![]() Post-spinel transitions in pyrolite and Mg 2SiO 4 and akimotoite–perovskite transition in MgSiO 3: precise comparison by high-pressure high-temperature experiments with multi-sample cell technique. Phase transitions in pyrolitic mantle around 670‐km depth: implications for upwelling of plumes from the lower mantle. Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe. Seismic scatterers in the lower mantle near subduction zones. High pressure-temperature phase relations of basaltic crust up to mid-mantle conditions. Phase relations of harzburgite and MORB up to the uppermost lower mantle conditions: precise comparison with pyrolite by multisample cell high‐pressure experiments with implication to dynamics of subducted slabs. Phase relations in hydrous MORB at 18–28 GPa: implications for heterogeneity of the lower mantle. The fate of subducted basaltic crust in the Earth’s lower mantle. Phase transformations in subducted oceanic crust and buoyancy relationships at depths of 600–800 km in the mantle. Iron partitioning and density changes of pyrolite in Earth’s lower mantle. Broad plumes rooted at the base of the Earth’s mantle beneath major hotspots. Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity. Depressed 660-km discontinuity caused by akimotoite-bridgmanite transition. Post-spinel transition in Mg 2SiO 4 determined by high P-T in situ X-ray diffractometry. Experimentally determined postspinel transformation boundary in Mg 2SiO 4 using MgO as an internal pressure standard and its geophysical implications. Postspinel transformations in the system Mg 2SiO 4‐Fe 2SiO 4 and some geophysical implications. Compositional mantle layering revealed by slab stagnation at ~1000-km depth. Effects of mantle and subduction-interface rheologies on slab stagnation and trench rollback. ![]() Effects of an endothermic phase transition at 670 km depth in a spherical model of convection in the Earth’s mantle. Layered convection induced by phase transitions. Role of phase transitions in a dynamic mantle. In contrast, the positive slope at high temperatures would impart upward buoyancy on hot plumes and enhance their upwelling, which may account for the invisibility of plumes in seismic observations above 1,000 km depth. This could impede slab downwelling and may explain slab stagnation between 660 and 1,000 km depth. The negative slope at low temperatures would impart upward buoyancy on cold slabs that is significantly larger than that by thermal expansion. We find that the post-garnet phase boundary has a downward-convex shape: the slope changes from negative to positive with increasing temperature. Here we identified the phase boundary of the post-garnet phase transition-the breakdown of garnet to bridgmanite plus corundum-under mantle conditions using in situ X-ray diffraction multi-anvil techniques that can accurately determine phase stability. Accurately determining phase boundary slopes is, therefore, essential for understanding mantle dynamics. ![]() Mantle convection is either enhanced or impeded depending on the sign of the slope of the phase transition boundary (the temperature dependence of transition pressures). Phase transitions of mantle minerals at high pressure are associated with changes in density and viscosity. ![]() While our linear glasses are perfect for breaking down light and color into its most basic, spectral form for study, our double axis glasses are a great way to turn every splash of color and sparkle of light into a captivating display.Mantle convection manifests in the subduction of cold slabs and the upwelling of hot plumes, driving both near-surface processes such as volcanism and seismicity and the chemical evolution of the Earth’s interior. Choose from linear or double axis holographic diffraction glasses and explore the world with the science behind uniquely designed lenses that feature 500 lines/mm, 1000 lines/mm, and 13,500 lines per inchĮach style is ideal for a different application. ![]() Whether you need to hand out glasses at your corporate booth or you want to teach students of all ages about color and light, has a large selection of styles, colors, and types of diffraction glasses. Choose from our selection of light diffraction grating glasses and discover how our glasses can make any event extraordinary. With over 40 years of experience in the optics industry, has the experience and innovative solutions you need to enhance an event, captivate a classroom, or advertise your business. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |