Early – Middle Miocene Suez Syn-rift-Basin, Egypt: A sequence stratigraphy framework

Abstract

The analyses of thirteen planktonic and benthonic biozones, paleobathymetry and electric log data were used to interpret the sequence stratigraphy of the Early to early Middle Miocene syn-rift section in the Gulf of Suez. The study area is located in the central province of the Gulf and includes six boreholes located in two half grabens and the October Field. The new framework proposes the Suez Supersequence and Suez Depositional Sequence DS 50 instead of the five paleontological sequences commonly cited in the literature (S10 to S50). The Supersequence starts above the regional unconformity that separates the pre-and syn-rift rocks, commonly referred to as Terrace T00. The shallow-marine deposits of the Aquitanian Nukhul Formation form the lowstand systems tract. The Burdigalian Mheiherrat Formation starts with the Uvigerina costata flooding event and forms the transgressive systems tract deposited in outer-neritic to upper-bathyal settings. The overlying Langhian Hawara Formation was deposited in upper to middle bathyal settings and represents the maximum flooding interval. The Langhian Asl Formation (early falling stage systems tract, upper bathyal to outer neritic) and overlying Langhian Lagia Member of the Ayun Musa Formation (late falling stage systems tract) closed the Supersequence. Suez Depositional Sequence DS 50 lies unconformably on the Supersequence, and represents a major transgression starting with the Praeorbulina glomerosa s.l. flooding event. DS 50 corresponds to the Ras Budran Member of the Ayun Musa Formation (paleontological sequence S50). Its setting is outer neritic and its upper sequence boundary is an unconformable with the Belayim Formation. The Suez Supersequence is interpreted in terms of 35 genetic parasequences and DS 50 by 10 more. The parasequences are interpreted by the coincidence of quantitative paleontological faunal and paleobathymetric breaks with the electric log shifts. The sequences and parasequences are correlated between the six wells to show the evolution of the half-grabens and October Field at different times.