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Our Earth, its minerals and ore bodies
Published in Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith, The Business of Mining, 2019
Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith
The mantle comprises 82% of the earth’s volume and we know from the continuity of S-waves through the mantle that it is solid, although due to the high temperatures the rocks can flow at very slow velocities. The mantle itself is also subdivided into two sublayers: upper mantle and lower mantle (Figure 1.3). The chemical composition of the upper mantle is revealed by rock fragments brought to the surface by deep-seated magmas. These indicate that the upper mantle is primarily composed of peridotite (an ultramafic rock consisting mainly of the mineral olivine). At approximately 660 km depth both S- and P-waves show a significant increase in velocity; this marks the boundary to the lower mantle, which is the single largest layer occupying 52% volume of our planet. At depths of ~ 2700 km the S-wave velocities decrease by 30% indicating a weakness in the material. This zone is known as D” layer and it is interpreted to be a zone with significant variations in composition as well as temperature, it also marks the boundary between the rocky mantle and the core (Figure 1.3). The speed of seismic waves through the mantle, calculated from travel times, indicates an overall increase in rock density from 3.3 g/cm3 in the upper mantle to 5.5g/cm3 at the base.
Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
The spheres are distinctly different. The hydrosphere contains ice, water vapor, and liquid water. It is mostly H2O; other compounds or elements are absent or present only in minor amounts. The lithosphere includes Earth’s crust and the upper mantle and is the key player in the plate tectonic system that moves continents, and creates and destroys ocean crust. The lithosphere mostly consists of rocks and other materials that are dominated by the elements oxygen and silicon, with lesser amounts of aluminum, iron, calcium, sodium, and potassium. The mineralogy and chemistry of the crust and mantle are very heterogeneous. Continental crusts are more enriched in silicon, oxygen, sodium, and potassium, and depleted in magnesium, calcium, and iron, when compared with oceanic crusts. Beneath the crust, the mineralogy of the mantle varies with depth, mostly because different minerals are stable at different pressures. The upper mantle consists mostly of olivine, pyroxene, and garnet. At extremely high pressures, at depths of 400–1000 kilometers (250–620 miles), olivine transforms into a different mineral, spinel. And, as discussed later in this chapter, carbon, when present in the upper mantle, exists mostly as carbon dioxide or the carbon mineral graphite, but at the high pressures of the deeper mantle, carbon is mostly in diamonds.
Petroleum Pre-Period
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
The transition zone between the upper and lower mantles contains complex materials. The lower mantle is a homogenous molten zone with higher temperatures. The mantle consists of different layers of materials of different melting points at the existing pressure/temperature. The upper mantle mostly contains three types of silicate minerals, namely garnet, pyroxene and olivine. In the transition zone, all three silicate minerals undergo a phase transformation, forming different minerals and solid solutions from the same types of element molecules. In the lower mantle zone, due to high pressure and temperature, silicate mineral are split into simpler oxides of Si, Mg and Fe elements.
Implications of upper-mantle seismicity for deformation in the continental collision zone beneath the Alpine Fault, South Island, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2018
Carolin M. Boese, Tim A. Stern, Konstantinos Michailos, John Townend, Calum J. Chamberlain
Collins and Molnar (2014) analysed Pn-wave arrivals of ∼330 earthquakes recorded by on- and offshore stations. Pn-waves are the first arriving phases at regional distances. They are critically refracted at the Moho and propagate as head waves along the Moho, sampling the uppermost 20 km of the mantle (Collins and Molnar 2014). Their directional velocity variance can be used to infer the strength and orientation of upper mantle P-wave anisotropy. Pn-anisotropy in the offshore area southeast of the South Island is low (2%, direction 350° ± 4°) but increases to 8% towards the Alpine Fault (their Fig. 15a) with a direction of 060° ± 3°, parallel to the relative plate motion direction over the last ∼20 Myr. The average P- wave velocity in the upper mantle of central South Island is 8.2 km/s. Scherwath et al. (2002) estimated Pn-anisotropy of 11% by using air-gun-generated Pn-waves, which sampled a 50 km-wide area just beneath the Moho beneath and west of the surface trace of the Alpine Fault.
Sorptive equilibrium profile of fluoride onto aluminum olivine [(FexMg1−x)2SiO4] composite (AOC): Physicochemical insights and isotherm modeling by non-linear least squares regression and a novel neural-network-based method
Published in Journal of Environmental Science and Health, Part A, 2018
Partha S. Ghosal, Ashok K. Gupta
Olivine [(FexMg1−x)2SiO4] is the most abundant mineral in the Earth's upper mantle and is rich in mostly magnesium, silica, iron along with some percentage of aluminum.[20] This sandy material is used as a potential support in the field of catalysis.[21] However, the aluminum impregnated olivine has rarely been used either in the field of catalysis or for the water treatment, although the composition of olivine indicates that the material may be promising for environmental engineering. The present study aims to explore the adsorption potential of the AOC for defluoridation.