Characteristic elemental compositions of the Yangtze River and Yellow River surface sediments and their geological background

Significant differences are noticed in major and trace element compositions between the Yangtze River and the Yellow River surface sediments.The former sediments are rich in some major elements such as K,Fe,Mg,Al,and most of the trace elements which show wide variations in element concentrations,whereas the Yellow River sediments only have higher Ca,Na,Sr,Ba,Th,Ga,Zr,Hf contents and show slight variations in element contents.In the Yangtze River Basin are widely distributed intermediate-acid igneous rocks and complicated source rocks together with strong chemical weathering which determine the elemental compositions of the Yangtze River sediments,while the elemental compositions of the Yellow River sediments are decided by the chemical composition of loess from the Loess Plateau and intense physical weatering.Cu,Zn,Sc,Ti,Fe,V,Ni,Cr,Co,Li and Be can be used to distinguish the Yangtze River sediments from te Yellow River sediments and be treated as tracers for both the sediments to study the processes of their mixing and diffusion in the coastal zones of China.     

长江与黄河沉积物中磁铁矿成分标型意义

长江与黄河沉积物中磁铁矿的元素组成揭示,两者的ＦｅＯ与Ｆｅ２Ｏ３及一些置换元素的含量差异明显。长江磁铁矿中ＦｅＯ与Ｆｅ２Ｏ３含量稍高于黄河磁铁矿,而Ｔｉ、Ｖ、Ｓｉ、Ａｌ、Ｃｒ、Ｍｇ及Ｍｎ等元素含量明显地低于黄河磁铁矿,元素含量变化显著小于黄河磁铁矿。这反映长江磁铁矿中Ｆｅ＾２＋及Ｆｅ＾３＋的类质同象置换较少,主要为均质相单矿物颗粒,而黄河磁铁矿中元素含量变化大,既有均质相的颗粒,也存在一些Ｆｅ＾２     

长江与黄河沉积物REE地球化学及示踪作用

长江与黄河沉积物的稀土元素（ＲＥＥ）组成特征不同。长江沉积物ＲＥＥ含量较高,元素含量变化也大于黄河样品;球粒陨石标准化模式表明长江沉积物的（Ｌａ／Ｌｕ）Ｎ、（Ｌａ／Ｙｂ）Ｎ、（Ｇｄ／Ｙｂ）Ｎ的值也相应地比黄河沉积物中的高１０％左右,分布曲线均呈明显的石倾状,轻重稀土分馏明显,相对富集ＬＲＥＥ。且长江样品比黄河样品更富集ＬＲＥＥ,但Ｅｕ亏损不及黄河样品;两者的北美页岩标准化曲线均呈平坦稍右倾状,具有     

基于硅酸盐中磁性矿物包裹体的长江和黄河沉积物区分

环境磁学指标已被用来区分中国近海沉积物中长江和黄河物质来源,但是该方法会受到潜在的成岩作用影响。硅酸盐中的磁性矿物包裹体不受成岩作用影响,具有可靠区分物源的潜力。本研究将盐酸（10 mol/L）处理后样品的磁性特征视作硅酸盐中磁性矿物包裹体的贡献,以提供区分长江和黄河沉积物的新指标。结果表明,盐酸处理后样品中与磁性矿物含量有关的参数（χ、SIRM、χ_ARM、HIRM）不到处理前样品参数值的10%;硅酸盐中的磁性矿物包裹体以低矫顽力的亚铁磁性矿物为主,相比原样中的亚铁磁性颗粒更细;盐酸处理后长江沉积物相比黄河,具有更高的SIRM、χ_ARM、HIRM值,表明前者包裹体中亚铁磁性矿物和不完整反铁磁性矿物含量更高。分粒级的磁学参数显示,两个河流沉积物磁性矿物包裹体SIRM与HIRM值随着粒级的增大而增大。由于长江支流众多,岩石类型复杂,包裹体磁性参数变化较大,而黄河物质主要来自于黄土高原的黄土,黄土由源区至高原的风力搬运过程中的分选和混合,使得包裹体磁性矿物含量较低,但磁性参数相对均一。本研究表明,利用硅酸盐中磁性矿物包裹体SIRM和S_-100散点图、磁性参数主成分分析和热磁曲线,可有效区分长江和黄河沉积物。

