Geochemistry, Zircon U–Pb Ages, and Hf Isotopes of the Devonian Mafic and Acidic Dykes of the Jinba Gold Deposit, NW China: Petrogenesis and Tectonic Implications

The Jinba deposit is an orogenic gold located in the Markakuli shear zone, southern part of Altay belt, northwestern China. Several granite and diorite dykes are present area mine, with ore bodies occurring dykes. However, diagenetic age, genesis, evolution these magmas, tectonic setting dyke emplacement process, remain unclear. study based on a detailed geological survey, zircon U–Pb dating, Lu–Hf isotopes, geochemical analysis granitic crystallization ages 384.5 ± 1.2 Ma 393.9 3.5 Ma, respectively, which indicates formation Early to Middle Devonian. Zircon εHf(t) values 1.43 5.2 −4.47 −1.18, corresponding two-stage model depleted mantle (TDM2) 1046 1285 1242 2623 respectively. This that were formed by mixing magma crustal materials varying degrees, more obviously contaminated lower crust. Geochemical shows have high SiO2 (72.51%–74.87%) moderate Al2O3 (12.88%–14.04%) content, total alkali (K2O + Na2O = 5.51%–6.44%), aluminous (A/CNK 1.0–1.02). Granite enriched LREE Th, U, Pb, P, Sr, Nb elements, clear Eu negative anomalies (δEu 0.62~0.66). content 51.48%–53.71%, contents (14.70%–15.99%), K2O 1.94%–2.54%, 2.97%–3.96%, MgO (5.15%–6.46%), TFe2O3 (13.42%–15.13%), deficient Th rare earth fractionation not obvious, anomaly obvious 0.93~1.1). We conclude Devonian magmatism margin (which corresponds deposit) may island arc-related subduction environment.