The epithermal deposits in the northern margin of north China Craton: Spatiotemporal distribution and tectonic setting

Abstract

This paper summarizes the geological-geochemical characteristics of the E-W trending epithermal Au/Ag deposits in the northern margin of North China craton. The epithermal Au/Ag deposits distribute in the Liao-Ji block, Yanshan orogen and the northern end of the Taihang Mountains, in the Mesozoic volcanic basin which was superimposed onto the cratonic basement. Occurrences of the deposits are controlled by faults and/or volcanic craters. Most of the isotope ages for ores and related igneous rocks fall in a span of 170 Ma-100 Ma. The ore-forming fluid-systems were dominated by meteoric water, with input of magmatic fluid, as traced by D-O isotope systematics. Ore metals, indicated by S-Pb isotopes, were mainly sourced from Precambrian basement and contaminated by cover-strata of the craton. Consequently, it is argued that the metallogenic belt along the northern margin of the North China craton was resulted from the Siberia-North China continental collision, instead of from the subduction of the Paleo-Asian, Pacific and Mongol-Okhotsk oceanic plates. The metallogenic magma-fluid systems were originated from intracontinental (A-type) subduction during continental collision. The large-scale granitic magmatism and metallogenesis occurred at transition regime from collisional compression, to extension.