الفهرس 
introduction and previous workOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
The Miocene exposures at Wadi Hagul, Sadat area at the north western part of the Gulf of Suez were sampled petrographically, mineralogically and geochemically studied. Eighty-five samples, representing four stratigraphic sections, were collected, described and their microfacies are elucidated. The Miocene sequence, in the study area was differentiated into three formal rock units from older to younger as; Sadat Formation (Lower Miocene) a unique reefal carbonate sequence at Sadat quarry hill and at Wadi Tweirg sections, more clastic nature Hommath Formation (Middle Miocene) at Wadi Hommath and Wadi Umm Zeityia-Wadi Hagul sections and Hagul Formation (Upper Miocene) exposed at the entrance of Wadi Hagul.
Petrographically, the carbonate rocks differentiated into nine microfacies associations (mudstone, wackestone, wackestone/packstone, packstone, packstone/grainstone, grainstone, floatstone, rudstone and framestone). The non-carbonate rocks are differentiated into three clastic microfacies associations (lithic arenite, ferruginous siltstone and calcareous claystone). The facies association of the Lower Miocene of Sadat Formation was deposited in shallow shelf lagoon environment, but the facies associations of the Middle Miocene of Hommath Formation was deposited in shallow water inner ramp. The facies associations of the Upper Miocene of Hagul Formation was deposited in tidal to shallow sub-tidal depositional environment. Diagenetically, the original texture and compositional characteristics of the studied carbonate and non-carbonate rocks were modified by several diagenetic processes. These are: compaction, cementation, aggrading recrystallization (neomorphism) and degrading recrystallization (micritization), dolomitization and dissolutionbelonging to three diagenetic stages (Eogenesis, Mesogenesis and Telogenesis).
Mineralogically, the main clay mineral constituents are kaolinite and montimorillonite. Geochemically, SiO2 and CaO are alternatively the main major oxides whereas Sr, Rb and Li are the main trace elements of limestone samples. Sr concentration in the studied limestone is lower than its concentration in modern carbonates as aresult of the diagenetic processes. Ni, Co, V, Cu, Zn and Cr are accommodated within alumino-silicates and iron-titanium minerals and tend to concentrate upon weathering. This is confirmed by their strong positive correlation with both Al2O3 and Fe2O3 while their derivation from one common source can be detected from the strong relationships among each other. Zirconium is generally transported with terrigenous influx in the form of heavy mineral (Zircon). Zr/Hf ratio lies over UCC ratio suggesting that these elements are related to minerals within the terrigenous materials.The averages of U/Th ratio and authigenic U indicate prevail area of anoxic condition. The LREE are enriched over the HREE. Ce/Ce* values suggest shallow water an oxic to suboxic condition during formation stage. There is no correlation between both Ce/Ce* and Eu/Eu*. The REE in studied samples are formed by weathering products of sedimentary parent rocks such as carbonate rock and phosphorite. Negative Eu anomalies due to its tendency; enter in the structural positions occupied by Ca in carbonate minerals (siderite, magnesite). The heavy minerals are the sole carrier of Y and HREE. The terrigenous matter is the main source of many elements beside the affecting of sedimentary processes. The geochemical records have widely been implemented to realize the provenance, tectonics, climate and weathering conditions in their source. The environments of deposition of the Miocene formations are somewhat realized. The prevailing reducing conditions is dominant.