MINERAL COMPOSITION OF TH E COASTAL SEDIMENTS
BETWEEN HURGHADA AND EL-QUSIER,
RED SEA COAST
YOUSRIA. M. SAMY AND AMR M. EL-GOHARY
National Research Center |
The mineralogical studies on the coastal sediments in the area between Hurgahda and El-Quseir revealed that the non-carbonate light minerals are composed mainly of quartz with subordinate amounts of alkali feldspar and plagioclase. The majority of the quartz grains are monocrystalline with uniform extinction, however, a composite subtype quartz is also recorded. The calculated value of the maturity index (F/Q) ratio shows a marked increase southward along the coast, i.e. the sediments are more mature northward.
Aragonite, calcite and dolomite are the main carbonate minerals detected by X- ray diffraction analysis, however, aragonite is the most abundant one.The carbonate contents are generally more frequent in the north than in the south along the study coastal area.
The percentage of the heavy minerals varies along the coast and reaches as high as 70.72% in some localities (Safaga). The heavy minerals encountered in the sediments consist mainly of opaques and non-opaque minerals. The latter include amphiboles, pyroxenes. epidotes, zircon, tourmaline and rutile. The variation of the zircon characters as regards to colour, grain shape, forms and size points out to a decided varied origin. Ore microscopic study shows that magnetite, ilmenite and hematite, and their intergrowths are the main opaque minerals.
The recorded mineral assemblage and the characteristics of the different minerals reflect that the sediments were derived frorn the basement complex which comprises many types of igneous and metamorphic rocks in addition to some derivation from reworked sediments (e.g., Nubian sandstones).
|
|