processtore.blogg.se

When glaciers melt, a tremendous weight is lifted from the ground that once supported them. “Another significant thing is that the viscosity is higher beneath the southern part of the Southern Patagonia Icefield compared to the Northern Patagonia Icefield, which helps to explain why uplift rates vary from north to south,” he said. “This explains why GPS has measured large uplift due to the loss of ice mass. “Low viscosities mean that the mantle responds to deglaciation on the time scale of tens of years, rather than thousands of years, as we observe in Canada for example,” Wiens said. These particular mantle conditions are driving many of the recent changes that have been observed in Patagonia, including the rapid uplift in certain areas once covered by ice. The scientists found very low seismic velocity within and around the gap, as well as a thinning of the rigid lithosphere overlying the gap. The seismic data that Mark and Wiens analyzed reveals how a gap in the down-going tectonic plate about 60 miles beneath Patagonia has enabled hotter, less viscous mantle material to flow underneath South America.Ībove this gap, the icefields have been shrinking, removing weight that previously caused the continent to flex downward. Mark is now a postdoctoral investigator at the Woods Hole Oceanographic Institution. “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,” said Hannah Mark, a former Steve Fossett postdoctoral fellow in earth and planetary sciences at Washington University, the first author of the publication. In a new publication in the journal Geophysical Research Letters, they describe and map out local subsurface dynamics. Brookings Distinguished Professor in Arts & ­Sciences, recently completed one of the first seismic studies of the Patagonian Andes. Louis, led by seismologist Douglas Wiens, the Robert S. Scientists at Washington University in St. Geologists have discovered a link between recent ice mass loss, rapid rock uplift and a gap between tectonic plates that underlie Patagonia.