Red Sea isolation history suggested by Plio-Pleistocene seismic reflection sequences

Comparison and Synthesis of Sea‐Level and Deep‐Sea Temperature Variations Over the Past 40 Million Years

“…In contrast, glacial sea‐level minima underwent three major steps, to −70 m at ∼1.25 Ma, −90 m at ∼0.9 Ma, and about −120 m at ∼0.65 Ma (Figure 15b). Independent evidence from seismostratigraphic assessment of Red Sea sediments indicates a first lithified “aplanktonic” layer at ∼0.65 Ma during the marine isotope stage 16 glaciation (Mitchell et al., 2015). This supports our inference of a major step in glacial sea‐level lowering at ∼0.65 Ma because such lithified layers, which lack planktonic foraminifera and contain abundant inorganically precipitated aragonite, developed only during extreme sea‐level lowstands when Red Sea exchange with the open ocean was restricted severely (e.g., Almogi‐Labin et al., 1991; Deuser et al., 1976; Fenton et al., 2000; Halicz & Reiss, 1981; Hemleben et al., 1996; Ivanova, 1985; Ku et al., 1969; Locke & Thunell, 1988; Milliman et al., 1969; Reiss & Hottinger, 1984; Rohling, 1994a; Rohling et al., 1998; Schoell & Risch, 1976; Thunell et al., 1988; Winter et al., 1983).…”

Phylogeographical patterns and a cryptic species provide new insights into Western Indian Ocean giant clams phylogenetic relationships and colonization history

“…An alternative hypothesis—the one which has our favour—is that T. squamosina originated in the north‐western Indian Ocean and repeatedly colonized the Red Sea during interglacial periods, whenever conditions were favourable (Mitchell, Ligi, & Rohling, ). Under this scenario, likely barriers leading to the diversification of the WIO T. squamosina and T. elongatissima could be the cold‐water upwelling and related gyres and eddies off Somalia and/or off Oman that act as environmental barriers, isolating the populations of the Arabian Sea from those of the Gulf of Aden and further south along the Indian Ocean coast of Somalia (DiBattista, Howard Choat, et al, ; Schott, Xie, & McCreary, ).…”

Reconstructing the level of the central Red Sea evaporites at the end of the Miocene

“…This implies a 10‐m uncertainty in Z e (uncertainty 3). A bias could arise from picking basement towards the upper envelope of diffraction hyperbolae (Mitchell, 1995). We estimate this bias could be 100 m, hence affecting average overflown area by 2.4 km 2 , which implies a 13‐m underestimation in Z e (uncertainty 4).…”

“…This compromise assumes the section above the basement is mainly halite based on the transparency of seismic reflection images typically observed (Izzeldin, 1987), though presence of reflective seismic data suggesting also a layered evaporite sequence like that found at DSDP Sites 225, 227 and 228 (Whitmarsh et al., 1974). Their overlying Plio‐Pleistocene sediments sampled at the DSDP sites have a similar density to halite (Mitchell et al., 2010) and are typically a uniform 200–300 m thickness away from the coasts (Mitchell et al., 2015, 2017; Ross & Schlee, 1973), so 2.2 g/cm 3 is suitable for those sediments also.…”