(Press-News.org) The Earth's mantle and its core mix at a distance of 2900 km under our feet in a mysterious zone. A team of geophysicists has just verified that the partial fusion of the mantle is possible in this area when the temperature reaches 4200 Kelvin. This reinforces the hypothesis of the presence of a deep magma ocean. The originality of this work, carried out by the scientists of the Institut de minéralogie et de physique des milieux condensés (UPMC/Université Paris Diderot/Institut de Physique du Globe/CNRS/IRD), lies in the use of X-ray diffraction at the European Synchrotron Radiation Facility in Grenoble (France). The results will have an effect in the understanding of the dynamics, composition and the formation of the depths of our planet.
On top of the core of the Earth, constituted of liquid iron, lies the solid mantle, which is made up essentially of magnesium oxides, iron and silicon. The border between the core and the mantle, located at 2900 km under our feet, is highly intriguing to geophysicists. With a pressure of around 1.4 million times the atmospheric pressure and a temperature of more than 4000 Kelvin, this zone is the home to chemical reactions and changes in states of matter still unknown. The seismologists who have studied this subject have acknowledged an abrupt reduction of the speed of the seismic waves, which sometimes reach 30% when getting close to this border. This fact has led scientists to formulate the hypothesis, for the last 15 years, of the partial melting of the Earth mantle at the level of this mantle-core border. Today it has been confirmed.
In order to access the depths of the Earth, scientists have not only seismological images but also a precious experimental technique: diamond anvil cells, coupled with a heating layer. This instrument allows to re-create the same pressure and temperature condition than those in the interior of the Earth, on samples of a few microns. This is the technique used by the researchers of the Institut de minéralogie et de physique des milieux condensés on natural samples that are representatives of the Earth mantle and that have been put under pressures of more than 140 gigapascals (or 1.4 million times the atmospheric pressure), and temperatures of more than 5000 Kelvin.
A new approach to this study has been the use of the X-ray diffraction technique at the European synchrotron ESRF. This has allowed the scientists to determine what mineral phases melt first, and they have also established, without extrapolation, fusion curves of the deep Earth mantle, i.e. the characterization of the passage from a solid state to a partially liquid state. Their observations show that the partial fusion of the mantle is possible when the temperature approaches 4200 Kelvin. These experiments also prove that the liquid produced during this partial fusion is dense and that it can hold multiple chemical elements, among which are important markers of the dynamics of the Earth mantle. These studies will allow geophysicists and geochemists to achieve a deeper knowledge of the mechanisms of differentiation of the Earth and the history of its formation, which started around 4.5 billion years ago.
INFORMATION:
When the Earth mantle finds its core
2010-09-17
ELSE PRESS RELEASES FROM THIS DATE:
Study finds possible 'persistence' switch for tuberculosis
2010-09-17
HOUSTON -- (Sept. 17, 2010) -- An examination of a portion of the tuberculosis genome that responds to stress has allowed Rice University bioengineers Oleg Igoshin and Abhinav Tiwari to zero in on a network of genes that may "switch" the disease into dormancy.
The bacteria that cause tuberculosis (TB), Mycobacterium tuberculosis, can transition into a dormant state to ward off attacks from antibiotics and the immune system. A new report from Igoshin and Tiwari in this month's issue of Physical Biology examines a network of genes that may make this possible. A computer ...
Lack of access to healthy food may contribute to health disparities in kidney disease
2010-09-17
Processed and fast foods enriched with phosphorus additives may play a role in health disparities in chronic kidney disease, according to a study appearing in an upcoming issue of the Journal of the American Society of Nephrology (JASN). Previously, genetics was considered the leading reason blacks are four times more likely to progress to end stage renal disease than whites and have much higher rates of cardiovascular disease and mortality in early chronic kidney disease (CKD).
Phosphorus, a mineral found naturally in foods such as milk, cheese, beans and peanut butter, ...
