Bedrock in Central Asia that would have formed mountains instead was sand-blasted into dust, said lead author Paul Kapp.
"No one had ever thought that wind could be this effective," said Kapp, an associate professor in the UA's department of geosciences. "You won't read in a textbook that wind is a major process in terms of breaking down rock material."
Rivers and glaciers are the textbook examples of forces that wear down mountains and influence their evolution.
Wind can be just as powerful, Kapp said. He and his colleagues estimate wind can be 10 to 100 times more effective in eroding mountains than previously believed.
The team's paper, "Wind erosion in the Qaidam basin, central Asia: implications for tectonics, paleoclimate, and the source of the Loess Plateau," is in the April/May issue of GSA Today.
Kapp's co-authors are Jon D. Pelletier and Joellen Russell of the UA; Alexander Rohrmann, formerly of the UA and now at the University of Potsdam in Germany; Richard Heermance of California State University, Northridge; and Lin Ding of the Chinese Academy of Sciences, Beijing.
The American Chemical Society Petroleum Research Fund and a UA Faculty Small Grant funded the research.
The geoscientists figured out wind's rock-sculpting abilities by studying gigantic wind-formed ridges of rock called yardangs.
Kapp first learned about yardangs when reviewing a scientific paper about Central Asia's Qaidam Basin. To see the geology for himself, he booted up Google Earth–and was wowed by what he saw.
"I'd never seen anything like that before," he said. "I didn't even know what a yardang was."
Huge fields of yardangs that can be seen from space look like corduroy. Wind had scoured long gouges out of the bedrock, leaving the keel-shaped ridges behind. Kapp wondered where the missing material was.
The team's initial research was conducted using geological maps of the region and satellite images from Google Earth. Then Kapp and his team went to the Qaidam Basin to collect more information about the yardangs, the history of wind erosion and the dust.
"What we're proposing is that during the glacials, when it's colder and drier, there's severe wind erosion in the Qaidam basin and the dust gets blown out and deposited downwind in the Loess Plateau," Kapp said.
The term "loess" refers to deposits of wind-blown silt. Parts of the U.S. Midwest have large deposits of loess.
"Up until 3 million years ago, the basin was filling up with sediment," he said. "Then like a switch, the wind turned on and basin sediments get sandblasted away."
Known as the "bread basket of China," the Loess Plateau is the largest accumulation of dust on Earth. Scientists thought most of the dust came from the Gobi Desert.
In contrast, Kapp and his colleagues suggest more than half of the dust came from the Qaidam Basin. Co-author Pelletier, a UA geomorphologist, created a computer model indicating that dust from the basin could have formed the plateau.
The wind is not having such effects now because the climate is different, Kapp said. Co-author Russell plus other research groups suggest the westerly winds shift north during interglacial periods like that of the current climate and shift toward the equator during glacial periods.
Therefore since the last Ice Age ended about 11,000 years ago, the winds have blown from the Gobi Desert toward the Loess Plateau. During glacial periods, the winds blew from the Qaidam basin toward the Loess Plateau instead.
"During the interglacials, the basin fills up with lakes. ... When it goes back to a glacial period, lake sediments blow away," he said. "Our hypothesis is that you have lake development, then wind erosion, lake development, wind erosion, lake development–and so on."
The team suggests wind erosion also influenced how fast the basin's bedrock is folded. In Central Asia, bedrock folds and crumples because it's being squeezed as the Indian plate collides with the Asian plate.
"The folding accelerated 3 million years ago," Kapp said. "That's when the wind erosion turned on. I don't think it's a coincidence."
During the glacial periods, the winds whisked sediment out of the basin. As a result, the bedrock deformed faster because it was no longer weighed down by all the sediment.
Kapp calls the process "wind-enhanced tectonics." The term "tectonics" refers to forces that cause movements and deformation of the Earth's plates.
The whole process is driven by global climate change, he said. "The unifying theme is wind."
Kapp and his team are quantifying the processes further as they analyze more samples they brought back from the Qaidam basin and Loess Plateau.Researcher contact:
Mari N. Jensen | University of Arizona
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy