



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