The icefields that stretch for hundreds of miles atop the Andes mountain range in Chile and Argentina are melting at a rate that is some of the fastest on the planet. As the glaciers disappear, the ground beneath them is shifting. A link has been found between recent ice mass loss, rapid rock loss and a gap between plates in Argentina.
One of the first seismic studies of the Patagonian Andes was completed by the scientists at Washington University. They describe and map out local dynamics in a new publication.
Hannah Mark, a former Steve Fossett postdoctoral fellow, said that variations in the size of glaciers as they grow and shrink, combined with the mantle structure that we've imaged in this study are driving rapid and spatially variable uplift in this region. Mark is working at the Woods Hole Oceanographic Institution.
The data that Mark and Wiens analyzed shows how a 60 mile gap in the down-going tectonic plate has allowed hotter, less viscous mantle material to flow underneath South America.
The icefields have shrunk above the gap, removing the weight that had caused the continent to flex downward. The scientists found 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299 888-353-1299
Many of the recent changes that have been observed in Patagonia are being driven by these particular mantle conditions.
The mantle responds to deglaciation on the time scale of tens of years, rather than thousands of years, as we observe in Canada.
He said that the southern part of the Southern Patagonia Icefield has a higher viscosity than the northern part.
Increasing in strength and then decreasing in strength and then increasing in strength and then decreasing in strength and then increasing in strength and then decreasing in strength and then increasing in strength and then decreasing in strength and then increasing in strength and then decreasing in strength and then increasing in strength and then increasing in strength
The weight is lifted from the ground when glaciers melt. Huge amounts of water are moving toward the ocean. The earth rebounded and rose.
There is evidence of ice mass changes in places all over the world.
Predicting sea level rise under future climate warming scenarios is affected by the ongoing movement of land.
Mark said that one of the most interesting things they discovered in this study was that the hottest parts of the mantle were found below the part of the icefields that had opened up recently.
Mark suggests that the mantle dynamics associated with the slab window may have intensified over time, or that the continental plate in the south started out thicker and colder than the part of the plate farther north.
The National Science Foundation funded the study and Mark and Wiens worked with colleagues from other universities to complete it.
It is a remote area that is not densely populated and has low earthquake hazard, which helps explain why few studies have been done in this area in the past. The data he and his team collected is being used for other purposes.
More than 25 years ago, Wiens first visited the region. He said that he is shocked by the changes he has seen.
The beautiful glaciers are being reduced in size as the ice fronts retreat. I can easily see that the glaciers have shrunk.
There are ups and downs of field work.
A group of Washington University students helped Wiens and his team service and collect data from the seismographs that were installed for this study as part of a field trip led by Phil Skemer and Alex Bradley in the Department of Earth and Planetary Sciences. During their spring break, the students had the chance to experience the geology of the region and learn about the effects of glaciers.
International travel ground to a halt after the coronaviruses hit.
The instruments weren't returned in April 2020 as planned because they were trapped in Argentina and Chile.
He said that the seismographs operated well without any servicing over this time, so we collected about 10 months more data than originally planned.
Knowing more about what's happening below the ground is important for monitoring future changes.
Mark said that one thing they can do now is incorporate the 3D mantle structure into a model for glacier isostatic adjustment.
The properties of the deep earth are important for understanding how the land responds to glaciation.
More information: Hannah F. Mark et al, Lithospheric Erosion in the Patagonian Slab Window, and Implications for Glacial Isostasy, Geophysical Research Letters (2022). DOI: 10.1029/2021GL096863 Journal information: Geophysical Research Letters Citation: Seismic study reveals key reason why Patagonia is rising as glaciers melt (2022, February 28) retrieved 28 February 2022 from https://phys.org/news/2022-02-seismic-reveals-key-patagonia-glaciers.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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