the zagros ftb contains 49% of the world's hydrocarbon reserves hosted in fold and thrust belts and about 7% of all reserves. the zagros province includes many giant and supergiant oilfields, such as the kirkuk field with over ten billion barrels of remaining oil reserves as of 1998, and the asmari reservoir, an oligocene-miocene limestone subsequently folded into anticline structural traps during the zagros orogeny.