Lead isotope systematics of the Weishancheng Au-Ag belt, Tongbai Mountains, central China: implication for ore genesis

The Weishancheng ore belt in the Tongbai Mountains consists of the Yindongpo large gold deposit, the Poshan and the Yindongling large silver deposits, and several other, smaller, ore deposits. All these ore deposits are stratabound within the Neoproterozoic Waitoushan Group, and are characterized by relative uniform lead isotope compositions: 206Pb/204Pb = 16.7529-17.2163, 207Pb/204Pb = 15.4166-15.6380, and 208Pb/204Pb = 38.2505-39.0500. These lead isotopic values are close to those of common lithologies of the Waitoushan Group, and quite different from other lithologic units or granitic batholiths in the Tongbai region. The lead isotope systematics of the Weishancheng ore belt suggests that the ores originated from the Waitoushan Group through metamorphic devolatilization. Based on the regional tectonic evolution, we propose that the ore-forming process occurred during the continental collision between the Yangtze and North China blocks; attendant metamorphic devolatilization of underthrust slabs induced the development of ore-forming fluids. Subsequently, intense water-rock interaction allowed the ore materials contained in the Waitoushan Group to be extracted, migrated, and enriched in the host carbonaceous sericite schist. We conclude that the Weishancheng Au-Ag ore belt can be classified as a stratabound, orogenic-style metallogenic system.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000287706900011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701GeologySCI(E)35ARTICLE5-6,SI656-6765