Geochemical Characteristics and Indication of Sedimentary Environment and Mineral Provenance of Phosphorite-Type REE Ore Deposit of Early Cambrian in Guizhou
The phosphorite deposit of the Lower Cambrian Gezhongwu Formation(∈1gz)in Zhijin of the central Guizhou tableland facies area and the bottom of phosphorite deposit of the Lower Cambrian Niutitang Formation(∈1n)in BaHuang of the eastern Guizhou terrace edge slope facies area are both highly enriched in rare earth el-ements.In this paper,based on the isochronous stratigraphic framework of the Early Cambrian Meishucun stage,the sedimentary characteristics,rare earth elements and some trace elements geochemical characteristics of typical phosphorus-bearing(REE)rock of Gezhongwu Formation in Zhijin and Niutitang Formation in Ba-huang were compared and analyzed by means of section measurements,rocks and minerals identification,ICP-MS method and other analytical tools.It is found that the total rare earths(Σ REE+Y)in the phosphorite of both study areas are highly concentrated,with the average values reaching 1258.66×10-6 and 808.09×10-6,re-spectively,and are significantly correlated with P2O5 and it is speculated that rare earths may exist mainly in flu-orocarbon apatite in a homogeneous form,and a small amount of rare earths may be adsorbed by clay minerals in rare earth-rich phosphorite rock in Bahuang.The obvious negative Ce anomalies and low V/Cr values in phos-phorus-bearing(REE)rock suggest that sedimentary environment is more favorable for the deposition of phos-phate massive type rare earth due to turbulent change of the water medium in the course of deposition period and relative oxidation.The"hat"or slightly left-leaning rare earth distribution curves,the strong positive Eu anomaly in the majority of the samples,the La/Yb-Σ REE relationship diagram cast in the granite area or gran-ite-basalt intersection,the high U/Th values and the low Co/Ni values all reveal that the mineralized materials of the two phosphorite(REE)bearing rock are from the same source,mainly from hot water,followed by deep-wa-ter P-REE water masses.
REE of phosphoriteore-forming material sourcedepositional environmentgeochemical characteristicsGuizhou
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