湖北省张家垭磷矿床磷块岩元素地球化学特征及成因意义  

Geochemical characteristics and genetic significance of phosphorite elements in Zhangjiaya phosphate deposit in Hubei Province

作　　者：吴颖慧[1] 李春阳 金涛[1] 李津 许晋瑞 张明明[1] Wu Yinghui;Li Chunyang;Jin Tao;Li Jin;Xu Jinrui;Zhang Mingming(Geology Institute of China Chemical Geology and Mine Bureau,Beijing,100101,China;Tianjin Jiachen Environmental Engineering Co.,Ltd,Tianjin,300111,China)

机构地区：[1]中化地质矿山总局地质研究院,北京100101 [2]天津佳晨环境工程有限公司,天津300111

出　　处：《化工矿产地质》2022年第2期130-136,共7页Geology of Chemical Minerals

基　　金：中国煤炭地质总局科技创新项目“磷矿伴生氟资源评价及利用研究”(ZMKJ-2020-J06-2)。

摘　　要：湖北省张家垭磷矿床磷块岩赋存于下震旦统陡山沱组,矿石自然类型主要有块状磷块岩、白云质条带磷块岩和泥质条带磷块岩。通过对各自然类型磷块岩中主量元素、微量元素和稀土元素数据进行研究分析,查明磷块岩主量化学成分主要为CaO、P_(2)O_(5)及SiO_(2)等。磷块岩中Sr、Ba等微量元素相对富集,表明其形成与有机质和微生物作用有关,Sr/Ba为0.17~0.72,反映在沉积过程中有热液作用参与;Co/Ni小于1,U/Th多小于1,在lgω(U)-lgω(Th)的关系图上,张家垭磷矿样品落在正常远洋沉积与古热水喷溢沉积之间,反映本磷块岩在正常沉积的过程中可能有海相热水流的加入。LREE/HREE范围为2.20~3.39,具有显著的轻稀土富集,重稀土亏损特征;δEu大于1,呈明显的正异常,表明磷块岩形成与被动大陆边缘的热水沉积作用相关;Ce_anom为-0.14~-0.17,小于-0.01,显示该磷块岩沉积时处于氧化环境。在LaN/YbN-REE图解中,张家垭磷矿床磷块岩样品结果主要落在大洋拉斑玄武岩区域,表明可能为海底与玄武岩有关的海底热液作用。认为本区磷块岩形成与热水作用相关,沉积形成于陆缘海且为氧化环境,磷块岩沉积过程有海相热水流的参与,磷块岩沉积物质来源于陆缘海周围的玄武岩,可能为海底与玄武岩有关的海底热液。The phosphorite of Zhangjiaya phosphate deposit in Hubei province exists in Doushantuo Group,and the natural types of ore mainly include massive phosphorite,dolomite-strip phosphorite and muddy strip phosphorite.Through the study and analysis of the main quantity elements,trace elements and rare earth elements in each natural phosphorites,the main chemical components of phosphorite are CaO,P_(2)O_(5),SiO_(2) and so on.The relative enrichment of trace elements like Sr and Ba in phosphorite indicates that its formation is related with organic matter and microbial action.Sr/Ba is 0.17~0.72,which reflects the involvement of the hydrothermal action during the deposition process;Co/Ni is less than 1,U/Th is mostly less than 1,On the relation diagram of lg(U)-lg(Th),Zhangjiaya phosphate ore samples fall between the normal marine deposition and the overflow deposition of palaeo thermal water,which reflects the addition of marine thermal water in the normal deposition.LREE/HREE is in the range of 2.20~3.39,which is of some significant characteristics of LREE enrichment and HREE depletion;δEu is more than 1,which shows a clear positive abnormality.It indicates that phosphorite formation is associated with the hydrothermal deposition at the passive continental margin,Ce_anom is-0.14~-0.17,and is less than-0.01,it indicates that the phosphorite was deposited in the oxidizing environment.On the diagram of LaN/YbN-REE relation,the results of phosphorite samples showing in Zhangjiaya phosphate deposit mainly fall in the marine tholeiite area,indicating a possible submarine hydrothermal action related to basalt on the seabed.It is believed that the formation of phosphorite is related to the action of thermal water,and the deposition is formed in the epicontinental sea and is in an oxidizing environment.The deposition of phosphorite is involved in the marine thermal water fluid.The phosphorite comes from the basalt around the epicontinental sea,and may be the seabed hydrothermal fluid related to the basalt.

关 键 词：张家垭 磷块岩 地球化学特征 热水沉积 氧化环境 

分 类 号：P619.213[天文地球—矿床学] P595[天文地球—地质学]