U–Pb geochronology, Sr–Nd isotopic compositions, geochemistry and petrogenesis of Shah Soltan Ali granitoids, Birjand, Eastern Iran

Nadermezerji, Samaneh; Karimpour, Mohammad Hassan; Shafaroudi, Azadeh Malekzadeh; Santos, J. F.; Mathur, Ryan; Ribeiro, Sara

doi:10.1016/j.chemer.2018.08.003

Cited by 7 publications

(1 citation statement)

References 46 publications

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“…Therefore, the parent magma of the alkaline rocks from the Guandimiao complex is anhydrous, and may have been formed in an anorogenic setting [68]. The alkaline rocks are A-type granites, indicating an extensional decompression process during the magma emplacement [70][71][72][73][74]. Previous studies show that the Izanagi plate subduction might have played an important role in the magmatic activity of the eastern NCB during the Early Cretaceous [69].…”

Section: Tectonic Implicationsmentioning

confidence: 99%

Partial Melting of Lithospheric Mantle and Formation of the Early Cretaceous Alkaline Rocks in the Guandimiao REE Deposit, Luxi Terrane, Eastern China

Qiu

Zhi

et al. 2022

Minerals

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The Luxi Terrane (eastern China) exposes widespread Early Cretaceous alkaline rocks, whereas their petrogenesis remains controversial, including fractional crystallization, partial melting and crustal contamination regime. Here, we present petrology, geochemistry, sphene U-Pb geochronology and trace element data from the syenogranite, quartz syenite and quartz monzonite of the Guandimiao alkaline complex rocks to investigate their petrogenesis. Geochemical data suggest that these alkaline rocks show alkalic and peralkaline characters, and high Ga/Al ratios, SiO2, light rare-earth element (LREE), Zr and Nb, and low MgO, CaO, Eu contents, corresponding to A-type granites. Sphene trace elements in syenogranite and quartz monzonite show obvious fractionation between LREE and heavy rare-earth element (HREE) and high Th/U ratios, indicating a magmatic origin. They yield U-Pb lower intercept ages of 128 ± 2.3 Ma and 127 ± 1.3 Ma, representing the crystallization ages of these alkaline rocks. The negative correlations between CaO, Fe2O3 (Total), MgO, P2O5, TiO2, MnO and the pronounced depletion in Nb, Ta and Ti suggest that the alkaline rocks were formed by fractional crystallization. Additionally, the positive correlation between La/Hf and La, Th and Th/V, Ce/Yb and K2O, and Tb/Yb and Yb suggest that the alkaline melts are generated by partial melting. Such high Rb/Nb, (Th/Nb)N and Nb/Th ratios indicate crustal contamination during the magma emplacement. We, therefore, propose the magma source of the alkaline rocks in the Guandimiao complex originated by partial melting of lithospheric mantle, which experienced fractional crystallization and crustal contamination processes during its emplacement. Such complex alkaline rocks were probably formed in an extensional back-arc setting induced by the retreat of the subducting Izanagi plate.

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