海南文昌第四系沉积物粒度特征对砂矿型锆铪矿成矿环境的指示OA

Placer-type Zr-Hf deposits constitute the principal source of zirconium and hafnium for industrial production in China.The Wenchang area of Hainan Province hosts a series of important placer-type Zr-Hf deposits and repre-sents a key metallogenic district for these critical metals.These deposits occur within Quaternary sediments of the Yandun,Basuo,and Beihai formations,forming continuous coastal belts that extend inland along fluvial systems.Understanding the depositional environment of the ore-bearing sediments is essential for constraining mineraliza-tion processes and guiding exploration in this region.In this study,Quaternary Zr-Hf-bearing sediments from the Wenchang area were investigated.Grain-size characteristics were analyzed,and grain-size end-member modeling was applied to identify sedimentary components and interpret sediment transport processes,thereby providing in-sights into the depositional environment of Quaternary placer-type Zr-Hf deposits.The results indicate that the av-erage grain size of the ore-bearing sediments in the research area falls within the silt range(5.85～6.85 Ф).Among the formations,the Beihai Formation exhibits the coarsest grain size,followed by the Basuo Formation,while the Yandun Formation has the finest grain size.In vertical section,the sediment grain size gradually fines upward from older to younger strata.Overall,the Quaternary sediments are moderately to poorly sorted,with a relatively concentrated grain-size distribution.Compared to the mean grain size,coarse particles constitute a relatively high proportion,showing a negatively skewed trend,indicates the tidal flat environment is the main sedimentary envi-ronment,but the formation of sediments does not follow a single sedimentary pattern.Grain-size end-member analysis reveals that the Quaternary sediments in Wenchang are composed of four end members(EM1～EM4),with EM1～EM3 representing suspended components and EM4 representing saltation components,indicates the scouring effect of the tidal channel during the rising tide process has a significant impact on the formation of min-eral-bearing sediments,and during this period,high-energy events also occur.The characteristics of grain-size pa-rameters and end-member modeling suggest that the sedimentary environment of the Quaternary ore-bearing sedi-ments in Wenchang was primarily a low-energy tidal flat influenced by intermittent storm waves or alluvial flood-ing,with deposition mainly occurring in intertidal to subtidal zones.