Calcareous nannofossil changes in the Early Oligocene linked to nutrient and atmospheric CO2  

作　　者：Ruigang Ma Haizhang Yang Xiaobo Jin Zhao Zhao Gongcheng Zhang Chuanlian Liu 

机构地区：[1]State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China [2]CNOOC Research Institute Co.,Ltd.,Beijing 100027,China

出　　处：《Acta Oceanologica Sinica》2020年第10期70-80,共11页海洋学报（英文版）

基　　金：Foundation item:The National Science and Technology Major Project of the Ministry of Science and Technology of China under contract No.2016ZX05026007-03;the National Natural Science Foundation of China under contract Nos 41876046 and 41930536。

摘　　要：Rapid changes on nutrient supply and CO2 concentration that occurred in the northern South China Sea(SCS)during the Early Oligocene,provides an ideal natural laboratory,allowing us to peer into the coccolithophores’physiology in the geological records.In this study,we established a new nannofossil assemblage index,termed as E^*ratio,which is calculated by the relative abundance of eutrophic taxa and meso-oligotrophic taxa(E^*=e/e+c,where e is eutrophic taxa,and c is meso-oligotrophic taxa)Eutrophic taxa include small Reticulofenestra,Reticulofenestra lockeri group,Reticulofenestra bisecta group and Coccolithus pelagicus group,while meso-oligotrophic taxa include Cyclicargolithus spp.The E^*ratio is well correlated with nutrient proxy during the Early Oligocene,while with different covarying patterns under the higher and lower CO2 condition.By comparing the assemblage changes to the published data,we suggest that coccolithophores may change the way they use carbon source and nutrient with the decline of CO2.Furthermore,this implies a possible initiation of the carbon concentrating mechanism.

关 键 词：COCCOLITHOPHORE assemblage change weathering intensity carbon concentrating mechanism northern South China Sea 

分 类 号：X131.1[环境科学与工程—环境科学]