长江第一弯河段阶地特征及年代学研究

通过DEM及野外调查,提取和分析长江第一弯河流阶地的空间位置及分布特征,认为在河流弯曲及宽阔河段阶地的保存范围大于其他河段;根据阶地序列年代学研究提出,长江第一弯河段T₁和T₂堆积阶地分别形成于9~12 ka和15~20 ka,这两级最新阶地分别形成于不同的气候背景。T₂开始堆积于末次冰盛期（LGM）,下切于15 ka前后;而T₁堆积于全新世初期的大暖期,下切于9 ka前后。而且,两级阶地均存在向断裂方向的上翘,河谷摆向断裂上升盘的相反一侧;河流下切速率也向着断裂方向增大。因此,河流阶地的形成应该受到构造因素的控制,而气候作用对河流下切有明显的影响。

     

长江第一弯虎跳峡的贯通——来自于地表地貌和弹性挠曲的数值模拟分析

以往注入南海的古金沙江的袭夺及其相关的长江第一弯的形成不仅造成了南海一系列盆地内部充填物质的急剧变化,同时还记录了与南海北部边缘海扩张相关的构造活动机制的重大变革。尽管如此,由于缺乏直接证据,对于金沙江东流和长江第一弯形成的时间和机制还存在较大分歧。鉴于此,本研究通过TTLEM和LIFFE模型直接对虎跳峡的贯通和下切过程开展数值模拟分析。结果显示虎跳峡现今深切峡谷的形成是两阶段地表快速侵蚀的产物。而其初始的贯通应形成于中新世中期(~15 Ma)前后,和虎跳峡背斜的形成同期,与大理断裂系大规模走滑兼具逆冲运动直接相关。随后,进入第四纪(~2 Ma)以来,大理断裂系的构造活动由压扭转变为张扭性。虎跳峡由于地壳的弹性挠曲变形再次快速下切,剥蚀厚度达到~3 km,最终形成了现今的地貌样式。结合区域的其他研究结果,我们认为伴随着印度板块向欧亚板块之下持续的俯冲,青藏高原东南缘南东向的物质运移曾发生过一系列构造活动机制的重大转变,不仅引起了区域内断裂系统活动性质的转换,造成了大型水系的袭夺和重组,同时还与南海海盆的扩张和最终形成紧密关联。     

长江江都嘶马段岸崩灾害的形成机理与防治对策

江岸稳定性取决于最大崩塌临界机制的驱动力和抵抗力的平衡,二者的平衡又受控于岸边坡形态、岩土组成、水流浪涌特征、植被覆盖等。崩岸是长江嘶马弯道床演变的一个重要方面。通过对嘶马弯道遥感解译图像资料进行对比分析,查清研究区江岸岸线特征及其变迁历程。为了揭示北岸崩塌产生的原因,通过野外踏勘、测量与钻探等技术方法查明该区地质基础条件,并基于实时动态定位技术(Real Time Kinematic,RTK)的水下测量数据建立典型剖面,分析凸岸和凹岸的水流运动特征及其对边岸的影响。从地质基础和水动力条件2个方面揭示嘶马段江岸坍塌形成机理,即具有上细下粗二元结构的边岸地层是岸崩形成的基础,丁坝回流和弯道螺旋流的掏蚀作用是岸崩形成的重要条件。并基于江岸稳定性现状及其发展趋势,提出相应的江岸整治措施。     

滇西北丽江地区石鼓古湖的发现及其在现代金沙江河谷发育中的意义

在云南石鼓"长江第一湾"附近河段两岸发现了10多处典型的第四纪湖相沉积物露头,它们构成了金沙江第二、三、四级阶地的基座。热释光(TL)和U系法年龄测定及磁性地层学研究结果表明,该套湖相沉积物中上部的时代属于243.3～88.0kaBP的中更新世晚期至晚更新世早期,上覆的第四级阶地沉积物的年龄为88.0～80.9kaBP。湖相沉积物的粒度、地球化学和粘土矿物分析结果表明,其沉积环境有由温湿向湿热转化的趋势。根据对玉龙雪山更新世冰川作用的研究,石鼓古湖最初应是玉龙雪山西麓中更新世早期玉龙冰期冰碛物堰塞金沙江河谷而成的,中更新世晚期丽江冰期的冰水沉积物进一步加以堰塞,直至8万多年前被金沙江侵蚀而再次贯通。     

