Oligocene crustal xenolith‐bearing alkaline basalt from <scp>J</scp>andaq area (<scp>C</scp>entral <scp>I</scp>ran): implications for magma genesis and crustal nature

<jats:title>Abstract</jats:title><jats:p>The <jats:styled-content style="fixed-case">O</jats:styled-content>ligocene alkaline basalts of <jats:styled-content style="fixed-case">T</jats:styled-content>oveireh area (southwest of <jats:styled-content style="fixed-case">J</jats:styled-content>andaq, <jats:styled-content style="fixed-case">C</jats:styled-content>entral <jats:styled-content style="fixed-case">I</jats:styled-content>ran) exhibit northwest–southeast to west–east exposure in northwest of the central‐east <jats:styled-content style="fixed-case">I</jats:styled-content>ranian microcontinent (<jats:styled-content style="fixed-case">CEIM</jats:styled-content>). These basalts are composed of olivine (<jats:styled-content style="fixed-case"><jats:roman>Fo<jats:sub>70–90</jats:sub></jats:roman></jats:styled-content>), clinopyroxene (diopside, augite), plagioclase (labradorite), spinel, and titanomagnetite as primary minerals and serpentine and zeolite as secondary ones. They are enriched in alkalis, <jats:styled-content style="fixed-case"><jats:roman>TiO<jats:sub>2</jats:sub></jats:roman></jats:styled-content> and light rare earth elements (<jats:styled-content style="fixed-case"><jats:roman>La</jats:roman></jats:styled-content>/<jats:styled-content style="fixed-case"><jats:roman>Yb</jats:roman></jats:styled-content> = 9.64–12.68) and are characterized by enrichment in large ion lithophile elements (<jats:styled-content style="fixed-case"><jats:roman>Cs</jats:roman></jats:styled-content>, <jats:styled-content style="fixed-case"><jats:roman>Rb</jats:roman></jats:styled-content>, <jats:styled-content style="fixed-case"><jats:roman>Ba</jats:roman></jats:styled-content>) and high field strength elements (<jats:styled-content style="fixed-case"><jats:roman>Nb</jats:roman></jats:styled-content>, <jats:styled-content style="fixed-case"><jats:roman>Ta</jats:roman></jats:styled-content>). The geochemical features of the rocks suggest that the <jats:styled-content style="fixed-case">T</jats:styled-content>oveireh alkaline basalts are derived from a moderate degree partial melting (10–20%) of a previously enriched garnet lherzolite of asthenospheric mantle. Subduction of the <jats:styled-content style="fixed-case">CEIM</jats:styled-content> confining oceanic crust from the <jats:styled-content style="fixed-case">T</jats:styled-content>riassic to <jats:styled-content style="fixed-case">E</jats:styled-content>ocene is the reason of mantle enrichment. The studied basalts contain mafic‐ultramafic and aluminous granulitic xenoliths. The rock‐forming minerals of the mafic‐ultramafic xenoliths are <jats:styled-content style="fixed-case"><jats:roman>Cr</jats:roman></jats:styled-content>‐free/poor spinel, olivine, <jats:styled-content style="fixed-case"><jats:roman>Al</jats:roman></jats:styled-content>‐rich pyroxene, and feldspar. The aluminous granulitic xenoliths consist of an assemblage of hercynitic spinel + plagioclase (andesine–labradorite) ± corundum ± sillimanite. They show interstitial texture, which is consistent with granulite facies. They are enriched in high field strength elements (<jats:styled-content style="fixed-case"><jats:roman>Ti</jats:roman></jats:styled-content>, <jats:styled-content style="fixed-case"><jats:roman>Nb</jats:roman></jats:styled-content> and <jats:styled-content style="fixed-case"><jats:roman>Ta</jats:roman></jats:styled-content>), light rare earth elements (<jats:styled-content style="fixed-case"><jats:roman>La</jats:roman></jats:styled-content>/<jats:styled-content style="fixed-case"><jats:roman>Yb</jats:roman></jats:styled-content> = 37–193) and exhibit a positive <jats:styled-content style="fixed-case"><jats:roman>Eu</jats:roman></jats:styled-content> anomaly. These granulitic xenoliths may be <jats:styled-content style="fixed-case"><jats:roman>Al</jats:roman></jats:styled-content>‐saturated but <jats:styled-content style="fixed-case">S</jats:styled-content>i‐undersaturated feldspar bearing restitic materials of the lower crust. The <jats:styled-content style="fixed-case">O</jats:styled-content>ligocene <jats:styled-content style="fixed-case">T</jats:styled-content>oveireh basaltic magma passed and entrained these xenoliths from the lower crust to the surface.</jats:p>