---

Mafic rocks including basalts and gabbros are the main constituents of Birjand ophiolites. They are found in several places and show low grade metamorphism in the field and under the microscope. Chondrite-normalized REE patterns for basalts and gabbros indicate that these rocks are transitional-enriched to depleted mid-oceanic ridge basalts respectively. Otherwise, N-MORB normalized trace elements patterns for basalts and gabbros are considered to be enriched in some LIL elements. Depletion in Ti and also in Nb (in gabbros) is other characteristic of these rocks. Therefore an incomplete short-lived subduction regime for generation of those heterogeneities can be suggested. The primary mantle-normalized trace elements pattern for Birjand harzburgite also confirms some LIL enrichments.

---

The Plio–Quaternary volcanic eruptions have made basaltic lavas in NW Iran and Azerbaijan. Basaltic lavas with prismatic structure cover the Plio-Pliostocene volcano-sedimentary or Quaternary alluviums. The studied regions are situated in Azerbaijan provinces in areas of Monnavar, Herris, Ahar, Kaleibar, Mahabad, Salmas, Maku, Marand, Sarab and Zunuz. The studied sample rocks are olivine basalt, trachy basalt and basaltic andesite. These rocks have microlithic porphyritic vesicular, hyallo microlithic vesicular porphery and doleritic textures in thin sections. On the basis of chemical analysis, magma that has formed the rocks had alkaline nature with a Na₂O/K₂O>1 ratio. The tectonic environment for the samples in discriminate diagrams is post collisional volcanic arc setting. The study of Rare earth elements patterns in diagrams show that, common dip of variations have descending trend and indicate basaltic rocks enriched in LREE and depleted in HREE. Other features of the diagrams are small negative anomaly for Eu, Ta, Nb and distinct positive anomaly for U, Th, La, Rb, Ba, and Cs. The study of rare earth elements patterns display that magma originated from an enriched asthenospheric mantle with garnet in source.

---

Diabases, pillow lavas and basaltic flows in the Nain-Dehshir ophiolites are marked with flat to slightly depleted pattern in REE chondrite-normalized diagram and are characterized by depletion in HFSE and enrichment in LILE. This geochemical behavior can be considered for lavas erupted in arc-related environments. Clinopyroxene in these rocks shows low content of TiO₂ and resemble those found in island-arc tholeiites. These characteristics are consistent with back-arc formation during middle to upper Cretaceous, due to the oblique subduction of Neotethyan Ocean along the active continental margin of the central Iranian block.

---

The Javaherdasht Basalts show compositional range from olivine basalts to quartz basaltic andesites. Petrographic studies indicate that the differentiation of clinopyroxene and olivine minerals has main role for lithologic variety of the basalts.The corosion golf, crenated margins and lack of the same colour in the clinopyroxene phenochrysts margins with matrix Pyroxene grains express a nonequilibrium and are petrographic features for crustal contamination of the basalts.The positive correlation CaO,CaO/Al₂O₃ and Cr with Mg^# and CaO/Al₂O₃ with Sc and the negative correlation Al₂O₃ with Mg^# are geochemical  characters for the differentiation of clinopyroxene and olivine in the magmatic evolution of the area.The high ratios of Ba/Zr and Pb/Nd and low ratio of Ce/Pb and positive correlation of SiO₂ and Rb with ⁸⁷Sr/⁸⁶Sr and negative correlation of Nd-Sr isotopes display the contamination of these basalts with continental crust.

---

Soltan Maidan Basaltic Complex consists of a thick succession of basaltic lavas associated with some thin sedimentary interlayers that are exposed in the northwest to northeast of Shahrood. Soltan Maidan basaltic rocks has been generated from magma with transitional to mildly alkaline nature and derived by 14-20 percent partial melting of an enriched garnet peridotitic mantle source in an intra-continental rift setting during Late Ordovician to early Late Silurian. These basaltic rocks are relatively uniform in mineralogical composition and they have undergone moderate to high degrees of alteration. Labradorite plagioclase and augite clinopyroxene are major minerals, and Fe-Ti oxides as titanomagnetite and ilmenite form accessory minerals in these rocks. Thermobarometry results on the clinopyroxenes indicate that they have crystallized in temperatures between about 1100^oC to 1200^oC, with pressures less than 6 kbar and show that they have crystallized in magma chamber/chambers located at depths less than 23 kilometers.

