2012年12月，第18卷，第4期，751-758页 December 2012，Vol.18，No.4，p.751758
高校地质学报
Geological Journal of China Universities
晚第四纪中北太平洋铁锰结壳Fe/Mn变化：
对古气候变化的响应胡，陈天宇，凌洪飞*
南京大学地球科学与工程学院，内生金属矿床成矿机制研究国家重点实验室，南京210093
摘要：大洋铁锰结壳是沉积于海山硬质基岩上的“壳状”沉积物。水成型铁锰结壳被认为是从海水中直接沉淀出来的，并且，形成以后Fe，Mn等元素活化迁移程度很小。因此，铁锰结壳的Fe，Mn含量可以大致反映其生长沉积时的海水化学特征。由于结壳生长通常会受到许多因素（包括水动力环境）的影响而使其生长不够稳定，从而难以准确获取结壳元素在千年尺度上变化的规律。为了克服这一影响，本文选取了中北太平洋两块生长韵律较好，结构致密的结壳（MP3D07和CXD55）进行了高精度化学成分探针分析。结果表明，两块结壳的Fe/Mn比值都可以和~1Ma以来的深海底栖有孔虫氧同位素曲线很好地对应起来，冰期结壳的Fe/Mn比值比间冰期高。铁锰结壳的Fe/Mn比值在冰期-间冰期的显著变化，说明至少1Ma以来，铁锰结壳中Fe-Mn的含量变化与全球气候变化紫密相关。我们认为冰期结壳较高的Fe/Mn比值，是由于冰期风沙输人量增大带来大量的Fe和其它营养元索，加之亚北极水流的影响，使得太平洋表层的生物生产力增大，进而导致由生物颗粒向深水释放的Fe通量增高造成的。
关键词：铁锰结壳；中北太平洋；Fe/Mn；冰期-间冰期
中图分类号：P539.2
文献标识码：A
文章编号：1006-7493（2012)04-0751-08
Fe/MnVariationsofLateQuaternaryFerromanganeseCrusts
fromthe CentralNorthPacific:
Implications for thePaleoenvironment Change
HU Rong, CHEN Tianyu, LING Hongfei
School of Earth Sciences and Engineering, State Key Laboratory for Mineral Deposits Research
Nanjing University, Nanjing 210093, China
Abstract: Ferromanganese crust is shell-like precipitate growing on hard substrate of deep sea mountains. Hydrogenous feromanganese crusts are considered to incorporate elements from ambient seawater during their growth on seamounts. After the formation of crusts, the mobility of their constituent elements is low. Accordingly, the contents of Fe and Mn can reflect the chemical characteristics of the seawater during the crust formation. Since the crusts can easily be influenced by many factors, including hydrodynamic environment, they usually cannot grow in a steady condition, Therefore, it is difficult to judge the chemical evolution process of the crusts' elements in millennium scales. To circumvent this problem, this study selected two densely structured crusts (MP3DO7 and CXD55) with well rhythmic growth pattern and analyzed their spatially high-resolution element contents by an electron probe. The results show that the Fe/Mn ratios of both crusts in this study reveal rhythmic variations, which coincides with benthic oxygen isotope fluctuation in glacial-interglacial cycles since ~1 Ma and the Fe/Mn
收稿日期：20111129；修回日期：20120220
基金项目：中国大洋矿产资源研究开发协会“十—五”项目(DY-115-01-2-2)
作者简介：胡铬，1988生，女，硕士研究生，同位素地球化学专业；E-mail:hurong0618@gmail.com；
通讯作者：凌洪飞，教授；E-mail:hfing@nju.edu.en