Saharan dust played a major role in the formation of the Bahamas islands, a new study suggests. Researchers showed that iron-rich Saharan dust provides the nutrients necessary for specialized bacteria to produce the island chain's carbonate-based foundation. Persistent winds across Africa's 3.5-million square mile Sahara Desert lifts mineral-rich sand into the atmosphere where it travels the nearly 5,000-mile northwest journey towards the U.S. and Caribbean.
This study provides evidence that amphibole develops by evolved melts overprinting earlier clinopyroxene—a near-ubiquitous mineral in arc magmas. Reaction-replacement of clinopyroxene ultimately forms granoblastic amphibole lithologies. Reaction-replacement amphiboles have more primitive trace element chemistry (for example, lower concentrations of incompatible Pb) than amphibole phenocrysts, but still have chemistries suitable for producing La/Yb and Dy/Yb ‘amphibole sponge’ signatures.
The authors show that age distributions of zircons, a mineral often present in crustal magmatic rocks in combination with thermal modelling, provide an accurate means of retrieving magma fluxes. The characteristics of zircon age populations vary significantly and systematically as a function of the flux and total volume of magma accumulated in the Earth’s crust.
Higher Cr(VI) values are observed in aquifers in alluvial and neogene sediments of serpentine and amphibolite, originating from the erosion of ophiolithic and metamorphic rocks. In contrast, Cr(VI) concentration in samples from ophiolithic and metamorphic rocks was always below 10 μg/L due to both low contact time and surface area, as verified by low conductivity and salt concentration values. These findings indicate that under specific conditions, pollution of water by Cr(VI) is favorable by a slow MnO2-catalyzed oxidation of soluble Cr(III) to Cr(VI) in which manganese products [Mn(III)/Mn(II)] are probably re-oxidized by oxygen.
University of Nottingham-British Geological Survey Centre for Environmental Geochemistry (RT @MelJLeng: Some new blogs from the @BritGeoSurvey @UniofNottingham Centre for Environmental Geochemistry http://t.co/lvRr955181)...
The authors present a high-resolution transect of dissolved stable iron isotope ratios (δ56Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ56Fe signatures, which persist throughout the water column. This allowed to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. They found that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71–87 per cent of dissolved iron.
The results demonstrate an instrumental bias associated with APT that needs to be quantified and corrected to obtain accurate isotope ratios. After this correction is applied, this technique should allow determination of the distribution of 12C/13C ratios in individual diamond grains, solving the decades-old question of the origin of meteoritic nanodiamonds.
One of Europe's premier scientific research laboratories is to go through a major upgrade. The improvements to the European Synchrotron Radiation Facility (ESRF) will cost some 150m euros (£120m) and take until 2022 to complete fully. The 850m accelerator ring used to prime these bright X-rays will be replaced.
Ancient sulfide-bearing cumulates would be characterized by unradiogenic Pb and He isotopes (high-3He/4He). These primitive signatures are usually attributed to primordial, undifferentiated mantle, but in this case, they are the very imprint of mantle differentiation via continent formation.
Iceland has been considered a suitable analogue for the generation of Earth’s earliest continental crust. However, the geochemical signature of sialic rocks from Iceland is distinct from the typical 3.9- to 2.5-billion-year-old Archaean rocks discovered so far. Here the authors report the discovery of an exceptionally well-preserved, 4.02-billion-year-old tonalitic gneiss rock unit within the Acasta Gneiss Complex in Canada.
Reactions among minerals and organic compounds in hydrothermal environments are critical components of the Earth’s deep carbon cycle.
Ath Godelitsas's insight:
The ASU team set out to understand how different minerals affect hydrothermal organic reactions and found that a common sulfide mineral (ZnS, or Sphalerite) cleanly catalyzes a fundamental chemical reaction: the making and breaking of a C-H bond.
Los Alamos National Laboratory has announced an impending partnership with Toshiba Corporation to use a Los Alamos technique called muon tomography to safely peer inside the cores of the Fukushima Daiichi reactors and create high-resolution images of the damaged nuclear material inside without ever breaching the cores themselves. The initiative could reduce the time required to clean up the disabled complex by at least a decade and greatly reduce radiation exposure to personnel working at the plant. Muon radiography (also called cosmic-ray radiography) uses secondary particles generated when cosmic rays collide with upper regions of Earth's atmosphere to create images of the objects that the particles, called muons, penetrate. The process is analogous to an X-ray image, except muons are produced naturally and do not damage the materials they contact. Muon radiography has been used before in imaginative applications such as mapping the interior of the Great Pyramid at Giza, but Los Alamos's muon tomography technique represents a vast improvement over earlier technology.
Nature Milestones in Crystallography, a collaborative effort between Nature, Nature Materials, Nature Nanotechnology and Nature Structural & Molecular Biology, is the eleventh supplement in the series and is timed to coincide with the celebration of the 2014 International Year of Crystallography. Exactly 100 years ago, Max von Laue received the Nobel Prize in Physics “for his discovery of the diffraction of X-rays by crystals”. Since that discovery, crystallography has become an essential tool of investigation throughout the sciences, largely because it provides conclusive information on molecular structure down to the atomic level.
Scientists used the ChemCam instrument on NASA's Curiosity Mars rover to examine a Martian rock "shell" about one inch across, embedded in bedrock and with a hollow interior. This graphic combines an image of the target with results from using ChemCam's laser on the rock and adjacent points
Recent developments in shock-free dynamic (ramp) compression now allow laboratory access to this dense matter regime. Here we describe ramp-compression measurements for diamond, achieving 3.7-fold compression at a peak pressure of 5 terapascals (equivalent to 50 million atmospheres). These equation-of-state data can now be compared to first-principles density functionalcalculations and theories long used to describe matter present in the interiors of giant planets, in stars, and in inertial-confinement fusion experiments. Our data also provide new constraints on mass–radius relationships for carbon-rich planets.
The Earth Sciences Division (ESD) at Berkeley Lab brings together geoscientists, mathematicians, microbiologists, computer scientists and engineers to address local, national and global problems related to energy resources, environmental...
Researchers of Chapman University, the U.S. Geological Survey and SSRL have investigated the speciation of arsenic changes within mine tailings and surrounding soil samples. The scientists identified arsenic-containing mineral and sorbed species in size-fractionated mine wastes and adjacent soils from the Solomon Mine and the Descarga Tailings Dam in the Randsburg Historic Mining District, California, using extended x-ray absorption fine structure (EXAFS) spectroscopy at SSRL’s Beam Line 11-2. These analyses were paired with micro-x-ray fluorescence (μXRF) mapping of separate size fractions to identify multiple populations of particles with different arsenic-to-iron ratios.
Easily separable humic acid coated magnetite (HA-Fe3O4) nanoparticles are employed for effective adsorption and reduction of toxic Cr(VI) to nontoxic Cr(III). The adsorption and reduction of Cr(VI) is effective under acidic, neutral, and basic pH conditions.
Experimental data reveal that mineral precipitation takes place directly on free viruses and, as a result of viral infections, on cell debris resulting from cell lysis. Viruses are initially permineralized by amorphous magnesium silicates, which then alter to magnesium carbonate nanospheres of ~80–200 nm in diameter during diagenesis.