钱塘江河口区重矿物特征及其与动力环境的关系

本文研究钱塘江河口区的重矿物组成、组合类型、重矿物的分区及其与水动力的关系,同时探讨其物质的来源。钱塘江河口区已鉴定的重矿物有25种,分为四种组合类型,同时存在与其相适应的四个重矿物区,近口段重矿物区、河口段重矿物区,杭州湾重矿物区与金山深槽重矿物区。钱塘江河口区在不同的区段其沉积物来源不一样。近口段主要来自钱塘江流域,口外海滨主要来自长江口,河口段则两者兼有,而金山深槽主要来自槽下被冲刷出来的全新世的沉积物。     

钱塘江河口区重矿物特征及其与动力环境的关系

本文研究钱塘江河口区的重矿物组成、组合类型、重矿物的分区及其与水动力的关系,同时探讨其物质的来源。钱塘江河口区已鉴定的重矿物有25种,分为四种组合类型,同时存在与其相适应的四个重矿物区,近口段重矿物区、河口段重矿物区,杭州湾重矿物区与金山深槽重矿物区。钱塘江河口区在不同的区段其沉积物来源不一样。近口段主要来自钱塘江流域,口外海滨主要来自长江口,河口段则两者兼有,而金山深槽主要来自槽下被冲刷出来的全新世的沉积物。     

长江口拦门沙全新世微体化石群特征及其意义

本文通过对长江口拦门沙地区崇明岛、横沙岛三个钻孔的微体古生物综合分析,发现全新世地层中有四个微体化石层,它们分别指示了该地层经历了(由下往上)由滨海-河流相→滨海-河口相→浅海相→河口相的环境演变过程。并结合孢粉和 C~(14)测年资料认为该区全新世地层可以四分,即古全新世、早全新世、中全新世、晚全新世。     

长江口拦门沙全新世微体化石群特征及其意义

本文通过对长江口拦门沙地区崇明岛、横沙岛三个钻孔的微体古生物综合分析,发现全新世地层中有四个微体化石层,它们分别指示了该地层经历了(由下往上)由滨海-河流相→滨海-河口相→浅海相→河口相的环境演变过程。并结合孢粉和 C~(14)测年资料认为该区全新世地层可以四分,即古全新世、早全新世、中全新世、晚全新世。     

蒙古高原北部全新世风成沉积粒度分析及沉积环境

经野外观察和室内粒度分析,蒙古北部Shaamar剖面上部层段为弱古土壤层和砂层的互层;中部为2层古土壤层夹粒度相对较细的粉砂质细砂;下部主要为砂层,中间夹1层古土壤层.经分析Shaamar剖面风成沉积物应该是近源的,以低空悬浮或跃移为主要搬运方式.邻近的Selenge河洪泛平原是Shaamar剖面风成沉积的最主要物源.沉积物的粒度参数在纵向上明显地分为3段,即末次冰期沉积物粒度最粗,中晚全新世次之,而冰消期和早全新世沉积物的粒度最细.说明蒙古北部走廊地带近地面盛行风速在末次冰期时最大;冰消期至早全新世近地面的风速减小;而在中晚全新世,平均风速再一次增大,但略小于末次冰期.     

陆丰、惠来地区第四纪沉积物粒度、微体古生物与沉积相分析及其对古环境的指示意义

粤东地区是研究华南沿海地区古地貌变迁及海陆相互作用的重要窗口.本文提供了汕尾及揭阳惠来地区实测沉积物粒度组成数据和微体古生物组合数据,为进一步开展该区域第四纪研究提供了基础资料.微体古生物鉴定结果表明,样品中所含的有孔虫、介形虫和硅藻化石均属于第四纪常见种.综合结果表明,陆丰钻孔LFZK05和惠来钻孔HLZK02的岩芯中可能存在三个海相层,说明汕尾陆丰和揭阳惠来地区在第四纪以来至少经历过三次海侵.推测最年轻的海侵层沉积于全新世.该全新世海侵层见于陆丰螺河沿岸的钻孔LFZK04中,但在更为上游的钻孔LFZK03中却没有发现,这可能说明汕尾陆丰地区全新世海侵范围没有到达钻孔LFZK03（自海岸线沿螺河上游约10 km处）的位置;但也不能排除钻孔LFZK03之前存在的海侵层被河流活动侵蚀而未能保存的可能性.上述推论需要结合年代数据进一步厘定.本文提供了汕尾及揭阳惠来地区第一批发表的沉积物粒度分布数据和微体古生物数据,为进一步开展该区域第四纪研究提供了基础资料.     

