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The Dalampar ophiolite is an unknown part of the Neo-Tethys ophiolite and is located NW of Iran between Piranshahr and Salmas ophiolites within the Sanandaj-Sirjan metamorphic belt. Serpentinized peridotites, pillow basalt, various gabbro, pelagic limestone, and radiolarite along with volcano-sedimentary units are the main rock types in the area. These rocks are mixed together in most places as tectonic and “coloured” mélanges. Peridotite rocks in the complex were replaced by serpentinite completely or partly due to hydrothermal alteration. Dalampar serpentinites exhibit affinity to the typical metamorphic peridotites with Harzburgitic and Dunitic protolith compositions. Petrographically, they are composed essentially of chrysotile and lizardite with subordinate amounts of chrome spinel, magnetite, talc, calcite, tremolite and chlorite. geochemical features marked by LILE-LREE enrichment, HFSE depletion, and U-shaped chondrite-normalized REE pattern with (La/Sm)N > 1 and (Gd/Yb)N < 1, Suggest multistage petrogenetic processes including refertilization of a depleted, refractory mantle wedge by subduction-derived fluids and boninitic mantle melts operative in an intraoceanic fore-arc environment. The calculated phase diagram for the studied samples shows that serpentinites probably formed in two metamorphism events; the first one includes alteration and hydration of harzburgite in T< 200 Co and P < 4 kbar, while the second one occurred due to increasing T and P to more than 400 Co and 4 kbar.

Ophiolites are slices of oceanic lithosphere obducted onto a continental margin and can be classified as mid-oceanic ridge (MOR) or suprasubduction zone (SSZ) types based on the tectonic setting in which they originally formed (Pearce et al., 2000; Shervais, 2001). The Zagros Orogen extends from eastern Turkey through northern Iraq and northwest of Iran to the Hormuz Strait and Oman (Alavi 1994; McQuarrie, 2003; Homke et al., 2004; Agard et al., 2005; Shafaii Moghadam et al., 2018). The geodynamic evolution of the Zagros Belt is mainly related to the opening and closure of the Neo-Tethys oceanic basin. Ophiolites, as Neotethys oceanic lithosphere remnants, are emplaced along the Zagros Orogen. These ophiolites are emplaced along two main belts (Saccani et al., 2013; Shafaii Moghadam et al., 2018). The Neo-Tethys suture zone coincides with the Main Zagros thrust fault (Agard et al., 2005) and ophiolites are exposed scattered along this zone. 

The Dalampar ophiolite, located between the Piranshahr and Salmas ophiolites. The Dalampar ophiolites consist mainly of strongly sheared serpentinized ultramafic rocks including harzburgite, dunite overlaid by gabbro and basalt units. The emplacement mechanism of the Dalampar ophiolite massifs into the Iranian microcontinent and structural evolution is completely unknown. There has been not performed a systematic investigation of these ophiolites and geodynamic and relation with other ophiolites are not well Studied.
Thus, the main purpose of the present paper is to investigate the petrogenetic processes, tectono-magmatic environment, using mineral chemistry and textural evidences of Dalampar ophiolite which are fundamental for understanding the tectonic evolution of the Neo-Tethyan Ocean.

During the fieldwork, a number of suitable peridotites samples with least alteration effects were selected. Folloing the petrographic studies, a thin polished section was prepared from several harzburgites for microprobe analysis using JEOL JXA-8600 M model,15 kv accelerator voltage and 2-ray current 10-8 Amp, placed at the Department of Earth Sciences and Environment of Yamagata University, Japan.

