新西兰坎特伯雷盆地MIS6~12期表层海水温度与亚热带锋迁移

发布时间：2018-02-04 16:38

本文关键词： 坎特伯雷盆地表层海水温度 Mg/Ca 亚热带锋迁移古海洋环境　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：本文以位于新西兰南岛中部坎特伯雷平原东南边缘大陆架之下的坎特伯雷盆地(Canterbury Basin)为研究区。南阿尔卑斯山脉隆升所剥蚀的碎屑物质为研究区的沉积提供物源,该研究区地处亚热带水团(STW)和亚南极水团(SAW)交接处,并靠近诸如亚热带锋(STF)这样的主要海洋锋面,这些海洋锋及洋流的存在也强烈地影响着沉积作用。加之研究区内STF的迁移受区域海平面变化和气候的双重影响,因此该研究区成为探讨STF及水团的迁移与沉积过程之间关系及古海洋环境变迁研究的理想海区。本文选取IODP317-U1352B站位岩芯9H-18H(75-163.8m)段落进行研究,通过浮游有孔虫Globigerina bulloides壳体的Mg/Ca比值重建研究区MIS6-12期(150-450ka)以来的SST变化,并结合粒度特征和有机碳含量等分析,共同探讨研究区内第四纪晚期以来的古海洋环境的变迁,得出以下结论:在150-450ka内,研究区内的海平面变化主要是受区域沉积过程影响,并且区域沉积过程对海平面的影响与全球海平面变化的影响一致;海平面升降变化和气候冷暖变化是研究区内STF迁移的主要控制因素;研究区内的古生产力变化主要受陆源营养物质供应的控制,同时在一定程度上也受控于表层海水温度(SST)的变化。在MIS7期、MIS11期和MIS9早期,气候变暖,STF向海向迁移,SST较高,气候变暖使得南阿尔卑斯冰川消融,河流入海的陆源输入量增多,营养物质供应充足,沉积速率高、沉积物粒度粗、表层生产力高;在MIS6期和MIS8期,气候变冷,STF向陆向迁移,SST较低,气候变冷使得南阿尔卑斯冰川消融减少,河流入海的陆源输入量少,营养物质供应不足,沉积速率低、沉积物粒度细、表层生产力低;在MIS9晚期,海平面上升,STF向陆向迁移,SST处于低值,此时粒度特征主要受到温度影响,沉积速率低、沉积物粒度细,陆源输入量减少,营养物质供应不足,再加之此时较低的SST值,表层生产力也低;在MIS10期,STF受海平面和气候双重影响而在研究区内频繁往复迁移,STW多次入侵研究区,水体性质变化十分强烈,SST波动剧烈,陆源物质的输入量少,沉积物粒度细,此时较高的沉积速率和较高的表层生产力主要受到较高的SST影响。
[Abstract]:The Canterbury Basin located below the southeastern margin of the Canterbury Plain in Central South Island, New Zealand, is used in this paper. The denudated debris material from the uplift of the Southern Alps provides a source of sediment for the study area. The study area is located at the junction of the subtropical water mass (STW) and the subAntarctic water mass (SAW) and is close to major ocean fronts such as the subtropical front (STF). The presence of these oceanic fronts and currents also strongly affects sedimentation, and the transport of STF in the study area is influenced by both regional sea level change and climate. Therefore, the study area is an ideal sea area for the study of the relationship between migration and sedimentary processes of STF and water masses and paleo-marine environmental change. In this paper, the core 9H-1 of IODP317-U1352B station is selected. 8H (. 75-163.8m) paragraphs are studied. The Mg/Ca ratio of planktonic foraminifera Globigerina bulloides shell was used to reconstruct the MIS6-12 phase of the study area (150-450 ka). The SST changes since then. Based on the analysis of grain size and organic carbon content, the changes of paleo-marine environment since the late Quaternary in the study area are discussed, and the following conclusions are drawn: within 150-450 ka. The sea level change in the study area is mainly affected by the regional sedimentation process, and the influence of the regional sedimentation process on the sea level is consistent with that of the global sea level change. The changes of sea level rise and fall and climate cold and warm are the main controlling factors of STF migration in the study area. The variation of paleoproductivity in the study area is mainly controlled by the supply of nutrients from terrestrial sources and to some extent by the variation of surface seawater temperature (MIS7). During the MIS11 period and the early period of MIS9, the climate warming (STF-STF) migrated to the sea with high SST, and the climate warming caused the melting of the southern Alps glacier and the increase of the terrestrial source input of the rivers into the sea. The nutrient supply is sufficient, the deposition rate is high, the grain size of the sediment is coarse, and the surface layer productivity is high. In the MIS6 and MIS8 phases, the cold climate is lower in the continental migration, the cold climate causes the melting of the southern Alps glacier, and the input of the rivers into the sea is less. The nutrient supply is insufficient, the deposition rate is low, the grain size of the sediment is fine, and the surface productivity is low. In the late stage of MIS9, the grain size characteristics are mainly affected by temperature, the sedimentation rate is low, the grain size of sediment is fine, and the input amount of land source is decreased. Insufficient supply of nutrients, combined with the low SST value at this time, the surface productivity is also low; During the MIS10 period, due to the influence of sea level and climate, there are frequent reciprocating migration and multiple intrusions in the study area, and the changes of water properties are very strong and the water bodies fluctuate violently. The higher deposition rate and the higher surface productivity are mainly affected by higher SST due to the low input amount of land-based material and fine grain size of sediments.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P731

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