晚全新世毛乌素沙地东南缘沉积物粒度特征及其指示的环境变化

地处我国东亚季风边缘区的毛乌素沙地,因其对气候变化响应敏感而成为研究古气候环境变迁的理想场所。利用毛乌素沙地东南缘厚273 cm的沉积地层,通过分析沉积物粒度端元特征和环境指示意义,并结合光释光(OSL)测年结果和磁化率指标,重建了研究区2.6 ka B.P.以来的环境变化过程。结果表明：(1)剖面沉积物的粒度组成以粗粉砂、极细砂和细砂为主,其中细砂最多,平均体积分数为57.29%;粉砂层细砂体积分数明显低于砂层,粗粉砂和极细砂显著增多;沉积物粒度频率分布曲线多呈现典型的风成沉积物特点,峰高且窄,分选性较好。(2)剖面沉积物粒度可分离为3个端元组分,端元EM1是最细的粒度端元组分,指示了短时间的强尘暴活动,端元EM2和EM3是在不同风动力条件下跃移搬运的亚组分,端元EM3指示了当地风沙活动的强弱。(3)研究区晚全新世环境变化过程可分为3个阶段。2.6 ka B.P.之前,冬季风较强,气候冷干;2.6 ka B.P.之后到近百年,冬季风减弱,气候趋于暖湿;近百年以来,风沙活动增强,人类活动影响较大。     

豫南黄土粒度和常量元素地球化学特征及其对物源的指示意义

选取豫南驻马店地区埋藏黄土样品进行了粒度、常量元素化学测试分析,探讨了其成因与物源.结果表明:驻马店黄土的粒级组分以粉砂为主,分选较差,峰态中等.粒径频率曲线以双峰为主,而且主峰突出;常量元素分析显示,驻马店黄土来源广泛并且经过了充分混合,化学风化作用处于中等风化阶段;沉积环境判别显示,驻马店黄土大部分为典型的风成成因,但部分层位可能受到古洪水带来的河流相物质的影响;结合黄土粒度与豫东地区风场模拟分析发现,驻马店与黄土高原黄土物源有所差异,驻马店黄土中的粗颗粒是近源风尘沉积物,主要来源于黄河下游泛滥造成的风沙带,受控于冬季豫东地区近地面盛行的东北风.豫南黄土是中国黄土的重要组成部分,深入了解该套沉积物的成因与物源对于研究该地区古环境具有重要意义.      

湖光岩玛珥湖表层沉积物粒度特征及其物源指示意义

对湖光岩玛珥湖82个表层沉积物样品进行粒度分析,计算平均粒径、分选系数、偏度和峰度等参数。结果表明:湖光岩玛珥湖表层沉积物主要包括泥、粉砂、砂质粉砂和粉砂质砂4种类型。粉砂和泥在湖内分布范围最广,为主要沉积类型;砂质粉砂和粉砂质砂主要分布在近岸区域,分布范围较小。沉积物平均粒径(Φ值)变化范围2.1~7.5,平均值为6.8,粒度具有由岸向湖随水深增加而逐渐变细的趋势,但在部分近岸区域,由于雨水汇集入湖导致粒度参数变化剧烈。靠近湖岸和火山岩壁,沉积物颗粒最细的区域并未出现在湖水最深处。湖光岩玛珥湖的表层沉积物频率曲线表现为4个明显的组分峰值,尽管沉积物质主要来源为四周火山岩风化产物,但是远距离搬运的细颗粒仍然对沉积物的粒度组分产生较大的影响。     

河北丰宁黄土粒度特征及其环境意义

对河北丰宁黄土剖面进行了系统的粒度分析，粒度参数显示:①丰宁剖面粒度以粗粉砂颗粒（粒径３２～６３μｍ）和砂级颗粒（粒径＞６３μｍ）为主，较西北黄土高原典型黄土的粒度偏粗，反映丰宁黄土中粗颗粒组分含量不仅受冬季风风力变化的控制，还受到其北部的浑善达克沙地活动的影响；②丰宁剖面在２３６ｃｍ 深度（年代为６１．５ｋａ）处砂颗粒成分（粒径＞６３μｍ）增加、平均粒径增大，分析认为是在全球气候变得更为寒冷干旱的背景下，由其物源区浑善达克沙地的扩张造成的。      