     

长江河流沉积物磁铁矿化学组成及其物源示踪

运用电子探针分析了长江干流和主要支流河漫滩沉积物中磁铁矿的元素组成.磁铁矿中的FeO平均含量稍高于其标准组成,而Fe2O3平均含量则明显低于标准组成;Ti、Al、Cr、V、Mn、Mg、Co和Zn等元素在磁铁矿中含量变化大,不同支流的磁铁矿的元素组成不同,同一取样点不同样品磁铁矿的元素组成变化也较大.金沙江、湘江、汉江及长江干流磁铁矿与钛磁铁矿、钛尖晶石、钒钛磁铁矿和铬铁矿等出溶交生,TiO2、Cr2O3和V2O3等元素含量高且变化大.金沙江磁铁矿富Mg、Al和Cr;大渡河、雅砻江和岷江磁铁矿中微量元素含量大多低于0.5%;涪江、汉江磁铁矿富Ti和V,而湘江磁铁矿富Ti和Al;总体上,长江干流上游磁铁矿富Ti,而下游磁铁矿中Ti、Al、Cr、V、Mg和Mn含量低于0.15%.干流磁铁矿的元素组成变化反映主要支流源岩组成及对干流影响程度的差异.     

新疆库车盆地晚三叠世-早侏罗世沉积碎屑矿物成分及其物源区示踪与构造意义

通过同构造沉积物质记录了解物源区剥蚀作用过程进而探索盆山构造相互关系,是大陆构造动力学研究的一个重要方面。砂岩骨架成分分析和重矿物及部分标型矿物分析方法,已被较多地用来探索新疆天山造山带与其南部库车盆地晚中生代以来的相互关系和构造演变过程,但是关于中生代较早时期库车盆地构造属性及北部造山带隆升剥蚀过程的认识仍存在较大分歧。本文运用电子探针微区成分分析方法,对库车盆地北缘中段晚三叠世和早侏罗世砂岩中具代表性的15个砂岩样品中的38颗碎屑长石和26颗碎屑白云母矿物进行了矿物化学成分分析。结果表明,长石主要来自变质岩物源区,25颗碎屑白云母均属多硅白云母,表明其源区岩石曾经历了高压变质作用。这些多硅白云母中Si原子含量显示它们比目前保留在天山造山带高压变质带蓝片岩和榴辉岩中的多硅白云母形成的压力要低,可能反映了源区高压变质岩的正常剥露顺序。这项研究结果表明,至少在晚三叠世-早侏罗世时期,库车盆地北部天山造山带中的高压变质岩已经剥露于地表并遭受剥蚀成为物源供给区。具体是中天山南缘早古生代高压变质带还是晚古生代南天山高压变质带作为重要物源区,尚需进一步的研究工作。     

黄河源区黄河袭夺长江水系之初探

对黄河源区的河流地貌研究表明,该区共发育三级阶地,其中第一、第二级阶地形成于晚更新世的末期至全新世,而第三级阶地形成于晚更新世晚期。在晚更新世晚期,多石峡被切开,黄河源区晚更新世湖泊消失,现今黄河形成。随着现今黄河的形成和晚更新世湖泊的消失,南岸支流之一的多曲向南溯源侵蚀加强,并穿越巴颜喀拉山,夺取了巴颜喀拉山南侧原属于长江流域的贝敏曲和洛曲,使分水岭向南推进了25km,袭夺的时间为晚更新世末期。     

