Research progress on the role of organics in the mineralization of Mississippi Valley-Type (MVT) Pb-Zn deposits: Mechanisms, applications, and prospects

Organics exhibit close spatial, temporal, and genetic relationships with Mississippi Valley-Type (MVT) Pb-Zn deposits. Understanding its specific roles in ore formation is therefore crucial for advancing metallogenic prediction and exploration. This study focuses on the thermal evolution of organics in sedimentary basins and the key controlling effects of its products on MVT Pb-Zn mineralization. By systematically analyzing the thermal evolution history and thermal maturity characteristics of organics, it provides a new perspective for revealing the genetic mechanisms of Pb-Zn deposits and guiding exploration. Research demonstrates a significant coupling relationship between organics and MVT Pb-Zn deposits in spatial-temporal distribution and genetic mechanisms, with organics exhibiting different functional mechanisms at various stages of mineralization: During the activation-extraction stage of metallogenic materials, organic acids generated from the thermal evolution of organics possess strong complexation capabilities for metal elements like lead and zinc, effectively activating and extracting these elements from source rocks, thereby providing favorable conditions for initial enrichment. During the transport stage, oilfield brines, as important ore-forming fluids, likely serve as ideal carriers for the migration of metal elements such as lead and zinc. During the precipitation stage, organics primarily facilitate metal sulfide precipitation either by directly providing reduced sulfur or by acting as a reducing agent to reduce sulfate, thereby supplying reduced sulfur. Based on the coupling relationship between organics and mineralization, and leveraging interdisciplinary advantages from inorganic-organic geochemistry, economic geology, and tectonic geology, modern analytical techniques such as Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and artificial intelligence-assisted methods can be employed to precisely identify and quantitatively analyze biomarkers (e.g., n-alkanes, isoprenoids, steranes, organic sulfur compounds) in organics like solid bitumen and organic inclusions. Their characteristic parameters can be used to trace the source of metallogenic materials, constrain the physicochemical conditions (e.g., temperature, pressure) of the ore-forming fluids, delineate the mineralization process, and constrain the metallogenic epoch, thereby constructing a multi-stage comprehensive metallogenic model involving organics. Simultaneously, organic geochemical surveys can delineate organic geochemical anomalies (e.g., methane, aromatic hydrocarbons) related to mineralization in rocks and soils, facilitating the construction of multi-scale, multi-factor metallogenic prediction models. This approach can significantly enhance the accuracy and reliability of metallogenic prediction, thereby improving the effectiveness of both deposit research and exploration.