Petrogenesis of the Early Cretaceous A-type granite in the Huanggang Sn-Fe deposit, Inner Mongolia: Constraints from zircon U-Pb dating and geochemistry

Huanggang tin-iron deposit, Inner Mongolia, is an important deposit of the South Daxinganling metallogenic belt. LA-ICP-MS zircon U-Pb dating results show that the K-feldspar granite and granite-porphyry in the Huanggang rocks were formed at 136.7 +/- 1.1 Ma and 136.8 +/- 0.57Ma, respectively. The Huanggang granites are characterized by SiO2 content (66.81% similar to 77.39%), Al2O3 content (11.33% similar to 14.54%), and significant depletion of magnesium, high ALK (5.65% similar to 10.67%), the K2O/Na2O values format a range of 0.32 to 10.53, averaging 2.78. The chondrite-nomalized REE pattern shows LREE enrichment, strong negative Eu anomalies, and delta Eu at 0.03 to 0.20. The high field strength elements such as Zr, Hf and lithophile elements such as Rb, U and Th are enriched, whereas the elements P, Ti, Ba and Sr are significantly depleted and their have similar Y/Nb values (>1.2) to those of oceanic island basal tic These features are coincident with the typical A1 within-plate anorogenic granite. Its genesis might be ascribed to the underplating of the mantle-derived magma which caused younger crust partial melting to form granitic magma within the lithosphere extension environment and its magma source are related to the crust-mantle mixed remelting.