Introduction
Iranian ophiolites are part of the Tethyan ophiolites of the Middle East. They link the Middle Eastern and Mediterranean Hellenides–Dinarides ophiolites (e.g. Turkish, Troodos, Greek and East European) to more easterly Asian ophiolites (e.g. Pakistani and Tibetan) (Shojaat et al., 2003). Tethyan evolution in Iran and neighboring Turkey, Oman and Baluchistan is very complex and hard to work out.
The main tectonic elements of Iran and the locations of the major Iranian ophiolites are depicted in Figure 1. Geographically, the Iranian ophiolites have been divided into four groups (Takin, 1972; Stocklin, 1974; McCall, 1997; Hassanipak and Ghazi, 2000 and Shojaat et al., 2003): (i) ophiolites of northern Iran along the Alborz range, (ii) ophiolites of the Zagros Suture Zone, including the Neyriz and Kermanshah ophiolites, which appear to be coeval with the Oman (Samail) ophiolite emplaced onto the Arabian continental margin, (iii) unfragmented ophiolites of the Makran accretionary prism which include the complexes of Band-e-Zeyarat/Dar Anar and Remeshk/Mokhtar Abad, and (iv) ophiolites and colored melanges that mark the boundaries of the central Iranian microcontinent (CIM), including Shahre-Babak, Nain, Baft, Sabzevar and Tchehel Kureh ophiolites. The CIM is composed of the Yazd, Posht Badam, Tabas and Lut blocks.
Figure 1. Distribution of the ophiolite belts in Iran
Distribution of the ophiolite belts in Iran after Emami et al. (1993), and location of the SCO area. Main Iranian ophiolite complexes: BZ: Band-e-Ziyarat (also called Kahnuj complex). KM: Kermanshah. NA: Nain. NY: Neyriz. SB: Sabzevar. SHB: Shar Babrak. THL: Torbat Hydariyah. TK: Tchehel Kureh
The Alborz range of northern Iran is a region of active deformation within the broad Arabia–Eurasia collision zone (Allen et al., 2003). It is an active orogenic belt that contains a number of ophiolites, which suggests that the continental collision between Arabia and Eurasia occurred along the Alborz Suture Zone. On the southern coast of Caspian Sea, in Northern side of Alborz range, two ophiolite sequences are reported: 1) Asalem-Shanderman (Talesh) ophiolite in Paleozoic (Berberian, 1983 and Eftekharnejad et al., 1993); and, 2) Southern Caspian Sea ophiolite complex (SCO) in Mesozoic (Salavati, 2000).
The results of most of the petrological and geochemical studies on the Iranian ophiolites show mid-ocean ridge basalt (MORB) and island arc tholeiite (IAT) affinities with a harzburgite mantle that indicate a HOT type ophiolite (Desmons and Beccaluva, 1983; McCall and Kidd, 1981; Wampler et al., 1996; Ghazi et al., 1997; Hassanipak and Ghazi, 1996a: Ghazi and Hassanipak, 1999a). Also some LOT ophiolite type are reported in Iran such as Upper Cretaceous Khoy ophiolite (Khalatbari-Jafari et al.,2006).
In this paper with the results of petrological and geochemical studies of the Southern Caspian Sea ophiolite and comparison SCO with other famous world ophiolites, we attempt identification of SCO ophiolite type, and suggest a possible tectonic formation for this ophiolite within the context of the Neo-Tethyan tectonic reconstruction models of Iran and the Middle Eastern region.