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At a glance of its stratighraphy, the Taftan Volcano can be classified as three groups: pre-, syn-and post-volcanic deposits. The pre-volcanic deposits consist mostly of flysch facies and colored mélange complex. The syn-volcanic deposits are mainly the product of the Taftan Volcano which is mostly composed of pyroclastic and lava flows from the main body of this volcano. The post-volcanic deposits are mostly epiclastic and reworked materials from the Taftan Volcano due to its erosion and weathering. Major and trace elements, and Sr/Rb isotopic compositions determined on whole-rock samples from the Taftan Volcano showed that the volcano was formed at the continental margin. The whole-rock isotopic composition of the Taftan Volcano showed a feature of strong enrichment with 87 Sr/ 86 Sr=0.705326-0.705921. Geochronological samples of the Taftan Volcano determined by the 40 K/ 40 Ar method gave an age range of 6.95±0.72 to 0.71±0.03 Ma. The rare-earth element patterns are characterized by high LREE and nearly strongly linear patterns for MREE to HREE, suggesting that distinctive minerals such as olivine and pyroxene crystallized in the early magmatic stage and then were involved in reaction between the lower crust and residual magma. The integrated isotope and trace element systematics and tectonic structure beneath the Taftan Volcano suggested the lower-crust assimilation by the primary magma. The primary magma had generated from a heterogeneous mantle source and a secondary petrogenetical process. This magma could have been affected by the subduction of the Oman Sea underneath the continental Eurasia plate.

In the Gandom Beryan area, basanitic lava flows erupted from fractures in the Nayband fault zone and formed an area of about 300 km 2 of basanitic rocks in the western part of the Lut Block. Olivine and clinopyroxene are the major phenocrysts in a microlitic groundmass for these basanitic rocks. The geochemical data show that Gandom Beryan rocks are basanite in composition and belong to intercontinental rifts related to alkali basanites. These rocks have low Fe/Mg ratios (Fe 2 O 3t /MgO = 1.07-1.43) with low silica content (SiO 2 = 44.89-48.26 wt.%) and are high-Ti basanites. The investigated rocks are characterized by a significant enrichment of total REE and LREE relative to chondrite. Moreover, the REE patterns of these rocks are linear without any negative Eu anomalies. The low abundances of HREE in basanitic rocks and the REE modeling together reflect the relation between these elements and residual garnet in the partially melted mantle. The 207 Pb/ 204 Pb and 206 Pb/ 204 Pb ratios of the basanitic rocks fall near the field of enriched mantle II (EM-II). The Gandom Beryan volcanism, which was related to partial melting of mantle within an extensional setting, resulted from a left-step, pull-apart basin in the Nayband N-S trending strike-slip fault system. Although the fault system is older than Gandom Beryan volcanism, it seems that it has been reactivated during and after the volcanism.

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