长江流域矿产资源特征及成矿规律

长江流域分布着我国很多重要的矿产资源基地。在长江流域不搞大开发的前提下，如何合理地开发利用矿产资源以保障国家的能源资源安全，同时又要保护生态环境，达到人类与环境和谐共赢的目的，是当前迫切需要研究的新课题。本文系统梳理了长江流域已发现的128种矿产、14683处矿产地信息，总结了长江流域矿产资源分布特征，系统分析了长江领域矿产资源的时空演化规律。长江流域矿产种类较齐全，能源矿产总体不发育但页岩气有潜力，金属矿产以铁、有色金属为主，矿物类和岩石类非金属矿产都比较发育，水气矿产潜力很大。时间上，成矿历史悠久，按构造演化时段，可分为太古宙、元古宙、晚古生代、早古生代、中生代、新生代6个时段，以中生代和晚古生代为主要成矿期；空间上，可划分八大资源集中区，上游矿产地数量较多，但下游成矿密度更大。只要合理布局，科学谋划，加强法制，严格管控，通过矿产资源的高端开发利用，不但可以为社会经济的高质量发展提供资源保障，也可以为环境保护作出新的贡献。     

Study on the runoff and sediment-producing effects of precipitation in headwater areas of the Yangtze River and Yellow River,China

Natural runoff observation fields with different vegetation coverage were established in the Zuomaoxikongqu River basin in the headwater area of the Yangtze River, and in the Natong River basin and the Kuarewaerma River basin in the headwater area of the Yellow River, China. The experiments were conducted using natural precipitation and artificially simulated precipitation between July and August to study the runoff and sediment-producing effects of precipitation under the conditions of the same slope and different alpine meadow land with coverage in the headwater areas. The results show that, in the three small river basins in the headwater areas of the Yangtze and the Yellow Rivers, the surface runoff yield on the 30° slope surface of the alpine meadow land with a vegetation cover of 30% is markedly larger than that of the fields with a vegetation cover of 95, 92, and 68%. Furthermore, the sediment yield is also obviously larger than the latter three; on an average, the sediment yield caused by a single precipitation event is 2–4 times as large as the latter three. Several typical precipitation forms affecting the runoff yield on the slope surface also influence the process. No matter how the surface conditions are; the rainfall is still the main precipitation form causing soil erosion. In some forms of precipitation, such as the greatest snow melting as water runoff, the sediment yield is minimal. Under the condition of the same precipitation amount, snowfall can obviously increase the runoff yield, roughly 2.1–3.5 times as compared to the combined runoff yield of the Sleet or that of rainfall alone; but meanwhile, the sediment yield and soil erosion rate decrease, roughly decreasing by 45.4–80.3%. High vegetation cover can effectively decrease the runoff-induced erosion. This experimental result is consistent in the three river basins in the headwater areas of the Yangtze and Yellow Rivers.     

Effects of grain size distribution on mineralogical and chemical compositions: a case study from size‐fractional sediments of the Huanghe (Yellow River) and Changjiang (Yangtze River)

The influence of hydrodynamics on the chemical composition of sediments is based on the uneven distribution of element abundances in different size fractions. In this study, 72 size‐fractional sediments from the Huanghe (Yellow River) and Changjiang (Yangtze River) riverbeds were measured with XRD, SEM, ICP‐AES and ICP‐MS. The analysis results show that the mineral and chemical characteristics change with grain size in the Huanghe and Changjiang sediments. According to the principal components analysis, three independent geochemical factors were found. The first factor elements, Zr, Hf, Th, U, Y, La and TiO₂ are influenced by the existence of heavy minerals. The second factor elements, Al₂O₃, alkalis, alkaline earth (excluding Ca and Sr) and most of the transitional metals are dominated by clay minerals. The third factor group includes Ca and Sr, which were controlled by calcium‐bearing mineral contents and chemical weathering intensities. The various grain size distributions greatly affect the mineralogical and chemical compositions of bulk sediments. Compared to other size fractions, the 5–6PHI size fractions of the Huanghe and Changjiang sediments have special mineralogical and chemical compositions, and intermediate volume percentages. Weight or volume percentage of each size fraction may be more suitable than mean grain‐size of the bulk sediment to elucidate the grain size effects. Chemical Index of Alteration (CIA) values increase steeply with decreasing grain size, while Weathering Index of Parker (WIP) values are relatively stable. Because of the big influence of the abundance of clay minerals on CIA values, it is questionable to use CIA as a proxy of weathering intensity. Considering the clay mineral effects, stability in values and heterogeneous material properties, WIP has the potential to indicate the chemical weathering intensity of sediments. Copyright © 2014 John Wiley & Sons, Ltd.     

