Аңдатпа
Cenozoic crustal melting in the Pamir records complex tectonomagmatic processes during the India–Asia collision, however, the magma sources and geodynamic processes controlling their petrogenesis remain unresolved. This study integrates zircon U-Pb geochronology and Hf isotopes with whole-rock major–trace element and Sr-Nd isotope data from Cenozoic granitoid–pegmatite suites in the Shatput complex (eastern Central Pamir, Tajikistan) to constrain progressive crustal melting and evolution. Two major magmatic pulses are recognized: mid-Eocene biotite granites and scapolite-bearing albitites (ca. 41–39 Ma) and early–mid Miocene granites and pegmatites (23–14 Ma). The mid-Eocene granites are metaluminous (A/CNK = 0.37–0.96). Zircons yield ε Hf (t) values ranging from –6.4 to +2.9, which are predominantly positive with a mean value of +0.13. The rocks formed through shallow crustal melting of a hybrid source integrating mantle-derived juvenile components with minor ancient Central Pamir basement, linked to subduction-related magmatism during the Neo-Tethyan oceanic slab break-off. The early–mid Miocene granites and pegmatites are metaluminous to strongly peraluminous (A/CNK = 0.8–3.9). They show pronounced isotopic variability (ε Hf (t) = −12 to +7.6; ε Nd (t) = –12.4 to –5.4; 87 Sr/ 86 Sr (i) = 0.7076–0.7100). They were derived from melting of mid- to lower-crustal sources with minor juvenile mantle input triggered by lithospheric delamination and asthenospheric upwelling following Indian slab breakoff beneath the Pamir. The youngest (∼13 Ma) granites exhibit moderately negative ε Nd (t) values (–8.8), elevated initial 87 Sr/ 86 Sr ratios (0.7087), and elevated Dy/Yb ratios, suggesting derivation from exotic underthrust Indian crustal material. Collectively, the Cenozoic granites in Central Pamir record a tectonic transition from post-collisional asthenospheric upwelling to Indian continental flat subduction and associated lithospheric reorganization during the India–Asian collision.