【摘要】 采薇海山位于西北太平洋麦哲伦海山区,是由中国发现、命名并负责资源勘探的重点调查区之一.本文利用大洋27航次在采薇海山北坡MABC-05站获得的箱式沉积物样品,开展了详细的岩石磁学研究.结果显示表层沉积物中的磁性矿物以颗粒较细的、矫顽力较低的磁铁矿为主;利用对数正态分布函数可以区分三个具有不同矫顽力值的磁性颗粒组分,并发现磁性颗粒的矫顽力值变化可以有效指示沉积物埋藏后的早期成岩特征.在参考现代物理海洋过程的基础上,我们推测南极底层水团的演化和太阳辐射的变化可能共同影响了采薇海山区海洋底层环境过程.这一结果为探讨南极气候状况对北太平洋的可能影响,评估海洋上层与底层的相互作用等重要科学问题提供了新途径.更多还原

【Abstract】 Seamounts constitute some of the most direct evidence about intraplate volcanism,and can profoundly affect physical and biological processes,mesoscale circulation and primary production.Caiwei Guyot locates within the Magellan Seamounts of the Northwest Pacific Ocean,where is one of the key investigation areas discovered,named and responsible for resource exploration by China.In this study,we carried out detailed rock magnetic investigations on a sedimentary sequence obtained from the Caiwei Guyot.The methods include hysteresis loops,isothermal remanent acquisition curves,and first-order reversal curves.It is found that the magnetic minerals in the surface sediments of the Caiwei Guyot are mainly fine-grained magnetite with low coercivity;and three magnetic sub-groups with different coercivity values can be mathematically distinguished by a log-normal distribution function,inferring that the change of the coercivity of the magnetic particles can effectively indicate the intensity of the early diagenesis of the sediments.Referring to the physical ocean process,we speculate that the production changes of the Antarctic bottom water and solar insolation may affect the environmental evolution of ocean bottom.Therefore,we suggest that this result provides new perspective to explore the possible impacts of the Antarctic climate on the North Pacific,and to assess the interactions between the upper and lower parts of the oceans,which both may have directly contributed to global changes.更多还原