Lithium geochemistry and its implications for ore prospecting in the Shirenbei Basin, northeastern Guangdong

This study aims to determine the geochemical characteristics of sedimentary clay-type lithium (Li) deposits and their implications for ore prospecting in the Shirenbei Basin, northeastern Guangdong, China, as well as exploring the regional metallogenic conditions and ore-prospecting indicators. Based on a 1∶200,000 stream sediment geochemical survey, this study conducted a comprehensive analysis of the geochemical characteristics of Li and their relationships with strata, lithologies, and sedimentary environments using methods of economic geology, sedimentology, mineralogy, and geochemistry. Two Li anomalies were delineated in the study area. Among them, the Li anomaly in the north exhibits a larger scale and a peak anomaly value of 234.3×10⁻⁶, with the Yetang Formation (K₂yt) exposed in the anomaly center. The composite anomaly consists of 16 elements (or oxides), including Li, fluorine (F), and sodium oxide (Na₂O), with distinct overlapping relationships observed among them. Investigations reveal that the Yetang Formation is a lacustrine evaporative sedimentary suite, with its sedimentary center located in the northern part of the basin. Zones with high Li content correspond primarily to zones containing calcareous, fine-grained clastics. Rock and mineral analyses indicate a significant positive correlation between whole-rock Li₂O content and clay mineral content. The Yetang Formation exhibits significantly higher geochemical background values of whole-rock Li content than other geological units, with the Li enrichment center identified in the fourth layer of the formation. Three ore-bearing layers were delineated in the study area. They are primarily distributed in the middle and upper parts of the Yetang Formation, with a total thickness of 226.14 m. The ore-bearing rock series show an exposed area of approximately 5.2 km², demonstrating great potential for ore prospecting. The results of this study suggest that the Li geochemistry in stream sediments can effectively reflect the regional metallogenic background and that the Li-F-Na₂O anomaly combination serves as a significant ore-prospecting indicator for clay-type lithium deposits. Lithium mineralization is jointly controlled by factors including paleoclimate, evaporative sedimentary environment, lithofacies paleogeographic framework, specific stratigraphic units, and lithologic suites. Additionally, multiple similar sedimentary basins occur in the eastern segment of the Nanling metallogenic belt and its adjacent Wuyi metallogenic belt, holding prospects for further breakthroughs in ore prospecting.