Polymetallic mineralization in early Cambrian black shale: Insights from Guizhou, South China

Abstract

During the Early Cambrian period, black shale series were widely developed across the globe, with their distribution in China primarily concentrated in the South China. This region has revealed significant deposits of Ni-Mo, V, and barite associated with black shale, alongside varying concentrations of PGE, REE, and U. The Ni-Mo deposits are primarily located in the Hunan-Guizhou region, whereas V and barite deposits are mainly found in eastern Guizhou. Guizhou stands out as the most comprehensive area for the development of polymetallic deposits within Early Cambrian black shale. To enhance the understanding of sedimentation and mineralization processes in the Early Cambrian paleo-marine environment of South China, a systematic review of the metallogenic system related to Early Cambrian black shale in Guizhou has been conducted, based on existing geological surveys and theoretical research. Key findings include: (1) The types of minerals are closely linked to paleo-sedimentary facies, with Ni-Mo, V (Mo), and barite deposits corresponding to shelf, slope, and basin sedimentary environments, respectively. (2) The cores of anticlines and their adjacent wings are crucial for the enrichment of polymetallic elements. The Ni-Mo and V polymetallic layers are enriched within black shale, whereas the barite deposits are encased in siliceous rock or siliceous shale. (3) Volcanic activity has played a significant role in both sedimentary and metallogenic processes. It affects the formation of Ni-Mo, V and barite deposits in different degrees. This indicates that the formation of polymetallic deposits results from the combined effects of continental weathering, submarine hydrothermal activities, and biological processes, influenced by temporal and spatial variations. This comprehensive analysis not only sheds light on the complex interplay of geological factors leading to mineralization but also underscores the importance of regional geological settings in the formation of economically significant mineral deposits. This would not only contribute to a more holistic understanding of the region’s mineralization processes and their broader implications, but also holds a insightful significance for the study of the genetic mechanisms of global polymetallic deposits in black shales and the research on paleoclimate during the Early Cambrian period.