In a groundbreaking study published in Communications Earth & Environment, researchers at King Abdullah University of Science and Technology (KAUST) have unveiled compelling evidence that the Red Sea, a vital marine corridor today, completely desiccated approximately 6.2 million years ago. This profound geological event, whose timing and dynamics had remained elusive until now, fundamentally transformed the basin before it was abruptly refilled by an extraordinary cataclysmic flood from the Indian Ocean. This research not only revises our understanding of the Red Sea’s paleoenvironmental history but also provides new insights into the complex interplay between tectonics, oceanography, and climate during the Messinian Salinity Crisis.
The interdisciplinary approach employed by the KAUST team combined advanced seismic imaging, meticulous microfossil analyses, and precise geochemical dating methods to construct a detailed chronology of the desiccation and subsequent reflooding. Their data reveal a rapid transition, accomplished in less than 100,000 years—a geological instant—during which the Red Sea transformed from a shallow marine extension connected to the Mediterranean into an arid, hypersaline basin. This transformation culminated in the complete evaporation of seawater and the precipitation of extensive salt and gypsum layers, marking one of the most extreme environmental states recorded in Earth’s recent geological past.
Prior to drying out, the Red Sea maintained a connection to the Mediterranean Sea via a shallow sill to its north. This delicate hydrological linkage was severed, likely due to a combination of tectonic uplift and climatic aridity, which severely restricted water exchange and amplified evaporative loss. As the basin progressively concentrated salts, marine ecosystems collapsed, and the environment transitioned into a salt-encrusted desert. Simultaneously, at its southern end near the Hanish Islands, the Red Sea was isolated from the Indian Ocean by a volcanic ridge barrier that prevented direct inflow of seawater.
The dramatic finale of this desiccation phase was the sudden breaching of the volcanic dam separating the Red Sea from the Indian Ocean. Approximately 6.2 million years ago, a colossal marine flood surged through this barrier, carving a massive 320-kilometer-long submarine canyon that remains etched in the seafloor today. This inundation event rapidly restored marine conditions, flooding the basin and re-establishing its connection to global ocean systems within a remarkably brief geological timeframe. The scale and speed of this natural flood event are comparable to, yet distinct from, the later and more widely known Zanclean flood responsible for refilling the Mediterranean Sea nearly a million years afterwards.
From a geological standpoint, the Red Sea is a young ocean basin born from the divergent tectonic activity separating the Arabian and African plates beginning around 30 million years ago. Initially a narrow rift valley, this depression evolved from lacustrine environments into a marine gulf through episodic flooding events, with the Mediterranean connection established roughly 23 million years ago. This tectonic and hydrological evolution set the stage for frequent environmental fluctuations, including episodic hypersalinity and biotic stress that eventually led to the remarkable Late Miocene desiccation cycle extensively documented now by the KAUST team.
Evaporative concentration over millions of years created ultra-saline conditions that decimated native marine biota, as evidenced by the disappearance of fossil reefs along the northern Red Sea coastline. The onset of desiccation stimulated the deposition of thick evaporite sequences—salt and gypsum—that filled large portions of the basin. These sediments serve as critical archives delineating past ocean chemistry and climatic oscillations, offering a window into the environmental stresses experienced by marine ecosystems during the Messinian Salinity Crisis.
The renewed marine inundation following the Indian Ocean flood marked a pivotal reset in the Red Sea’s ecological trajectory. The sudden inflow of seawater restored salinity balance, oxygenation, and nutrient exchange, which facilitated the resurgence of coral reef ecosystems and other marine fauna. This rebirth set a foundation for the rich biodiversity observed in the modern Red Sea, validating the basin as a living natural laboratory for studying oceanographic and evolutionary responses to extreme environmental perturbations.
This study also contributes substantially to our understanding of how ocean basins form, expand, and evolve through the coupling of tectonic processes and extreme climatic events. The Red Sea’s unique geological narrative exemplifies the dynamic nature of ocean gateways and the interplay between crustal movements and global oceanographic circulation. Moreover, identifying the timing and impact of such a mega-flood enhances reconstructions of paleoclimate and paleoceanography during critical intervals of Earth history.
The implications of this research extend beyond regional geology, linking the Red Sea to broader patterns of Messinian environmental upheaval and ocean circulation changes. By detailing one of the most dramatic marine desiccation-reflooding cycles yet documented, the KAUST scientists have provided a crucial reference point for geoscientists investigating ancient flood events, sea level fluctuations, and their influence on sedimentation and marine biodiversity.
The novel submarine canyon carved by the flood demonstrates the immense erosive power of oceanic waters released under extreme conditions. Its preservation on the seafloor affords researchers a rare opportunity to analyze the geomorphological and sedimentological consequences of such high-magnitude hydrological events, which are analogues for other ancient and possibly future marine catastrophes under climate change scenarios.
Lead author, Dr. Tihana Pensa, emphasizes how “the Red Sea basin chronicles one of Earth’s most extreme environmental transformations—from a desiccated salt desert to a vibrant marine ecosystem—reshaping our understanding of ocean basin development and resilience in the face of climate-driven crises.” The research not only elevates the scientific profile of the Red Sea but also reinforces KAUST’s prominence in pioneering oceanographic and geological investigations in the region.
In conclusion, this seminal work on the Red Sea’s Messinian history underscores the intricate connections between plate tectonics, climatic shifts, oceanographic barriers, and ecosystem survival during Earth’s dynamic past. The insights gleaned pave the way for further multidisciplinary studies aimed at unraveling the complexities inherent in marine basin evolution and the environmental forces that have shaped our planet’s oceans through deep time.
Subject of Research: Not applicable
Article Title: Desiccation of the Red Sea basin at the start of the Messinian salinity crisis was followed by major erosion and reflooding from the Indian Ocean
News Publication Date: 9-Aug-2025
Web References: http://dx.doi.org/10.1038/s43247-025-02642-1
Keywords: Marine geology, Geologic history, Floods
