Critical metal resources in the Middle-Lower Yangtze River Valley metallogenic belt

Abstract

Critical metals are strategic key mineral resources for global competition, with research on mineralization characteristics and metallogenic regularity attracting attention. The Middle-Lower Yangtze River Valley metallogenic belt (MLYB) is a part of the circum-Pacific magmatic belt. Under complex continental dynamic setting, such as the Mesozoic transformation of structural systems and intensive crust-mantle interactions, a large amount of porphyry-skarn Cu-Fe-Au deposits have been formed. During large-scale mineralization processes, critical resources, including Cr, Co, Se, Re, and Te, are produced from these deposits, in addition to bulk metals such as Cu, Ag, Fe, and S-rich ores. These critical metals are urgently needed in China’s strategy. Therefore, research should receive emphasis to achieve new breakthroughs. In recent years, large mining companies in the Yangtze River economic belt have paid special attention to the comprehensive use of critical metals. Therefore, studies on critical metals in the belt have important theoretical and economic significance. This paper has systematically reviewed and summarized the research outcomes and literature related to the exploration and research work of critical metals in MLYB and preliminarily investigated the enrichment characteristics of the critical metals in the deposits in the belt. The preliminary investigation indicates that if the dominant metals in skarn deposits differ, the subsequent byproduct critical metals also differ. Most critical metals are hosted in sulfides in these skarn deposits. This paper shows a spatial distribution map of the critical metal deposits. Based on this map, the relationships between the dominant metal and the associated critical metal elements are summarized. Moreover, this paper has reviewed and summarized the deportment and enrichment mechanism of Cr, Co, Se, Re, and Te in the porphyry-skarn Cu-Fe-Au deposits in the belt and clarified the key host minerals and their abundances by referring to the five critical elements. Based on comprehensive analyses of previous studies on critical metals in the belt, we have raised three key scientific points that should be the focus of future studies on related topics. First, the primary research clue about sources and enrichment mechanisms should consider the systematic evolution of the porphyry-skarn Cu-Au deposits in the intracontinental setting. The second is a key question and challenging issue regarding the recovery and comprehensive utilization of the critical metals in specific sulfides. Finally, the full use of microscale to nanoscale lab analyses and related theories about the synthesized host minerals bearing critical metals may provide important evidence that can help interpret the enrichment mechanism of the critical metals. This point should be based on research on the crystallinity relationships and interface correlations between the host and critical metal elements.