Harzburgites are the most basic and widespread ultramafic units in Dalampar ophiolite complex. They show evidences including the presence of exsolution of clinopyroxene in orthopyroxene, the orientation and elongation of the crystals indicating these rocks were formed in the upper mantle conditions and reached equilibrium in the crustal environment. Exsolutions of clinopyroxene lamellae from orthopyroxene are one of the textures observed in the rocks under study and is widespread in both abyssal and SSZ peridotites (Tamura and Arai, 2006). The Cr# of spinel in abyssal peridotites is a good indicator of the degree of partial melting for the mantle-derived spinel peridotite. Low Cr# spinels represent less depleted peridotites, whereas the high Cr# spinels highlight more depleted peridotites (Dick and Bullen, 1984; Arai, 1994). in the Mid-oceanic ridges, the degrees of partial melting and depletion are generally low. In contrast, the supra-subduction zone peridotites have a high degree of partial melting and depletion (Niu and Hekinian, 1997). The content of Cr# in presented Cr-spinels are high (78-83%), and associated with boninitic melts formed by high degrees of partial melting or much more extensive melt-rock reaction (Arai, 1994). As the the Cr# of spinel versus the Fo content of olivine diagram shows the harzburgites fall in SSZ domain. Furthermore, all rock types fall into olivine-spinel mantle array (OSMA). This is regarded as the evidence for their residual origin, i.e. they form a trend which was likely caused by partial melting. Experimental studies confirm that the Al2O3 and TiO2 contents, as well as FeO/MgO ratios in chromian spinel are directly related to those of the parental melt (Rollinson, 2008). According to Maurel and Maurel (1982), The Al2O3 contents of the parental melt range from 10 to 11 wt. % for the studied Harzburgites. Such values are consistent with boninitic melts, which typically contain 10–14 wt.%, respectively (Dilek and Thy, 2009). In the Cr# versus TiO2 diagram, the Dalampar peridotites classify as depleted peridotites. In consequence, chemistry of the chromian spinels in the Dalampar peridotites are compatible with a genesis in a suprasubduction zone from boninitic or primitive arc magmas. However, forearc regions may contain both SSZ and abyssal peridotites, although the former are typically dominant (Pearce et al., 2000). Olivine-spinel and orthopyroxene-clinopyroxene thermobarometry in the harzburgites shows equilibrium temperatures of 1000-1100 ºC at a pressure of 28 kbar and suggests that they have been equilibrated in spinel peridotite field.

The Dalampar Ophiolitic Complex as a part of the Tethyan ophiolites is exposed in the northwestern part of the Iranian-Azerbaijan province, extending to the Anatolian ophiolites in southeastern Turkey. The petrography, geochemistry and microstructural studies of the residual mantle sequence in Dalampar Ophiolitic Complex provide important information regarding the degree of partial melting and deformation in the oceanic mantle lithosphere. Mineral chemistry clearly indicate that Dalampar ultramafic rocks record an episode of boninitic magmatism occurred within the southern Neo-Tethys Ocean in the Late Cretaceous. Boninitic melts in Dalampar Ophiolites were formed by partial melting of depleted peridotite, a residue after MORB-type melt extraction. Mineral chemical data indicate that SSZ peridotites are the residues from ∼30–40% of mantle melting. Nonetheless, the very low (< 0.25 wt. %) TiO2 calculated for the parental melt in equilibrium with chromian spinel are only consistent with boninitic-type parental melts. Based on geothermobarometry calibration the temperature and pressure of crystallization of harzburgite rocks were 1000 to 1200 ° C and 24 Kbar, corresponding to the SSZ tectonic environment.

The Kamyaran ophiolites, with the age of Late Cretaceous, are a part of the Iranian Mesozoic ophiolites, which are exposed in the SW of Zagros Main Thrust. This massif is bordered at the NE by the Sanandaj-Sirjan metamorphic rocks and at the SW by the Bisotun limestones and Kermanshah radiolarites and then by the Zagros Fold-Thrust Belt. The Kamyaran ophiolite is made of the mantle and crustal sequences. The crustal sequence is distinguished by pillow lavas, sheeted dike complex, and lava flows. The positive LILE anomalies with the HFSE depleted confirm their arc-related affinity. The geochemistry signatures of sheeted dikes show that these rocks have two different patterns. The REE pattern in some of the sheeted dikes samples with the pillow and flow lavas sample is similar to E-MORB; their element ratios support this likeness too. The positive LREE and LILE anomalies with the depletions of the HFSE suggest the calc-alkalic tendency and subduction-related affinity for these rocks; however, dacitic dikes with the flat REE pattern, LILE enrichment, and HFSE depletions have the Island-arc tholeiites affinity. The similarity of element ratios in all the samples may suggest that these rocks have the same magma source, and the tectonic environment of the ophiolitic rocks can be correlated with the oceanic subduction environment.

