27Ka以来日本海北部的沉积记录与环境响应

发布时间：2018-01-10 17:29

本文关键词：27Ka以来日本海北部的沉积记录与环境响应　出处：《中国海洋大学》2014年硕士论文　论文类型：学位论文

【摘要】：边缘海既是连接大洋跟陆地之间的纽带和桥梁，又是与陆地进行物质能量交换的主要地区，其对大陆的气候演变具有显著的影响。日本海作为西北太平洋最大和最典型的半封闭边缘海，重建其沉积记录对于认识日本海本身、太平洋乃至全球的气候演化和海平面波动具有重要的意义，同时对分析其与东亚各区域气候系统及环境特征之间的关系，了解东亚古环境在特殊气候事件和关键地质时期的演变，以及预测今后可能发生的气候变化及环境演化趋势，都具有参考的价值。本文选择位于日本海北部深层水环流通道上的岩芯作为研究对象，综合沉积物粒度参数、环境磁学、化学元素相对含量及颜色反射率等指标，通过与相关文献及资料对比分析，对其沉积地层进行划分，分析该区域的沉积环境演化历史。结果显示，沉积物以粉砂粒级为主，含量大多超过了60%，砂的含量和粘土的含量都相对较少，但是由于沉积年代跨度较大，且经历了较多的冷暖气候突变，，因此颗粒大小在垂向上浮动变化较大，通过粒度分析结果得到敏感组分（22.1-420.4μm）的平均粒径和含量来做为日本海北部研究区域沉积环境的替代指标，结合开样记录和现场观测，将柱状样初步分为八层。通过对磁化率各向异性参数的分析，整个沉积过程保持了较为原始的沉积状态，自形成后并未受到明显的扰动影响。通过样品磁化率的垂向变化趋势发现，与粗颗粒（砂）含量变化的相关性更好，基本表现出样品的颗粒越粗，磁化率值越大的特征，此外结合颜色反射率数据，推测粗颗粒沉积物中的深色铁磁性矿物是造成沉积物磁化率改变的关键因素。通过Ti元素相对含量的变化曲线可以得出沉积过程中陆源物质的输入变化。Fe元素相对含量可以与粒度参数、磁化率参数、颜色反射率成良好的相关关系。Co、Zn等过渡金属元素的相对含量可以初步的反映沉积环境中的含氧量及氧化还原条件。Ca、Sr元素相对含量则可以作为非陆源沉积的标志，从而间接的推断出沉积环境的氧化还原条件和水动力强度。对岩芯的96cm处和346cm处进行的AMS14C测年结果显示，两处的沉积年代分别为8910±25a.BP和26900±90a.BP。通过对柱状样沉积记录的分析，结合已有的资料，初步推断在末次冰期以来发生的全球性冷暖气候突变事件在日本海北部有所响应，对研究区的沉积环境进行初步的反演，得到以下的结果：岩芯346cm深度处从距今约27000年开始沉积，整个沉积过程可能分别经过了D-O事件——H2事件（24.1Ka BP的Heinrich事件）——D-O事件——末次盛冰期——D-O事件——H1事件（16.8Ka BP的Heinrich事件）——波令-阿勒罗德暖期——新仙女木事件——8Ka BP冷事件——全新世大暖期。
[Abstract]:The edge of the sea is the connecting bridge between the ocean with the land, and is the main area of the exchange of material and energy and land, the continental climate change has a significant impact. The sea of Japan as the Pacific Northwest largest and most typical semi enclosed marginal sea, the sedimentary record of reconstruction for the understanding of the sea of Japan itself, has an important the significance of climate change and sea level fluctuations in the Pacific and the world, and the analysis of its relationship with the East Asian regional climate system and environmental characteristics, understand the evolution of the East Asian ancient environment in special climate events and key geological period, and predict the possibility of future climate change and environmental evolution tendency, has the reference value.
This choice is located in the Japan sea deep water circulation channel on the core as the research object, comprehensive sediment parameters, environmental magnetism, chemical elements and relative content of color reflectance index, and through the analysis of relevant literature and data comparison, classify their sedimentary strata, sedimentary environment in the region of evolutionary history. The results showed that the sediment the main content of silt, mostly more than 60%, the content of sand and clay are relatively small, but because the depositional age of large span, and experienced more cold climate change, so the particle size in the vertical floating vary by the particle size analysis results of sensitive components (22.1-420.4 m). The average particle size and content as a substitute index of Japan north of the study area the sedimentary environment, based on the sample records and field observation, the columnar sample was divided into eight layers. The analysis of the anisotropy of magnetic susceptibility parameters, the deposition process keeps the deposition state more primitive, since after the formation has not been disturbed obviously. Discoveries to the trend of the magnetic susceptibility in the vertical, and coarse particles (sand) better correlation between the content changes of the samples showed more coarse particles of magnetization the rate of eigenvalue is larger, in addition to combine color reflectance data and that of coarse sediment in dark ferromagnetic minerals is a key factor to cause the change of magnetic susceptibility of sediments. The change curve of Ti content can be obtained by.Fe element input changes terrigenous deposition process with the relative content of grain size parameters, magnetic susceptibility parameters and a good correlation between the color reflectance.Co, sedimentary environment can reflect the initial relative content of Zn transition metal elements in oxygen and redox conditions.Ca, S The relative content of R element can be used as a marker for non terrigenous sediments, thereby indirectly infer the oxidation of sedimentary environment and hydrodynamic conditions to restore strength. 96cm and 346cm of the core of the AMS14C dating results show that in the two deposition were 8910 + 25a.BP and 26900 + 90a.BP.
Through the analysis of the sedimentary record of columnar samples, combined with the existing data, concluded that in the event of global changes since the last glacial climate change events respond in Japan Sea and preliminary inversion sedimentary environment in the study area, we obtain the following results:
The core at the depth of 346cm from about 27000 years ago began to deposition, the deposition process may be respectively after the D-O H2 event (24.1Ka BP event, Heinrich event, D-O event) - LGM - D-O - H1 events (16.8Ka event BP Heinrich event) - wave to Al Rhodes, the Younger Dryas warm period the event 8Ka BP cold event - Holocene warm period.

【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P736.2

【参考文献】