长江、黄河入海沉积角闪石的矿物化学特征及对中国陆架泥质沉积的物源指示意义

发布时间：2018-06-06 20:30

本文选题：长江 + 黄河　；参考：《中国海洋大学》2014年硕士论文

【摘要】：中国东部陆架海域分布着若干厚度不等、斑块状的泥质沉积体，其蕴含着丰富的海陆环境信息，成为全新世以来高分辨率海洋环境演化及全球变化区域响应研究的良好地质记录。大陆径流（主要为长江、黄河等）输入的巨量陆源碎屑物质对泥质沉积体的形成具有重要作用，它携带着大量的成因、物源、气候和环境等方面的信息，可为认识和理解重大地质事件、地质发展过程、区域以及全球气候变迁和环境演化提供定性和定量依据。目前，基于碎屑矿物对物源示踪的研究上多侧重矿物种类及组合特征的分析，矿物化学方法在现代海洋沉积研究中应用较少且不全面。因此，基于碎屑角闪石的矿物化学特征，建立一种新的长江和黄河物源识别的可靠指标，并对中国东部泥质沉积区开展物源示踪研究，对于了解长江和黄河物质运移扩散特征、认识东部陆架泥质沉积区演化规律及进一步理解海陆作用的“源—汇”问题等均有着重要的科学意义。本文针对采自长江、黄河河口以及中国东部典型泥质沉积区的表层样和柱状样，利用沉积物粒度测试、X射线衍射矿物分析、碎屑矿物鉴定、单矿物EPMA等多种分析手段，分析探讨了长江、黄河入海沉积角闪石的矿物化学特征，以及其对中国陆架泥质沉积的物源指示意义。得到以下几点结论： 1）长江、黄河入海沉积物中的角闪石矿物种属类型多样，，均以镁角闪石为主，镁钙闪石次之，铁角闪石、铁镁钙闪石含量较低，相比于黄河源角闪石，长江源镁角闪石、阳起石含量更高，镁钙闪石、铁镁钙闪石则相对较少；成因上，二者大部分属于中高级变质、中酸性侵入及退变质或交代成因，长江口沉积物中退变质或交代成因的角闪石比例相对较高，黄河口沉积物中的角闪石以高级变质岩中的角闪石及退变质或交代成因的角闪石为主，较长江变质程度高，而长江角闪石成因类型分布较黄河分散，说明长江角闪石成因类型及对应的结晶环境更为复杂；特征元素Mg/Fe2+比值差异明显，黄河源物质的Mg/Fe2+2，长江源物质的Mg/Fe2+2.3。以上差异特征的获取是基于测试样品随机、数据充足的基础上，获取的数据具有统计意义，因而可将其作为长江、黄河物源识别的有效矿物化学指纹。 2）利用角闪石的矿物化学指纹能够较好地对东部泥质区表层沉积物的物源进行示踪，其对现代长江和黄河物质在东部陆架海区的分布具有良好的响应。研究发现，中国东部陆架泥质区均受黄河物质不同程度影响，其中渤海和北黄海海域物源主要为黄河物质；南黄海中部泥质区为长江、黄河及黄海两岸物质的多源沉积，而黄河物质贡献最大；长江口以北泥质海域主要受长江物质的影响，同时黄海西岸及外海物质的加入对其也具有显著影响；济州岛西南泥质区除受长江、黄河影响外，外源物质的加入对其具有重要影响，可能为台湾岛大南澳群双变质带岩石风化产物由台湾岛东部地区的河流带入台湾东部海域，后经黑潮带至该泥质区。 3）综合分析了山东半岛泥楔B03孔岩芯粒度、黏土矿物、碎屑矿物以及典型层位角闪石的矿物化学特征。结果表明，钻孔沉积物源供应及沉积环境较为稳定，主要物源为沿岸流输送的现代黄河源物质及山东半岛陆架、临近海底基岩剥蚀产物的混源。依据沉积特征，以85cm深度为界可将其分为上下两个沉积层，下沉积层与山东半岛及临近海底基岩剥蚀产物的物质亲缘性更大，暗示了沉积物源可能存在一定的变化。结合210pb测年数据分析认为，上下沉积层的分界线可能代表了黄河1855年改道事件在山东半岛东部陆架的区域响应。
[Abstract]:The plentiful muddy sedimentary bodies of the continental shelf of eastern China contain abundant marine environment information, which has become a good geological record for the study of high resolution ocean environment evolution and regional response to global change since the Holocene. The continental runoff (mainly the Yangtze River, the Yellow River, etc.) It plays an important role in the formation of argillaceous sediments. It carries a large number of information, sources, climate and environment. It provides a qualitative and quantitative basis for understanding and understanding major geological events, geological development processes, regional and global climate change and environmental evolution. More emphasis is placed on the analysis of mineral species and combination characteristics. The mineral chemistry method is less and less comprehensive in modern marine sedimentary studies. Therefore, based on the mineral chemical characteristics of clastic amphibole, a new reliable index for the identification of the source of the Yangtze and the Yellow River is established, and the source tracer study is carried out in the muddy sedimentary area of the eastern part of China. It is of great scientific significance to understand the characteristics of material migration and diffusion in the Yangtze River and the Yellow River, to understand the evolution of the muddy sedimentary area in the eastern shelf and to further understand the "source sink" problem of land and sea action.
In view of the surface and columnar samples collected from the Yangtze River, the the Yellow River estuary and the typical argillaceous sedimentary areas in the east of China, the mineral chemical characteristics of the amphibolite in the Yangtze River and the Yellow River into the sea are analyzed and discussed by means of sediment granularity test, X ray diffraction mineral analysis, detrital mineral identification and single mineral EPMA. The following are the following conclusions:
