Transition from continental rifting to oceanic spreading in the northern Red Sea area

Weakened continental lithosphere beneath the northern Red Sea inferred from elastic thickness

The northern Red Sea (NRS) is considered an extended continental region that has resulted in a rift system. Gravity and bathymetry data were used to estimate the Moho depth and the elastic thickness Te of the lithosphere beneath the NRS region to characterize its flexural rigidity and understand its mechanical behavior. Focusing on the Mabahiss Deep in NRS, we analyzed the lithosphere's flexural rigidity. The observed long-wavelength positive Bouguer anomaly is attributed to crustal thinning and lithospheric mantle uplift. The crustal thickness varies from 28 km in coastal areas to 24 km beneath the axial rift, supporting a regional compensation model over the Airy model. Forward modeling suggests that the optimal model explaining the regional Bouguer anomaly is a flexural model with Te equal to 7 km, indicating a weak and irregular continental crust. The primary factor contributing to this weakness is heating activity. Given the weakened state of the crust and the ongoing extension in the region, the NRS rift could evolve into a rupture, potentially leading to the formation of oceanic crust.

New magnetic anomaly map for the Red Sea reveals transtensional structures associated with rotational rifting

The Red Sea is a modern analogue for studying continental break-up. Particularly, the Red Sea shows along-strike variability in the architecture, magmatism and associated style of rifting. In order to study these variabilities, continuous geophysical data that cover the entire length of the basin is desired. Our study aims to produce a continuous, reliable and robust magnetic anomaly map for the Red Sea. We present a new magnetic anomaly map for the Red Sea, derived from re-processing of shipborne data, merged and conformed to a recent satellite model, LCS-1. The new magnetic map reveals prominent patterns of magnetic anomalies in sub-perpendicular directions to the Red Sea, with a northward increase in obliquity. We provide further analysis for the magnetic data and associate sets of magnetic trends with transtensional basement structures. Directional analysis suggests a gradual increase in shear component along the Red Sea. The magnetic trends are coaxial with independent indicators of finite and instantaneous strains, and thus implies that these structures and their variability are related to the kinematic framework of the rift. We discuss the consequences of rifting close to the Euler pole, i.e. rotational rifting, and argue that both passive and active forces can explain an increased along-strike transtension, and accordingly the associated variability along the Red Sea.