University of Southampton researchers have found that rainwater can penetrate below the Earth's fractured upper crust, which could have major implications for our understanding of earthquakes and the generation of valuable mineral deposits.
It had been thought that surface water could not penetrate the ductile crust - where temperatures of more than 300°C and high pressures cause rocks to flex and flow rather than fracture - but researchers, led by Southampton's Dr Catriona Menzies, have now found fluids derived from rainwater at these levels.
Fluids in the Earth's crust can weaken rocks and may help to initiate earthquakes along locked fault lines. They also concentrate valuable metals such as gold. The new findings suggest that rainwater may be responsible for controlling these important processes, even deep in the Earth.
Researchers from the University of Southampton, GNS Science (New Zealand), the University of Otago, and the Scottish Universities Environmental Research Centre studied geothermal fluids and mineral veins from the Southern Alps of New Zealand, where the collision of two tectonic plates forces deeper layers of the earth closer to the surface.
The team looked into the origin of the fluids, how hot they were and to what extent they had reacted with rocks deep within the mountain belt.
"When fluids flow through the crust they leave behind deposits of minerals that contain a small amount of water trapped within them," says Postdoctoral Researcher Catriona, who is based at the National Oceanography Centre. "We have analysed these waters and minerals to identify where the fluids deep in the crust came from.
"Fluids may come from a variety of sources in the crust. In the Southern Alps fluids may flow upwards from deep in the crust, where they are released from hot rocks by metamorphic reactions, or rainwater may flow down from the surface, forced by the high mountains above. We wanted to test the limits of where rainwater may flow in the crust. Although it has been suggested before, our data shows for the first time that rainwater does penetrate into rocks that are too deep and hot to fracture."
Surface-derived waters reaching such depths are heated to over 400°C and significantly react with crustal rocks. However, through testing the researchers were able to establish the water's meteoric origin.
Funding for this research, which has been published in Earth and Planetary Science Letters, was provided by the Natural Environmental Research Council (NERC). Catriona and her team are now looking further at the implications of their findings in relation to earthquake cycles as part of the international Deep Fault Drilling Project, which aims to drill a hole through the Alpine Fault at a depth of about 1km later this year.
Notes to editors
1. "Incursion of meteoric waters into the ductile regime in an active orogen" by Catriona D. Menzies, Damon A. H. Teagle, Dave Craw, Simon C. Cox, Adrian J. Boyce, Craig D. Barrie, and Stephen Roberts is published in Earth and Planetary Science Letters, v. 399, p. 1-13. http://dx.doi.org/10.1016/j.epsl.2014.04.046
2. Picture: The Southern Alps Mountain Range, New Zealand. Rain and snow falling on the mountains percolate to great depths. Photo credit: Simon Cox
3. To arrange interview opportunities with Dr Catriona Menzies, please contact Steven Williams, Tel: 023 8059 2128, email: S.Williams@soton.ac.uk
4. Through world-leading research and enterprise activities, the University of Southampton connects with businesses to create real-world solutions to global issues. Through its educational offering, it works with partners around the world to offer relevant, flexible education, which trains students for jobs not even thought of. This connectivity is what sets Southampton apart from the rest; we make connections and change the world. http://www.southampton.ac.uk/ http://www.southampton.ac.uk/weareconnected
Follow us on twitter: http://twitter.com/unisouthampton
Like us on Facebook: http://www.facebook.com/unisouthampton
Steven Williams | Eurek Alert!
Satellites Peer Into Rock 50 Miles Beneath Tibetan Plateau
27.07.2015 | Ohio State University
Marine plankton brighten clouds over Southern Ocean
27.07.2015 | NASA/Goddard Space Flight Center
Researchers have developed an ultrafast light-emitting device that can flip on and off 90 billion times a second and could form the basis of optical computing.
Joint BioEnergy Institute study identifies bacterial protein that is key to protecting rice against bacterial blight
A bacterial signal that when recognized by rice plants enables the plants to resist a devastating blight disease has been identified by a multi-national team...
Researchers in the Cockrell School of Engineering at The University of Texas at Austin are one step closer to delivering smart windows with a new level of energy efficiency, engineering materials that allow windows to reveal light without transferring heat and, conversely, to block light while allowing heat transmission, as described in two new research papers.
By allowing indoor occupants to more precisely control the energy and sunlight passing through a window, the new materials could significantly reduce costs for...
Argonne scientists used Mira to identify and improve a new mechanism for eliminating friction, which fed into the development of a hybrid material that exhibited superlubricity at the macroscale for the first time. Argonne Leadership Computing Facility (ALCF) researchers helped enable the groundbreaking simulations by overcoming a performance bottleneck that doubled the speed of the team's code.
While reviewing the simulation results of a promising new lubricant material, Argonne researcher Sanket Deshmukh stumbled upon a phenomenon that had never been...
A NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite has returned its first view of the entire sunlit side of Earth from one million miles away.
The color images of Earth from NASA's Earth Polychromatic Imaging Camera (EPIC) are generated by combining three separate images to create a...
23.07.2015 | Event News
10.07.2015 | Event News
25.06.2015 | Event News
27.07.2015 | Materials Sciences
27.07.2015 | Information Technology
27.07.2015 | Power and Electrical Engineering