--> Presalt to Salt Paleogeography and Stratigraphic Architecture in a Rift Basin: Insights From a Basin-Scale Study of the Gulf of Suez (Egypt)

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Presalt to Salt Paleogeography and Stratigraphic Architecture in a Rift Basin: Insights From a Basin-Scale Study of the Gulf of Suez (Egypt)

Abstract

The Gulf of Suez is a continental rift providing both outcrops and subsurface dataset to illustrate a rift dynamic at high resolution (time steps < 1Myr, basin scale ~300×100km). The sedimentary fill includes thick salt layers overlying presalt continental to marine syn-rift series. The objective of the present study is to characterize the presalt to salt dynamic based on stratigraphic correlation at basin scale (~300 × 100km) of 279 wells and 31 sedimentological sections. Several stages of rift evolution can thus be summarized as follow: Rift initiation (ca. 4Myr duration): the Suez rift was initiated at the end of the Oligocene along the NNW-SSE trend of the Red Sea with evidences of active volcanism. Continental to lacustrine deposits are only preserved in isolated depocenters. Rift widening (ca. 3Myr duration): the rift was progressively propagated from south to north (Aquitanian), with first marine incursions from the Mediterranean Sea. The rift was subdivided into numerous depocenters controlled by active faults. Rift climax (ca. 5Myr duration): the rift was then flooded during Burdigalian times. The faults were gradually connected and reliefs on the rift shoulders were maximums as evidenced by a strong increase of the uplift/subsidence rates and sediment supply. Three main depocenters were then individualized across the rift. Flexuration to rift narrowing (ca. 4Myr duration): during the Langhian, the basin recorded several falls of relative sea level and bathymetry in the rift axis was progressively reduced. The former reliefs induced during the rift climax were quickly destroyed as evidenced by the drastic drop in sediment supply. During Serravalian times, the rift basin has recorded several disconnections with the Mediterranean Sea as evidenced by massive evaporites in major fault controlled depocenters. Tectonic quiescence to flexuration (ca. 7Myr duration): the Tortonian is then characterized by the deposition of very thick salt series (>1000m) which has recorded a period of maximum restriction for the Suez rift. The basin was still subdivided into several sub-basins bounded by major faults. The basin was totally and permanently disconnected from the Mediterranean Sea, and possibly connected to open marine condition via the Red Sea. The Messinian is also characterized by a thick salt series, but the evaporite typology and sedimentary systems distribution suggest a more humid climate than during Tortonian times.