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Ophiolites in the Zagros orogen represent relics of the Neo‐Tethyan Ocean that existed between the Laurasia and Gondwana continents. There is much debate about the formation and evolution of the Neo‐Tethyan Ocean. Knowledge of its pre‐collisional tectonic evolution is essential in constraining the timing and process of the collision between the Eurasian and Arabian continents. We present a combined analysis of zircon LA–ICP–MS U–Pb ages and Hf–O isotopes of the Sardasht ophiolite from the NW Zagros orogen. Our new data demonstrate that the Sardasht ophiolite formed at ca. 50.6 Ma. Geochemistry of plagiogranite and diabase indicates that the Sardasht ophiolite probably originated in the mantle wedge, influenced by subduction fluids. The mafic rocks of the Sardasht ophiolite include boninites, arc basaltic rocks, and OIBs, which accreted together when the Neo‐Tethys finally closed. Finally, we argue that there was an intra‐oceanic fore‐arc extension and arc system during 50–24 Ma in the southern branch of the Neo‐Tethys in NW Zagros. [ABSTRACT FROM AUTHOR]

The Makran complex in southeast Iran provides a spectacular subduction-related accretionary complex to understand the mechanism of oceanic accretion and the evolution of subduction zones. In this paper, we present new major and trace element data as well as isotopic compositions of mafic volcanic blocks from the Makran ophiolitic mélange complex (OMC). Our aim is to assess the genesis of these rocks and discuss their implications on the evolution of Neotethys Ocean. These volcanic blocks are composed mainly of basalts with minor trachytes. The Makran lavas are occasionally interlayered with tuff layers. Zircons from these tuffs give U-Pb ages of 95 Ma, which is well in accordance with the reposted microfossil data for the interlayered pelagic limestones with pillow lavas. Makran basalts can be geochemically subdivided into four groups; normal to transitional MORB, enriched-MORB, Plume-type MORB and alkaline (-OIB-like) basalts. The OIB-like pillow lavas are represented by high values of Th/Tb (6.3–7.4) which are higher than other basalts (group 1 = 0.3–0.8; groups 2 = 0.7–1.6; group 3 = 1.58–1.36).143Nd/144Nd(t) ratios for basalts ranges from 0.51247 to 0.51292, whereas 87Sr/86Sr(t) isotopic composition of the OMC lavas varies from 0.704433 to 0.709466. The Pb isotopic composition of the lavas are quite high, ranging from 15.49–15.66 for 207Pb/204Pb(t), 18.09–19.12 for 206Pb/204Pb(t) and 37.80–39.23 for 208Pb/204Pb(t). The chemistry of these rocks suggests that they were formed most likely in an oceanic setting with clear plume-ridge interaction. These rocks can form from partial melting of a highly heterogeneous mantle source, which is extensively metasomatized with deep mantle OIB-type components. We suggest these rocks have been generated in an oceanic ridge with plume-ridge interaction, similar to the Iceland-Reykjanes Ridge, before being fragmented and accreted into the Makran accretionary complex. [ABSTRACT FROM AUTHOR]