25. júlí 2018

Töfra möttulstraumanna má finna í Þorlákshöfn

25. júlí, 2018 - Katla UNESCO Global Geopark

Þann 5. júlí síðastliðinn var opnuð jarðfræðisýning í Gallerí undir stiganum á Bæjarbókasafni Þorlákshafnar. Sýningin inniheldur myndir sem sýna legu og lýsir virkni möttulstrauma undir landinu samkvæmt úttekt sem Steingrímur Þorbjarnarson jarðfræðingur hefur unnið. Meginskil milli N-Ameríkuflekans og Evrasíuflekans liggja um Ölfusið og leitast hann við að skýra það nánar á sýningunni.

Steingrímur Þorbjarnarson er jarðfræðingur að mennt með BS-gráðu frá Háskóla Íslands og fluttist til Þorlákshafnar 2016. Steingrímur hefur kennt jarðfræði við Menntaskólann við Sund, Keili og Leiðsöguskóla Íslands. Einnig hefur hann unnið að kortlagningu á þverbrotabelti Suðurlands.

Á sýningunni er lögð áhersla á þrennt:

Í fyrsta lagi er gert grein fyrir möttulskilum sem liggja frá Ölfusi um landið þvert yfir í Skjálfandaflóa.

Í öðru lagi er straumþáttakerfið sýnt eftir 64°N, en einmitt þar kemur það fram á sérlega skýran hátt. 

Í þriðja lagi er dregið fram hvernig þverbrotabelti Suðurlands er mótað af straumþáttakerfinu og skýrir tilvist þess.


Sýningin er tímabundin og mun henni ljúka um miðjan ágústmánuð. Því fer hver að verða síðastur að rýna í þessa sérlega fróðlegu samantekt um þessa merkilegu rannsókn. 


Hægt er að skoða ítarlegt rit um rannóknina hér. Ritið er á ensku en hér að neðan má lesa ágrip úr ritgerðinni (e. abstract):

 

The convection system of Earth‘s mantle and how heat is conveyed to the surface

Abstract

A new method to calculate the direction of basic tectonic features of different latitudes is introduced. The interplay of convection cells of the Earth‘s mantle and the Coriolis effect makes possible to take this step from measurements to calculations. Two basic preconditions make it possible to trace the convection cells within the mantle. First, according to physical law, convective mantle under balanced conditions shall have equal height and width. Second, the layers of the Earth have exactly the thickness that fit to convection cells with equal height and breadth. Along the convection cells, horizontal flow must occur, also following perfectly balanced Coriolis governed path. It follows the curvature of the Earth, resulting in a circle with the same diameter as Earth‘s radius. Therefore, just to take an example, the directions of the volcanic zones of Iceland have been calculated in a very simple way.

The convection cells can then be mapped accurately for each convection layer respectively. Each layer affects the surface independently, and the effects can be traced on the surface. As a result of the mapping procedure is a grid that appears all over the world from the South Pole to the North Pole. This includes of course a map of the grid over Iceland which can be studied individually. Iceland is remarkably geologically active compared with most other areas, and that activity can be compared with the convection cell system underneath. The convection cells are found to form rolls convecting side by side, and the grid lines are drawn along the rolls to show their positions. These grid lines are also of special interest because they represent the middle zone of convective upwelling or downwelling. 

The study has taken almost two decades, taking into account many different aspects of physics not necessarily mentioned in geological literature. The flow of heat was traced from core to surface, resulting in a very convincing model showing remarkable consistency with surface features. This was checked by my father, Þorbjörn Ármann Friðriksson, according to the science of radiation. His findings explain why the core of the Earth remains much hotter than the mantle. By referring to the so called Munroe Effect he also explained how magma can flow up through the tectonic plates to the surface.

With all the heat flow process from beginning to end clarified, the distribution of volcanoes, geothermal areas, earthquake zones and topography in general can be understood in much more detail than hitherto thought possible. This will lead geology to become more a science of calculations than before. The novelty of this approach is tremendous, and necessary for us to get a holistic picture of heat flow within the Earth.

 

Steingrímur Þorbjarnarson

Oddabraut 13

Þorlákshöfn

Twitter Facebook
Til baka