长江三角洲晚更新世第一硬土层研究进展

长江三角洲晚更新世晚期的第一硬土层是划分更新统与全新统地层界面的标志层,也是上海中、高层建筑物的主要桩基持力层,具有第四纪科学研究和工程地质应用价值。由于缺乏明显指相意义的沉积标志和古生物化石等特征,对于第一硬土层的成因、物源和次生演化等问题,各家学者的观点相差甚远,至今没有达成共识。在讨论第一硬土层的沉积年代、沉积环境和沉积特征的基础上,评析了硬土层研究中的三大争论,即成因的"水成与风成"之争,物源的"近源与远源"之争和次生演化过程之争,认为硬土层经历了复杂的冷暖干湿变化和海侵海退旋回,可划分为早期冷干环境的沉积阶段、中期全新世海侵之前暖湿环境的风化和成土阶段、后期海侵及海退之后的掩埋改造阶段等3个时期。解决第一硬土层争论的途径是建立高精度连续年代序列标尺,运用地层追踪方法进行区域性标志地层的对比,在此基础上探索硬土层的形成与演化机制。     

Terraces Development and Their Implications for Valley Evolution of the Jinsha River Since Late Pleistocene near Longjie,Yunnan

The drainage evolution and valley development of the Jinsha River is an important issue constantly concerned by researchers in geology and geomorphology. Despite hundreds of years of research, there is a big dispute on the formation time and the evolution process of the fluvial valley. Fluvial terraces are very important geomorphic markers for studying the formation and evolution of the fluvial valley. Through field investigation combined with Electron Spin Resonance (ESR) dating, we confirmed that 5 fluvial terraces were formed, and then preserved, along the course of the Jinsha River near the Longjie, which are all strath terraces. Among them, T5 developed on the base rock, with an age of (78±12) ka; all T4~T1 developed on the lacustrine sediments, named Longjie Group by Chinese, with an age of (29±1.4) ka, (26±2.4) ka, (23±1.4) ka, (18±1.7) ka, respectively. Compared with the global and regional climate change history, the terraces are all the result of the river responding to the climate change. T5 formed at MIS 5/4, and T4~T1 formed at the period of regional climate fluctuation. The relationship of terraces and the Longjie Formation, combined with sedimentary characteristics analysis demonstrate that the Longjie Formation is landslide dammed lake sediment. The landslide and blocking events.seriously influenced the valley evolution, inhibiting the river incising, and making the valley evolution defer to the mode of “cut-landside-damming-fill-cut” in the period of Late Pleistocene. Synthesized studies of the terraces and the correlative sediments indicate that the formation of the Jinsha River valley may have begun in the late Early Pleistocene.     

长江中下游转换构造结与区域成矿背景分析

中国东部中生代以来的地壳运动频繁,构造演化复杂,岩浆活动剧烈,成矿作用多样,是不同体制构造转换的重要地区.长江中下游地区是中生代特提斯构造体制与太平洋构造体制转换的经典地区,是两大构造体制交汇和转换的焦点部位,具有岩石圈物质重组、结构重建的时-空演化关系.长江中下游转换构造结由是中国东部中生代特提斯构造体制与太平洋构造...     

长江中下游成矿带地质与矿产研究进展

长江中下游成矿带是我国重要成矿带之一,矿产资源开发利用历史悠久.自20世纪20年代至今,国内外学者在该地区开展了广泛深入研究工作,取得了丰硕的研究成果,并发表了大量科学研究论文和50余部专著.据统计,1959年～2012年间在公开发行的中文地质学期刊中,有关长江中下游地区的学术论文共888篇;1990年～2012年间公开发表的SCI检索论文中该区有185篇.这些论文中涉及矿床学方面的研究最多,约占论文总数的一半.成矿带内,铜陵矿集区研究程度最高,发表的相关论文数量也最多.有关成矿带的论文发表数量总体趋势逐年增加,在20世纪90年代初和2010～2012年出现两个研究高峰,反映了长江中下游成矿带近年来仍然是我国地质学研究的热点地区之一.近年来,长江中下游成矿带的地质找矿和科学研究均取得了重要进展,地质与矿产研究主要集中在以下几方面:(1)中生代构造转换与成岩成矿的地球动力学背景;(2)岩浆作用与深部过程;(3)成矿系统及其演化;(4)成矿潜力.本专辑收录的26篇论文基本反映了当前长江中下游成矿带及邻区的最新研究进展,所报道的大量地质学新观察、矿床学和岩石学研究、元素和同位素地球化学数据、同位素年代学特别是高精度锆石U-Pb年龄等对深入进一步探讨长江中下游成矿带形成与演化具有重要参考价值,对于推动成矿带基础理论研究和指导找矿勘探均有重要意义.     