1) there are various types of hornblende minerals in the sediments of the Yangtze River and the Yellow River, which are mainly magnesium hornblende, MgO calcite, iron hornblende, iron magnesium calcium amphibole, compared to the Yellow River source amphibole, the source of magnesium hornblende in the Yangtze River, higher content of enimite, magnesium calcium amphibole, and iron magnesium calcium amphibole. It belongs to middle and high grade metamorphism, intermediate acid intrusion and retrogression or metasomatism, and the proportion of amphibolite with retrograde metamorphism or metasomatism in the sediments of the Yangtze Estuary is relatively high. The hornblende in the the Yellow River sedimentary deposits is dominated by hornblende and demetamorphic or metasomatism of amphibolite in high metamorphic rocks, which is higher than the Changjiang River, while the Changjiang amphibolite is formed. The type distribution of the type and the corresponding crystallization environment in the Yangtze River angle is more complex because of the distribution of the type and the corresponding crystalline environment in the Changjiang River. The difference of the Mg/Fe2+ ratio of the characteristic elements is obvious. The Mg/Fe2+2 of the source material of the Yangtze River and the Mg/Fe2+2.3. of the source material above the Changjiang River are obtained on the basis of the testing sample with the machine and the data is sufficient. Therefore, it can be used as an effective Mineral chemical fingerprint for identifying the provenance of the Yangtze River and the Yellow River.
2) the mineral chemical fingerprint of hornblende can be used to trace the source of the surface sediments in the eastern argillaceous area, and it has a good response to the distribution of modern Yangtze and the Yellow River materials in the eastern shelf sea area. It is found that the muddy areas of the eastern continental shelf of China are affected by the different degree of physical quality in the Yellow River, including Bohai and the North Yellow Sea sea. The main source of the domain is the Yellow River matter, and the muddy area in the middle of the South Yellow Sea is the multi source sediment of the Yangtze River, the Yellow River and the Yellow Sea, while the Yellow River has the largest material contribution, and the muddy sea area in the north of the Yangtze Estuary is mainly influenced by the material of the Yangtze River, while the addition of the West Bank and the outer sea material in the Yellow Sea has a significant influence on it, and the southwest muddy area of Jeju Island has a significant influence. Under the influence of the Yangtze River and the Yellow River, the addition of foreign substances has an important influence on it. It may be the rock weathering product of the double metamorphic belt of the Da Nanao group, Taiwan Island, from the eastern part of Taiwan island into the eastern Taiwan sea, and then the Kuroshio zone to the muddy area.
3) the mineral chemical characteristics of the core granularity, clay minerals, clastic minerals and typical amphibolite in the mud wedge of the Shandong Peninsula are analyzed comprehensively. The results show that the supply and sedimentary environment of the borehole sediments are more stable, the main source is the modern the Yellow River source material and the Shandong Peninsula shelf which is transported by the coastal flow, and the erosion products near the base rock of the seabed are near the bottom. According to the sedimentary characteristics, it can be divided into the upper and lower two sedimentary layers with the boundary of 85CM depth as the boundary. The lower sedimentary layer is more closely related to the material of the erosion products of the Shandong Peninsula and the bedrock near the bottom of the sea. It suggests that the source of the sediment may have some change. According to the analysis of 210Pb dating data, the boundary of the upper and lower sedimentary layers may be represented. The response of the the Yellow River 1855 diversions to the eastern shelf of the Shandong peninsula.
【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;P588.125

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