IOCAS-IR
晚全新世山东半岛沿岸流海域高分辨率沉积记录及其环境指示意义
Alternative TitleHigh-resolution sedimentary records and its significance of environment in the Shandong Peninsula coastal current area during the Late Holocene
杨立建
Subtype博士
Thesis Advisor阎军
2022-05-18
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Degree Discipline海洋地质
Keyword沉积演化 山东半岛沿岸流 黄河 晚全新世 东亚冬季风
Abstract

山东半岛沿岸流海域覆盖了黄河近端三角洲和远端泥质楔,是黄河入海泥沙的主要沉积区及向外扩散通道,是研究河流-陆架沉积体系“源”-“汇”过程的良好靶区。近几十年来,山东半岛沿岸流海域水动力环境、沉积物输运模式、沉积特征演化已被广泛的研究,但沿岸流系统下从近端三角洲到远端泥质楔沉积特征的时空演化仍不清楚。本研究根据山东半岛沿岸流海域悬浮体浓度和粒度、表层沉积物粒度结果,探讨了沉积物的空间分异特征和动力学机制;依据山东半岛沿岸流海域岩心沉积物粒度、主微量元素、稀土元素、Sr-Nd同位素以及TOC\TN含量结果,在AMS14C210Pb测年基础上重建了高分辨率沉积记录,并在百年和千年时间尺度上探讨了其环境指示意义。

山东半岛沿岸流海域悬浮体浓度与潮流流速具有明显的正相关关系。近端三角洲海域的悬浮体混合了黄河输入物质和再悬浮物质,其粒度分布通常是多峰态,而远端泥质区的悬浮体粒度分布多为单峰态。表层沉积物粒度空间分布受河流输入、水动力以及海洋锋面等因素控制。山东半岛沿岸流海域沉积物可分为粗粒级端元(< 5 φ)和细粒级端元(> 5 φ。粗粒级端元只能在冬季强风条件下随着沿岸流向远端泥质楔输运,且受到海洋锋面的阻隔。相比之下,细粒级端元不受海洋锋面限制,常年在潮流和沿岸流的作用下向外扩散。这种沉积物输运模式解释了山东半岛沿岸流海域沉积物粒度分布峰型的变化。

近百年来山东半岛沿岸流海域沉积物粒度、主微量元素和TOC\TN时空演化存在明显差异。远端泥质楔沉积环境相对稳定,区域沉积特征演变具有相似性,其主要受到冬季风引起的沿岸流强弱的影响。而近端三角洲区域的沉积特征时空变异性明显大于远端泥质楔,其原因一方面是随着三角洲向海进积,近端三角洲区域水动力环境和沉积物扩散过程不断变化,另一方面是黄河改道和输沙量变化影响近端三角洲沉积特征演化。

人类活动对沿岸流海域沉积特征产生重要影响。诸如水库建设、人为排水排沙等活动不仅影响黄河输沙量,也改变了黄河沉积物供给模式和输运过程,影响了近端三角洲的沉积物粒度特征。另外,山东半岛地区工、农业活动排放的污染物导致山东半岛沿岸流海域沉积物中As富集。近百年来重金属累积过程与中国经济发展过程具有一致的时间变异性。

Bayesian年龄-深度模型基础上获得了山东半岛泥质楔2.6 ka BP以来高分辨率沉积物粒度、主微量元素演化特征。稀土元素配分模式、87Sr/86Sr-εNd图解显示黄河改道南黄海入海期间,渤海废三角洲再悬浮物质在沿岸流下持续供给远端泥质楔。以沉积物粒度粗粒级端元丰度及Zr/Rb比值为指标反演了2.6 ka BP以来东亚冬季风强度。2630 - 900 cal. BP东亚冬季风强度在低水平上旋回变化,900 - 400 cal. BP冬季风强度不断增强,400 cal. BP - 至今冬季风强度在高位振荡。能谱分析和小波分析显示晚全新世冬季风强度演变存在太阳活动周期和PDO周期。在千年时间尺度上,东亚冬季风强度主要受控于太阳活动。而在百年和多年际时间尺度上,东亚冬季风强度与ENSOPDO等过程关系密切。中世纪暖期(MWP)前,东亚冬季风强度与El Niño发生频率反向变化,MWP - 至今,冬季风强度与PDO具有一致的变化趋势。

Other Abstract

The Shandong Peninsula Coastal Current (SPCC) area covering the Yellow River proximal delta and distal mud wedge, is the most significant area of the source-sink system and an important channel for material derived from the Yellow River diffusing outward. In recent decades, the hydrodynamic environment, sediment transport model and sediment characteristics evolution in the SPCC area had been studied extensively, but the spatiotemporal evolution of sediment characteristics from the proximal delta to the distal mud wedge under coastal current was still unclear. In this study, the spatial differentiation characteristics and dynamic mechanism of sediments were studied based on the concentration of suspended particulate matter (SPM), grain size of SPM and surface sediments in the SPCC area. The grain size, Sr-Nd isotopes, content of rare earth elements, TOC\TN, major and trace elements in the core sediments recovered from the SPCC area were analyzed. Combining with AMS14C dating and 210Pb dating, the high-resolution sedimentary records were reconstructed. The environmental significances of the sedimentary records were discussed on centennial and millennial scales.

The concentrations of SPM were related to the tidal current strength in the SPCC area. Generally, the concentrations of SPM in the region with strong tidal current were higher. The grain size distribution of the SPM in the proximal delta of the Yellow River was multi-modal and variable with depth, whereas that in the distal much area was typically unimodal. Such grain size variability of sediments in the SPCC area was controlled by the input of the Yellow River, the coastal currents under East Asian Winter Monsoon (EAWM), local tidal currents and waves, and sea fronts in the water column. The sediments in the SPCC area could be divided into coarse-grained end-member (<  5 φ) and fine-grained end-member (> 5 φ). The coarse-grained end-member of suspended sediments was hindered from further diffusion under fair weather and could be only transported to the distal mud area under strengthened coastal currents in winter. By contrast, the fine-grained end-member was not restricted by ocean fronts and could transported far away under tidal currents and coastal currents all year round. These transport patterns supplied bimodal grains and were responsible for the sediment grain size distribution in the distal mud wedge in the SPCC area.

The temporal and spatial evolution of grain size, major and trace elements, TOC \TN of sediments in the SPCC area was quite different over the past century. The sedimentary environment was relatively stable in the distal mud wedge. And the trend of sediment characteristics evolution of the region was similar, and was mainly affected by the strength of the coastal current caused by the winter monsoon. The temporal variabilities of sediment characteristics in the proximal delta region were more complex than that in the distal mud wedge. On the one hand, the hydrodynamic environment and sediment diffusion process were complicated and changeable with the deltaic progradation to the sea; on the other hand, the shift channel of the Yellow River and changes in sediment load affected the evolution of sediment characteristics in the proximal delta.

Human activities had greatly influenced the sediment characteristics of coastal current area in recent decades. Such activities as reservoir construction and the regulation of large reservoirs not only reduced the sediment load of the Yellow River, but also changed the sediment supply model and transport process, which affected the grain size characteristics of sediments in the proximal delta. In addition, the industrial and agricultural activities in the Shandong Peninsula resulted in the enrichment of As in the sediments of the SPCC area. The accumulation process of heavy metals in sediments was consistent with the process of economic development of China.

Based on the Bayesian age-depth model, the high-resolution sedimentary record on evolution of grain size, major and trace elements in core sediments of the Shandong Peninsula mud wedge since 2.6 ka BP had been obtained. The results the REE partition model and 87Sr/86Sr-εNd analysis showed that erosion material from the proximal delta became the main source of the Shandong Peninsula mud wedge when the Yellow River diverted to the South Yellow Sea. The EAWM intensity since 2.6 ka BP had been retrieved using sediment coarse-grained endmember abundance and Zr/Rb as indices. The EAWM intensity cycled at low level in 2630 - 900 cal. BP, increased continuously in 900 - 400 cal. BP, oscillated at high level since 400 cal. BP. Spectral analysis and wavelet analysis showed that the existence of solar and PDO cycles in the evolution of winter monsoon. The EAWM intensity was controlled by solar radiation on a millennium time scale, while was closely related to ENSO and PDO on centennial and multiannual time scales. The EAWM intensity was inversely related to the frequency of El Niño before the Medieval Warm Period (MWP), while changed with PDO since the MWP.

Subject Area海洋科学
MOST Discipline Catalogue理学::海洋科学
Language中文
Table of Contents

第一章 绪论... 1

1.1 引言... 1

1.2 研究现状... 2

1.2.1 沿岸流作用下世界大河三角洲-远端泥质区沉积体系... 2

1.2.2 山东半岛沿岸流海域沉积演化历史与沉积物输运模式... 4

1.2.3 黄河演变历史及沉积响应... 8

1.2.4 晚全新世东亚冬季风演化历史... 10

1.3 选题依据... 12

1.4 研究内容与工作量... 13

第二章 区域概况... 15

2.1 地质背景... 15

2.1.1 地理位置及海底地形... 15

2.1.2 周围入海河流... 16

2.1.3 海底沉积特征和沉积速率... 17

2.2 气候背景... 18

2.3 水文背景... 19

2.3.1 海水温度和盐度... 19

2.3.2 海浪... 19

2.3.3 潮汐与潮流... 20

2.3.4 表面环流... 21

2.3.5水团与海洋锋面... 23

第三章 研究材料与方法... 25

3.1 研究材料... 25

3.2 研究方法... 27

3.2.1 悬浮体浓度分析... 27

3.2.2 悬浮体和沉积物粒度测试分析... 28

3.2.3 沉积物粒度端元分解和组分分离... 30

3.2.4 沉积物中TOC\TN含量测试分析... 31

3.2.5 沉积物中主微量元素分析... 31

3.2.6 沉积物稀土元素和Sr-Nd同位素分析... 32

3.2.7 210Pb测年... 34

3.2.8 AMS14C测年... 35

3.2.9 能谱分析与小波分析... 35

第四章 山东半岛沿岸流海域现代沉积特征和输运模式... 37

4.1 山东半岛沿岸流海域悬浮体特征及其分布... 37

4.1.1 悬浮体浓度特征... 37

4.1.2 悬浮体粒度特征... 39

4.2 山东半岛沿岸流海域表层沉积物粒度特征及其分布... 44

4.2.1 表层沉积物粒度空间分布特征... 44

4.2.2 表层沉积物粒度端元组分... 45

4.2.3 表层沉积物的起动和沉降... 47

4.3 山东半岛沿岸流海域现代沉积物输运模式... 50

4.3.1 沉积物粒度分布的控制因素... 50

4.3.2 山东半岛沿岸流海域沉积物从近端三角洲到远端泥质楔的输运模式... 51

4.4 小结... 54

第五章 近百年来山东半岛沿岸流海域沉积特征及其环境意义... 57

5.1 近百年来山东半岛沿岸流海域沉积特征演变... 57

5.1.1 岩性特征和干容重... 57

5.1.2 沉积速率与年代框架... 59

5.1.3 沉积物粒度特征与端元分解... 61

5.1.4 沉积物中主微量元素特征... 69

5.1.5 沉积物中TOCTN特征... 73

5.2 近百年来山东半岛沿岸流海域沉积记录对黄河演、东亚冬季风和人类活动的响应... 75

5.2.1 山东半岛沿岸流海域沉积物元素特征空间变异的控制机制... 75

5.2.2 山东半岛沿岸流海域沉积记录对黄河演化和气候变化的响应... 80

5.2.3 沉积物中重金属累积对人类活动的响应... 84

5.3 小结... 91

第六章 晚全新世山东半岛泥质楔沉积特征及其古环境意义... 93

6.1 晚全新世以来山东半岛泥质楔沉积特征... 93

6.1.1 岩性描述... 93

6.1.2 年代框架与沉积速率... 94

6.1.3 沉积物粒度特征... 95

6.1.4 沉积物主微量元素特征... 98

6.1.5 沉积物稀土元素和Sr-Nd同位素特征... 103

6.2 晚全新世山东半岛泥质楔沉积记录的古环境指示... 106

6.2.1 沉积物端元组分物源分析... 106

6.2.2 晚全新世东亚冬季风强度的演变... 108

6.2.3 东亚冬季风强度演化的影响因素... 111

6.3 小结... 115

第七章 结论以及未来展望... 117

参考文献... 119

... 143

作者简历及攻读学位期间发表的学术论文与研究成果    145

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/178355
Collection中国科学院海洋研究所
Recommended Citation
GB/T 7714
杨立建. 晚全新世山东半岛沿岸流海域高分辨率沉积记录及其环境指示意义[D]. 中国科学院海洋研究所. 中国科学院大学,2022.
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