| Popis: |
The sequence stratigraphic framework of the Cenomanian Galala Formation (north Eastern Desert, Egypt) is estimated on the basis of the Sedimentological and obtainable biostratigraphic data, in addition to the regional correlation of the studied sections. Five sequence boundaries are identified. The first sequence boundary separates between the Galala and Malha formations. The second, third and fourth sequence boundary exhibit a differentiated nature. It is noticed that such sequence boundaries in Gebel El-Zeit are mainly represented by paleosols and caliche, while those of the Northern Galala, Gebel Ataqa and Gebel Shabraweet are mostly typified by emergence horizons of dolomites and dedolomites. The fifth (last) sequence boundary separates the Galala Formation from the overlying El-Khashm Formation at Gebel El-Zeit, the Northern Galala and Gebel Ataqa and from Maghra El-Hadida Formation at Gebel Shabraweet. The Galala Formation in the study area is subdivided into four depositional sequences, which are built up of three systems tracts; the lowstand (LST), transgressive (TST) and highstand (HST) systems tracts. The LSTs are realized only from Gebel El-Zeit, where they are made up of clastic facies organized in coarsening- and fining-upward parasequences. The TSTs form a series of aggradational-retrogradational, shallowing-upward parasequences, which transgress across the ramp till the point of maximum flooding is reached. The HSTs are built up of aggradational–progradational, shallowing-upward parasequences of shallow subtidal to peritidal facies. |
Full Text from ScienceDirect