The two ring structures of Western Ghurfa and Gaziret Khashm Natash as well as the ring dyke, G.
El Ghurfa have extruded through the volcanic flows. The three rings range in composition from volcanic
flows, represented by trachybasalt, trachyandesite, normal trachyte and alkaline trachyte and pyroclastic
rocks (agglomerates, tuffs, pumice and scoria). The rings are semicircular to circular in outline range from
1 km to 0.6 km.
The high contents of uranium in the studied rocks are due to the presence of secondary uranium minerals
such as meta-autunite and kasolite as well as the accessory minerals bearing uranium such as monazite,
xenotime, zircon and allanite.
The geochemical studies of the volcanic rocks revealed that the rock samples fall in the trachyte,
trachyandesite , trachybasalt and basalt fields. These rocks were originated from alkaline magma, and
developed in continental basalt environment. The enrichment of the LREEs (182 - 391 ppm) is most due to
the presences of garnet in the source.