长江三角洲南翼PJ孔岩芯沉积特征及环境指示意义

根据对长江三角洲南翼第四纪沉积物的磁化率、粒度、地球化学元素、色度等环境指标的综合分析,试图重建该地区全新世气候变化序列,可划分为五个冷暖旋回阶段:1)10.4~8.8kaBP末次冰期结束快速升温的早全新世;2)8.8~5.4kaBP温暖湿润的早中全新世;3)5.4~2.8kaBP频繁波动相对趋冷的中晚全新世;4)2.8~1.2kaBP气候有所回暖的晚全新世;5)1.2~0.4kaBP,气候快速变冷期。在此基础上,与中国西北及其他地区全新世研究成果对比分析,旨在说明长三角沉积物记录的全新世气候变化具有普遍性。     

长江河口地区全新统的分层与分区

根据长江河口地区全新世气候、沉积环境的变迁以及三角洲地貌发育阶段和考古资料,将本区全新统划分为三段.各段厚度、岩性和沉积相在不同地区表现不同,据此又把全区全新统划分为五个分区。     

北部湾北部近岸全新世沉积环境变化及对8.2 ka小冷期的响应

【目的】北部湾北部是东亚夏季风、印度季风以及蒙古冷高压影响的交汇处,对气候变化敏感,该区沉积物要素在全新世的分布与变化,可反映该区气候波动特征和海岸格局演进之影响因素。【方法】在北部湾北部广西水域依次钻取3孔岩芯并进行粒度、矿物、元素、微体古生物测试鉴定以及~(14) C测年,综合分析对比沉积物要素的垂直分布、变化以及响应特征。【结果】全新世孢粉组合为热带-亚热带山地组合。岩芯粒度波动旋回变化,经历了自河床向浅海湾的变迁,沉积物具有陆源性,元素等几乎与沉积旋回细组分同步变化。早期三角洲盆地钻孔显示为盐沼环境;相对晚更新世或者末期,全新世早期沉积物颗粒粗减细增,有机质增幅超过700%。碎屑矿物种类增加,孢粉和硅藻化石逐步丰富,硅藻属种数也保持增加趋势,沉积速率为全新世平均值的1.36~1.85倍,具有风化较强、水沙丰沛、沉积快、物质分配活跃、生物较为繁盛的特点,与邻区全新世中早期气候适宜期相符合。早期气候仍然波动,可辨认出8.2ka小冷期事件的影响,Sr/Ba比值偏低。【结论】研究区作为东亚低纬度季风区海陆过渡界面,其环境变化与气候变化相联系。     

四川盆地西部海相碎屑岩-陆相碎屑岩的转换过程

四川盆地是一个叠合盆地,经历了海相碳酸盐岩到海相碎屑岩、海相碎屑岩到陆相碎屑岩的转换和变迁.这两个转换过程最终结束均发生在四川盆地西部.海相碎屑岩到陆相碎屑岩的转换发生在晚三叠世末,相对应的地层单位为上三叠统须家河组.通过对须家河组厚度和沉积相变化,以及龙门山前砾岩的分布特征研究,认为这一转换主要发生于须家河组沉积末期(T_3x~4-T_3x~6),时间上随地区不同而不同,空间上具有由北往南的先后顺序.这揭示龙门山造山带的造山隆升过程具有由北往南的特点.这一转换过程导致川西前陆盆地内南、北段油气地质条件存在差异.寻找河口沙坝、三角洲平原河道砂等形成的优质储层应是须家河组油气勘探的关键.     

Sedimentologic evidence for date of southward moving of the Yangtze River in the Jianghan Plain since the Holocene

The study of the sediment of Core M1 from Jianghan Plain suggests that the sediment source of this area changed in the Holocene, which corresponds with thr south moving of the Yangtze River. Since then, the sediment source has been mainly from the Hanshui River.     

江苏岸外海底沙脊群的物质来源

本文通过对江苏岸外海底沙脊群的沉积物的粒度、矿物和孢粉以及沉积结构、构造的分析研究,并与苏北废黄河水下三角洲、古长江水下三角洲、现代长江水下三角洲以及长江三角洲平原第四纪地层的沉积物的对比分析,指出江苏岸外海底沙脊群的沉积物主要是晚更新世冰期古长江入海的物质。     

Spatial and temporal distribution of trace elements in Yangtze Estuary, China: Significance of diluted setting

