Following up on theories that ringwoodite minerals deep within the Earth’s mantle may contain water, a BBC News report says researchers have provided the first direct evidence of this theory.
Diamonds, brought to the Earth’s surface in violent eruptions of deep volcanic rocks called kimberlites, provide a tantalising window into the deep Earth.
A research team led by Prof Graham Pearson of the University of Alberta, Canada, studied a diamond from a 100-million-year-old kimberlite found in Juina, Brazil, as part of a wider project.
They noticed that it contained a mineral, ringwoodite, that is only thought to form between 410km and 660km beneath the Earth’s surface, showing just how deep some diamonds originate.
While ringwoodite has previously been found in meteorites, this is the first time a terrestrial ringwoodite has been seen. But more extraordinarily, the researchers found that the mineral contains about 1% water.
According to the news report, this discovery is important because it solves a 25-tyear-old controversy about deep Earth being wet, dry, or wet in patches. The finding implies that the interior of the planet may store several times the water in the oceans, and demonstrates how hydrogen plays a critical role in the interior processes of the planet, and possibly other planets including Mars.
For more information on ringwoodite:
In a article on Phys, they report scientists have found clues in Alaska that has them rethinking how to continental crust forms based upon research published in Nature Geoscience.
A new study appearing in this week’s Nature Geoscience raises questions about one popular theory and provides new support for another, in which arc lava from the surface and shallow “plutons” – magma that solidified without erupting – are pulled down into the Earth at subduction zones and then rise up to accumulate at the bottom of the arc crust like steam on a kitchen ceiling. Scientists have found compelling evidence to suggest that this could have produced the vast majority of lower continental crust through Earth history.
The process, called relamination, starts at the edge of a continental plate, where an oceanic plate is diving under the continental plate and magma is rising to form a volcanic arc. As the oceanic plate dives, it drags down sediment, lava and plutonic rock from the edge of the arc. As arc material descends, minerals within it become unstable with the rising pressure and heat, and they undergo chemical changes. New minerals form, and chunks of the rock and sediment can break off. When those chunks are denser than the mantle rock around them, they continue to sink. But when they are less dense, such as those that form silica-rich granulites, they become buoyant and float upward until they reach the bottom of the arc crust and accumulate there.
For more information, see:
A new study and timeline has been released showing 190 million years of tetrapod biodiversity, exceptional data for fossils and paleontology.
Recently, we have been able to provide some answers to the questions of how diverse through time has life been, based on the building of large fossil occurrence databases and new methods of analysing them. One such development has been the Paleobiology Database, a professional crowd-sourced archive of fossil history, where the context of fossils is provided in both space and time, and largely based on the published record of fossil discoveries.
…By applying SQS with our development of large fossil occurrence datasets, voila, we are able to gain renewed insight into the diversity of life through history in a way that accounts for the inherent biases of the fossil record!
And that’s just what a new study in PLOS Biology set out to do. Led by Roger Benson of the University of Oxford, an international team of researchers applied SQS to one of the largest tetrapod fossil occurrence databases ever assembled (if not the largest!), comprising more than 27,000 individual fossil occurrences! This represented almost 5000 fossil species, and the data were restricted to just those fossils that dwelled on land – so this excludes groups like ichthyosaurs and plesiosaurs, for example. They also excluded flying tetrapods, so birds, bats and mammals, as these are known to have very different preservational histories in the fossil record. For palaeontology though, this is definitely ‘big data’.
The team restricted their analyses to just the Mesozoic to early Paleogene, a time span of around 190 million years (a fairly long time, even by geological standards!). If you think about it, that’s 5000 species over about 190 million years, which compared to 30,000 around today is pretty weird even in itself.
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For those working in the lapidary arts, we’ve been dazzled by the strength of the minerals and gems we find. The Washington Post announces there is something in nature stronger than diamonds and steel, and unbreakable by bullets.
