Petrogenesis of Plio-Quaternary basanites in the Gandom Beryan area, Kerman,Iran: geochemical evidence for the low-degree partial melting of enriched mantle

Abstract

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.

Meteorites from the Lut Desert (Iran)

“…Gandom Beryan DCA, which hosts the Gandom Beyran volcanic complex (Yousefi et al. ), is a well‐known geotourism site attracting adventurers and leading to an increase in meteorite finding chance along their route.…”

Petrogenesis and Geochemistry of Tabas Black Land volcanic field: implications for volcanic activity along the Nayband fault, East Iran

“…For the Iran plateau, the previous studies in eastern Lut include those along the southern and northern segments of Neh Fault [Elahpour and Heuss-Aßbichler 2017;Pang et al 2012], western Lut, along the southern segment of the Nayband Fault, mainly focused on Gandom Beryan volcanic plain [Yousefi et al 2017;Saadat et al 2010;Walker et al 2009], and western Lut Volcanica 2(2): 105 -127. doi: 10.30909/vol.02.02.105127 along the northern part of the Nayband Fault [Pang et al 2012;Saadat et al 2010;Hashemi et al 2008]. Also within the Iran plateau there are studies on the major stratovolcanoes of Taftan [Ghazban 2004;Biabangard and Moradian 2008;Nicholson et al 2010] and Bazman [Saadat and Stern 2011;Saadat et al 2008;Saadat et al 2009;Saadat et al 2010;Saadat 2010] in the southern part of the Lut Block within the Makran arc.…”

“…The second one, the Gandom Beryan area, is located in the southern part of the Nayband Fault [Yousefi et al 2017;Saadat et al 2010;Walker et al 2009].…”

“…Saadat et al [2010] have concluded that these rocks were formed by low to moderate degrees of partial melting and suggest the involvement of EM-type mantle asthenosphere in their source. Yousefi et al [2017] concluded that the parental magmas of Gandom Beryan volcanics might have originated in the garnet-lherzolite stability field. Pang et al [2012] concluded that these post-collisional and intra-plate alkali basalts underwent small amounts of fractionation of olivine, clinopyroxene and Fe-Ti oxides with minor crustal contamination before eruption.…”

“…We compare these results with data from the other volcanoes along the Nayband Fault to chart the degrees of partial melting, crustal contamination, and fractional crystallization. We compare in particular with the Gandom Beryan volcanic field, which is located in the southern part of Nayband Fault where compositions [Yousefi et al 2017] and ages are best known [2.2-2.6 Ma;Walker et al 2009].…”