磷块岩成矿过程及其稀土元素富集机理综述  

Review on metallogenic process and rare earth elements enrichment mechanism of phosphorite deposits

作　　者：雷梦丹 钟日晨 崔浩 王赵依 陈缓 李艳霞 于畅 邓依 凌一凡 李默洁 黎子萌 陈昂快 LEI Meng-dan;ZHONG Ri-chen;CUI Hao;WANG Zhao-yi;CHEN Huan;LI Yan-xia;YU Chang;DENG Yi;LING Yi-fan;LI Mo-jie;LI Zi-meng;CHEN Ang-kuai(School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing 100083,China;School of Earth Sciences and Resources,China University of Geosciences Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《岩石矿物学杂志》2024年第5期1199-1217,共19页Acta Petrologica et Mineralogica

基　　金：国家重点研发计划重点专项项目(2021YFC2901703);国家自然科学基金项目(42222303,42203064);中央高校基本科研业务费项目(FRF-TP-22-004C1)。

摘　　要：磷块岩矿床是以细晶磷灰石为主要矿石矿物的一种海相沉积磷矿床,形成于古元古代后6个历史时期的上升流地区,与生物活动重要节点、大陆风化加剧时期密切相关。磷块岩矿床的形成受海平面升降、微生物活动与沉积物孔隙水中的物理化学条件等因素控制,而形成高品质磷块岩矿床的关键是极低的沉积速率与周期性的海底风暴。部分磷块岩中超常富集中重稀土元素,是潜在的稀土资源来源。磷块岩中稀土元素的主要赋存矿物为细晶磷灰石,其中的稀土元素主要来源于沉积时期的海水和早期成岩时期的沉积物孔隙水,并以吸附或晶格替代的方式储存于细晶磷灰石中。稀土元素可以通过形成稀土-碳酸盐络合物等方式吸附于海洋微粒表面,当氧化还原条件变化时,海洋微粒分解并将稀土元素释放至沉积物孔隙水中。本文通过文献综述发现不同海洋微粒对于稀土元素的吸附具有选择性,从而导致不同的孔隙水具有不同的稀土元素配分模式,进而影响磷块岩矿床中细晶磷灰石的稀土元素配分模式。细晶磷灰石对于稀土元素的富集不具有选择性,故受海水影响较大时呈现重稀土元素富集特征,而受孔隙水影响较大时则呈现中稀土元素凸起特征。由于超常富集稀土元素的磷块岩矿床常呈现中稀土元素凸起的稀土元素配分模式,这与海底热液输入的铁锰氧化物的稀土元素配分特征以及早期成岩过程中孔隙水的稀土元素配分特征相符,这或许指示着海底热液活动输入的铁锰氧化物及早期成岩过程对于磷块岩矿床稀土元素富集过程的影响。本文从磷块岩矿床的特征、时空分布及成矿的控制要素等方面对于磷块岩矿床的成矿过程进行了综述,从磷块岩矿床的稀土元素含量及稀土元素异常分析磷块岩成矿过程中稀土元素的富集行为和分异行为,并讨论了超常富集稀土元�Phosphorite deposit is a kind of marine sedimentary phosphate deposit with the francolite as the main ore mineral.These deposits were formed in the upwelling areas during six historical periods after Paleoproterozoic,and are generally related to the biological activity and the intensity of continental weathering.The formation of phos-phorite deposits is controlled by marine transgressions and regressions,microbial activities and physical and chemi-cal conditions of sediment pore water.The key factors for the formation of phosphorite deposits with high rare earth elements(REEs)content are low sedimentation rate and periodic submarine storms.Some phosphorite deposits are rich in medium and heavy REEs,which are potential important REE resources.The main host mineral of REEs in phosphorite is francolite.The REEs in francolite are mainly derived from seawater in sedimentary period and sedi-ment pore water in early diagenetic period,and are incorporated into francolite via adsorption or lattice substitution.REEs can be adsorbed on the surface of marine particles by forming as REEs-carbonate complex and released by the marine particles decomposing that is induced by the change of redox conditions in the sediment pore water.Through the previous research,it is found that different marine particles preferentially adsorb different REEs,which results in the formation of different REEs patterns of pore water and then affects the patterns of francolite in phosphorite de-posits.The enrichment of REEs in francolite is equal for light,medium and heavy REEs and different REEs pat-terns in francolite are derived from contrasting fluid sources.In general,seawater can produce a HREEs-enriched pattern,and pore water might yield a MREEs-bulge pattern(enrichment of medium REEs).As the phosphorite deposits with significant REEs contents are characterized by MREEs-bulge patterns that are consistent with Fe-Mn(oxyhydr)oxides input by the submarine hydrothermal process and the pore water in the early diagenetic process,which may indicates t

关 键 词：磷块岩 稀土元素 深海沉积物 早期成岩过程 铁锰氧化物 

分 类 号：P619.213[天文地球—矿床学] P618.7[天文地球—地质学]