Kamyaran ophiolitic complex located in the northeast Zagros orogeny along the crush zone between Arabian-Iranian plates. This complex outcropped between the Harsin ophiolites in southeast and Sarwabad ophiolite in northwest. Field observation reveal the fact that the Garmab Ophiolite in the northeast of Kamyaran is a tectonic mélange including peridotites and gabbros cut by microgabbroic dikes. Olivine, clinopyroxene and orthopyroxene with chromian spinel made the peridotites minerals with mesh and porphyroclastic fabrics and Gabbros include plagioclase, clinopyroxene and minor amphibole with intergranular, pegmatoidic and interstitial texture. According to the geochemical results, gabbros have tholeiitic to calk-alkaline nature and show the MORB to island arc characteristics. According to the geochemical and geotectonic results, Garmab peridotites plotted to the abyssal peridotites area that represent from the residual mantle spinel lherzolite after extraction of 15–20% partial melting. The break-off of Neo-Tethyan slab and subduction of this slab branch beneath the oceanic lithosphere during cretaceous led to cessation of the Neo-Tethyan subduction beneath the Sanandaj-Sirjan block, and forming arc-back arc basin (second step of subduction) and related rocks in the Kamyaran ophiolite. Presence of tholeiitic to calc-alkaline magmatism is in response to the slab retreat in the Eurasian continental margin.

The Garmab area is located in NW of Kamyaran and belongs to the Kermanshah Ophiolite Zone. This complex is located between the Sanandaj-Sirjan and the Zagros thrust zones. Peridotite rocks in the complex were replaced by serpentinite completely or partly due to hydrothermal alteration. Petrographic studies show that the serpentines formed by hydration of both olivine and orthopyroxene minerals. Electron microprobe and X-ray diffraction (XRD) analyses of the samples indicate that the Garmab serpentinites contain all the three serpentine polymorphs (chrysotile, lizardite, antigorite). Those serpentines replacing olivines have higher SiO2 and lower Al2O3, Cr2O3 and TiO2 than those replacing orthopyroxene. This clearly demonstrates their different sources. The calculated phase diagram for the studied samples shows that serpentinites probably formed in two metamorphism events; the first one includes alteration and hydration of harzburgite in T< 200 oC and P < 4 kbar, while the second one occurred due to increasing T and P to more than 400 oC and 4 kbar.

The Noorabad-Harsin ophiolite complex as part of the Kermanshah ophiolite is located in the high Zagros zone. The ophiolitic complex from the lower part to upper part is composed of serpentinized peridotites, layered gabbro, isotropic gabbro, plagiogranite, sheeted dike complex, basaltic lava, andesite and sedimentary rocks, respectively. The structure such as orientation and elongation of crystals in these rocks show that Noorabad-Harsin peridotites have been formed in the upper mantle and then emplaced in the crust. The detailed electron microprobe study olivine composition is forsterite with Fo (91-93). The composition of pyroxenes is diopside and enstatite with low contents of TiO2 and Al2O3. The study of chrome spinels has high Cr # (57-80), Mg # (61-89) and very low TiO2 content which indicate the ophiolitic and depleted mantle origin. The serpentines have Al2O3 content in the range of 0.01 to 10.42 wt. % with SiO2 content between 36.75 to 41.08 wt. percent and are chrysotile and lizardite. Low modal of clinopyroxene, Mg rich olivines and high Cr# content and Cr/Al ratio of chromian spinel from ultramafic cumulates indicate that dunites and harzburgitic rocks have formed by high degrees of partial melting. The chemical compositions of different minerals show different petrogenesis for ultramafic rocks of the Noorabad- Harsin ophiolite complex and show characteristics of the abyssal environment to supra-subduction zone. It seems these peridotites have derived by high degree partial melting of the depleted and sub-oceanic mantle in a supra-subduction zone-Fore arc and have same properties with residual mantle peridotites.

