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 similar to 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 similar to 16 my (176-160 Ma) and produced multiple mineralising events (similar to 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.