摘要
In order to reconstruct the paleoproductivity evolution history of the West Philippine Sea during the last 700 ka, the vertical gradient of Δδ13C in dissolved inorganic carbon Δδ13C between those of foraminifera Pulleniatina obliquiloculata and Cibicidoides wuellerstorfi） and planktonic foraminiferal assemblages were analysed in piston Core MD06-3047 retrieved from the Benham Rise （east of the Luzon Island）. Paleoproductivity evolution in the West Philippine Sea during the last 700 ka is closely related to glacial-interglacial cycles and precession-controlled insolation. Controlling factors ofpaleoproductivity could have been both thermocline fluctuations related with ENSO-Iike processes and eolian input associated with East Asian winter monsoon, and the former could have been the primary factor. A higher productivity and a shallower thermocline coeval with the occurrence of low CO2 concentrations in the EPICA Dome C ice core might indicate that biological export production in the low-latitude could act as a significant sink in the global carbon cycle, and modify atmospheric CO2 concentrations. Spectral analysis further reveals that the paleoproductivity is mainly controlled by thermocline fluctuations subjected to ENSO processes responding to processional variability of insolation. High coherences in eccentricity, obliquity and precession periods fiuther revealing the close link between thermocline fluctuations, paleoproductivity and atmospheric CO2 levels.
In order to reconstruct the paleoproductivity evolution history of the West Philippine Sea during the last 700 ka,the vertical gradient of δ 13 C in dissolved inorganic carbon(δ 13 C between those of foraminifera Pulleniatina obliquiloculata and Cibicidoides wuellerstorfi) and planktonic foraminiferal assemblages were analysed in piston Core MD06-3047 retrieved from the Benham Rise(east of the Luzon Island).Paleoproductivity evolution in the West Philippine Sea during the last 700 ka is closely related to glacial-interglacial cycles and precession-controlled insolation.Controlling factors of paleoproductivity could have been both thermocline fluctuations related with ENSO-like processes and eolian input associated with East Asian winter monsoon,and the former could have been the primary factor.A higher productivity and a shallower thermocline coeval with the occurrence of low CO 2 concentrations in the EPICA Dome C ice core might indicate that biological export production in the low-latitude could act as a significant sink in the global carbon cycle,and modify atmospheric CO 2 concentrations.Spectral analysis further reveals that the paleoproductivity is mainly controlled by thermocline fluctuations subjected to ENSO processes responding to processional variability of insolation.High coherences in eccentricity,obliquity and precession periods further revealing the close link between thermocline fluctuations,paleoproductivity and atmospheric CO 2 levels.
基金
Supported by the National Natural Science Foundation of China(Nos.41230959,41076030,40906038,41106042,41006032)
the Pilot Project of the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-221)
the Foundation of Key Laboratory of Marine Geology and Environment of Chinese Academy of Sciences(No.MGE2011KG01)
