Geologic interpretation of the aeromagnetic survey in the Agourai area (Central Morocco)

Abstract The aim of this work is to interpret the geologic structures of the Agourai area (Paleozoic and Mesozoic structures) from processed magnetic maps. The detected magnetic anomalies from different standard methods used in aeromagnetism (Residual map, RTP map, horizontal gradient map) were compared to geologic structures and permit enhancing the mapping quality of some areas, and thus defining many geologic features. Existing geologic maps and geologic field studies allow interpreting some detected anomalies. It was thus possible to define the limits between the Paleozoic basement and the Mesozoic cover, to determine magnetic anomalies according to NE-SW trends compatible with the regional geologic structures and finally to detect a NE to SW-oriented fault system in the Mesozoic cover of the Agourai Plateau. Despite the reliability of this approach, some folded basaltic sills occurring in this region were not well detected, probably because of their reduced thickness

Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study

Modeling of a turbulent two-phase gaseous-solid flow still faces challenges. The present study is devoted to two-phase flow in an annular pipe (hollow cylinder) operating at an elevated pressure of 15 bar and moderate Reynolds numbers of circa 6 x 103. The influence of the various factors – such as the particle loading, the interaction between the phases, and turbulent dispersion – on the flow dynamics is systematically studied by means of the computational simulation employing the ANSYS FLUENT commercial package. To be specific, particle loading with a volumetric fraction of 1.2 % is defined as high particle loading, while the flow with a volumetric fraction of 0.13 % is referred to as low particle loading. In particular, seven various cases for a gas-solid phase flow are investigated: 1) Pure gas flow; 2) Low particle loading two-phase flow with one-way coupling and with turbulence dispersion; 3) Low particle loading two-phase flow with two-way coupling but without turbulence dispersion; 4) Low particle loading two-phase flow with two-way coupling and with turbulence dispersion; 5) High particle loading two-phase flow with one-way coupling and with turbulence dispersion; 6) High particle loading two-phase flow with two-way coupling but without turbulence dispersion; 7) High particle loading two-phase flow with two-way coupling and with turbulence dispersion. The boundary layer was found to be growing without fluctuations of the turbulent kinetic energy (TKE) for Cases 1, 2, and 5 above. For Case 4, the TKE fluctuations have been identified though appeared not as substantial as in Cases 6 and 7. The author attributes such a difference in the fluctuations to the particle loading. In addition, the onset and development of the flow instability have been observed at a random axial distance in Cases 4, 6, and 7. Such instability is presumably attributed to the two-way coupling with turbulence dispersion in a flow. It is concluded that the particle loading, one-way, or two-way coupling between the phases, and the turbulence dispersion models significantly influence the flow dynamics. The present computational results inspire to perform experimental verification and validation of the simulations, so the simulation results can subsequently be used for the design analysis

A reassessment of impact crater degradation by climatic processes on early Mars

Crater degradation on Mars is a key to understand erosion through time. Strongly eroded craters in the highlands are interpreted to be the result of enhanced erosion rate during the Noachian epoch. While fluvial valleys climatic meaning and duration are still difficult to define (strongly warmer climate or episodic activity under slightly warmer climate), the enhanced Noachian craters degradation favors a prolonged erosion with high erosion rates. Most data used for classification and understanding of these craters were done using Viking data by photoclinometry. We choose here to use MOLA data in two Noachian regions to study the evolution of this degradation in time: North Hellas and Southern Margaritifer Terra