Абстрактный

Application of magnetic susceptibility measurements to study and map heavy mineral spatial distribution patterns in a sample area in Egypt

Mohamed A.El-Sadek, Sayed A.Elkhateeb

The sample (Koam-Mashaal), east Rosetta, Egypt, lies on the coastal plain of theMediterranean Sea, 15 kmto the east of Rosetta mouth of the River Nile, Egypt. The study area extends for about 3.0 kmalong the coast, and forms 5.4 km2 in surface area that ismostly covered by beach sands. The magnetic susceptibilitymeasurements were first applied as surface field measurements. Besides, quartered 966 field samples, taken fromlarge samples collected till a depth reaching 50 cmfromthe ground surface, weremeasured for theirmagnetic susceptibilities in the laboratories. The measurements of fieldmagnetic susceptibility (kF) attain theirmaximumvalue reaching about 38.0 × 10-3 SI unit in the central northeastern part of the study area, showing a great anomaly running parallel to the shoreline. Meanwhile, the measurements of laboratorymagnetic susceptibility (kL) attain their maximumvalue reaching about 28.6 × 10-3 SI unit in the same central NE part of the study area. Eleven samples were selected for mineral separation and mineralogic study. This study indicates that both ilmenite and magnetite represent 87.81 % of the total economic heavy minerals in the field (TF), while the remaining four economic minerals (zircon, monazite, garnet and rutile) represent only 12.9 %.An empirical polynomial equation was designed to determine the total economic heavy mineral percentage (TL) in unknown black-sand placer samples, if their laboratory magnetic susceptibility (kL) is known, in SI units. Besides, another empirical equation was designed to determine the (TF) in unknown black-sand placer deposits, when their field magnetic susceptibilities are known, in SI units.