沉积物粒度分析在厦门市第四纪环境研究和地层划分对比中的应用

采用MS2000型激光粒度分析仪进行测试，利用计算机粒度分析软件对数据进行整理和计算，绘制出样品的频率曲线、概率累积曲线以及粒度众数位值曲线等图件并进行沉积环境分析。厦门地区第四纪环境演化经历了中更新世同安组(含泥中粗砂、含泥细中砂、砂为主)海积一冲积一更新统上部龙海组(含泥粗中砂、含泥细中砂、含泥粗砂、粗砂、细中砂、含细砾中粗砂、中细砂等)冲积一洪冲积一更新世上部东山组(砂、砂砾、含泥中粗砂、粗砂、泥质中细砂、细砂、中粗砂等)冲洪积及部分海积(粉砂、细粉砂、含碳质泥、粘土、淤泥质粘土、粉砂质粘土等)一全新世长乐组(粉砂，淤泥质粘土、粉砂质粘土、碳质粘土、含砂淤泥质粘土，粉砂质亚粘土、粉细砂亚粘土等)海湾沉积。在解释环境变化的同时，说明粒度变化曲线在一定程度上可以作为地层划分的依据之一，并以此对研究区地层进行了详细划分。     

大路沟地区三叠系延长组长6储层特征及影响因素

通过露头、岩心、测井分析测试资料,对大路沟地区长6油层组储层岩石学、孔隙结构和储集物性等特征进行研究.结果表明:该区延长组长6油层组为典型的低孔、低渗储层;储集砂体为成分成熟度低而结构成熟度高的长石砂岩;储层孔隙类型为原生粒间孔、粒内溶蚀孔、铸模孔或残余铸模孔;孔隙结构具有小孔隙、微细喉道的特点;储层性质明显受原始陆源组分、沉积相和成岩作用的相互影响;原始陆源组分的结构和含量对储层物性有直接影响;沉积相是基础,砂体厚度大、粒度较粗的水下分流河道的储集物性明显优于其他微相砂体;成岩作用对储层物性优劣起主导作用,压实作用、胶结作用导致储层致密,物性变差,溶蚀作用使储层得到改善.     

粒度端元记录的靖边地区MIS 3以来的气候变化

黄土作为典型的多物源沉积物，粒度分布常呈现多峰分布。端元分析可以从复杂的沉积物粒度中分离出代表不同沉积物源和沉积动力的端元组分，在黄土研究中得到了广泛应用。利用Paterson参数化端元模型对处于毛乌素沙漠东南缘的靖边三道沟剖面粒度进行端元分离与解释，并讨论其代表的环境意义。靖边三道沟黄土可分为4个端元:EM1（众数粒径8.93 μm）为背景粉尘；EM2（众数粒径25.18 μm）为与季风环流有关的组分；EM3（众数粒径39.91 μm）和EM4（众数粒径56.37 μm）都是与冬季风有关的组分，其中EM3为黄土高原黄土主要组分，EM4与现代沙尘暴的粒级大致相同。通过对各端元组分随年龄变化的曲线进行分析，得到以下结论:该剖面记录了靖边地区自MIS 3以来经历了MIS 3（32.8~29.8 ka BP）、LGM（29.8~22.8 ka BP）、冰消期（22.8~11.3 ka BP）和全新世（8.7~1.7 ka BP）共4个气候时期。端元组分还记录了冰消期H 1事件（16.2~13.8 ka BP）、B/A事件（13.8~12.8 ka BP）、YD事件（12.8~11.3 ka BP）共3次气候快速变化事件和D-O旋回。该剖面还记录了毛乌素沙漠末次冰期经历的3次主要的扩张-收缩旋回以及全新世8.7~8.2，6.0~5.0，3.5~2.5 ka共3次干旱沙进事件。      

山东烟台地区芝罘剖面粒度分维特征及其环境意义

山东半岛北部存在一系列黄土-古土壤沉积序列。在野外调查的基础上,通过对山东烟台地区芝罘岛黄土状沉积物粒度和分维值特征的分析,结合光释光测年,探讨了山东半岛北部晚更新世气候环境演变。结果表明:芝罘剖面末次冰期—末次间冰期(62.85～124.90 ka B.P.)主要由砂黄土、黄土和古土壤叠覆堆积组成;芝罘剖面沉积物具有良好的分形结构,可以清楚区分黄土与古土壤,分维值从大到小分别为古土壤(2.379)、黄土(2.194)、砂黄土-黄土(2.157);分维值与标准偏差成显著的正相关关系,相关系数为0.889 4,与平均粒径有较好的正相关性,与峰态和偏度相关性较低;芝罘剖面沉积物分维值在垂向上呈现出峰谷交替的3个旋回,可以替代粒度参数指示沉积环境,分维值低反映气候干冷,冬季风强盛,黄土堆积速率加快,反之则气候暖湿,古土壤发育。     

金矿物的性状及其次生作用与地质找矿意义

原生矿床中金的主要性状有自然金与金的碲化物.自然金可分为"明金"和"微细粒金"."明金"的次生作用,使金的成色得到提高,粒度更大,往往有利于残坡积型砂金矿床的形成."微细粒金"的次生作用,常形成卡林型氧化金矿或红土型金矿和铁帽型金矿.显然,以"明金"为主的矿床及金的重砂异常区,不存在找红土型金矿的可能,应寻找脉金矿床.而在有低值金的重砂异常叠加的化Au异常区,有望找到中小型红土型金矿床.     