A sequence of Tertiary basic volcanic rocks is exposed in the east of Qazvin. The volcanic sequence is mainly composed of olivine-basalt to trachyandesite with porphyrictic, microlitic, and glassy textures. Clinopyroxene, plagioclase, amphibole, and iddingsitized olivine are the main phenocrysts. According to EPMA data plagioclase shows labradorite to bytownite composition and clinopyroxene is diopside. Geothermobarometry of clinopyroxene and amphibole represents the temperature of 1100 C to 1200 C and pressure of 1 to 5 kbar during crystallization of these minerals. According to the geochemical data, the sequence shows calc-alkaline affinity which is related to volcanic arc setting. In comparison to chondrite, they are enriched in LILEs and depleted in HFS elements. Also based on geotectonic diagrams, these rocks have been derived from a high potassium calc-alkaline to shoshonitic magma in an active continental margin setting. Ti and Nb negative anomalies and LILE enrichment support an enriched mantle in a supra-subduction zone as a source for magma. According to this study, the magma originated from a low grade 5 to 10 % partial melting from an enriched garnet-spinel lherzolitic mantle source at depth of 50-70 km and finally has risen to the surface via deep fractures and faults within an intra-arc extensional basin in Central Alborz zone during the Middle and Upper Eocene time.

The Shahini ophiolitic complex is located west of Kamyaran as a ring connection between the Kermanshah and Kurdistan ophiolites, outcropped along the Zagros and Neotethys suture zone, in western Iran. This complex include the mantle peridotites and crustal sequence. The peridotites are highly serpentinized mantle peridotites consist of cpx-bearing harzburgite and lherzolite that cross cut by isolated diabasic dikes. The crustal sequence include pegmatic gabbros, Isotropic gabbro, microgabbroic dykes, basalt and pyroclastic andesite. The sedimentary-volcanic sequence consist of shale, limestone, sandstone and tuff horizons covered the extrusive sequence. Based on chemical analyses the crustal sequence shows the various composition with tholeiitic to calcalkaline affinity. In the tectonomagmatic diagrams, these rocks are often plotted in the MORB regions and in some occasions, they are plotted in volcanic arcs regions. The enrichment in LILE, slightly depletion of HFSE, different enrichment in LREE and linear trends of HREE suggested the magma source originated in the arc environment from the heterogeneous mantle with varying degrees of partial melting. However, the low ratios of Th/Yb, La/Nb, Ce/Nb and Ce/Th inclined the tendency between the IAB and MORB environments. The depth of partial melting estimate between 50 to 60 km correlating and show the partial melting happens in the spinel lherzolite zone. Field relationships and geochemical evidence indicate that Kamyaran ophiolites formed in the oceanic basin in the ocean-continent borders zone in the northwest margin of Neotethys Ocean.

The fourteen numbers of ultrabasic volcanoes eruption in the west of Nowbaran are located in the west margin of Iranian central zone near to the Sanandaj-Sirjan zone. The combination of volcanic material consists mainly of low viscosity lava and in some cases pyroclastic material. According to the petrography and geochemical data, these rocks are nephelinite and melilite-nephelinite. Several chemical characterizations such as low content of SiO2, high rate of CaO and MgO, depleted from HFSE and enrichment of LILE, shown the magma originated from depleted mantle source. Ti and Nb negative anomalies presented the subduction component for this magma source. The Nawbaran magma with sodic-alkaline nature, formed within plate geodynamic environment. The geochemical evidences have shown the magma originated from enrichment garnet-lherzolite mantle with low partial melting (1-3%) in the 90 to 110 km depth of earth surface. Existence of mantle calcite, calcium rich apatite and perovskite whit the high rate of CaO and MgO in the rocks composition signed the carbonated component and carbonate metasomatism is candidate for the evolution of west Nawbaran young magmatism.

