Late Albian-Cenomanian paleoenvironmental and paleoclimatic reconstructions in northeastern Gondwana: Palynological perceptions

Paleoredox Conditions, Paleoproductivity, and Terrigenous Sediment Influx of the Lower-Middle Cenomanian Strata in the Abu Gharadig Basin, Northern Egypt

“…The Bahariya Formation rests conformably above the Kharita Formation and underlies the Abu Roash Formation (Figure 2). Recent palynological achievements erected four interval zones within the Bahariya Formation from the Gindi Basin, including the lowermost Cenomanian Trilobosporites laevigatus, lower Cenomanian Cretacaeiporites densimurus and Elaterosporites klaszii zones, and lower-middle Cenomanian Afropollis jardinus zone [2]. Similar age constraints were reported for the same interval from the BED2-3 well in the Abu Gharadig Basin [8].…”

“…These two assemblages indicated the deposition of the lower Bahariya in fluvial to fluvio-deltaic and marginal marine settings, whereas the middle-upper Bahariya was deposited in an inner neritic shelf. Interestingly, in the adjacent Gindi Basin (North Qarun-1x well), the Bahariya Formation was categorized into three palynofacies assemblages suggesting the deposition from fluvio-deltaic-to-shallow marine similar environments [2]. In the Shushan Basin (Salam-17 well), palynofacies and palynomorph analyses of the lower Bahariya Formation indicated a predominantly regressive phase of relative sea level, characterized by distributary and tidal channels, and deltaic settings [7].…”

“…These conditions likely led to a well-stratified water column and the preservation of moderate-to-high amounts of organic carbon [4,8], with the dominance of active rifting and spreading in the north Western Desert basins [11]. This active tectonic setting likely caused a relatively low relief fluvio-deltaic belt intermittent by marginal marine inundation from the Tethys Ocean in the southern part of the Western Desert [2,6]. Consequently, there was limited water mass exchange and restricted settings with a stagnant water column during deposition, which aligns with the adsorption of high amounts of redox-sensitive elements into the shales and siltstones of the lower Bahariya Formation.…”

“…During the Cenomanian transgression, thick sequences of siliciclastic and carbonate sediment were deposited in the southern Tethys, such as in the north Western Desert of Egypt [1,2]. The north Western Desert was a major shelf area attested to the deposition of a complete petroleum system during the Late Cretaceous.…”

“…Specifically, the study focuses on analyzing total organic carbon (TOC), whole-rock major and trace elements, and carbonate content. The primary objectives of this study are as follows: (1) reconstruct the paleo-redox conditions and marine biological productivity prevalent during deposition of the lower-middle Cenomanian Bahariya Formation; (2) investigate the role of terrigenous sediment flux, weathering intensity, and paleoclimate conditions that were prevalent during the early-middle Cenomanian in this part of the southern Tethys; and (3) interpret the mechanisms governing the quantity of the organic matter in terms of abundance and distribution within the Bahariya Formation, such as the factors controlling production and preservation potential versus dilution and decomposition of labile organic matter. Illustrating a location map of the Abu Gharadig Basin, along with other sedimentary sins, major highs, and structural features that have a significant influence on northern Egypt.…”