The rgion covered by the Gonabad Quadrangle Map is situated in central part of the Khorassan Province- The relief consists of a number of variously - trending mountains and hills separated by extensive flat areas filled in with Quaternary deposits. Three main structural zones have been distinguished: fl) the Northeastern Ranges, bounded to the Southwest by the WNW - trending Central Plain; 12] the Southwestern Structural Complex (SSC); (3) the Khaltabad Range (to the southeast).
Restricted outcrops of low-grade wet dimorphic rocks whose age is Proterozoic or uncertain, occur in the northeast and southwest of the quadrangle. A fairly extensive sequence of Paleozoic deposits is exposed in the northeast of the SSC. It underwent a regional and / or contact metamorphism of variable intensity and is virtually devoid of diagnostic fossils. However this sequence could be subdivided into the following Devonian to Permian formations;(1) the Niur and Padeha Formations (mostly quartzitic sandstones); (2) a formation of quartzites, shales and limestones (Dsq) believed to overlie the Padeha Formation; (3)a fairly thick series of carbonate racks assigned to the undistinguished Sibzar and Bahrain Formations; (4)the Shistu and Sardar Formations; (5)massive limestones assigned to the Jamal Formation. In the major part of their outcrops these limestones are closely associated with dolomites; in this ease the aggregate limestones and dolomites have been mapped as the Tabas Group (Permian to Mid-Triassic in age). Deposits tentatively assigned to the Lower Paleozoic: are exposed in the northwest of the SSC and in the Khaltabad Range. In the latter also Occur Sediments attributed to the Sardar Formation and restricted outcrops of Permian limestone. Carbonate rocks belonging to the Tabas Group are exposed in the south of the SSC; they locally include red-colored deposits probably representing the Sorkh Shale Formation.