南极冰下水体沉积物柱状取样地层破坏机理及样品内部扰动特性的研究

Obtaining of Antarctic subglacial aquatic sediment core samples has a great significance for research of paleo-climate, paleo-environment, ice sheet history and subglacial life exploration. Only a handful of organizations recovered aquatic sediment samples from sub-ice-shelves and subglacial lake, with short core length and heavy layer disturbance. Problems attribute to special forming process and regional difference, resulting in difficult sediment destruction and heavy samples disturbance mismatching with unsuitable coring methods and parameters. This project aims in obtaining Antarctic subglacial sediments with longer length and lower disturbance. We propose studies on sediment physical and mechanical properties, destruction mechanisms and sample internal disturb characteristics. The project includes, on the base of numerical simulation and experimental methods, (1) building relationships between sediment physical prosperities and mechanical characteristics, (2) studying of sediment destruction and (3) observation of samples disturbance under different coring methods and penetration parameters. X-ray diffractions tagged particles experiment method is planned to use for observation of sample internal deformation. Experiment results will be parametrized with 2D PIV or DIC digital image processing method. As a result of research, theoretical basis and technical validation will be obtained for future sub-ice-shelf and subglacial lake sediments sampling of our country.

获取南极冰下水体沉积物柱状样品对研究古气候、古环境、顶部冰层历史以及探索冰下生命形态具有极为重要的科学意义。目前仅少数组织成功取得了南极冰架下、冰下湖水体沉积物样品，且存在样品长度短、层理扰动剧的等现象，归因于南极冰下沉积物的特殊形成过程及地域差异性，造成取样方式、钻进参数与沉积地层破坏机理、扰动特性不匹配。本项目以获取长尺寸、低扰动南极冰下沉积物柱状样品为目标，针对沉积物力学性质、地层破坏机理及样品内部扰动特性展开研究。通过数值模拟与实验手段，建立沉积物物理性质与力学特征之间的关联性，研究取样方式、钻进参数对沉积物破坏、扰动程度的影响规律。采用X光衍射示踪颗粒的方法对样品内部变形过程进行观测，利用二维PIV或DIC数字图像处理法将实验结果参数化。结合数值模拟与实验结果，得出各类沉积物的破坏机理及样品内部扰动特性，为我国未来南极冰架下、冰下湖沉积物柱状取样开展提供理论基础和技术支撑。

获取南极冰下水体沉积物柱状样品对研究古气候、古环境、冰层历史以及探索冰下生命形态具有极为重要的科学意义。本项目以为南极冰下沉积物取样提供低扰动冰下沉积物取样技术为目标，针对取样技术及样品扰动观测方法开展研究。对已获取的东、西南极冰下沉积物样品开展矿物组分分析及粒径分析。结合其他文献样品分析数据，完成模拟冰下沉积物配比方案设计。针对水-沉积物易受取样扰动的技术问题，提出并设计了表层沉积物低扰动取样方法并完成试验验证。完成多种深层冰下沉积物取样装置的设计，包括势能拓展型重力式冰下沉积物取样器、全自动冰下沉积物振动取样器、冰下采样-探测型地热探针在内的深层冰下沉积物取样装置。提出了柱状沉积物样品内部扰动观测方法，设计并建立了模拟沉积物贯入试验台、带管样品剖切装置、样品剖面扫描装置及多维载荷同步监测装置，为未来南极冰下环境低扰动沉积物样品的获取提供理论基础与技术支撑。