Sequence Stratigraphic Analysis of The Carbon-Siliciclastic Miocene Sediments, North Eastern Desert, Egypt

Document Type : Original Article

Authors

1 Geology Department, Faculty of Science, Port Said University 42521, Egypt

2 Geology Department, Suez Canal University, Ismailia41522, Egypt

Abstract

The depositional and stratigraphic studies of the Miocene sediments exposed at the north part of the eastern desert, clearly established. It is divided into two rock units, the lower siliciclastic one termed as Gharra Formation, representing the lower Miocene (Burdigalian) and upper carbonate, termed as Genefa   Formation   of  Middle   Miocene   age   (Langhian). The  microfacies investigations of  thirteen  thin  sections in  the Gharra  Formation  revealed  the presence  of  inner-shelf  to  intertidal  lagoons  facies  whereas  the  microscopic investigations  of  twenty  two  thin  sections  from  Genefa  Formation  revealed inner-shelf, middle neritic and outer shelf facies. The depositional sequence was initiated and developed as a result of the first advance of the Miocene Sea over  the  study  area  with  type-1  Sb  over  the  continental  sediments  of  the Oligocene. Retrogradational parasequence are successively stacked within the LST, whereas   the   transgressive   surface   (ts)   almost   coincides   with   the stratigraphic contact between the Gharra and Genefa formations with a marked change  in  the  parasequences  geometry  into  retrogradational–aggradational nature with  clear  sea-level  rise.  By the Middle Miocene,  a general  sea  level rise   accompanied   by  deeper   accommodation   depositional   setting  due   to tectonic subsidence, where relatively deeper  marine facies started to deposits the Genefa Formation, just over the transgressive surface (ts). These sediments constitute the general transgressive system tract in the study area. It includes well-stacked  retrogradational-aggradational  parasequences  mainly  deposited within shelf zones.

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