黄河和长江沉积角闪石亲石元素地球化学特征对比与物源辨识

为辨识黄河和长江入海沉积物中角闪石的物源差异,对采自黄河口段、长江口段以及废黄河口和苏北沿岸,共26个样点、38组粒度粗细不同的碎屑角闪石进行了矿物元素地球化学测试,获得了这些角闪石群体的50种常量和微量元素含量值.结果表明:不同粒级测量的同源角闪石元素含量除少数大离子活泼元素相对偏差较大之外,大部分元素含量差异性较小...     

中国东部入海河流沉积物磁性矿物化学特征及物源意义

大量陆源碎屑物质主要通过以长江、黄河为代表的大江大河和以瓯江、浊水溪为代表的山溪性小河流的携带输移至中国东部海域,海域沉积物的物源识别是当前的研究热点。本文通过原子吸收光谱法测试了磁性矿物中的11种元素（Ti、Fe、Cr、Mg、Al、V、Ca、Co、Zn、Mn和S）,旨在探讨这些河流沉积物（ < 45μm）的磁性矿物群体化学特征,提取其物源指示意义,为边缘海沉积物物源判别提供依据。研究结果表明,这些河流沉积物的磁性矿物主要是以铁氧化物（磁铁矿）为主,铁硫化物含量很低（ < 2%）,只有台湾浊水溪沉积物中含有相对较多的铁硫化物（主要是磁黄铁矿）,为1.84%。除此之外,各河流沉积物磁性矿物中铁氧化物的化学元素组成（Ti、Mg、Ca、Al、Cr、V、Mn、Co和Zn）差异也很明显,其中黄河富含Mg和Ca,长江富含Ti,钱塘江富含Al,瓯江富含Cr,台湾浊水溪相对来说富含Al和Co,而其余元素含量远低于其他河流。从磁性矿物成因图上看,黄河沉积物中磁性矿物落在碱性岩浆岩成因区,但这并不是反映了流域磁性矿物的母岩为碱性岩浆岩,而是由于流域中黄土土壤化过程中产生的细颗粒磁性矿物中含有较高的碱土金属元素（如Mg和Ca）所致;其他河流磁性矿物成因与其流域母岩关系密切,如长江和浙闽河流主要为超基性-基性-中性岩浆岩成因,浊水溪为沉积变质-接触交代成因,都与其所处流域的磁性矿物的母岩类型较为一致。利用Ti+V-S+Co-Ca+Mg三角图可以有效地区分黄河、长江和浙闽河流、浊水溪沉积物物源。磁性矿物群体中的Mn、Zn、Al、Cr元素的差异有助于进一步确定长江和浙闽河流的泥沙来源。同时,发现磁性矿物单颗粒和群体化学组成特征具有一定差异性,很可能是由于分析方法不同所造成。

     

河口三角洲海岸侵蚀及防护措施浅析——以黄河三角洲及长江三角洲为例

进入20世纪50年代以来,我国海岸侵蚀日趋明显,一些海岸带资源或油田设施遭到破坏。针对我国黄河三角洲和长江三角洲海岸线的侵蚀现状,分析了我国海岸线侵蚀的主要因素:河流泥沙减少;海平面的上升或海洋动力因素增强以及人为因素的影响。并对目前我国所采用的海岸防护措施进行了分析。提出了我国海岸防护工程类型较多,应根据海岸侵蚀的特点采用不同的措施或多种形式组合,因势利导,使工程达到最好的防护效果。     

长江-黄河源寒区径流时空变化特征对比

长江源区比黄河源区寒冷而干燥, 年径流量仅为黄河源区的60%, 径流年内分配较黄河源区均匀性差, 丰水年与枯水年比例基本相当, 而黄河源区枯水年占较大优势. 近40 a来长江源区径流量总体上呈明显的递减趋势, 黄河源区径流量则呈现略微增长趋势. 长江源区径流量以8～9 a的周期变化较为显著, 黄河源区径流量则以7～8 a周期比较显著. 对寒区径流变化的主要影响因子分析表明, 长江源区温度因子对径流年际变化影响大于黄河源区, 而降水因子影响相对较小, 长江源区寒区水文环境对径流影响较大是造成长江、黄河源区径流差异形成的主要原因.     

