【摘要】 准确评估古生产力变化对了解古气候、古海洋演化,探索石油、天然气的形成机制及分布规律十分重要.尽管众多的地球化学指标被用于表征海洋生产力,但大多指标容易受后期地质作用的改造而导致信息失真,其应用仅限于第四纪沉积物.在现代海洋研究的基础上,本文从海水铁制约海洋生产力的生物地球化学原理出发,提出了碳酸盐中的铁作为古生产力的一个新指标.该指标用于广西来宾蓬莱滩二叠纪瓜德鲁普统-乐平统全球界限附近海相碳酸盐的研究,发现它与响应生产力变化的δ13C有相同的变化,说明海相碳酸盐中的铁可以表征地质历史时期的海洋生产力.更多还原

【Abstract】 The assessment of paleo-productivity is of importance, not only for the understanding of paleoclimate and paleoceanography, but for studies on the genesis and the distribution of petroleum and natural gas. A lot of geochemical proxies have been developed to evaluate the past marine productivity. However, most of them are inclined to diagenetic alteration, with the application being limited in Quaternary sediments. Noticeably, dissolved iron deficiency will prevent phytoplankton growth in the modern oceans, and iron trapped in the lattice of carbonate minerals was not easily affected by the post-depositional processes. This raises the possibility of iron abundance as a proxy of paleo-productivity. Here we present an investigation on iron trapped in the marine carbonate in the Permian boundary between the Guadalupian and the Lopingian,Penglaitan, Laibin, Guangxi. Our data show that iron abundance could be used as a proxy of paleo-productivity, supported by its co-variation with δ13C of bulk carbonate which is proposed to relate to the productivity.更多还原