中文摘要：

富钴结壳是发育在深海海山之上的一种重要沉积矿产资源,建立准确可靠的年代学格架,无论对富钴结壳成矿作用研究还是对古海洋环境研究,都具有重要意义。但迄今为止,由于定年技术的限制,可靠的富钴结壳年代学框架资料并不多。文中以钙质超微化石生物地层学方法为主要手段,并结合Co经验公式法、样品的结构特征和磷酸盐化作用时代等资料,对麦哲伦海山群MK海山MKD13-3号富钴结壳样品的年代学框架进行了综合限定。研究结果如下。（1）该样品剖面从下到上可以分4层,分别为：磷块岩基岩,其中包括R层（残留层）结壳,时代为112.0~70.6Ma B.P.;I层,进一步划分为I-1和I-2层,其时代分别为55.0~48.0Ma B.P.和44.0~23.0Ma B.P.;Ⅱ层,时代为23.0~14.0Ma B.P.;Ⅲ层,时代为5.0~0Ma B.P.。（2）该富钴结壳样品在生长过程中发育了3个生长间断,分别为：基岩与I-1层之间的生长间断,时代为70.6~55.0Ma B.P.;I-1层与I-2层之间的生长间断,时代为48.0~44.0Ma B.P.;Ⅱ层与Ⅲ层之间的生长间断,时代为14.0~5.0Ma B.P.。

英文摘要：

Co-rich ferromanganese crusts on deep-sea seamounts are one of the important sedimentary mineral resources.It is critical to build up a reliable geochronological framework for the research of metallogenic process and paleaoceanographic records of Co-rich ferromanganese crust.However,reliable geochronological frameworks are sparse so far because of the respective shortages of dating methods.By the means of calcareous nannofossil biostratigraphy,combined with Co geochronology,the characteristics of texture of section,and the time of phosphatization in the Pacific,we dated a Co-rich ferromanganese crust MKD13-3from Magellan Seamount Cluster in detail：（1）the section of this sample can be divided into four major intervals from bottom to top,which include phosphate substrate with relict ferromanganese crust（112.0-70.6 Ma B.P.）,sub-intervalⅠ-1with the age of 55.0-48.0 Ma B.P.,sub-subintervalⅠ-2with the age of 44.0-23.0 Ma B.P.,intervalⅡ with the age of 23.0-14.0Ma B.P.,and intervalⅢ with the age of 5.0-0Ma B.P.;（2）there are three hiatuses during the growth of this Co-rich ferromanganese crusts,which are the hiatus between substrate and sub-intervalⅠ-1with the age of 70.6-55.0 Ma B.P.,the hiatus between sub-intervals Ⅰ-1 and Ⅰ-2 with the age of48.0-44.0Ma B.P.,and the hiatus between intervalsⅡandⅢ with the age of 14.0-5.0Ma B.P.respectively.