A seismic station on the Greenland Ice Sheet set up by authors. Snow build-up in one year is ~1.5 m, and the photovoltaic panels are buried in the snow. Snow elimination and upkeep are done by hand by a number of individuals. Credit: Genti Toyokuni
A group of scientists comprehends more about the melting of the Greenland ice sheet. They found a circulation of hot rocks, referred to as a mantle plume, increasing from the core-mantle limit below main Greenland that melts the ice from listed below.
The outcomes of their two-part research study were released in the Journal of Geophysical Research.
“Knowledge about the Greenland plume will bolster our understanding of volcanic activities in these regions and the problematic issue of global sea-level rising caused by the melting of the Greenland ice sheet,” stated Dr. Genti Toyokuni, co-author of the research studies.
The North Atlantic area is awash with geothermal activity. Iceland and Jan Mayen consist of active volcanoes with their own unique mantle plumes, whilst Svalbard — a Norwegian island chain in the Arctic Ocean — is a geothermal location. However, the origin of these activities and their interconnectedness has actually mostly been undiscovered.
The research study group found that the Greenland plume increased from the core-mantle limit to the mantle shift zone below Greenland. The plume likewise has 2 branches in the lower mantle that feed into other plumes in the area, providing heat to active areas in Iceland and Jan Mayen and the geothermal location in Svalbard.
A schematic diagram revealing the primary tectonic functions and mantle plumes below Greenland and the surrounding areas. Vp = P wave speed; MAR = the Mid-Atlantic Ridge; MTZ = the mantle shift zone (410-660 km depths); CMB = the core-mantle limit at 2889 km depth. Credit: Tohoku University
Their findings were based upon measurements of the 3-D seismic speed structure of the crust and entire mantle below these areas. To acquire the measurements, they utilized seismic topography. Numerous seismic wave arrival times were inverted to acquire 3-D pictures of the underground structure. The approach works likewise to a CT scan of the body.
Toyokuni had the ability to use seismographs he set up on the Greenland ice sheet as part of the Greenland Ice Sheet Monitoring Network. Set up in 2009, the task sees the cooperation of scientists from 11 nations. The United States-Japan joint group is mainly accountable for the building and construction and upkeep of the 3 seismic stations on the ice sheet.
A map view of P wave speed tomography at 5 km depth below Greenland and surrounding areas (left). Blue and red colors represent low and high speed perturbations, respectively, whose scale (in %) is revealed next to the map. The white dotted lines are the thermal tracks of Iceland and Jan Mayen plumes that are impacted by the Greenland plume. The location surrounded by the black dotted lines is where the circulation, triggered by melting at the bottom of the ice sheets, exists (Northeast Greenland Ice Stream); its water source lies at the crossway of the 2 heat tracks. A vertical cross-section of whole-mantle tomography travelling through main Greenland and Jan Mayen (right). We can see that the Greenland plume is the heat source for the Jan Mayen volcano. Credit: Tohoku University
Looking ahead, Toyokuni wants to check out the thermal procedure in more information. “This study revealed the larger picture, so examining the plumes at a more localized level will reveal more information.”
References:
“P Wave Tomography Beneath Greenland and Surrounding Regions: 1. Crust and Upper Mantle ” by Genti Toyokuni, Takaya Matsuno and Dapeng Zhao, 31 October 2020, Journal of Geophysical Research – Solid Earth.
DOI: 10.1029/2020JB019837
“P Wave Tomography Beneath Greenland and Surrounding Regions: 2. Lower Mantle ” by Genti Toyokuni, Takaya Matsuno and Dapeng Zhao, 30 October 2020, Journal of Geophysical Research – Solid Earth.
DOI: 10.1029/2020JB019837
