Carbon-bearing phases in shock-induced melt zones of the Elga meteorite

The mineralogy and texture of shock-induced melt veinlets and melt pockets in silicate inclusions in the Elga IIE iron meteorite have been studied by reflected-light optical microscopy, EMPA, SEM, Raman spectroscopy and TEM. The results suggest that Elga experienced two discrete impact events. The earlier event involved the collision of a metallic projectile with a silicate target and resulted in partial melting and recrystallization of the silicate material, forming schreibersite and oxide rims between the metal and silicate. The later impact event resulted in melt pockets in the silicate inclusions and was associated with fragmentation, melting, and brecciation of the rims and displacement of some fragments into the melt pockets. These fragments are shown to contain carbon-bearing phases: siderite and amorphous sp ² carbon, which form carbon–oxide, siderite–oxide, and siderite–schreibersite associations. The fact that the carbon-bearing fragments are spatially constrained to shock breccia and melt zones indicates that these fragments are genetically related to the impact process and that their carbon-bearing phases are of cosmic origin.     

Wind–Sand Flux Electrization over Desertified Areas

Doklady Earth Sciences - Using the measurement data in a wind–sand flux on the desertified areas of Astrakhan oblast and Kalmykia, it has been established that the time variability of...     

Experimental modeling of the effect of relative thermal power on the shape of a plume conduit and the structure of free-convection flow in it

The shape of a plume conduit produced by melting solid paraffin block above a local heat source was studied experimentally as a function of the relative thermal power of the plume Ka= N/N₁, where N₁ is the power of the plume source and N₁ is the power corresponding to the amount of heat transferred by conduction through the plume conduit to the surrounding solid paraffin block. The limiting power of the plume source at which the plume erupts at the Earth’s surface (N_lim1= (1.35–1.60) × 10¹⁰ W) and the power at which the mushroom-shaped plume ^{head formed at the base of the refractory layer (N}_lim2= ^{(1.78–1.90) × 1010 W) with no horizontal mantle flow were determined. The dependence} of the diameter of the base of the plume on the Ka number was established. The Ka value and the diameter of the plume base were determined for the Hawaiian and Iceland plumes, for the plume responsible for the formation of the Tunguska syneclise and for the McKenzie and Central Atlantic continental plateau-basalt provinces and for the Ontong Java and Manihiki oceanic lava plateaus.