Re-Os geochronology and trace element characteristics of the hydrothermally reworked pyrite of the Gaobanhe sediment-hosted polymetal pyrite deposit in Northern China and its geological significance

Abstract

The Gaobanhe polymetal pyrite deposit is a SEDEX-type deposit hosted in a Mesoproterozoic sedimentary sequence in the central part of the northern margin of the North China Craton (NCC). The primary ore-forming age is the same as the formation age of the host rock. However, the SEDEX deposit was reworked by the Mesozoic hydrothermal process during the destruction of the NCC. Re-Os isotopic analysis for the reworked pyrite yields an isochron age of 152.3 ± 5.1 Ma, indicating that late hydrothermal activity had occurred during the late Jurassic. At the same time, some information on the sulfur isotopic composition and trace elements geochemistry suggest that the late hydrothermal fluid was most likely a mixture of magmatic and stratum-derived water. Moreover, the major components of pyrite indicated that the elements were released into the hydrothermal fluid from the syn-sedimentary pyrite. We infer that the regional folds and faults that formed during the Late Mesozoic disrupted the primary SEDEX deposit and created space for hydrothermal activity. The hydrothermal fluid reformed the primary ore bodies along the faults during the Late Jurassic.