The Simorgh prospecting area is located in the central part of the Lut Block in eastern Iran. The Lut Block, the eastern part of the Central Iranian Microcontinent (CIM), has a complex tectonic evolution and is characterized by extensive magmatic activities with a range of geochemical signatures. The Simorgh intrusions have features typical of calc-alkaline to high-K calc-alkaline rocks, metaluminous to slightly peraluminous and formed in a volcanic arc setting. Mineralization in the area is believed to be related to these intrusions. To better understand the petrogenesis of these intrusions, we report zircon U-Pb dating and Hf isotopes and whole rock geochemistry of two granites and one diorite. Age dating using Zircon U-Pb method on pyroxene diorite porphyry stock and two granite porphyry dikes revealed 24.85±0.51 Ma, 25.37±0.56 Ma and 25.94±0.76 Ma ages respectively (late Oligocene, Chattian). Field observations and U-Pb dating indicate that there are at least two stages of emplacement: pre-mineralization intrusions (diorite porphyry) and syn-mineralization intrusions (granite porphyry, granodiorite porphyry and pyroxene diorite porphyry). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements (LILE) and light rare earth elements ((La/Yb)N=9.26-14.48), and depletion in high field strength elements (HFSE) and heavy rare earth elements, as well as negative Eu anomalies (Eu/Eu*=0.49-0.91). Zircon Hf isotope data from the Simorgh intrusive rocks show largely positive εHf(t) (average=3.6±2.0). Hf model ages are ranging from 720 to 1320 Ma, indicating its derivation from a relatively juvenile source. The presence of zircon xenocrysts may prove its contamination by older continental crust (Siderian).

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