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In the depths of the earth, it is anything but peaceful: largequantities of liquids carve their way through the rock as fluids,causing magma to form. A research team led by the University ofMunster, has shown that the fluids flow a lot faster through solidrock than previously assumed. In the Chinese Tian Shan Mountains,fluids pushed their way to the earth's mantle from great depths injust 200 years rather than in the course of tens or even hundredsof thousands of years. The researchers from Munster, Kiel, Bochum, Erlangen, Bethlehem(USA) and Lausanne (Switzerland) present their findings, based onan innovative combination of fieldwork, geochemical analysis andnumerical calculations, in the current issue of the journal NatureGeoscience. The RUB geoscientists are experts in determining timescales using numerical models. How the "Ring of Fire" is formed When tectonic plates move towards each other and push over eachother at the edges, so-called subduction zones are formed. Thedescending plate is heated and continuously releases the waterstored in its rocks as fluid. The fluid penetrates the earth's mantle, which is located above thedescending plate. The fluids thus lower the melting point of themantle rocks, and the liquid rock formed rises to the volcanoes asmagma. This magma feeds the many volcanoes throughout the world that occuralong the convergent plate boundaries and form the "Ring of Fire",a volcanic belt that encircles the Pacific Ocean. The fluids arecommonly assumed to flow through the rock in a defined flow system.Geologists call these structures veins. Only two hundred years During field work in the Chinese part of the Tian Shan Mountains(Celestial Mountains), the research team found structures in therocks they were studying which can be ascribed to massive fluidflows at great depth. "Our investigation has shown that a great deal of fluid must haveflowed through a rock vein at about 70 km depth and that this fluidhas obviously already covered a distance of several hundred metersor more - the transport of such large quantities of fluid over sucha great distance has not been demonstrated by anyone before us"explains Timm John from the Institute for Mineralogy, University ofMunster. "And the most exciting thing is that this amount of fluid flowedthrough the rock in what is for geological processes a very shorttime, only about two hundred years", adds Nikolaus Gussone of thesame institute. Like in a reservoir The release of fluids from minerals in the descending plates is alarge-scale and continuous process that takes place at depths up totwo-hundred kilometres and takes millions of years. During thistime, the fluids first accumulate. As the researchers have now shown for the first time, the releasedfluids then flowed through the plate on their way to the mantle inpulses in a relatively short time along defined flow paths. "It'slike a reservoir that continuously fills and then empties in asurge through defined channels" Timm John points out. "The fluid release is focused in space and time, and is much fasterthan expected - almost like a jet through solid rock". The researchers hope to be able to show the spatial and temporalcorrelations between such fluid pulses and volcanic activity infuture studies. It is also possible that such focused fluidreleases are associated with the occurrence of earthquake events insubduction zones. To be able to demonstrate such relations,however, intensive research is still needed. RUB experts for time scales The RUB's petrologists were involved in modelling the chemicaldata. This enabled the research team to determine the time it tookthe fluids to make their way to the mantle. Determining the time scales of various geological processes is aparticular expertise of Bochum's petrologists. Among other things,they use minerals and rocks with zones that exhibit a differentchemical composition. T. John et al. (2012): Volcanic arcs fed by rapid pulsed fluid flowthrough subducting slabs. Nature Geoscience, doi: 10.1038/NGEO1482. We are high quality suppliers, our products such as Copier Toner Cartridges Manufacturer , Fuser Film Sleeve Manufacturer for oversee buyer. To know more, please visits Brother Printer Toner Cartridges.
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