The present study is to examine the spatial and temporal distribution of eight trace elements (Sr, Ba, B, Ga, Ni, V, Cu, and F) in various Holocene marine subfacies in the Yangtze Estuary, including its subaqueous delta by sediment borehole and vibrocore. Results demonstrate that grain size is the determinant factor in controlling the concentration of most trace elements discussed. Prodelta mud that occurs usually below the normal wave base can serve as a depository sink for trapping trace elements over the long-term time period. For example, copper concentration is 5-6 times higher than those found in the estuarine sediment. Boron, which is used to be a salinity indicator, shows a strong negative correlation with paleosalinity (using sediment phosphate method), implying desalinized water setting in the Yangtze Estuary, into which a large quantity of the Yangtze freshwater (924 × 10⁹ m³/a) has discharged. Trace element concentrations of the study area were compared with those collected from the middle and lower Yangtze River reaches, and from the east China continental shelf, including the Okinawa Trough. Result tends to show a terrigenous derivation of most geochemical components of the study area. Concentrations of strontium and barium are correlated with an increase in distance away from the estuary, rather than affected by grain size. Variation of trace elements in downcore Holocene sediment sections are fairly consistent with concentrations revealed by the modern vibrocore transect that extends from nearshore delta front, to offshore prodelta and to the delta-shelf transit zone. The overall distribution of geochemical elements discussed is capable of environmental implication to characterize the Yangtze estuarine transit between land and sea.     

Reconstruction of flood events over the last 150 years in the lower reaches of the Changjiang River

The reconstruction of paleofloods in the Holocene has become one research highlight for the present global change study. The core sediments from one newly-emerged bar in the lower Changjiang River (Yangtze River) mainstream were collected for grain size and organic elemental measurements, with aim to reconstruct the flood events over the past 150 years. Major grain size parameters such as mean grain size, probability cumulative curve and C-M diagram of the core sediments clearly indicate the flood event deposition. Furthermore, the TOC/TN ratios in the sediments can indicate flood events considering that during the flash floods, strong surface erosion in the upper and lower reaches of the Changjiang River can transport a large amount of undecomposed plant debris and organic components with relatively low C/N ratios into the lower mainstream. Based on 210Pb dating and sedimentary geochemical results, the research profile recorded several large floods happened from 1850 to 1954, which agrees well with the historical documents and hydrological observations. Interesting to note that the flood events since the 1960s cannot be distinctly recognized on the basis of sediment grain size and organic elemental compositions of the profile, which mainly reflects the intensive human activities over the last fifty years, especially condense dam construction, have significantly changed the characters of suspended sediment into the lower mainstream.     

洞庭湖新石器文化遗址与古环境

洞庭湖地区丰富的古文化遗址为研究历史时期环境演变提供了条件。洞庭湖在晚更新世末至早全新世呈现深切河谷与零星洼地湖泊共存的河湖切割平原景观。进入全新世暖期，人类活动开始在洞庭湖平原周边地区频繁出现；大溪文化时期人类已在平原湖区中部开始渔猫活动；屈家岭文化时期人类活动从洞庭湖平原中部退出；龙山文化时期人类文化活动遗址向湖中推进，湖泊三角洲有所发展。商周至秦汉时期，洞庭湖三角洲平原发育，河间洼地湖泊、沼泽形成。魏晋以来，特别是长江分流入洞庭，导致了洞庭湖的迅速扩张，19世纪以后，由于大量泥沙入洞庭湖及人类围垦，使洞庭湖迅速淤浅，湖泊面积锐减。     

人类活动与全球变暖影响下长江口海岸地貌动态与灾害趋势研究

在基于区域文献资料查阅整理及分析的基础上,结合野外实地调查等方法,综合分析了各种人类活动与全球变暖对长江口海岸地貌动态和灾害趋势的重要影响.综合分析表明,以三峡为代表的中上游水利工程投入使用,加上水土保持工程及南水北调工程的实施和进一步展开,长江入海通量将一直呈明显下降的趋势.入海泥沙量减少、人类对河口海岸湿地滩涂的过度围垦以及海平面上升伴随的海岸动力增强等主要影响因素的作用下,长江口海岸也由长期的整体淤积转变为近些年来的整体淤积减缓、局部侵蚀加重.与此同时,长江口各种海岸带灾害也呈现出发生周期短,强度大,种类增多的趋势.因此,人类活动与全球变暖协同作用下的长江口海岸地貌动态与灾害学的深入研究是河口三角洲地区可持续发展的重要支撑.     

