The most apparent geothermal areas in Greenland are found around Scoresbysund. Considering the second layer of convection rolls, the areas in Greenland are found as a continuation of the volcanically and geothermally active zones of Iceland. No one expects underlying connection in that direction, because the upper most convection rolls mark the main trend of tectonic alignment in Iceland. In this way, the exceptional activity level in Iceland makes itself felt in Greenland too.
The numbered convection rolls are leading to: 1) West Volcanic Zone, 2) Mid Iceland Belt, 3) East Volcanic Zone, 4) North Volcanic Zone.
The geothemal areas at Disko are subject to similar effect, being exactly 30° farther to the west. The area is much older, and the main division line there is weaker, as the rifting process of Baffin Bay ceased a long time ago, which is explained here: https://en.wikipedia.org/wiki/Canadian_Arctic_Rift_System.
Basalt is mainly found in two areas of Greenland, in the western and eastern parts. These are found at similar latitude, and 30° apart. The convection rolls of lower mantle span 30° from east to west, so this leads attention to the history of tectonic events in the geological history of Greenland.
The separation from Baffinland and the Jan Mayen Ridge occurred due to the effect of two different hubs of convection rolls division lines (division lines of different layers coincide there). This occurred a long time ago, so these areas have drifted away from those hubs. One is now near Nuuk and the other under Iceland.
To understand the background of this, we have to keep in mind that the Baffin Bay was formed first and the northernmost part of the Atlantic second. Let us have a look at the position of Greenland 60 million years ago when the Baffin Bay was forming:
Because of this, most geoloscientists think that a ‘hot spot’ did travel from W-Greenland to E-Greenland and from there to Iceland. The actual story, according to the convection rolls model, is different. First, a division line of lower mantle opened up the Baffin Bay, resulting in eastwards drift of Greenland. Then the other main division line, 30° farter to the east, where Iceland is now located, became more active. The N-Atlantic started to form with the development of the Ægir Ridge. Greenland started drifting along the track which has been measured accurately with GPS technology. https://www.lmi.is/static/files/utgefid_efni/Maelingar/isnet_endurmael_2016_skyrsla.pdf . According to the drift vectors in that report, Scoresbysund of Greenland has been drifting to the NW from the volcanically active center of Iceland for about 40 million years, as stated in this paper: https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/0158.pdf. Therefore, the geoscientis seem to be a bit mistaken, counting these two ‘hot spots’ as one, and secondly, is has to be noticed that convection rolls division lines carry heat to these areas still today, and should not be thought of as ‘hot spot tracks’, as that is misleading.
The central area of the largest glacier of Europe, Vatnajökull, can be compared directly with the division lines of the convection rolls. Here are some details:
1) Firstly, the Vatnajökull large scale polygon, with upwelling division lines at the eastern side and downwelling ones at the western side, is almost entirely covered with ice. The combination of weather system and the mountain range has resulted in accumulation of a glacier in this area. The surroundings show resemblance with the system of convection rolls matrix underneath. 2) Öræfajökull volcano covers the main intersection point. 3) Grímsvötn volcanic area is found in context with the western mini-polygon. 4) Kverkfjöll volcano fits with the northern mini-polygon. 5) Skeiðarárjökull glacier tongue is rooted at the SW border line. 6) Skaftárjökull section forms a semi-circle east of the Grímsvötn corner. 7) Bárðarbunga has its own foothold with a caldera, along with Dyngjujökull outlet towards the north. 8) Brúarjökull covers the area between Kverkfjöll and the eastern edge in the NE. 9) A long mountain range over two polygons where mantle rolls division line coincides with the edge of the glacier.
The SW part of central polygon shows the same NW trend around Skeiðarárjökull as for the SE side of the same large scale central polygon.
The glacier has of course no direct connection with the convection rolls underneath, but it works like a marker pen for highlighting the geological conditions.
In an interesting article by H. Thybo and I.M. Artemieva, (Moho and magmatic underplating in continental lithosphere, published inTectonophysics, 2013) it is considered that there are connections between the three ridges, Baffin Bay Ridge, Greenland-Iceland Ridge and Faroe-Iceland Ridge. They study various types of the so called underplating within the tectonic plates.
Thybo and Artemia say that ‘Anomalous crust of the Greenland–Iceland Ridge may extend to the Faroe–Iceland Ridge and possibly also form the Baffin Bay Ridge.’
Here are the three ridges connected with lines drawn on Google Map:
The black line is only drawn to show the positional relationship between the three ridges. The red squares show the approximate location of the ridges. Baffin Bay Ridge to the left, Greenland-Iceland Ridge in the middle and Faroe-Iceland Ridge to the right.
According to the model of convection rolls presented here, volcanic anomalies develop due to the effect of convection rolls effect on the tectonic plates. The complex pattern of currents underneath Iceland, along with the tectonic drift, causes the exceptional activity level of volcanoes and geothermal areas.
Geologists did search for a hotspot of Iceland, and came to the conclusion it should be found under Vatnajökull. This is a very active area, as two main volcanic zones meet there (East Volcanic Zone and North Volcanic Zone). The different trends of NE-SW fractures and NS fractures meet there, and the large volcanic sites of Grímsvörn, Bárðarbunga and Kverkfjöll are found there. Magma, specially from Bárðarbunga and Grímsvötn, has been found to flow far into the nearby polygons, causing vast eruptions. The hotspot is here seen as an active part of the interplay between convection rolls division lines, local rifting of the polygons and the effect of large scale tectonic drift of the tectonic plates of N-America and Eurasia.