Abstract:

The Sena gold deposit recently discovered in Duolong metallogenic concentrated area is an epithermal gold deposit. There is few  high-precision petrogenic and metallogenic geochronological data. The zircon U-Pb dating, the major elements, trace elements and zircon Sr-Nd isotopic data of the ore-hosting quartz monzobiorite in Sena deposit are reported in this paper. Weighted mean U-Pb age of the Zircon from the quartz monzobiorite, (122.0±1.8) Ma, can be regarded as the age of magmatic crystallization. The ore-hosting quartz monzobiorite in the Sena gold deposit is characterized by low SiO₂( 57.26% to 58.88% ), high Al₂O₃ (16.58% to 17.50%), high MgO (2.65% to 2.98%), (A/CNK)=0.93 to 1.09, rich in LREE (LREE/HREE=6.28 to 7.25),  Eu=0.85 to 1.05, meanwhile by high Rb, U, La, Sr, Sm contents, coupled with low Nb, Ta, Zr, Hf contents. Compared with primary mantle, the quartz monzobiorite in Sena gold deposit has respectively high Sr \[(⁸⁷Sr/⁸⁶Sr)_i=0.705 023 to 0.705 453\], low Nd\[ε_Nd(t)=-0.18 to 2.43\]. The model age (T_DM2=0.78 to 1.03 Ga) indicates that the quartz monzobiorite belongs to the over aluminum granite. Authors suggest that the Early Cretaceous magmatism and mineralization be caused by crystallization differentiation and contact metasomatism of parent magma which consist of partial melting materials, few sediments and mantle derived magma.

Key words: zircon U-Pb dating, arc type granite, metallogenic background, Sena gold deposit, Bangonghu-Nujiang suture zone, gold deposit