Between the Nile and the Red Sea

The Medjay were a group of desert nomads inhabiting the region between the Nile and the Red Sea contemporaneous to the Bronze Age of Ancient Egypt (c. 3100-1050 bce). Well-known from textual sources from Pharaonic Egypt and Kushite Nubia, it has proven difficult to produce basic societal descriptions of the Medjay and their political status, especially in their desert heartland. Most studies dedicated to the Medjay evaluate their presence as a nomadic diaspora and emigres on the Nile or focus on their interaction with the Ancient Egyptian state. These approaches place little emphasis on their indigenous geography and nomadic heritage in the Red Sea Hills. This study takes a very different tact and attempts to reconstruct some basic information on their political geography in their indigenous homeland. Although the sources, both textual and archaeological, are currently scarce regarding a Second Millennium bce desert occupation, they do demonstrate complex arrangements between Medjay political actors and nearby states. Particularly notable was the ability of individual tribes to enact varying policies of entente, détente, and aggression towards their Nile neighbours as well as exercise de facto sovereignty over a wealthy desert consistently threatened by Egyptian and Kushite imperialism.

New Insights into the Evolution and Age of the Neoproterozoic Jebel Ohier Porphyry Copper Deposit, Red Sea Hills, Northeastern Sudan

New SHRIMP U-Pb data from dioritic to granodioritic synmineral intrusions associated with the Jebel Ohier porphyry copper deposit (mineral inventory, including NI43-101-compliant total inferred and indicated resources, of 593 million tonnes [Mt] at 0.33% Cu and 0.05 ppm Au, for 1.953 Mt of contained Cu and 933,600 oz of Au at 0.15% Cu cutoff) in the Red Sea Hills of northeastern Sudan have bracketed the age of mineralization to ca. 816 to 812 Ma. This age range, as well as constraints from new and existing lithogeochemical data, is consistent with the deposit’s formation from a productive parental magma source during the early stages in the evolution of an intra-Mozambique Ocean island arc. The Jebel Ohier porphyry copper deposit bears many similarities to well-documented Phanerozoic analogues elsewhere in terms of (1) the mapped style and zonation of hydrothermal alteration (i.e., proximal K-silicate–dominated, to sericitic, to distal propylitic alteration), (2) the occurrence of intense Cu-bearing A- and B-type vein stockwork, as well as sulfide-only C-type veins, anhydrite veins, and younger, peripheral D-type veins, and (3) the geochemical fingerprint of the associated porphyry, which is akin to those of ore-related Tertiary porphyries in the Escondida area in northern Chile. The multiphase intrusion hosting the Jebel Ohier porphyry copper deposit has been intruded by several generations of mafic to felsic postmineralization dikes and voluminous plutons, with a peak in magmatic activity coinciding with the suturing of the Gebeit terrane at ca. 724 Ma. In spite of, or perhaps because of, the occurrence of extensive postmineralization magmatism, and regardless of subsequent deformation, regional metamorphism, uplift, and erosion, the deposit has remained remarkably intact. The discovery of a relatively ancient, yet well-preserved porphyry copper deposit in the Neoproterozoic Arabian-Nubian Shield has major implications for the exploration potential of this resource-rich geologic terrain.

A remote-sensing-based intensity–duration threshold, Faifa Mountains, Saudi Arabia

Construction of intensity–duration (ID) thresholds and early-warning and nowcasting systems for landslides (EWNSLs) are hampered by the paucity of temporal and spatial archival data. This work represents significant steps towards the development of a prototype EWNSL to forecast and nowcast landslides over the Faifa Mountains in the Red Sea Hills. The developed methodologies rely on readily available, temporal, archival Google Earth and Sentinel-1A imagery, precipitation measurements, and limited field data to construct an ID threshold for Faifa. The adopted procedures entail the generation of an ID threshold to identify the intensity and duration of precipitation events that cause landslides in the Faifa Mountains, and the generation of pixel-based ID curves to identify locations where movement is likely to occur. Spectral and morphologic variations in temporal Google Earth imagery following precipitation events were used to identify landslide-producing storms and generate the Faifa ID threshold (I =4.89D−0.65). Backscatter coefficient variations in radar imagery were used to generate pixel-based ID curves and identify locations where mass movement is likely to occur following landslide-producing storms. These methodologies accurately distinguished landslide-producing storms from non-landslide-producing ones and identified the locations of these landslides with an accuracy of 60 %.

A Remote Sensing–based Intensity-Duration Curve, Faifa Mountains, Saudi Arabia

Construction of intensity-duration (ID) curves and early warning systems for landslides (EWSL) are hampered by the paucity of temporal and spatial archival data. We developed methodologies that could be used for the construction of an ID curve that could be used for the construction of an EWSL over the Faifa Mountains in the Red Sea Hills. The developed methodologies relies on temporal, readily available, archival Google Earth and Sentinel-1 imagery, precipitation measurements, and limited field data. These methodologies accurately distinguished landslide-producing storms from non–landslide producing ones and identified the locations of these landslides with an accuracy of 60 %.