Kebira Crater - Libyan Desert Silica Glass Source

Libyan Desert Silica Glass Source

As noted by Longinelli and others, the Carboniferous Wadi Malik Formation and erosional remnants of the Lower Cretaceous Gilf Kebir Formation, which are exposed within this proposed impact structure, "have been considered as possible source materials for LDG despite the lack of clear evidence" for the origin of this feature as the result of an extraterrestrial impact. Because of its size and hypothesize origin, El-Baz and Ghoneim speculated that the Kebira Crater was the source of Libyan desert glass that is found scattered over about 6,500 km2 (2,510 sq mi) within the Great Sand Sea in western Egypt and near the Libyan border. Aboud also suggested that if the Kebira Crater is an impact structure, it might be the solution to the mystery about the source of Libyan desert glass. However, he cautioned that origin of this feature was still largely conjecture that required additional research to confirm. Ramirez-Cardona and others also suggested that the Kebira Crater might be the source of Libyan desert glass. Instead of proposing that Libyan desert glass was ejected from this feature by an impact, they hypothesized that it was transported from it by a Oligocene-Miocene Gilf River system that contained the Kebira Crater within its drainage basin. They also noted that evidence for the Kebira Crater being an impact structure lacked direct field observations. Most recently, Longinelli and others studied the oxygen isotope and chemical composition of Libyan desert glass and samples of sands and sandstone from its proposed source areas. They found that the mean oxygen isotope values of the sandstone samples from the Kebira Crater differed greatly from their Libyan desert glass samples. Because of this, they concluded that the sandstone exposed in this feature can be ruled out as being the source of Libyan desert glass.