松嫩平原含水层沉积物特征及其对砷赋存态分布的影响

松嫩平原西部地区为中国砷中毒区域,含水层沉积物特征及砷赋存态对地下水砷迁移、转化的影响并不清楚。在对研究区高砷区与低砷区钻孔沉积物进行取样的基础上,运用激光粒度分析、Tessier五步提取法和Keon分步提取法分别确定了不同深度沉积物的粒度分布和不同赋存态砷含量,系统研究了沉积物的水力传导系数、不同赋存态砷的分布及其与高砷地下水形成的关系。结果表明:沉积物5种赋存态砷(包括可交换态、碳酸盐吸附态、铁/锰氧化物吸附态、有机物或硫化物吸附态和基质态)中,铁/锰氧化物吸附态砷含量最高,并且砷含量与铁、锰含量呈明显正相关性;高砷区钻孔沉积物铁/锰氧化物吸附态砷质量分数为(1.18~6.11)×10-6,低砷区为(0.67~2.60)×10-6;高砷区钻孔沉积物以粉砂、黏土为主,水力传导系数介于0.004~0.027m·d-1,低砷区钻孔沉积物以细砂、中砂为主,水力传导系数介于0.005~0.2m·d-1;沉积物中粉砂或黏土含量越多,则沉积物颗粒越小,其水力传导系数越低,各赋存态砷含量越高,因此,高砷区低水力传导系数有利于还原环境的形成。通过地下水的循环,高砷含水层沉积物的淋滤作用和铁/锰氧化物的还原性溶解形成了研究区高砷地下水。     

鲁西地区不同岩性地层热响应试验结果浅析

为研究地埋管换热器在不同岩性地层的换热情况,在鲁西黄河冲洪积平原、山前冲洪积平原和低山丘陵区进行了以粉土、粉质粘土、细砂,粘土、粉质粘土、中粗砂,灰岩和花岗岩为研究对象的热响应试验,初步试验结果表明:每延米换热量(W/m)和平均热导率(W/m·k)花岗岩灰岩粉质粘土、中粗砂粉土、粉细砂。在岩溶地下水富水性强,径流速度快的地段灰岩平均热导率花岗岩。此项研究结果可为不同岩性地层浅层地温能开发利用工程地埋管换热器类型的选择,浅层地温能评价和开发利用提供基础数据。     

The grain-size characteristics of Quaternary deposits at Xingshan near Siping in Jilin province, China

This research paper analyses the grain-size characteristics of the Quaternary deposits at Xingshan near Siping, Jilin province in China by employing graphic measures to study the grain size distribution and its mode of transport and deposition. The Quaternary deposits at Xingshan lie unconformable on Cretaceous rocks made of siltstone, mudstone and sandstone. The average grain size is between 8.06 to 8.55Φ (0.002 6 ～0.003 7 mm). The Quaternary deposits at Xingshan mainly compose of very fine silt to clay. The compositions of the grade are clay 63% and silt 37%. The clay size components are weathered debris transported and deposited by flowing water from the SE highlands or hills to the low lying NW Xingshan plains whereas the silty components accumulated by aoelian process. The Quaternary deposits at Xingshan accumulated in the middle and late Pleistocene interglacial periods from (459.12～39.03) ka to (88.92～7.56) ka. The standard deviation ranged from 0.96 to 1.36Φ, indicating that the sediments are moderately to poorly sorted, Coefficient of skewness ranged from 0.16～0.31 with an average skewness of 0.218, (Positively skewed towards fine). Kurtosis values (0.84～1.05) from the grain size distribution and visual inspection of the frequency curves indicate platykurtic to mesokurtic curves and unimodal to bimodal grain-size distribution. The type of deposit formation is sand dune and the source is at a distal from its provenance.     

Spatial variations in depth-distribution of trace metals in coastal wetland sediments from Quanzhou Bay, Fujian Province, China

Four short cores were obtained from the coastal wetland of the Quanzhou Bay, Fujian Province, China, and sediment samples were analyzed with a Mastersizer 2000 for grain size analysis and an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) for trace metal analysis. The results of grain size analysis show that the wetland sediments are mainly composed of silt and clay, and the distribution of median grain size is affected by human activities obviously. The results of trace metal analysis show that the wetland sediments mainly originate from terrestrial materials in the Luoyangjiang River estuary and from contaminants discharged from adjacent rivers in Shuitou area. The heavy metal contamination in Luoyangjiang estuary decreased from 1984 to 2004 due to industry transformation, but has increased since 2004 because of the discharge of contaminants to the Jinjiang River and much living sewerage to the bay, and a large number of trace metals are trapped within Spartina alterniflora marsh.     

