Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dust could settle Himalaya debates

14.03.2002


Great loess: layers of ancient dust give clues to mountains’ birth.
© Nature


Deserts covered Central Asia as early as 22 million years ago

The great Asian deserts developed 22 million years ago at the latest, 14 million years earlier than had been thought. So concludes a new analysis of Chinese soils, filling in another piece of the puzzle of the Himalayas’ birth.

Today, huge deserts characterize the vast landmasses inside Asia, the largest continent on Earth. Here, cut off by the Himalayas from the humidity of the Indian Ocean and far from any other seas, the climate is extreme. Winters are ice-cold, summers blazing hot and moisture scarce.



But some time between 36 and 22 million years ago, rivers flowed through these desiccated wastelands. The Himalayas had just started pushing up into the skies. And colliding continents had only recently swallowed the ancient equatorial ocean of Tethys, which had separated Eurasia from the fragments of what was once Gondwanaland.

The transition between these very different climates happened at least 22 million years ago, estimate Zhentang Guo of the Chinese Academy of Sciences and co-workers1. At two mountain sites in China’s Qinan basin, just 160 km northeast of the Tibetan plateau, the researchers found 231 layers of ancient, brownish, wind-blown dust, called loess.

The loess was deposited from 22 to 6.2 million years ago between layers of red clay. Each layer contains about 65,000 years’ worth of deposits. Such large layers imply that extensive deserts existed nearby: the Asian interior.

"The deserts would have been relatively cold, like the Gobi today, as opposed to the Sahara," explains Bill Ruddiman of the University of Virginia, one of the team. Cold, dry, winter monsoon winds transported the desert dusts to their long-term resting place.

The Qinan basin’s stripy landscape was produced by a climate of dry winter monsoons punctuated by moist summer monsoons. The reddish clay layers were produced locally during more humid periods, when weaker winter monsoons meant that desert dust didn’t make it to the Loess plateau, the researchers believe.

"To block the moisture, there must have been some sort of a mountain range in place 22 million years ago", says Jay Quade, a desert geoscientist at the University of Arizona in Tucson. The existence of the central Asian deserts 22 million years ago offers an independent perspective on the uplift of the Himalayas, the details of which are still controversial.

Before now, little was known about the region’s climate that far back in time. Most of the studies on Chinese loess have centred on the Quaternary period, less than 1.6 million years ago. Previously, the oldest reliably dated loess finds were only about 6 million years old.

References

  1. Guo, Z. T. et al. Onset of Asian desertification by 22 Myr ago inferred from loess deposits in China. Nature, 416, 159 - 163 , (2002).

HEIKE LANGENBERG | © Nature News Service

More articles from Earth Sciences:

nachricht Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

nachricht Modeling magma to find copper
13.01.2017 | Université de Genève

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>