Abstract: Continental rifting and ocean basin formation can be observed at the present day in the Red Sea, which is used as the modern analogue for the formation of mid-ocean ridges. Competing theories for how spreading begins - either by quasi-instantaneous formation of a whole spreading segment or by initiation of spreading at multiple discrete "nodes" separated by thinned continental lithosphere - have been put forward based, until recently, on the observations that many seafloor features and geophysical anomalies (gravity, magnetics) along the axis of the Red Sea appeared anomalous compared to ancient and modern examples of ocean basins in other parts of the world. The latest research shows, however, that most of the differences between the Red Sea Rift (RSR) and other (ultra)slow-spreading mid-ocean ridges can be related to its relatively young age and the presence and movement of giant submarine salt flows that blanket large portions of the rift valley. In addition, the geophysical data that was previously used to support the presence of continental crust between the axial basins with outcropping oceanic crust (formerly named “spreading nodes”) can be equally well explained by processes related to the sedimentary blanketing and hydrothermal alteration.
The observed spreading nodes are not separated from one another by tectonic boundaries but rather represent "windows" onto a continuous spreading axis which is locally inundated and masked by massive slumping of sediments or evaporites from the rift flanks. Volcanic and tectonic morphologies are comparable to those observed along slow and ultra-slow spreading ridges elsewhere and regional systematics of volcanic occurrences are related to variations in volcanic activity and mantle heat flow. Melt-salt interaction due to salt flows, that locally cover the active spreading segments, and the absence of large detachment faults as a result of the nearby Afar plume are unique features of the RSR.
The differences and anomalies seen in the Red Sea still may be applicable to all young oceanic rifts, associated with plumes and/or evaporites, which makes the Red Sea a unique but highly relevant type example for the initiation of slow rifting and seafloor spreading and one of the most interesting targets for future ocean research.
Bio: Dr. Nico Augustin is a senior research scientist at the GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany. He received his PhD in geosciences from the University of Kiel in the field of geochemistry and petrology of submarine mantle rocks in the vicinity of hydrothermal activity. During his PostDoc time he performed two-years of scientific excurses in isotope geochemistry of hydrothermal fluids and on the petrology and genesis of submarine authigenic carbonates. With his capability to look at the problems from a different perspective, he was able to develop some new, but controversial ideas. Since 2010 he moved his research focus from geochemistry to bathymetric mapping and geomorphology of mid-ocean ridges. At this time he started his research in the Red Sea Rift and was part of two major research expeditions there. He developed a model that brings the Red Sea Rift, that was geologically thought to be special, back in line with the known mid-ocean ridges worldwide. Even if his main research interest still lies in the Red Sea rift and research there is ongoing, he is further involved in numerous other seagoing expeditions, often working in internationally and interdisciplinary projects together with e.g. biologist, geophysicists and oceanographers. The aim of his current work is to understand volcanology and hydrothermalism in all oceans, but particularly in rift zones, by means of seafloor imaging and morphological analyses combined with information from other disciplines.