南京长江大桥附近长江古河谷的形成及沉积特征

末次盛冰期,由于海平面大幅度下降,长江发育古深槽.分析认为,研究剖面附近的深切河槽是局部的深切结果.南京古河谷沉积物,可以分为三期明显的由粗到细的沉积韵律:末次盛冰期深切古河谷,沉积物颗粒粗,从卵砾石到中砂、粗砂;冰后期河床较宽,沉积物从砾石、粗砂到中砂、细砂;全新世,河流进一步展宽,流速变慢,泥沙大量沉积,沉积物从粗砂、中砂到细砂、粉砂,细砂沉积厚度很大.各期河床形态和沉积物的特征,反映了末次盛冰期、冰后期、全新世时期的气候变化和环境演变.     

Impact on the Yangtze (Changjiang) Estuary from its drainage basin: Sediment load and discharge

This paper focuses on the sediment transport and freshwater discharging from upper Yangtze drainage basin downstream, primarily on the basis of multiyear hy-drological data collected from three major hydrological gauge stations (Yichang, Hankou and Datong). Data indicate highest sediment load in Yichang (5.6×108 t/a), lowest in Hankou (5.1×108t) and second highest in Datong (5.4×108 t). This fluctuations are identical with what has been observed from the annual flood season. About one thirds of the sediment load are trapped in the middle Yangtze River course, where meandering river pattern prevails; rest of them are directly transported to the river mouth area via lower Yangtze River channel, where the river is typically confined by the exposed base rock and almost none is being trapped, instead, minor being drained to the mainstream from the local tributaries. To recognize this sediment delivery and river flow media is vital, because it can highlight morphologic/topographic correlation between the upper drainage basin and the estuary and the erosion and siltation in the river mouth area, where extensive coast has been exclaimed and or being exclaimed, and new navigation channel and port is being constructed. It is particularly crucial for monitoring the impact on estuarine change after 3-Gorges dam being closed in 2009. Data also indicate an increase in freshwater discharging downstream (>7.7×1111 m3/a), of which -50% derived from the upstream and another half concentrated from the local tributaries. The result shows that this numerous freshwater has constantly flowed into the river mouth area to support the estuarine aquaculture and ecosystem, where it is confronted with huge amount of tidal prism (>10 times more than that of the annual runoff) transforming from offshore. Thus, a great concern for saltwater intrusion especially during the dry season is aroused, largely due to the intense upstream agriculture irrigation and large water transfer project, such as the well-planned South-North Water Transfer project.     

长江经济带沿线省域文化产业高质量发展水平测度与障碍因素分析

文化产业高质量发展是推动经济结构优化升级的重要路径,也是推进文化自信自强、全面建设社会主义现代化国家的战略选择。从经济效应、社会效应、协调效应、创新效应与开放效应5个维度构建了文化产业高质量发展综合评价指标体系。运用熵权-TOPSIS法测度长江经济带沿线省域文化产业综合效应指数与各子维度效应指数,分析其不同层级、不同区域的空间分布规律,并采用障碍度模型分析不同省份、不同层级与3大区域文化高质量发展的发展障碍及制约因素。研究发现,长江经济带沿线省域文化产业高质量发展水平较低,区域间差异明显,文化产业高质量发展水平综合效应指数呈现“下游地区>中游地区>上游地区”的空间格局;经济效应指数、社会效应指数、开放效应指数分布均呈现“下游地区>中游地区>上游地区”的空间特征,协调效应指数呈现“中游地区>下游地区>上游地区”的区域分布格局,创新效应指数呈现“下游地区>上游地区>中游地区”的分布特征;不同区域的发展障碍因素各不相同,经济效应、创新效应与协调效应是制约文化产业高质量发展的主要障碍因素。     

长江流域重大工程对滩涂冲淤变化影响及潜在土地资源的可持续利用

上海陆域面积现约7 000 km2,其中约65％是近6 000年由长江人海泥沙堆积而形成,约17.5％为1949年以来通过围涂新增的土地,后者极大缓解了上海市尖锐的人地矛盾关系.近几十年来,尤其是三峡大坝建成后长江年均人海泥沙已大幅减少,由1951-1968年间的4.97亿t降低至2003-2008年间的1.54亿t,今后随着流域内更多大型水利工程的实施完成将进一步降低.长江人海泥沙是建造滩涂的物质基础,随着人海泥沙大幅减少,河口滩涂自然淤涨速率趋于减缓,未来整个三角洲的冲淤演化趋势备受关注.以2005年为基准年,Delft3d模型预测结果认为长江口主要浅滩今后20年将继续向海淤涨,但速度减缓.综合分析认为,上海市今后20年可通过工程促淤770 km2,圈围485 km2,但滩涂资源利用一定要兼顾河口生态环境保护,努力实现人与自然相和谐的可持续发展.