Incipient seafloor spreading segments: Insights from the Red Sea

Abstract

Crustal‐scale forward models of marine satellite potential field data suggest that the Red Sea comprises a single segment of ocean crust, which extends along ~60% of the Red Sea. The segment “tips” are bounded by continental crust, and there is no evidence for transforms at the segment terminations at the south. These observations indicate that ocean crust formation does not necessarily occur in response to wholesale tearing or “unzipping” of continental lithosphere nor is it necessarily controlled by preexisting transform faults. Ocean crust initiation occurs as a series of isolated segments that coalesce as the basin evolves. The recognition of this process in an orthogonal extension setting is comparable to spreading segmentation in modern ocean systems generated at a highly oblique convergent margin, suggesting that oceanic crust segmentation is not controlled by kinematic boundary conditions. The Red Sea may represent a combination of incipient type I and type II passive margins development.

Seismicity Associated With the Formation of a New Island in the Southern Red Sea

“…There is uncertainty in the nature of the Red Sea ridge between 15.5 and 14.5 • N. A lack of magnetic anomalies suggests an absence in seafloor spreading in this region, however, bathymetry data suggest the ridge continues to 14.5 • N (Almalki et al, 2016). The revised dike position that we propose is somewhat similar is position and orientation to that constrained for the Jadid eruption (Figure 2), and suggests that both dikes were likely intruded along the same rift segment.…”

“…Rifting of the Red Sea then continued in episodic periods, with seafloor spreading initiating 5 Ma (Bosworth et al, 2005). Magnetic anomalies between 16 and 19 o N display five symmetrical magnetic stripes that are interpreted to have begun 3 Ma (Bonatti, 1985;Almalki et al, 2016). Further north, magnetic anomalies become discontinuous before disappearing.…”

“…Together these account for the total relative plate motion of the Arabian and Nubian plates. The termination of the Southern Red Sea rift is unclear due to conflicted data; bathymetry and gravity data suggests the termination at 14 • N, whereas magnetic stripes are only recorded until 15.5 • N (Almalki et al, 2016). This suggests a gradual change in spreading from the Red Sea ridge to the Danakil block; extension in the Red Sea ridge decreases to the south, whereas extension gradually increases to the south in the Danakil depression resulting in overlapping ridges in the region 14.5-15.5 • N.…”

3‐D Analog Modeling Constraints on Rifting in the Afar Region

“…These observations support the hypothesis that tensional forces above a mantle plume head focused the development and ~120° spacing of the Red Sea, the Gulf of Aden, and the Main Ethiopian Rift arms (Bosworth et al, 2005). However, regional geological and geophysical data show that the three rifts oriented asymmetrically and that they record different tectonic histories and relative timing (Almalki et al, 2015, 2016; Wolfenden et al, 2004).…”

Kinematics and deformation of the southern Red Sea region from GPS observations

“…Hofstetter and Beyth 2003;Varet 2018; ISC 2019), and there are no morphological or volcanological expressions of the rift axis extending this far south(Schettino et al 2016;Almalki et al 2016). Furthermore, vent alignments, crater elongations and eruptive fissure and/or volcanic ridge orientations in and around the Hanish-Zukur Islands and the Nabro-Dubbi volcanoes (N40°E,Fig.…”