中太平洋WX海山富钴结壳磷酸盐矿物学研究及成因类型分析  

A mineralogical study and genetic analysis of phosphate in Co-rich crusts from the Central Pacific WX seamount

作　　者：汪在聪[1] 李胜荣[1] 刘鑫[1] 施娘华[1] 初凤友[2] 佟景贵[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]国家海洋局第二海洋研究所海底科学国家重点实验室,浙江杭州310012

出　　处：《岩石矿物学杂志》2007年第5期441-448,共8页Acta Petrologica et Mineralogica

基　　金：国家大洋专项重点研究课题项目(DY105-01-01-01;DY105-01-04-14);中国地质大学(北京)本科生使用校内大型仪器设备科学研究基金

摘　　要：大洋富钴结壳普遍发生磷酸盐化,磷酸盐化对富钴结壳的各种属性存在显著影响,而磷酸盐的成因问题一直没有得到很好解决。中太平洋WX海山富钴结壳老壳层中发育着两期磷酸盐化事件所产生的上下两层磷酸盐,本文运用反光显微镜、扫描电子显微镜、电子探针、微量粉晶X衍射等手段分别对其进行了矿物学特征观察和测试,研究了老壳层上下两层磷酸盐特征并探讨其可能成因。上层磷酸盐由大量形态结构清楚的磷酸质有孔虫和超微化石以及非生物碳氟磷灰石(CFA)组成,成分均一,杂质少,表现出生物成因和原生自沉积特点;下层磷酸盐变化复杂,具有特征的交代结构,混杂较高的Si、Al、K、Fe成分,显示以磷酸盐交代碳酸盐成因为主。这表明不同磷酸盐化期形成的磷酸盐有不同的成因类型。Phosphatisation has widely occurred in oceanic Co-rich crusts and exerted a remarkable effect on the properties of Co-rich crusts. However, no agreement has so far been reached with regard to the genesis of phosphate. In this study, the upper and lower layers in the older portion of a crust from the Central Pacific WX seamount were systemically observed and tested by such means as reflecting microscope, scanning electron microscope, electron microprobe and X-ray diffraction, and their possible geneses and characteristics of formation were discussed. The upper layer, with homogeneous composition, is mainly composed of intact phosphatic foraminifer fossils and narmofossils as well as abiotic carbonate fluorapatites （CFA）, representing the biologic and autogenic origin. However, the lower layer, with visible metasomatic texture and relatively high Si, AI, K and Fe, is notably different from the upper one, and seems to have been formed mainly by replacement of carbonates. Therefore, different phosphate layers in crusts have different geneses.

关 键 词：碳氟磷灰石(CAF) 富钻结壳 矿物学 成因 

分 类 号：P578.92[天文地球—矿物学]