Hazard Assessment of Cold and Hot Damage for Double-Season Early Rice (DSER) in Lower-Middle Reaches of the Yangtze River Basin

Cold and hot damages which are both common disasters occurring in DSER growth time in lower-middle reaches of the Yangtze River Basin harm early rice. The two disasters occurrence should be deeply studied to protect the DSER yield. This study was based on meteorological data of 48 agricultural meteorological stations during 1961-2010 period and agricultural meteorological data during 1981-2010 for DSER in lower-middle reaches of the Yangtze River Basin. In this study, the growth time was divided into several phases according to the growth stage, including tillering stage, booting stage, flowering stage and filling stage. The disasters taking place at some stages was identified by building new judging standard and their intensity value was calculated by harm accumulated temperature calculation model. Fisher optimal division method was used to classify the disasters and H-P filter was used to consider the reduction of the yield. It was conducted to analize the disasters’ characteristics in growing season, the intensity of hazard and the weight of hazard at each stage by judging and quantifying cold and hot damage and developing hazard assessment model of disasters. All findings were displayed in maps by GIS technology. The results showed that: ①New disaster judging standard was more suitable for DSER and the hazard assessment model could reveal the disaster situation in lower-middle reaches of the Yangtze River Basin. ②Cold damage was severe at tillering stage while hot damage was severe at filling stage. In the view of the distribution of the decadal disaster intensity, cold damage became to be weak and hot damage became to be strong. Compared with the plains, mountainous region and hilly ground were attacked by cold damage frequently and hot damage rarely from the perspective of spatial distribution of disasters. Distinctly, plains near large areas of water were often harmed by cold damage at booting and flowering stage. ③The area of high hazard value and high disasters value at each stage were overlapped by each other roughly. Studying the hazard of the whole growth season showed that the highest hazard value was in Zhejiang province, and the next in Hubei Province. So Hu’nan and Jiangxi Provinces were quite suitable to grow DSER. ④In contrast with the hazard weight at each stage, the vulnerable phases of the whole growth time were in sequence of filling stage> tillering stage> flowering stage > booting stage. What’s more, aiming at defensing and fending off risk, some special stages in special province should be paid close attention including booting and filling stages in Hubei Province, tillering and flowering and filling stages in Hu’nan Province, tillering and filling stages in Jiangxi Province, flowering and filling stages in Zhejiang Province. The conclusion can be taken as theoretical basis for the government management of agricultural production, disaster prevention and mitigation.     

长江口北支水道萎缩淤浅分析

根据1958～2009年长江口北支水下地形实测数据,基于GIS技术进行计算分析,结果表明：长江口北支水道趋于萎缩淤浅,其发展特征表现在河道宽度缩窄、水深变浅、水域面积减少以及河槽容积缩小;其驱动原因为1955年左右的自然河势调整以及几十年来沿岸人工围垦工程;北支萎缩淤浅造成了水道消亡加速、水沙倒灌风险加大。拟应采取修闸建坝等水利设施,充分利用北支水道的价值,减小其负面风险。     

Integrated Risk Assessment and Governance of Multi-hazards in the Yangtze River Economic Belt

The construction of the Yangtze River Economic Belt is one of the major strategic initiatives to promote the sustained and steady growth of China's economy at current and the new normal stages. Comprehensive enhancing the governance levels of various natural disaster risks in the Yangtze River Economic Belt is the basic guarantee for promoting the implementation of the development strategy. Based on the multi-hazard integrated risk theory, the main disaster risks of the core cities (Shanghai, Wuhan, and Chongqing) of the Yangtze River Economic Belt and the major risk-earthquake disaster chain were systematically analyzed. The status and existing problems of multi-hazard integrated risk governance in the Yangtze River Economic Belt were expounded in this paper. The main problems include: Insufficient understanding of multi-hazard integrated risk formation mechanism; low level of safety fortification; Imperfect regional coordination and linkage mechanism; and insufficient role of insurance and reinsurance in risk transfer. Finally, the overall promotion strategies were proposed, including establishing multi-hazard integrated risk identification mechanism and governance capability evaluation system; comprehensive improving the fortification level of multi-hazard integrated risk prevention; establishing multi-hazard and multi-party linkage disaster monitoring and early warning systems; strengthening major disaster risk management and evacuation facilities construction; accelerating the construction of catastrophe insurance systems based on multi-hazard risks. This will provide a theoretical reference for major disaster risks studies in the Yangtze River Economic Belt.     

