Researchers for the first time have attempted to measure all the material leaving and entering a mountain range over more than a million years and discovered that erosion caused by glaciation during ice ages can, in the right circumstances, wear down mountains faster than plate tectonics can build them.
The international study conducted by the Integrated Ocean Drilling Program and led by scientists from the University of Florida, The University of Texas at Austin and Oregon State University, adds insight into a longstanding debate about the balance of climate and tectonic forces that influence mountain building. It is published today in the Proceedings of the National Academy of Sciences.
Researchers studied the St. Elias Mountains on the Alaskan coast and found that erosion accelerated sharply about 1 million years ago when global climate cooling triggered stronger and more persistent ice ages than times past.
"Humans often see mountain ranges as static, unyielding parts of the landscape,” said co-chief scientist John Jaeger, an associate professor of geology at the University of Florida. “But our work has shown that they are actively evolving along with, and responding to, Earth's climate, which just shows how truly dynamic and coupled this planet is."
The study, conducted by a team of scientists from 10 countries, culminated more than a decade of field work. Researchers first used seismic equipment to image and map a huge fan of sediment in the deep sea in the Gulf of Alaska caused by erosion of the nearby mountains and took short sediment cores to understand the modern system.
They then collected and dated almost 4 kilometers of sediment from the floor of the gulf and the Alaskan continental shelf, revealing millions of years of geologic history.
“It turned out most [sediments] were younger than we anticipated, and most rates (of sediment production and thus erosion) were higher than we anticipated,” said lead author and co-chief scientist Sean Gulick of the University of Texas Institute for Geophysics, a unit of the Jackson School of Geosciences.
“Since the big climate change during the mid-Pleistocene transition when we switched from short (about 40,000-year) ice ages to super-long (about 100,000-year) ice ages, erosion became much greater... In fact, there was more erosion than tectonics has replaced.”
“We were pleasantly surprised by how well we could establish ages of the sediment sequences as we were drilling, and the composition of the sediment gave clear evidence of when the glaciation started and then expanded, in synch with global climate trends over the past several million years,” said co-author Alan Mix of Oregon State University. “Only by drilling the sea floor where the sediment accumulates could we see these details.”
Mountain ranges form when tectonic plates thrust into one another over millions of years and scrunch up the Earth’s outer crust. But even as mountains are built by these titanic forces, other agents -- some combination of tectonic and climate processes -- work to remove the accumulating crust.
Since the mid-Pleistocene, erosion rates have continued to beat tectonic inputs by 50 to 80 percent, demonstrating that climatic processes, such as the movement of glaciers, can outstrip mountain building over a span of a million years. The findings highlight the pivotal role climate fluctuations play in shaping Earth’s landforms.
The study was funded by the U.S. National Science Foundation and the Integrated Ocean Drilling Program.
Writer: Steve Orlando, 352-846-3903
Source: John Jaeger, 352-846-1381, firstname.lastname@example.org
Steve Orlando | newswise
Multi-year submarine-canyon study challenges textbook theories about turbidity currents
12.12.2017 | Monterey Bay Aquarium Research Institute
How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas
11.12.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences