斋堂岛南部海域沉积物特征及物源分析

发布时间：2018-07-23 16:23

【摘要】：第四纪海平面变化，对全球海陆格局的变化起到了尤为重要的决定性作用。海洋沉积物沉积特征、沉积过程的分析，是揭示沉积物物质来源、沉积环境变化、海陆变迁、以及气候更替的重要手段和依据。研究区域位于青岛市斋堂岛南部海域，属于我国南黄海西北部浅海大陆架沉积区。本文以取自斋堂岛南部海域的ZT1孔、ZT2孔柱状样沉积物样品作为分析对象，采用粒度分析，矿物分析（重矿物分析、粘土矿物分析、粘土级碎屑矿物分析），浅地层剖面解译分析的研究方法，通过对研究区域内底质柱状沉积物样品、高分辨率浅地层剖面等资料数据的统计分析，系统分析了研究区域沉积物的沉积特征与物质来源。根据粒度成分特征和岩性特征，将两钻孔上下分为两层：第一层沉积物类型为：粘土质粉砂和含砾粉砂质砂，含贝壳碎屑和砾石；第二层沉积物类型为：含砾砂，含大量砾石。研究样品沉积物分选差或极差，为近源搬运的坡、洪积物、甚至是原地风化堆积的等陆源沉积物，只有第一层受到现代海洋沉积作用的影响，原始陆源残留沉积，并混杂有部分海相沉积因子；第二层不曾接受现代海洋沉积作用的扰动，沉积环境单一，为原始陆源残留沉积物。沉积物极细砂粒级中的重矿物主要有：不稳定矿物角闪石、绿帘石；片状矿物；稳定矿物锆石、石榴石、磷灰石、电气石、金红石；金属矿物钛铁矿；自生矿物海绿石；沉积物的粘土矿物的组合类型为：伊利石-高岭石-绿泥石-蒙皂石。伊利石含量异常高；而蒙皂石含量异常低；沉积物粘土级碎屑矿物包括粘土矿物、石英、长石、方解石、白云岩。研究样品为陆源沉积物，形成于寒冷干燥的沉积环境。第二层的各矿物含量变化趋势相比第一层较稳定，反映了第一层的更为复杂的沉积环境。通过浅地层剖面分析可知，研究区内海底基岩埋深浅，浅地层结构简单，现代海洋沉积物作用影响弱，基岩面以上部为松散沉积物，且沉积层较薄，可划分为上层沉积物层和下层基岩层，根据反射界面特征可将上层沉积物层可分为两层，佐证了根据粒度和岩性特征对沉积物的分层结论的正确性。其中第一层由于外动力作用的影响，在研究区域局部区域存在损耗和缺失现象。研究结果表明，研究区域内沉积物属粗粒级沉积物，分选差或极差，，具有明显的陆源沉积物特征，沉积物为近源搬运沉积或原地风化沉积而成，受强水动力影响；而后期受海洋改造影响较弱，与其所处的现代海洋沉积环境的动力条件不平衡，因此，推测可能是由于海平面下降陆架裸露成陆风化沉积而成，而后又经历快速海浸活动残留下来的原始沉积物，即为残留沉积物。
[Abstract]:Quaternary sea level change played a decisive role in the change of global sea-land pattern. The analysis of the sedimentary characteristics and processes of marine sediments is an important means and basis for revealing the source of sediment, the changes of sedimentary environment, the changes of sea and land, and the change of climate. The study area is located in the southern sea area of Maitang Island, Qingdao, which belongs to the shallow continental shelf sedimentary area in the northwest of Huang Hai. In this paper, the columnar sediment samples from the ZT1 hole ZT2 hole in the southern sea area of Jaitang Island were used as the analytical objects. Particle size analysis, mineral analysis (heavy mineral analysis, clay mineral analysis) were used. Clay grade clastic mineral analysis), shallow stratigraphic profile interpretation and analysis method, through the study of the sediment column sediment samples, high-resolution shallow stratigraphic profile and other data statistical analysis, The sedimentary characteristics and material sources of sediments in the study area are systematically analyzed. According to the characteristics of granularity composition and lithology, the two boreholes are divided into two layers: the first layer is clayey silty sand and gravel silty sand, which contains shell clastic and gravel, and the second layer is gravel-bearing sand with a large amount of gravel. The study shows that the separation of sample sediments is poor or extremely poor, that is, near source transport slopes, alluvial sediments, and even terrestrial sediments with in situ weathering and accumulation. Only the first layer is affected by modern marine sedimentation, and the original continental residual sediments are formed. The second layer is not disturbed by modern marine sedimentation, and the sedimentary environment is single, which is a primitive continental residual sediment. The heavy minerals in the very fine sand grains are: unstable hornblende, verdant; flake mineral; stable mineral zircon, garnet, apatite, tourmaline, rutile; metallite ilmenite; authigenic mineral sea turquoise; The composition types of clay minerals in sediments are Illite-kaolinite-chlorite-montmorillonite. The content of Illite is abnormally high, while the content of montmorillonite is abnormally low. The clastic minerals of clay grade in sediments include clay minerals, quartz, feldspar, calcite and dolomite. The studied samples are terrestrial sediments formed in cold and dry sedimentary environments. The change trend of mineral content in the second layer is more stable than that in the first layer, which reflects the more complex sedimentary environment of the first layer. Through the analysis of shallow strata profile, it can be seen that the undersea bedrock in the study area is deep and shallow, the structure of shallow stratum is simple, the influence of modern marine sediment is weak, the upper part of the bedrock is loose sediment, and the sediment layer is thin. It can be divided into upper sediment layer and lower bedrock layer. According to the characteristics of reflection interface, the upper sediment layer can be divided into two layers, which proves the correctness of the conclusion of stratification based on granularity and lithology. The first layer has the phenomenon of loss and absence in the local area due to the influence of external dynamic action. The results show that the sediments in the study area belong to coarse grained sediments with poor or very poor sorting and have obvious characteristics of continental sediments. The sediments are formed by near-source transport or in situ weathering and are influenced by strong hydrodynamic forces. However, in the later stage, the influence of ocean transformation is weak, and the dynamic condition of the modern marine sedimentary environment is not balanced. Therefore, it is assumed that it may be caused by the exposed continental weathering deposition of the sea level drop shelf. Then the primary sediment, which was left behind by rapid sea leaching, was called residual sediment.
【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】：P736.21

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