湘黔地区下寒武统黑色岩系型镍钼矿床中磷结核的成分特征初步研究  

PRELIMINARY STUDY ON COMPOSITION OF PHOSPHATE NODULE IN LOWER CAMBRIAN BLACK-ROCK-SERIES-HOSTED Ni-Mo DEPOSITS IN HUNAN-GUIZHOU AREA

作　　者：江永宏[1] 

机构地区：[1]中国地质调查局发展研究中心,北京100037

出　　处：《地质找矿论丛》2010年第1期12-17,共6页Contributions to Geology and Mineral Resources Research

基　　金：国家自然科学基金项目(40073012);国家重点基础研究发展规划项目(G1998040800);国土资源大调查项目(199910200264;20001020223023;200313000068-02)资助

摘　　要：对湘黔地区下寒武统黑色岩系底部镍钼矿床中磷结核的成分进行了电子探针分析。根据20个磷灰石成分的测定结果，得出Ca／P变化范围为1．36～1．710，平均值为1．605，认为磷结核中磷灰石类型为羟磷灰石，成因类型为生物化学沉积型。磷结核中Na^＋，Fe^2＋，Al^3＋，La^3＋，Sm^3＋，Ce^＋，Cr^3＋，Ti^4＋的含量较高，并且均显示了异常丰富的组合类型，如Na^＋和LREE。在1／4大小的磷结核横剖面上，存在着单核或双核沉积中心，结核的内部构造类型为不规则纹层状。磷结核从边部到中心的贵金属元素，其活性元素相对惰性元素的参数（Pd／Pt，Ag／Au，TD／SUHR）呈现同样的变化趋势。磷结核的外层是相对活性的元素，核部则为相对惰性的元素，部分相对活性的元素（如Pt，Pd，Ag）向外层发生初步迁移。铂族元素的超常富集归因于携带海底岩石物质的热水作用。Composition of phosphate nodule in Lower Cambrian black-rock-series-hosted Ni-Mo deposits in Hunan-Guizhou area is analyzed by electronic probe. Analytical result of twenty apatite samples shows Ca/P ratio in range of 1.36-1. 710 and the average of 1. 605 and the apatite belongs to bio-chemically deposited hydroxylapatite. Content of Na^＋ , Fe^2＋ , Al^3＋ , La^3＋ , Sm^3＋ , Ce^＋ , Cr^3＋ , Ti^4＋ is relatively higher in the nodule with various element combinations, such as Na＋ and LREE. On the 1/4 cross section of the phosphate nodule, two nucleis and single nuclei of sedimentary center exist with irregular lamina structure. From the rim to the center of the phosphate nodule parameter of the relative active noble metal elements and relative inert （Pd/Pt,Ag/Au, TD/SUHR） change in the same tendency. In the outer layer are the relative active elements and toward to the center the relative inert. Some relatively active elements （Pt,Pd,Ag） mobile toward the outer layer. The abnomal enrichment of PGE is attributed to the hot water transportation of rock materials at the sea floor.

关 键 词：湘黔地区 磷结核 羟磷灰石 贵金属元素 生物化学沉积 

分 类 号：P616.3[天文地球—矿床学] P618.63[天文地球—地质学]