Density Distribution In Regions Research Articles

Density heterogeneity of the Earth’s crust of the Black Sea megadepression and adjacent territories from three-dimensional gravity modelling. 1. Regional density distribution at different depths.

This paper presents a comprehensive analytical review of the various approaches to the gravity modelling of the Earth’s crust of the Black Sea and adjacent territories. It is shown that even in using the same thickness of sedimentary layers whose total gravitational effect makes a considerable contribution to the observed field the results of different authors do not coincide and in some cases contradict each other. The reason is that every researcher uses ad hoc reference density and a method of reducing the calculated curves. Therefore, an unified three-dimensional density model of this region was first developed that significantly increased the reliability of the geological interpretation of the modelling results. In additional the spatial distribution of density was first used for the Maykop Series, the Eocene- Pliocene, and Cretaceous deposits that allowed us to obtain principally new data on the heterogeneous structure of the main horizons of the sedimentary cover. An analysis of the density distribution of the consolidated crust revealed anomalously weakened and compacted areas in the shelf zones. A pattern was constructed for the distribution and depth to the basement of dislocated sediments. The density of rocks was also calculated on this surface. The granitic, granitic-diorite, dioritic and basaltoid types of the crust were identified that for the first time made it possible to delineate the areas of different composition in the present - day consolidated crust of the entire study region. A decrease in crustal basicity was unveiled in the direction from the deep-water basins to the northwestern, western, and southern offshore zones. On the shelf local density inhomogeneities were at the base of the basalt layer, which are indicators for penetration of basic and ultrabasic intrusions into the crust.

Temperature and Density Measurements in Free Jets and Shock Waves

The fluorescence stimulated by a 17.5-kV electron beam probe was used to obtain measurements of rotational temperature and gas density in supersonic nitrogen jets expanding from room temperature. The parameter P0d (where P0 is the stagnation pressure in Torricelli and d is the orifice exit diameter in millimeters) was varied from 15 to 480 Torr-mm. Density measurements were made using an interference filter-photomultiplier combination. The experimental density data follow the axial isentropic density distribution in regions of rotational nonequilibrium. Rotational temperature measurements were obtained from rotational spectra of the 0–0 band of the N2+ first negative system. The experimentally determined rotational temperatures, which initially follow the axial isentropic temperature distribution in a free jet, depart from the isentropic curve at low temperatures and freeze at a constant value, indicating a substantial degree of nonequilibrium in the expansion. A shock holder was inserted in the jet and a number of shock waves in the range M = 4 to M = 15 were investigated. Rotational spectra indicate a large departure from a Boltzmann distribution in the rotational levels in the center of a shock front. An apparent non-Boltzmann rotational distribution in the jet expansion was also observed.