Comparative Mineralogical and Geochemical Studies on the Mineralizations in the Contact Zone Between the Adediya and Um Bogma formations in Wadi Um Hamd Area, Southwestern Sinai, Egypt.

Abstract

Extensive field and laboratory studies were carried out on the rocks of the unconformable contact zone between the Lower Carboniferous Adediya and Um Bogma formations as well as those of the latter rock unit in three stratigraphic sections in G. Um Hamd. A detailed geologic map of the study area was constructed. It revealed the presence of two major dip- slip and a number of minor faults. The sedimentary succession is intruded by basaltic dykes that are connected with the Tertiary volcanicity. The contact zone consists of argillaceous rocks. The Um Bogma Formation could be subdivided into a lower siltstone- Fe, Mn ore member, a middle siltstone- mudstone- shale member and an upper dolostone- dolomitic limestone member. The argillaceous rocks in the succession are slightly calcareous, poorly- sorted and variably highly ferruginous; Fe- oxides have several modes of occurrence. Rocks of the contact zone are texturally classified as mudstone and sandy mudstone whereas those of the Um Bogma Formation are sandy siltstone, sandy mudstone, sandy claystone and muddy sandstone. On the other hand, the carbonates of the upper member of Um Bogma Formation are classified as microsparite, dolomitized microsparite, dolomitized sparite and dolomitized pel-oosparite.