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南大洋CaCO3沉积在记录生物泵调节大气CO2的同时,也记录了南大洋表层锋面系统和深部环流格局的重要转变。通过南塔斯曼海ODP 1170站位2 Ma以来CaCO3%和MAR-CaCO3的研究发现,CaCO3%以冰期低和间冰期高的“大西洋”型溶解作用旋回为主,并以MIS 34/35期(约1.15 Ma BP)和MIS 14/15期(约0.55 Ma BP)为界线,表现出3种沉积模式。而MAR-CaCO3以MIS 57/58,21/22,13/14和11/12为界表现出“两高三低”5个阶段。CaCO3%与轨道参数ETP和底栖有孔虫δ18O的交叉频谱和小波分析显示,其主导周期明显具有从40 ka向100 ka转变的中更新世气候转型(MPT)特征,转型起始与终止时间为1.15～0.55 Ma BP。CaCO3沉积模式的转变与南大洋太平洋区西风带和环南极表层锋面系统的迁移密切相关,在时间上与MPT同步。MPT时期,西风带和环南极表层锋面系统的快速南北迁移,导致CaCO3沉积受到硅质和陆源物质稀释作用的影响。而MAR-CaCO3的阶段性变化主要与南大洋深层环流的变化格局和水团化学性质的变化有关。在1.5～0.85 Ma BP期间,南大洋太平洋区深层水通风增强,利于CaCO3的保存和埋藏,MAR-CaCO3增加;在0.85～0.55 Ma BP期间,CO23-处于不饱和状态的CDW增强,导致南大洋深部CaCO3溶解作用增强,溶跃面上升,MAR-CaCO3降低。
Southern Ocean CaCO3 sedimentation While recording the biological pump to regulate the atmospheric CO2, it also recorded the important transformation of the surface ocean frontal surface system and the deep circulation pattern. The study of CaCO3% and MAR-CaCO3 since 2 Ma station of ODP 1170 station in the South Tasman Sea found that the CaCO3% is dominated by the “Atlantic” type dissolution with low glacial and interglacial periods and MIS 34/35 (About 1.15 Ma BP) and MIS 14/15 (about 0.55 Ma BP), showing three depositional patterns. However, MAR-CaCO3 shows five stages of “two high, three low” with MIS 57/58, 21/22, 13/14 and 11/12. The crossover spectrum and wavelet analysis of CaCO3% and orbital parameter ETP and benthic foraminifera δ18O showed that the dominant cycle obviously has the characteristics of mid-Pleistocene climatic transition (MPT) from 40 ka to 100 ka, and the transition start and end time 1.15 ~ 0.55 Ma BP. The transition of CaCO3 deposition mode is closely related to the migration of the surface frontal system in the westerly zone and the ring of the South Pacific Ocean in the Pacific Ocean and synchronizes with the MPT in time. During the MPT, rapid north-south migration of the westerly frontal and epicyclic surface frontal facies resulted in the CaCO3 deposition being affected by the dilution of siliceous and terrigenous materials. The stage change of MAR-CaCO3 is mainly related to the change pattern of deep circulation in the Southern Ocean and the change of chemical properties of water masses. During the period from 1.5 to 0.85 Ma BP, the deep water ventilation in the southern Pacific Ocean enhanced the conservation and burial of CaCO3 and increased the content of MAR-CaCO3. During the period of 0.85-0.55 Ma BP, the increase of CDW in the unsaturated state of CO23- The dissolution of deep CaCO3 is enhanced, the leaching surface is increased and the content of MAR-CaCO3 is decreased.