High-resolution reconstruction of the paleoenvironmental changes since the Last Glacial by the analyses of highland moor deposits

在兵库县北部的大沼沼泽采集了 5 个全岩心沉积物，其中 3 个是新开发的非磁芯取样器获得的定向样品。对岩心沉积物进行了综合分析，包括火山灰层岩石学分析、AMS-^ 14 C测年、花粉和硅藻分析，以及亮度、粒度、烧失量、磁化率和古地磁长期变化（PSV）的物理测量，以阐明末次冰期以来的古环境变化和沼泽的形成过程。大沼沼泽下方有超过 65 米厚的沉积物。上部约50米厚，主要由砂和砾石组成，而较细的沉积物约17米厚，主要由粘土和泥炭组成，上部包含K-Ah、SUk、MsP、Sh、AT和Nh 6个火山灰层。根据K-Ah和AT的估计喷发年龄和超过30个AMS-^ 14 C日期以及硅藻分析结果，推断大沼沼泽起源于约41 ka cal.BP的大规模滑坡形成的洼地，并在约32和29 ka cal.BP之间和约13 ka cal.BP之后发育为泥沼，直到约13 ka cal.BP为湿地。约 32 ka cal.BP 和约 29 至 13 ka cal.BP。所有测量的物理特性都显示出在 41 至 13 ka cal.BP 的时间间隔内，在没有气落火山灰层的情况下，存在小幅度的循环变化。时间变化可能反映了被称为海因里希事件的丹斯加德-厄施格振荡的全球气候变化。 PSV主要可以在35至32 ka cal.BP之间重建，这表明了新采样方法的有效性。但由于岩心样品受到扰动，特别是在其最上部和最下部，因此有必要对其进行改进。

Five all-cored sediments were taken at the Ohnuma Moor in the northern part of Hyogo Prefecture, three of which were the oriented samples obtained by newly developed non-magnetic core samplers. Synthetic analyses of the core sediments were performed including petrologic analysis of tephra layers, AMS-^<14>C dating, pollen and diatom analyses, and physical measurements of lightness, grain size, loss on ignition, magnetic susceptibility, and paleomagnetic secular variation (PSV), to clarify the paleoenvironmental changes since the Last Glacial and the formative processes of the moor. More than 65-m thick deposits underlie the Ohnuma Moor. The upper part about 50-m thick is composed mainly of sand and gravels, while the finer sediments about 17-m thick, mainly of clay and peat, comprise the upper part containing six tephra layers of K-Ah, SUk, MsP, Sh, AT, and Nh. Based on the estimated eruption ages of K-Ah and AT and more than 30 AMS-^<14>C dates along with the results of diatom analysis, it is inferred that the Ohnuma Moor originated the depression formed by the large scale landslide at ca.41 ka cal.BP and has been developed as a mire between ca.32 and 29 ka cal.BP and after ca.13 ka cal.BP and as a wetland until ca.32 ka cal.BP and from ca.29 to 13 ka cal.BP. All measured physical properties show the cyclic changes with small amplitude for the time interval from 41 to 13 ka cal.BP without the air fall tephra horizons. The temporal changes are possible to reflect the global climatic changes named the Dansgaadrd-Oeschger Oscillations with Heinrich Events. The PSV can be reconstructed mainly for the period between 35 and 32 ka cal.BP, suggesting the effectiveness of the new sampling method. However, it is necessary to improve it because the core samples were disturbed especially at their uppermost and lowermost parts.