Currently, the strongest natural material known is the silk of a spider. With this new research, your next tidal pool adventure along the Pacific Northwest coastline might come with a new perspective, and a new respect.
In a study set to come out this month in the Journal of the Royal Society Interface, British researchers announced that the teeth of shelled, aquatic creatures called limpets are the strongest biological material on Earth, overtaking the previous record-holder, spider silk.
The teeth, which are so small they must be examined with a microscope, are composed of very thin, tightly-packed fibers containing a hard mineral called goethite. Limpets use them to scrape food off of rocks, but lead author Asa Barber said humans can adapt the technology to build better planes, boats and dental fillings.
Testing found the mineral material in the snail-like creatures commonly found along tidal pool areas to be nearly flawless in their very thin filaments, reinforcing the structural components, and have a strength of 5 gigapascals, five times that of most spider silks.
The teeth also bested several man-made materials, including Kevlar, a synthetic fiber used to make bulletproof vests and puncture-proof tires. The amount of weight it can withstand, Barber told the BBC, can be compared to a strand of spaghetti used to hold up more than 3,300 pounds, the weight of an adult female hippopotamus.
For information on geothite, see:
The Rice has a great program called Adopt-a-Mineral, allowing the public to donate to the museum by adopting a rock and mineral. The following article is about one of those minerals, fluorite, available for adoption now.
Fluorite (AM 29, AM 30)
Carlo Galeani Napione named the mineral fluorite in the late 1700s. The name derives from the Latin “fleure”, meaning flow, because it is commonly used as a flux. Fluorite is a halide, in which a metal is bonded to one of the halogen elements (fluorine, chlorine, bromine, iodine).
The following images are used courtesy of Wiki Commons.
Fluorite is commonly translucent and found with a vitreous (glassy) luster. It has many colors including, green, purple, yellow, pink, brown and colorless. Its streak (color of the powdered mineral) is white. Fluorite has a hardness of ~4 and is the hardness reference species on Mohs’ scale. It is a brittle mineral, and it will fracture and break along perfect cubic and octahedral cleavage planes. Fluorite usually occurs as cubes, although it can also be found as octahedra (8-faced crystals), and rarely as dodecahedra (12-faced crystals). Sometimes these forms can be found combined in single crystals. When not seen as large crystalline specimens, fluorite is usu-ally massive, or an aggregate of very small cubes. Continue reading “Adopt-a-Mineral at the Rice Northwest Museum – Fluorite”
A press release on EurekaAlert, “Deep Carbon: Quest underway to discover its quantity, movements, origins and forms in Earth,” states that the The Deep Carbon Observatory 10-year project to explore the carbon found deep under the earth’s surface.
The program is investigating deep carbon’s movement in the slow convection of the mantle, the percolating fluids of the crust, and the violent emission from volcanoes. It searches for the ancient origin of the deep carbon, and the formation and transformation of its many forms, ranging from gas and oil to diamonds and deep microbes.
Ninety percent or more of Earth’s carbon is thought to be locked away or in motion deep underground–a hidden dimension of the planet as poorly understood as it is profoundly important to life on the surface, according to scientists probing the world’s innermost secrets in the decade-long, $500 million project.
In a landmark volume, DCO scientists say estimates of carbon bound in the metallic core alone range from 0.25 to 1 percent by weight. If 1 percent proves correct, the core by itself sequesters four times more carbon than all known carbon reservoirs in the rest of the planet–and 50,000,000 times as much as that held in the flora and fauna on Earth’s relatively wafer-thin skin far above.
Studies of meteorites suggest that the material that first formed Earth contained about 3% by weight carbon. Confirmed sources of Earth’s carbon, however — life, carbonate rocks like limestone, and carbon dioxide in the oceans and atmosphere — sum to only about 0.1% carbon content.
Carbon is the only element on earth so central to life on the planet, and the research into understanding how carbon influenced life may tell us even more about life evolving on this planet and elsewhere in space.
For more information on the The Deep Carbon Observatory, see:
Updated Jan 2016