U-Pb Geochronological and Geochemical Characteristics of the Kalate-Naser Intrusive Rocks, Eastern Lut, Iran

The Kalateh-Naser area is located in the northeast of the Lut block (Eastern Iran). The rock units of the region generally include Cretaceous limestone units and metamorphosed carbonate rocks. Intrusive rocks emplaced in the study area are mainly composed of quartz monzonite, monzodiorite, quartz diorite, and granodiorite. These rocks are typically I-type with strongly metaluminous signatures. Dating using the zircon U-Pb method on two intrusive rocks revealed ages between 104.23 ± 0.85 Ma and 102.13 ± 0.91 Ma. Rb-Sr and Sm-Nd isotopic data yield mantle derived magma modified by the addition of crustal materials, as shown by initial 87Sr/86Sr ratios (0.7049 - 0.7051) and 143Nd/144Nd ratios (0.512697 - 0.512796). The geochemical compositions indicate enrichment of LILE compared to HFSE with (La/Yb)N values of 2.61–8.43. The LREE versus HREE ratios, as well as depletion of Nb, Ta and Ti elements in these intrusive rocks represent the characteristics of the rocks belonging to the subduction zone. The subduction characteristics of these rocks can be attributed to the subduction inherited in this part of eastern Iran. The whole-rock geochemistry combined with the Nd and Sr isotopic data and similar ages suggest that quartz monzonite and granodiorite are more likely co-magmatic and fall in VAG category. Comparing isotopic composition variations of the Kalateh-Naser rocks with other intrusive rocks from the Lut block, indicates a heterogeneous mantle beneath the Lut block and different amount of the metasomatized mantle source in eastern Iran.