Mesozoic–Cenozoic metallogenesis in Iran

Abstract

A short description of the regional geology of Iran is followed by new data concerning grade of metamorphism, palaeomagnetism, continental drift and radiometric age determinations. Mineralization in Iran is considered in terms of four metallogenic epochs: Lower and mid-Cretaceous lead-zinc deposits in limestones, late Cretaceous chromium, copper and manganese associated with ophiolites, early Tertiary copper veins, skarns and porphyries and late Tertiary and Pleistocene porphyry copper deposits and lead-zinc veins. Eight areas are examined as regional exploration targets. In the Yazd-Golpaigan area Lower and mid-Cretaceous stratabound lead-zinc ores of Mississippi Valley type are associated with magmatism related to the initial rifting of Gondwanaland. In western Azerbaijan Upper Cretaceous chromite ores in serpentinised dunite are regarded as part of a plate boundary environment. In northern Azerbaijan Oligocene granodiorite intrusions, related to porphyry copper deposits in Russia, have given rise to copper-molybdenum skarns. The Sabzevar zone is thought to be a 200 km wide area of oceanic crust. Cretaceous ophiolites with chromite deposits occur in its northern part, while the southern part contains chalcopyrite and pyrolusite ores in submarine lavas and sediments and low grade copper ores associated with Eocene island arc volcanism. Eastern Lut contains Cretaceous chromite deposits and lead-zinc-copper-gold veins possibly related to Plio-Pleistocene intrusions. The Neogene-Pleistocene portion of the central Iranian volcanic belt is a chain of large stratovolcanoes and granodiorite intrusions, apparently fault-controlled, which includes important porphyry copper deposits. The Oligocene volcanics of western Alborz contain veins with galena, sphalerite and chalcopyrite and a large hydrothermal alunite deposit. The flows and tuffs are intruded by granodiorite, granite and monzonite, with potential for porphyry-type copper ores.

Porphyry copper assessment of the Tethys region of western and southern Asia: Chapter V in <i>Global mineral resource assessment</i>

“…Other possible porphyry-related prospects may be present at (1) the Sorkh Pey-Homeireh copper district in the Kuh Mish Range (Geological Survey of Iran, 2012a; Bazin and Hübner, 1969a), (2) the Cha-Mussa polymetallic vein deposit in the Torud Range (Bastani and others, 2009; Geological Survey of Iran, 2012a; Bazin and Hübner, 1969a;Imamjomeh and others, 2009), (3) the iron skarn deposits at Kuh-e-Zar-Torbat-e-Heidarieh (Karimpour, 1998;Abedi and Ziaii, 2004;Mazloumi and others, 2008;Mazloumi Bajestani and Rasa, 2010) and Sangan (Ghavi and Karimpour, 2010;Malekzadeh Shafaroudi, Karimpour, and Golmohammadi, 2013;Boomeri and others, 2006;Boomeri, Ishiyama, and others, 2010;Karimpour and Malekzadeh, 2006) in the Taknar-Kashmar Range; and (4) perhaps also the Neyshabour Cu-U historic mining district east of the Sabzevar Range (Förster, 1978;Karimpour and others, 2012; Geological Survey of Iran, 2012a; Bazin and Hübner, 1969a). The relation to porphyry-style mineralization has not been established in these epithermal and iron skarn (IOCG?)…”

“…Precambrian to pre-Late Cretaceous metamorphic basement is preserved along several of these ranges, suggesting that microcontinental fragments occupied parts of this intraoceanic basin. Ophiolite-bearing accretionary complexes exhibit both MORB and island-arc geochemical signatures (Delaloye and Desmons, 1980;Shojaat and others, 2003) and host chromium and manganese, as well as younger porphyry, skarn, and epithermal, mineralization (Förster, 1978;Geological Survey of Iran, 2012e). From south to north, they occur along three main ranges (Taknar-Kashmar, Sabzevar, and Torud), which suggests the presence of as many associated island arcs (Samani, 1998;.…”

“…Significant other sources of relevant information on porphyry deposits and prospects used for this study include Bazin and Hübner (1969a, b), Förster (1978), Karimpour and others (2011b), Boztuğ and others (2003), Kuşcu and Erler (1998), Yigit (2006Yigit ( , 2009Yigit ( , 2012, Jamali and others (2010), Al-Bassam and Hak (2006), Richards and others (2012), Perelló and others (2008), and Orris and Bliss (2002). The reader is referred to appendix A for these and additional sources of information on porphyry and porphyry-related occurrences in the assessment region.…”

“…Moreover, Late Triassic to Early Cretaceous arc magmatism is absent in middle part of the SanandajSirjan Terrane. During this time period, the central part of the Sanandaj-Sirjan Terrane appears to have been part of a back-arc or rift basin where Pb-Zn-Ba Mississippi Valley type (MVT), sedimentary exhalative (SEDEX), and VMS occurrences developed instead of porphyry-related mineralization (Ghazban and others, 1994;Mirnejad and others, 2011;Rajabi and others, 2012;Förster, 1978;Meshkani and others, 2011).…”

“…In contrast, porphyry copper systems may have not been identified in the part of the Esfahan tract that lies in the Central Iranian Terrane, likely because they are concealed under shallowly emplaced volcanosedimentary and volcanic rocks. In this area, Late CretaceousEocene mineralization is represented by abundant more shallowly emplaced VMS and epithermal deposits (Förster, 1978; Geological Survey of Iran, 2012e) and also several subvolcanic possible Climax-type porphyry molybdenum occurrences (Geomatics Management, [n.d.]). …”