大洋微锰结核中纤锌锰矿的发现及其矿物学特征

THE DISCOVERY AND CHARACTERISTICS OF MARINE WOODRUFFITE IN MANGANESE MICRONODULES

报道了发现于东太平洋海盆微锰结核中的一种纤锌锰矿及其矿物学特征。通过采用Ｘ射线衍射、透射电子显微镜及电子探针技术进行的综合研究，证实确为纤锌锰矿。电子探针测得该微锰结核中含Ｚｎ量高达１３．２９％。Ｘ射线及电子衍射特征亦与ＪＣＰＤＳ卡片中的纤锌锰矿数据相吻合。对纤锌锰矿的鉴定定名、成因及其发现的地质意义进行了讨论。

his paper reports the discovery of marine woodruffite in manganese micronodules from the eastern Pacific Ocean (site:10°1575′N,141°4572′W,water depth:5070m).The manganese micronodules are lying on the surface of siliceous ooze sediment and mainly consist of woodruffite and birnessite.Under optical microscope,Xray powder diffraction(XRD),electron microprobe and transmission electron microscope,including selected area electron diffraction (SAED)and energy dispersive Xray analysis,a systematic study is carried out on the marine woodruffite.By electron microprobe analysis,Zn content in the microndodules is known as high as 13.29%,Mn 21.23%,Fe 5.38%,and Cr,Ni,Na and Mg each slight>1%,and Cu,Co,K and Ca each<1% on the same analysis point in the micronodule.The micrograph of twodimension distribution of Mn,Zn and Si elements in the manganese micronodule cut is also got by electron microprobe.According to the micrograph,Zn content is positively related to Mn,but negatively related to Si.The data of XRD and SEAD of the woodruffite agree reasonably well with those of JCPDS card(16338) of the mineral,much better than has hitherto been reported for woodruffite from manganese nodules.Determination of woodruffite from other analogous manganese minerals is discussed in the paper.Besides chemical composition,difference of XRD data between woodruffite and todorokite is that d001value of the former is smaller than that of the latter (generally≤9.5×10-8cm),and its diffraction intensity is I001<<I002.