Rare earth element geochemistry of Cambrian phosphorites from the Yangtze Region

Analysis on P2O5 and REE (rare earth elements) in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province contained high REE contents in phosphorites, especially those from Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province. Among them, the highest REE contents reached up to 1361.59×10-6 and P2O5 contents up to 29.45%. In contrast, phosphorites from Kaiyang, Qingzhen and Zhenyuan in Guizhou Province had relatively low total REE contents and low P2O5 contents, with the lowest total REE content of 53.19×10-6, and the lowest P2O5 content of 0.07%. REE contents exhibited a positive correlation with phosphorous contents, indicating a close genetic relationship between REE and phosphorous element. The main reason was the difference of the sedimentary environments and the contents of phosphorous and REE in deep water mass formed in upwelling currents, at an upper slope facies (Slu) in reducing condition due to relatively closed sedimentary environment. It was very difficult for the upswelling phosphorous and REE to deposit, massive phosphorous deposits were hard to be formed. At a deep water ramp facies (DRa) in the ascending process of currents, phosphorus and REE underwent differentiation rather than sedimentation. Consequently, the contents of P2O5 sediments and REE were low. At a shallow water ramp facies (including shoals and tidal flats) (SRa), with active seawater circulation and phosphatic supplement, sunny weather, high nutrition and rapid growth of algae, were benefitial for the physical enrichment of carbonate sediments. Therefore, massive phosphorite deposits were easy to be formed with abundant REE minerals, and finally turned into high REE bearing phosphorous deposits.     

贵州磷块岩主要物质成分特征探讨

贵州主要磷块岩形成时期大致分为两大成矿时期，及新元古末陡山沱期和早寒武世梅树村早期。分属中国重要的两个成磷时期。形成的磷块岩分属黔中成矿域含磷岩系和黔西北早寒武世杨子成矿域含磷岩系。     

云南白龙潭磷块岩元素地球化学特征及其指示意义

产于下寒武统梅树村组的云南白龙潭磷矿,因矿层厚、储量高而备受关注。采用XRF荧光光谱仪和ICP-MS质谱仪对该矿不同类型磷块岩进行了主量、微量及稀土元素含量测定,并结合光学显微镜对样品进行分析。研究表明：磷块岩主要含磷矿物为胶磷矿,且含有小壳动物化石和藻类化石;小壳动物化石、藻类化石、 Ba富集(41.1×10^-6～274.0×10^-6)以及高SO₃含量说明,生物作用参与了磷块岩的形成,且对泥晶-球粒的磷块岩作用最明显;不同类型磷块岩均以富含U、Sr为特征,其中泥晶-球粒磷块岩和砾屑磷块岩富含P₂O₅,平均值分别为28%和27%; V/Cr为0.42～1.23、δCe为0.33～0.58、 Ce_anom为-0.53～-0.1、SiO₂/Al₂O₃为10.60～58.45、 Al₂O₃/MgO为0.04～11.0、镁铝含量比m>10、 Sr/B...     

贵州织金含稀土生物屑磷块岩稀土元素赋存状态研究

对贵州织金新华含稀土磷矿床进行的稀土元素分析结果表明,磷块岩中含稀土总量ΣREE较高,LREE/HREE比值较大,富集La、Nd、及Y等轻稀土及重稀土元素.普遍具Ce、Eu的负异常,稀土分配模式等显示海相沉积源区继承性及热水源加入特征.生物碎屑、白云石及胶磷矿的单矿物微量元素分析证明,稀土元素含量与胶磷矿密切相关.胶磷矿中稀土元素含量大于其它矿物中稀土含量.扫描电镜及电子探针分析研究表明,稀土元素主要不是以独立矿物形式存在.化学物相分析研究证明,稀土元素多以类质同象形式存在于磷灰石中,少量被粘土矿物相吸附.解决了该类型矿床稀土元素赋存状态长期未解决的问题.综合研究表明,稀土元素赋存状态主要以类质同象形式存在于磷灰石晶格中,稀土元素的含量与胶磷矿密切相关.     

Analysis on REE geochemical characteristics of three types of REE-rich soil in Guizhou Province,China

The three kinds of soil formed by the weathering of the basalt in Yema village,Weining county of Guizhou province,the carbonate rock in Guiyang district and the phosphorite in the REE-bearing phosphate mining area in Zhijin county of Guizhou province were all rich in REE.The contents of LREE in these three soil were higher than that of HREE,which was caused by the different properties of LREE and HREE complexes.Since light REE could be easily absorbed by kaolinite grains,LREE was fully enriched in the process of desorption,migration and re-absorption,which formed a typical LREE soil.The chondrite normalized distribution models of those three types of REE-enriched soil are basically similar,which belong to the right deviation type,namely,rich in light rare earth element but short of heavy rare earth element,and showing Ce negative anomalies.Eu showed intense negative anomalies in the REE in the soil formed by the weathering of the sedimentary parent rocks(such as carbonate rock and phosphorite),while no pronounced Eu anomaly was found in the REE in the soil formed by the weathering of volcanic rocks(such as basalt).It is clear that though there were intense migration and enrichment of REE during the weathering process of rocks,no obvious differentiation of REE occurred and some features of the parent rocks were retained.That is why REE is of value in analyzing the source of materials.