---

Amphibolite rocks with mylonitic texture exposed in the NE of Yan- Cheshmeh village (SE of Zayandeh-Rud Lake). Mineralogy of rocks include amphibole, plagioclase, quartz, rutile, clinozoesite, chlorite, titanite, biotite and opaque. Amphiboles are seen as fish. Basic igneous rocks are protolith of the amphibolites that have subalkaline nature. Ni (299-370 ppm), Cr (1169-1900 ppm) and SiO₂ (44.91-49.20 %Wt) contents highly resemble to unfractionation magmas. Chondrite normalized REE patterns exhibit pronounced LREE enrichment relative to HREE without Eu anomaly. Low TiO₂, Zr, P₂O₅ and Nb/Y contents with enrichment of LREE and negative Nb anomaly are pronounced characters of continental flood tholeiitic basalt within plate magmatism. Tholeiitic affinities, low values of alkali elements, high MgO, FeO, Cr and Ni contents suggest high partial melting in an extensional setting of continental within-plate with rapid decrease in pressure, resulting in high rate of partial melting and quick uplift which are effective factors for the formation of basaltic protolith of the amphibolites.   

---

The Gaz Boland area is located in Kerman Province, northwest of Shahr-e-Babak. This area is a part of the volcanic-plutonic belt of Urumieh-Dokhtar. Most of the exposed rocks in this region belong to Eocene age, however, the basalts with Pleio-Pleistocene age have also a relatively limited distribution in the region. The main texture of the basalts is microlithicporphyric and olivine, clinopyroxene and plagioclase form the main minerals. Due to the weathering and alteration processes, secondary minerals such as calcite, chlorite, and iron oxides have formed in these rocks. Based on the analysis of X-ray microprobe, the composition of pyroxenes is diopside-augite. The chemical composition of clinopyroxenes confirms the calc-alkaline nature for their parent magma of, which originates from the subduction-related tectonic setting. Based on clinopyroxene thermobarometric studies, the parent magma of the rocks, when crystallization of the clinopyroxene mineral with approximately 10% water under a pressure of 2 to 8 kbar occured, formed during uplift and before the eruption. The magma temperature variations during the crystallization of clinopyroxenes ranges between 1130 and 1249 °C.

---

The volcanic rocks of the Bagh Chenar region are located in the northeast of Hormozgan province, Hajiabad city. Structurally, these rocks are located in the collision range of Central Iran with the Sanandaj-Sirjan zone. The rock units in this area include pillow lava, microgabbro dyke, ultramafic, and deep marine sediments; including pelagic limestones and radiolarite cherts and some thin sedimentary layers and metamorphic rocks which have been piled on top of each other in the form of a colored mélange complex during the period of magmatic activity. Field studies show that this area's volcanic rocks include basalt and basalt andesite. The textures of these rocks are porphyry, hyaloporphyry, and glomeroporphyry. The main minerals include plagioclase and pyroxene as majors and minor and secondary minerals include calcite, chlorite, and opaque minerals located in a glassy and microcrystalline field. The pattern of rare earth elements (REE) and spider diagrams indicate the enrichment of LILE and LREE and some HFSE elements. According to the diagrams, the studied rocks are within the tholeiitic magmatic series with the origin of the mid-oceanic ridge. Also, based on the tectonic environment chart, the samples are located in the subduction zone or mid-ocean ridge. The results of this study show that the volcanic rocks of the Bagh Chenar ophiolite complex are composed of tholeiite magma. This magma was formed in a marine extension tectonic environment and the evolutionary processes of magma in this complex included fractional crystallization, magmatic isolation, and crustal contamination.