Geochemical Characterization of Hematite in Haidewula Uranium Deposit of East Kunlun Orogenic Belt and Its Implication for Mineralizing Fluids
The Haidewula uranium deposit is located in the South Kunlun Belt of the East Kunlun orogenic belt and represents the first independent volcanic-related uranium deposit in the Qinghai-Tibet plateau of China.While previous studies have examined the mineralization characteristics of the deposits,there has been preliminarily studied by predecessors,but the ore-forming fluid and gangue minerals of the deposit have been poorly limited research on the ore-forming fluids and gangue minerals.Hematite,which is commonly found in various uranium deposits,is closely associated with uranium mineralization.This research focuses on studying the petrographic and mineral chemical characteristics of hematite in the Haidewula uranium deposit to investigate its implications for the source and nature of the ore-forming fluid.The aim is to provide a theoretical foundation for understanding the genesis of the Haidewula deposit and guide future prospecting and exploration efforts.The findings reveal that fissure-filled hematite in the early stage of mineralization is formed through alkali alteration and cavitation effect.The mineralization clumpy hematite in the metallogenic period is a result of the reaction between strongly oxidized metallogenic hydrothermal fluids and Fe2+in pyrite and surrounding rock.This reaction restricts the oxidation of the mineralizing environment,reduces the oxidation of the mineralizing fluid,and leads to the precipitation of pitchblende.The ore-forming fluid during the formation of hematite in the Haidewula uranium deposit exhibits characteristics of a mixing of meteoric water and mantle-derived fluid.The mantle-derived fluid may have a connection with Triassic diabase magmatic activity.The fluid during the hematite formation is a high oxygen fugacity Cl-rich fluid,which gradually changes from a Cl-rich acidic fluid to an alkaline fluid through reactions with the surrounding rock.The simultaneous enrichment of U-Mo-W in Haidewula hematite suggests that the ore-forming materials in the deposit may primarily originate from the host felsic volcanic rock.
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