Benthic nutrient fluxes in the intertidal flat within the Changjiang （Yangtze River） Estuary

In an annual cycle from March 2005 to February 2006, benthic nutrient fluxes were measured monthly in the Dongtan intertidal flat within the Changjiang （Yangtze River） Estuary. Except for NH4^＋, there always showed high fluxes from overlying water into sediment for other four nutrients. Sediments in the high and middle marshes, covered with halophyte and consisting of macrofauna, demonstrated more capabilities of assimilating nutrients from overlying water than the low marsh. Sampling seasons and nutrient concentrations in the overlying water could both exert significant effects on these fluxes. Additionally, according to the model provided by previous study, denitrification rates, that utilizing NO3- transported from overlying water （Dw） in Dongtan sediments, were estimated to be from -16 to 193 μmol·h^-1·m^-2 with an average value of 63 μmol·h^-1·m^-2 （n=18）. These estimated values are still underestimates of the in-situ rates owing to the lack of consideration of DN, i.e., denitrification supported by the local NO3^- production via nitrification.     

福建闽江和九龙江现代沉积物重矿物特征及其物源意义*

通过对闽江和九龙江沿岸沉积物中重矿物的分析,发现重矿物组合与源区岩石具有极好的相关性。两条河流流域重矿物组合为不透明铁矿类—绿帘石—锆石—电气石—角闪石,特征矿物为绿帘石,含量高达原生透明重矿物比重的70%,其成因除与高级变质岩有关外,还与中酸性岩浆岩及其与围岩接触蚀变发生的绿帘石化有关。从重矿物组合、重矿物特征指数以及与锆石年龄谱系的比对分析发现,闽江流域重矿物源自闽西北武夷山前寒武纪的变质岩、闽东广泛出露的燕山期岩浆岩和接触变质岩,而九龙江流域重矿物源自闽西南的印支—燕山期花岗岩。闽江上游沉积物重矿物以源自高级变质岩的重矿物为特征,中下游由上游来源的重矿物和下游酸性岩浆岩及接触变质岩形成的重矿物共同构成;九龙江以印支—燕山期花岗岩中的副矿物组合为特征。研究结果显示,对于中小流域面积的河流,由于搬运距离有限,重矿物组合保存的源岩信息量大,可作为研究流域内构造演化和源汇对比的重要手段。     

Migration patterns of Neolithic settlements on the abandoned Yellow and Yangtze River deltas of China

Archaeological records of the Neolithic settlements on the eastern China coast between 35°N and 30°N, an area covering the abandoned Yellow River and the Yangtze River delta plains, reveal that Neolithic people moved from the Yellow River basin onto the northern coast for fishing, hunting and dry-land agriculture ~ 7000 yr ago. Marine transgression interrupted their activities on the low-lying (2-5 m in elevation) coastal wetlands between 6000 and 5000 yr ago, after which they reclaimed their land near the river mouths. Their migration routes on the southern Yangtze delta plain indicate another scenario: early Neolithic communities moved onto the plain for wet-rice cultivation. Despite relative sea-level rise from 7000 to 4000 yr ago, a large number of settlements were established on the lowlands between the eastern Chenier Ridges and the western Taihu Lake depression. The Chenier Ridges, with ~ 1.0 m higher topography than the adjacent coastal area, played a role in sheltering the Neolithic people. Subsequently, settlements waned considerably, possibly due to further marine inundation combined with cold climate. The present study shows that migration patterns of the Neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago.     

