PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Magnetic field, mantle convection and tectonics

2012-07-30
(Press-News.org) On a time scale of tens to hundreds of millions of years, the geomagnetic field may be influenced by currents in the mantle. The frequent polarity reversals of Earth's magnetic field can also be connected with processes in the mantle. These are the research results presented by a group of geoscientists in the new advance edition of "Nature Geoscience" on Sunday, July 29th. The results show how the rapid processes in the outer core, which flows at rates of up to about one millimeter per second, are coupled with the processes in the mantle, which occur more in the velocity range of centimeters per year. The international group of scientists led by A. Biggin of the University of Liverpool included members of the GFZ German Research Centre for Geosciences, the IPGP Paris, the universities of Oslo and Utrecht, and other partners.

It is known that the Earth's magnetic field is produced by convection currents of an electrically conducting iron-nickel alloyin the liquid core, about 3,000 kilometers below the earth's surface. The geomagnetic field is highly variable, there are changes in Earth's magnetic field on a multitude of spatial and temporal scales. Above the liquid outer core is the mantle, the rock in which behaves plastically deformable due to the intense heat and high pressure. At the boundary between Earth's core and mantle at 2900 km depth there is an intense heat exchange, which is on the one hand directed from the Earth's core into the mantle. On the other hand, processes within Earth's mantle in turn also affect the heat flow. The interesting question is how the much slower flow in the solid mantle influences the heat flow and its spatial distribution at the core-mantle boundary, and how this will affect the Earth's magnetic field which is produced due to the much faster currents in the Earth's core.

/Key variable heat transfer/ "The key variable is the heat flow. A cooler mantle accelerates the flow of heat from the hot core of the Earth, and in this way alters the also heat-driven convection in the Earth's core", said Bernhard Steinberger of the GFZ German Research Centre for Geosciences. "Ocean floor sinking into the mantle due to tectonic processes can lead to cooling in the mantle. They cause at these sites an increased heat flow into the cooler parts, namely until they have been heated to the ambient temperature." That might take several hundred million years, however.

Conversely, the hot core of the Earth leads to the ascent of heated rocks in form of large bubbles, so-called mantle plumes that separate from the core-mantle boundary and make their way up to the surface of the earth. This is how Hawaii came into existence. This increases the local heat flux out of the earth's core and in turn modifies the generator of the geomagnetic field.

/Reversals of the magnetic field/ In the Earth's history, polarity reversals of the geomagnetic field are nothing extraordinary. The most recent took place only 780 000 years ago, geologically speaking a very short period of time. The research team was able to determine that in the period of 200 to 80 million years before present, reversals initially happened more often, namely up to ten times in hundred million years. "Surprisingly, these reversals stopped about 120 million years ago and were absent for nearly 40 million years," explains GFZ scientist Sachs. Scientists presume that the reason for this is a concurrent reorientation of the whole mantle and crust with a shift in the geographic and magnetic poles of about 30°. Known as "true polar wander", thisprocess is caused by a change in density distribution in the mantle. If it increases the heat flux in equatorial regions, it would presumably lead to more frequent field reversals, if it decreases it, the field reversal might not occur.

/Looking to the future/ According to current knowledge, therefore, an influence of plate tectonics and mantle convection on the Earth's magnetic field seems quite possible. The article also shows, however, that further research is still needed for a better understanding of these relationships. In particular, more episodes of "true polar wander" should be derived from paleomagnetic data, and it should be determined whether these are usually associated with an altered behavior of the magnetic field (e.g. frequency of field reversal). Also, future models for the generation of the geomagnetic field should investigate the influence of the spatial and temporal variation of the heat flux at the core-mantle boundary in more detail.

