Riofinex, 1977. A preliminary review of mineral opportunities in Sadi Arabia, Report FR-1977-1.

Nawab, Z.A. 1979. Geology of the Al-Amar - Idsas region. IAG Bulletin 3, V. 2., p. 29-40.

Jackson, N., and Roobol, J. 1980. Notes on the geology of the Jabal Idsas – Jabal Tays area. Newsletter – “Pan-African Crustal Evolution in the Arabian-Nubian Shield”, 3, 30-36
GEOTECTONIC MODEL
	“Two geotectonic models have been proposed for this region. Al-Shanti and Mitchel (1976) proposed  that the Al-Amar - Idsas fault zone represents the site of an eastward dipping subduction zone at the site of collision of between and island arc volcano-sedimentary-plutonic rock complex (Ar-Rayn Province) with a passive continental margin (Western Ad-Dawadimi Province). In this interpretation the three formations of the Urdd Group are interpredted as stable shelf sediments (Ar-Ridaniyah Fm), ocean floor ophiolites (Ophiolite Complex) and ocean floor sediments (Abt Fm).”

	“Nawab (1979) modified this interpretation to suggest that the Ad-Dawadimi Province represents a small "back arc" ocean basin developed as a result of rifting of continental crust, the Ar-Rayn plutonic-volcanic-sedimentary complox representing a "continental" volcanic arc generated above a westward dipping subduction zone.”

	“An alternative hypothesis is that the eastern and western plutonic complexes formed a continuous "continental" substrate beneath the Urd and Halaban Groups. These complexes were intruded by mafic-ultramafic rocks )"ophiolite complexes", possibly as a result of crustal rifting, but an oceanic substrate did not form. The Ar-Radaniyah and Abt Formations would therefore, represent intercontinental marine deposits, while the Halaban volcanics amy be related to subduction or contintneal rifting processes?”

Jackson, N., Kroner, A., Church, W.R., and Hashad, A. 1980. Notes on some stratigraphic relationships in the Jabla Idsas area. Newsletter – “Pan-African Crustal Evolution in the Arabian-Nubian Shield”, 3, 16-17.
Abt Formation – “Primary structures such as planar-, trough-, and cross-bedding, slump beddng, ripples, cut-and-fill structures, and normal and reverse grading are preserved.”; “eastward coarsening succession.”; Near the eastern boundary polymictic conglomerates containing unfoliated granite boulders and cobbles probably represent channel-fill deposits… fluvial-deltaic regime.” “to the west … increase in carbonate content until thin-bedded carbonate-wackes predominate.”; “second-phase of deformation was concommitant with the emplacement of quartz-porphyry and rhyloite dykes which were emplaced into the S1 axial plane cleavage and deformed with it.”; 
Ophiolite ….”deformed along with the Abt during the F2 phase of folding.  …..emplaced between the F1 and F2 phases of deformation.”  “
Jabal Hammer (Hamir) volcanics …. “Have suffered only one phase of deformation …and are virtually unmetamorphosed.” “(given) the absence of volcanic debris in the Abt, the volcanics are considered to be younger”.
Idsas Conglomerate ….”contains blocks of magnetite dervied from the Jabal Idsas magnetite deposits emplaced in volcanics which are probably equivalent to the Jabal Hammer volcanics. If this assumption is correct then this tectonic-sedimentary deposit is probably the youngest Precambrian (?) deposit in the district.”

Baker, P. 1980. Volcanics of the Al Amar - Jabal Idsas region. Newsletter – “Pan-African Crustal Evolution in the Arabian-Nubian Shield”, 3, 24-25.
“Jabal Hamar (Hamir), some 30 Km south of Jabal Idsas, lies to the west of the Al amr Idsas fault, and appears to be the remnant of  central volcano. It is composed of lava flows, volcanic breccias, nd  series of tuffs of both pyroclastic nd volcaniclastic origin/ The laa flows include basaltic and andesitic types. One highly porphyritic basalt (or andesite) has a distinctive texture, with abundant plagioclse phenocrysts clustered in 'crow's foot' groups (Daisy Stone). Many of the fined grained tuffs apper to be of dacite to rhyodacite composition.”
	“East of the Al Amar - Idsas fault, 3 km south-west of Jabal Idsas, is  porphyritic plagioclase-phyric lava, similar to the flow collected at Jabal Hammer.  Felsite (?rhyolite) was also collected from the area.    “