Newly identified genetic marker involved in aggressive Alzheimer's disease
2010-09-17
A gene variation that appears to predict the rate at which Alzheimer's disease will progress has been uncovered by an international team of Alzheimer's disease experts, led by Washington University School of Medicine in St. Louis. Published in the open-access journal PLoS Genetics, the findings help determine how rapidly Alzheimer's patients may develop full-blown dementia after their diagnosis.
Alzheimer's disease, one of the most common neurodegenerative disorders, affects over 4.5 million people in the United States alone. Recent studies have found the presence of ...
Healthy diet rocks when it comes to fighting kidney stones
2010-09-17
Certain key ingredients of a diet designed to prevent high blood pressure can ward off kidney stones, according to a study appearing in an upcoming issue of the Clinical Journal of the American Society Nephrology (CJASN). The results suggest how low-fat dairy products and/or plants may have potent kidney stone–fighting properties.
The Dietary Approaches to Stop Hypertension (DASH) diet—which is high in fruits, vegetables, nuts and legumes, dairy products, and whole grains and is low in sweetened beverages and red and processed meats—effectively lowers blood pressure. ...
Native Hawaiians: Vulnerability to early death at all ages
2010-09-17
ANN ARBOR, Mich.---Throughout their lives, Native Hawaiians have higher risks of death than white Americans, according to a University of Michigan study.
The research is the first known study to assess mortality patterns among Native Hawaiians at the national level, including those living outside the state of Hawaii.
The study is published in the November 2010 issue of the American Journal of Public Health, online Sept. 16. It was funded by the National Center for Minority Health and Health Disparities, part of the National Institutes of Health.
"Native Hawaiians ...
Watch your seas: Marine scientists call for European marine observatory network
2010-09-17
Brussels, 16 September - More than 100 marine scientists, policy makers and members of industry unanimously call for action towards an integrated network of observatories monitoring Europe's seas, at the Marine Board-ESF Forum 'Towards a European Network of Marine Observatories'. This will give reliable, long-term data to underpin science and policy regarding the use of seas for fisheries, aquaculture, energy, shipping, as well as tourism and recreation.
"We should not take for granted the wealth and well-being provided by the seas and oceans" said Lars Horn from the ...
Better policing with private security?
2010-09-17
A new research report published today suggests the police service may have a resource in private security that could contribute to savings of up to £1 billion through collaboration and new ways of working as challenged by the Audit Commission and HMIC.
Interviews with police chiefs suggest that while many feel there is untapped potential in using private security as a resource in this testing climate; others feel that the private security sector lacks credibility and closer collaboration could damage the reputation of the police. Key findings include:
Some police ...
Researchers identify genetic marker of aggressive Alzheimer's disease
2010-09-17
AUDIO:
For years, researchers have known that two key proteins tend to characterize Alzheimer's disease in the brain. Amyloid makes up the senile plaques that form in the brains of Alzheimer's...
Click here for more information.
An international team of Alzheimer's disease experts, led by Washington University School of Medicine in St. Louis, has uncovered a gene variation that appears to predict the rate at which Alzheimer's disease will progress.
The investigators report ...
Development aid for maternal, newborn and child health doubled over 5 years
2010-09-17
Health experts will today call for a greater prioritization and targeting of aid to save the lives of mothers, newborns, and children in poor countries.
The amount of official development assistance (ODA) to maternal, newborn and child health (MNCH) in developing countries doubled between 2003 and 2008, but its ratio to overall aid for health remained static. The US, UK, EU, GAVI and the Global Fund have made the largest absolute increases, while Spain and a number of small bilateral donors including New Zealand and Belgium have made significant percentage increases, ...
Rising education levels among women save children's lives worldwide
2010-09-17
SEATTLE –Women are advancing further in school than at any time in recent history, a trend that is having a tremendous impact on child mortality, according to new research from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.
Between 1970 and 2009, mortality in children under age 5 dropped from 16 million to 7.8 million annually, and IHME researchers estimate that 51% of the reduction can be linked to increased education among women of reproductive age. This means that 4.2 million fewer children died in 2009 because women received ...