### J. Biggin et al., "Possible links between long-term geomagnetic variations and whole-mantle convection processes", Nature Geoscience, Vol. 5, August 2012, doi:10.1038/NGEO1521

Images in printable resolution and an animation can be found at: http://www.gfz-potsdam.de/portal/gfz/Public+Relations/M40-Bildarchiv/Magnetfeld_Waermefluss

contact : Dr. Bernhard Steinberger, +49-331-288 1881


ELSE PRESS RELEASES FROM THIS DATE:

BGI reports the latest finding on NMNAT1 mutations linked to Leber congenital amaurosis

2012-07-30
July 29th, 2012, Shenzhen, China – A five-country international team, led by Casey Eye Institute Molecular Diagnostic laboratory, BGI and Zhejiang University School of Medicine First Affiliated Hospital identified the NMNAT1 mutations as a cause of Leber congenital amaurosis (LCA), one of the most common causes of inherited blindness in children. The latest study was published online in Nature Genetics, reporting the genetic characteristics underlying some LCA patients, and providing important evidences that support NMNAT1 as a promising target for the gene therapy of LCA. LCA ...

Chronic 2000-04 drought, worst in 800 years, may be the 'new normal'

2012-07-30
CORVALLIS, Ore. – The chronic drought that hit western North America from 2000 to 2004 left dying forests and depleted river basins in its wake and was the strongest in 800 years, scientists have concluded, but they say those conditions will become the "new normal" for most of the coming century. Such climatic extremes have increased as a result of global warming, a group of 10 researchers reported today in Nature Geoscience. And as bad as conditions were during the 2000-04 drought, they may eventually be seen as the good old days. Climate models and precipitation projections ...

Breakthrough by U of T-led research team leads to record efficiency for next-generation solar cells

2012-07-30
TORONTO, ON – Researchers from the University of Toronto (U of T) and King Abdullah University of Science & Technology (KAUST) have made a breakthrough in the development of colloidal quantum dot (CQD) films, leading to the most efficient CQD solar cell ever. Their work is featured in a letter published in Nature Nanotechnology. The researchers, led by U of T Engineering Professor Ted Sargent, created a solar cell out of inexpensive materials that was certified at a world-record 7.0% efficiency. "Previously, quantum dot solar cells have been limited by the large internal ...

Researchers analyze melting glaciers and water resources in Central Asia

2012-07-30
After the fall of the Soviet Union twenty years ago, water distribution in Central Asia became a source of conflict. In areas where summer precipitation is low, glaciers play an important role when considering the quantity of available water. The Tien Shan region is a prime example; mountain glaciers in this region contribute significantly to the fresh water supply in the arid zones of Kyrgyzstan, Kazakhstan, Uzbekistan, Turkmenistan, and Northwestern China. Like Switzerland, Kyrgyzstan serves as a water tower for its neighboring countries. While the impact of climate ...

When the world burned less

When the world burned less
2012-07-30
SALT LAKE CITY, July 30, 2012 – In the years after Columbus' voyage, burning of New World forests and fields diminished significantly – a phenomenon some have attributed to decimation of native populations by European diseases. But a new University of Utah-led study suggests global cooling resulted in fewer fires because both preceded Columbus in many regions worldwide. "The drop in fire [after about A.D. 1500] has been linked previously to the population collapse. We're saying no, there is enough independent evidence that the drop in fire was caused by cooling climate," ...

'... But names could really hurt me'

2012-07-30
HAMILTON, ON (July 30, 2012) – Child abuse experts say psychological abuse can be as damaging to a young child's physical, mental and emotional health as a slap, punch or kick. While difficult to pinpoint, it may be the most challenging and prevalent form of child abuse and neglect, experts say in an American Academy of Pediatrics (AAP) position statement on psychological maltreatment in the August issue of the journal Pediatrics. Psychological abuse includes acts such as belittling, denigrating, terrorizing, exploiting, emotional unresponsiveness, or corrupting a child ...

What would happen without PSA testing?

2012-07-30
A new analysis has found that doing away with PSA (prostate specific antigen) testing for prostate cancer would likely cause three times as many men to develop advanced disease that has spread to other parts of the body before being diagnosed. Published early online in CANCER, a peer-reviewed journal of the American Cancer Society, the study suggests that PSA testing and early detection may prevent approximately 17,000 men each year from having such advanced prostate cancer at diagnosis. PSA testing has come under fire recently as a potentially ineffective screen for ...

