Timing of multiple magma events and duration of the hydrothermal system at the Yu'erya gold deposit, eastern Hebei Province, China: Constraints from U-Pb and Ar-Ar dating

The Yu’erya deposit is a large granite–hosted gold deposit in the eastern Hebei Province classified as an intrusion–related gold system. The Yu’erya complex contains the causative intrusion which was the source of hydrothermal metal-bearing fluids. This composite granite complex contains miarolitic pegmatite(–like) cavities and pegmatite veins. A combination of detailed field observations and U–Pb dating by SHRIMP and LA–ICP–MS is used to document multiple magmatic events which occurred at 210–220, 175–173, 171–170, 167–166 and ∼161 Ma formed the Yu’erya granite complex. The initiation of the hydrothermal system, as determined via Ar–Ar dating, is closely related to the exsolution of a magmatic volatile phase from the G1 granite at ca.176 Ma. The hydrothermal system operated for ∼16 my (176–160 Ma) and produced multiple mineralising events (∼176, 172–168 and 162–160 Ma) linked to emplacement of repeated magma pulses from 175 Ma to 161 Ma. Our results suggest that multiple magmatic–hydrothermal events over a time period of several million years may be a fundamental factor responsible for the enrichment process during formation of intrusion-related gold deposits and thus may be a requirement for forming economic orebodies.