The Garmab ophiolite complex, a part of the Ophiolite-Radiolithic zone of Kermanshah, is located in the northeast of Kamyaran. In view of the Iranian geo-structural zones, this complex is situated between the Sanandaj-Sirjan Zone and the Zagros thrust Zone. Field studies demonstrate that the dykes with gabbro (pegmatoidic gabbro, microgabbro and gabbronorite) and diabasic composition have crosscut the peridotites of the ophiolite complex. The main minerals of gabbroic rocks include plagioclase (andesine and occasionally anorthite in pegmatoidic gabbros and oligoclase to andesine in microgabbros) and clinopyroxene (diopside-augite). The amphiboles belong to calcic amphiboles group (magnesio-hornblende and actinolite). Mineralogical and geothermometry studies of the clinopyroxene, amphibole and the plagioclase from the pegmatoidic gabbro reveal that these rocks have originated at 800 to 1200 OC. Moreover, geobarometric measurements, based on aluminum content within the amphiboles, indicate pressures between 5 to 7 kbar for the final equilibrium of the minerals studied. The chemical compositions of the clinopyroxene and the amphiboles indicate that the aforementioned minerals have crystallized from a sub-alkaline magma in an island arc or volcanic arc (IAT) tectonomagmatic setting. In addition, the gabbroic dikes formed from a mantle source in a subduction zone.

Northeast Kamyaran ophiolitic complex is mainly composed of harzburgite along with small outcrops of lherzolite. Harzburgites are extensively altered to serpentinite. Small lenses of chromite mineralization are observed in harzburgites. The mineral assemblage present in the study harzburgite and lherzolite are olivine, orthopyroxene and clinopyroxene along with minor amount of spinel. Microprobe studies on the spinel indicate that it is Cr and Al bearing spinel (Cr-spinel) with very high Mg# (55.2-71.9) and Cr# (34.3-45.5) values and low values of TiO2 (with average value of 0.6 wt%). Fe3+ content of the Cr-spinel in the study rocks is high (with average value of 0.8 wt %) indicating that the crystallization occurred at high oxygen fugacity. According to the microprobe data, MgO content of olivine varies between 50.04 and 52.99 wt% and its composition is forsterite (Fo90.68-91.42). Based on the mineral chemistry of spinel, peridotites of Northeast Kamyaran ophiolitic complex belong to residual depleted peridotites which have formed in mid ocean ridge tectonic setting.

Kamyaran ophiolite sequence as a part of the Kermanshah ophiolite-radiolarite belt is located in the northeast of Kamyaran, northwest Iran. No complete ophiolitic sequence is seen in this area and only a peridotite part including harzburgite, lherzolite and serpentinite is observed. The sequence is cut by some gabbroic dykes. According to the microprobe analytical data, olivine in the studied rocks displays forsterite (Fo) contents of 90.11 to 92.5. Their clinopyroxenes are diopside and augite. Orthopyroxenes in the mentioned rocks are compositionally enstatite with Mg# ranging from 0.91 to 0.92. The studied pyroxenes are rich in chromium, with 0.80-01.39 wt% chromium oxide. High contents of chromium in clinopyroxenes and orthopyroxenes are consistent with the degree of partial melting and the depleted nature of these rocks. The studied Cr-spinels are Al rich in composition and their average Cr# and Mg# are 0.37 and 0.69, respectively. From the mineral chemistry of harzburgites and lherzolites, it is inferred that the studied rocks are similar to the abyssal peridotites belonging to residual peridotites remained after extraction of mid-ocean ridge basalt (MORB) in a back arc basin setting.