Would sliding back to pre-PSA era cancel progress in prostate cancer?

2012-07-30
Eliminating the PSA test to screen for prostate cancer would be taking a big step backwards and would likely result in rising numbers of men with metastatic cancer at the time of diagnosis, predicted a University of Rochester Medical Center analysis published in the journal, Cancer. The URMC study suggests that the prostate-specific antigen (PSA) test and early detection may prevent up to 17,000 cases of metastatic prostate cancer a year. Data shows, in fact, that if age-specific pre-PSA era incidence rates were to occur in the present day, the number of men whose cancer ...

Surgical patient safety program lowers SSIs by one-third following colorectal operations

2012-07-30
Chicago—(July 30, 2012): A surgical patient safety program that combines three components—accurate outcome measurement, support of hospital leadership, and engaged frontline providers—reduces surgical site infections (SSIs) by 33 percent in patients who undergo colorectal procedures, according to a new study published in the August issue of the Journal of the American College of Surgeons. SSIs are the most common complication for this high-risk population, occurring in 15 to 30 percent of patients after colorectal operations, according to the study authors. "Colorectal ...

Author Publishes New Kid's Adventure - The Scarecrow

2012-07-30
Author Max Elliot Anderson has published his 10th adventure book for children 8 - 13, The Scarecrow. "The Scarecrow is the first of my books to carry a stronger Christian message as part of the plot and story," Anderson said. "My primary intent in writing The Scarecrow is to provide an exciting book for readers 8 - 13, that can be used with confidence by parents, churches, children's ministries, homeschoolers, Christian schools, and others who wish to reach out to kids with this unique tool." The Scarecrow can also be given as a gift to a hurting ...

LAST 30 PRESS RELEASES:

A third of licensed GPs in England not working in NHS general practice

ChatGPT “thought on the fly” when put through Ancient Greek maths puzzle

Engineers uncover why tiny particles form clusters in turbulent air

GLP-1RA drugs dramatically reduce death and cardiovascular risk in psoriasis patients

Psoriasis linked to increased risk of vision-threatening eye disease, study finds

Reprogramming obesity: New drug from Italian biotech aims to treat the underlying causes of obesity

Type 2 diabetes may accelerate development of multiple chronic diseases, particularly in the early stages, UK Biobank study suggests

Resistance training may improve nerve health, slow aging process, study shows

Common and inexpensive medicine halves the risk of recurrence in patients with colorectal cancer

SwRI-built instruments to monitor, provide advanced warning of space weather events

Breakthrough advances sodium-based battery design

New targeted radiation therapy shows near-complete response in rare sarcoma patients

Does physical frailty contribute to dementia?

Soccer headers and brain health: Study finds changes within folds of the brain

Decoding plants’ language of light

UNC Greensboro study finds ticks carrying Lyme disease moving into western NC

New implant restores blood pressure balance after spinal cord injury

New York City's medical specialist advantage may be an illusion, new NYU Tandon research shows

Could a local anesthetic that doesn’t impair motor function be within reach?

1 in 8 Italian cetacean strandings show evidence of fishery interactions, with bottlenose and striped dolphins most commonly affected, according to analysis across four decades of data and more than 5

In the wild, chimpanzees likely ingest the equivalent of several alcoholic drinks every day

Warming of 2°C intensifies Arctic carbon sink but weakens Alpine sink, study finds

Bronze and Iron Age cultures in the Middle East were committed to wine production

Indian adolescents are mostly starting their periods at an earlier age than 25 years ago

Temporary medical centers in Gaza known as "Medical Points" (MPs) treat an average of 117 people daily with only about 7 staff per MP

Rates of alcohol-induced deaths among the general population nearly doubled from 1999 to 2024

PLOS One study: In adolescent lab animals exposed to cocaine, High-Intensity Interval Training boosts aversion to the drug

Scientists identify four ways our bodies respond to COVID-19 vaccines

Stronger together: A new fusion protein boosts cancer immunotherapy

Hidden brain waves as triggers for post-seizure wandering

[Press-News.org] Magnetic field, mantle convection and tectonics