长江中下游成矿带矿产勘查-科研工作回顾和展望

长江中下游成矿带是我国勘查-研究程度相当高的成矿带之一,地质勘查和相关研究工作可以追溯到二十世纪初。本文简要对成矿带自二十世纪初至今的勘查-科研工作成果进行了概括性回顾和综述。中华人民共和国成立后成矿带勘查研究工作总体上可以分为三个阶段:(1)第一阶段:点上起步、由点到面;(2)第二阶段:区域展开、重点突破;(3)第三阶段:立体调查、深部找矿。近年来,长江中下游成矿带的地质找矿和科学研究均取得了重要进展,主要集中在以下几方面:(1)控矿构造格架(包括大地构造,后期还尝试引入了动力学背景的探讨);(2)成岩成矿作用的时代;(3)成矿系列(系统)及其演化;(4)成矿规律;(5)深部找矿。包括本专辑(代序)20余篇文章在内的近年来的找矿新发现、新突破以及对成矿的新认识,深化了成矿带成矿理论研究,指示成矿带特别是深部"第二找矿空间"具有很好的成矿潜力,同时也揭示了成矿带值得关注和仍有待进一步研究的科学问题。     

长江源及其周边地区蒸发量特征及变化趋势研究

通过对长江源及其周边地区沱沱河等10处气象、水文站自建站至2000年蒸发量资料的分析，揭示了长江源及其周边地区蒸发量的特征值及蒸发年内年际变化规律，分析了该地区蒸发量的变化趋势。     

水利促进长江中下游地区经济社会协调发展的思考

长江流域在中国经济社会发展中具有极为重要的战略地位,长江中下游地区更是我国最具实力的经济带。水利是国民经济和社会发展的重要基础设施,是经济社会可持续发展的重要支撑,要实现长江中下游地区经济社会协调发展离不开水利的支撑和保障。根据长江中下游地区的水资源条件和水利发展现状,分析水利与长江中下游地区协调发展要求不相适应的主要问题,思考水利促进长江中下游地区经济社会协调发展的思路和重点,并提出相应的对策和建议。     

黑河流域地下水循环演化规律研究

大量野外调查研究表明，气候变化和人类活动对黑河流域地下水循环和更新演变具有重要影响；平原区浅层地下水主要是现代水补给，35％来自祁连山区基岩裂隙水通过地表径流转化补给，其他是降水和冰雪融水在山前戈壁带入渗补给，具有较强的更新能力；深层承压水主要形成于地质历史时期区域性补给，与现代水循环有联系；中游区人类活动是造成下游区地下水补给能力减弱、地下水水位持续下降和生态环境退化的重要因素。因此强化中游区人类活动的科学调控，是实现黑河流域地下水可持续利用和下游区生态环境有效保护的关键。     

Formation Mechanisms and Geomorphic Evolution of the Erlian Mudflow Fans,Eastern Guide Basin of the Upper Reaches of Yellow River

Several argillaceous platforms lie along the Yellow River(YR) of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages: early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.     

Basement Characteristics and Crustal Evolution of the Copper-Gold Metallogenic Belt in the Middle and Lower Reaches of the Yangtze River: Some Isotope Constraints

Studies of the Pb, Sr and Nd isotopic composition of Mesozoic intrusive rocks indicate that the basement of the copper-gold metallogenic belt of the middle and lower reaches of the Yangtze River has "two-layer structure" and partly has "multi-layered structure", and is inhomogeneous and shows the distinct feature of E-W provincialism. The calculated model lead ages (t1) are mostly greater than 2600 Ma, and the model neodymium ages (TDM) vary from 953 to 2276 Ma and concentrate in two time intervals: 1800-2000 Ma and 1200-1600 Ma. It is concluded that the basement of the MBYR is composed of the Late Archaeozoic to Middle Proterozoic metamorphic series and that the crust was initiated in the Archaean and continued to grow in the Early and Middle Proterozoic, and the proportion of new crust formed by mantle differentiation during the Late Proterozoic is low.     

江汉盆地沉积物微量元素特征与长江上游水系拓展

江汉盆地是长江出三峡后第一个大型卸载区,近2.77 Ma以来堆积了近300 m的碎屑沉积物,主要由河流相和湖沼相组成,形成了多个沉积旋回。选择江汉盆地中心位置的ZL钻孔,利用ICP-MS方法,展开微量元素组成分析,研究了新近纪以来江汉盆地沉积物物源的变化。结果表明,上新世以来微量元素化学组成的离散程度逐渐减小,且趋近上部陆壳平均值,可能反映了物源供应区范围的扩展过程。1.25 Ma B.P.以来,多种微量元素含量及Th/Sc、Co/Th、La/Sc、Cr/Cu等比值变化很小,显示长江可能形成于1.25 Ma B.P.以后。     

"引江济太"工程对太湖及周边地区的影响分析

引江济太是近年来太湖流域实施的一项重要调水工程。本文应用监测资料,分析了太湖流域实施引江济太工程对太湖及其周边地区水资源量和质的影响,说明了引江济太工程有效增加了太湖流域水资源的供给,改善了太湖水体水质和用边河网地区的水环境,提出了需加强引水期水资源量质监测,并建议研究增加新的调水线路,扩大引江济太效果。     

长江中下游及其邻区中生代构造体制转换

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