黄河和长江碎屑物质扩散研究——来自江苏沙脊物源示踪的约束

研究源-汇系统对于理解岩石风化、河流输砂、泥砂沉积以及陆地和海洋沉积过程具有重要意义。我国江苏省东海岸具有丰富的沉积物供应,在某些沿海地段形成了一系列沙脊,是进行沉积物源-汇过程研究的理想沉积记录之一。但目前对其物源区来自哪里还未达成共识。我们利用已发表的碎屑锆石U-Pb年龄和钾长石Pb同位素数据,结合江苏沙脊及其周缘区域的数据结果,详细厘定江苏沙脊的物源区,并运用蒙特卡罗反演模型定量评估江苏沙脊潜在物源区对其物质贡献率。结果表明江苏沙脊北部的碎屑物质主要受大别山(45%)和鲁中山区(24%)的共同影响;黄河(29%)、古黄河(27%)和长江(25%)的碎屑物质对江苏沙脊中部的物质组成起重要影响。江苏沙脊南部的物源主要来自长江(68%)。江苏沙脊的出现得益于黄河和长江这样的大陆尺度的大河搬运了丰富的碎屑物质到下游,南黄海西海岸的平坦地貌有利于保存这些碎屑物质,末次冰期后东亚陆架海动力过程(潮汐、海浪和沿岸流等)持续对其改造,这体现了河流-海洋在塑造河口-海岸地貌中的交互作用。     

淮河与长江和黄河沉积物的物源识别指标比较研究

淮河是中国东部输沙量仅次于黄河和长江的第三大河流,以往对其沉积物的物源识别指标研究甚少。文章测定了淮河与长江、黄河表层沉积物中 < 2 μm粒级组分中的常微量元素、稀土元素（REE）、Sr-Nd同位素以及粘土矿物组成,深入探讨了淮河和长江、黄河沉积物的地球化学特征以及粘土矿物组成的差异性。结果表明,3条河流沉积物中的Ti、Li、Zn、Cu、Sc、Zr、Y、Nb等元素含量有较大差别;淮河沉积物中的⁸⁷Sr/⁸⁶Sr平均值为0.72908,介于黄河与长江沉积物之间（平均值分别为0.72589和0.73238）,¹⁴³Nd/¹⁴⁴Nd同位素比值与长江和黄河沉积物较为相似。3条河流沉积物中REE的各项参数差异程度较小,经上地壳和球粒陨石元素校正后都具有相似的REE分布形态,仅在元素含量上有较大差别。淮河沉积物中蒙皂石和高岭石含量介于黄河沉积物与长江沉积物之间,伊利石含量高于黄河和长江沉积物,绿泥石含量低于黄河和长江沉积物。淮河沉积物与黄河、长江沉积物在地球化学和粘土矿物含量上的差异,是由于流域内源岩类型以及气候环境的不同所导致。Ti、Li、Zn、Cu、Sc、Zr、Y、Nb等常微量元素、Sr-Nd同位素和粘土矿物组成是区分淮河物质与长江和黄河物质的潜在指标。本研究结果可为今后苏北海岸带地区及毗邻海域的物源判别工作提供有价值的信息。

     

秦岭造山带泥盆系形成构造环境：来自碎屑岩组成和地球化学方面的约束

秦岭造山带中分布于商丹和勉略缝合带之间的泥盆系,发育有众多Au、Ag和Pb-Zn矿床,长期以来备受关注.对于泥盆系物源和形成环境认识始终存在不同认识.砂岩碎屑组成、碎屑重矿物、地球化学成分、砾岩组成以及古水流研究表明,北秦岭是秦岭泥盆系的主要物源区,盆地基底隆起也是泥盆系重要物源区.砂岩碎屑组成、碎屑重矿物和砾岩组成表明,泥盆系物源区曾出露有岛弧火山岩、花岗岩、变质岩及少量沉积岩、超镁铁岩.砂岩地球化学成分和砂岩碎屑模式研究表明,秦岭造山带中泥盆系主要形成于活动大陆边缘,其碎屑沉积物来自多种构造环境中的岩石单元.