DISTRIBUTION AND ORIGIN OF SEDIMENTS ON THE NORTHERN SUNDA SHELF, SOUTH CHINA SEA

ＩＮＴＲＯＤＵＣＴＩＯＮＯｎｅｏｆｔｈｅｍｏｓｔｅｘｔｅｎｓｉｖｅｓｈｅｌｖｅｓｏｆｔｈｅｗｏｒｌｄｌｙｉｎｇｗｉｔｈｉｎｔｈｅｓｏｕｔｈｅｒｎｐａｒｔｏｆｔｈｅＳｏｕｔｈＣｈｉｎａＳｅａｉｓｔｈｅ1850000ｋｍ2ＳｕｎｄａＳｈｅｌｆｌｏｃａｔｅｄｂｅｔｗｅｅｎｔｈｅｔｈｒｅｅｌａｒｇｅｉｓｌａｎｄｓｏｆＳｕｍａｔｒａ,Ｂｏｒｎｅｏ,ＪａｖａａｎｄｍａｉｎｌａｎｄＡｓｉａ(ＬａＦｏｎｄ,1966).ＴｈｅｎｏｒｔｈｅｒｎｐａｒｔｏｆｔｈｅＳｕｎｄａＳｈｅｌｆｉｓｓｅｐａｒａｔｅｄｆｒｏｍｔｈｅＪａｖａＳｅａｓ…     

Landslides & debris flows formation from gravelly soil surface erosion and particle losses in Jiangjia Ravine

Gravelly soils are made up of gravel, sand, silt and clay. They are widely used in engineering applications such as rock-fill dams with clay cores, which are the main researches at present. The strength and mechanical properties of the gravelly soils are affected by the content of coarse grain, fine particles, and their adhesive states. These Properties can be verified by laboratory unconsolidated undrained triaxial tests with grain size less than 5 mm and by large scale direct-shear tests with original grain content. Fine particles of the loose gravelly slopes are released under rainfalls, alternated the structures and mechanical properties, even affected the slope stability. There are a series of large scale direct-shear tests with different coarse grain contents to study the influence of fine particles releasing and migration, results showed the strength behavior of the gravelly soils were affected by the coarse grain content （5） and the inflection coarse grain contents. In order to study the erosion features of the gravelly soil slopes on rainfall conditions and the slopes stability alteration, we had carried out one sort of artificial rainfall local and model experiments, the runoff sediment contents were monitored during the experiments. Result showed that the shapes of the slopes surface transformed periodically, runoff sediment contents were divided into five phases according to the experiment phenomena, runoff sediment contents maintained downtrend during the rain time and the downtrend was obviouslyinterpreted by one descend belt no matter the rainfall intensity and the slope angels. Particle size analysis released the deposit on the slope surface lost almost all of the clay, most of the silt and sand after the experiments, this meant the fine particles releasing, migration and accumulation process on condition of rainfall resulted in the instability factor of the slopes even induced landslide or debris flow.     

High resolution records of flood deposition in the mud area off the Changjiang River mouth during the past century

This paper presents a paleoflood study to determine the flood frequency of the Changjiang River, based on core cj0702, taken from the Changjiang River subaqueous delta. We identified flood deposits by means of high-resolution grain-size variation, sensitive population, geochemical indexes and magnetic susceptibility. The core covers a time span of 120 years by 210 Pb dating and was sampled at 1–2 cm intervals. Grain size, geochemical elements, and physical parameters were analyzed. The results indicate that the sediment of the core is mainly composed of silt and clay, as well as groups of interbedded silt, clay silt, and clay. Vertically, the grain size pattern was controlled by seasonal variations in water discharge and by the sediment input in winter from the abandoned Huanghe River delta. River flooding caused extreme values in all our measured parameters. We identified more than 20 flood events that occurred since 1887 using the physical parameter analysis method. The environmentally sensitive component of sediment grain size(14.32–96.39 μm) contribution30%, Zr/Rb ratio1.5, and magnetic susceptibility16 were selected as the criteria for flood identification generally. We also found that floods that had taken place in the upstream, midstream, or downstream parts of the river were clearly identified by these indexes while the large-scale floods that covered the whole drainage area did not leave clear indications in the sediment record. This study for identification of flood events is of great significance for understanding hyperpycnal current sedimentation as well as for forecasting of floods.     

A STUDY ON BUFFERING CAPACITY OF THE FOREST SOIL AGAINST ACIDIC PRECIPITATION IN SEVERAL AREAS OF CHINA

Soil samples from several forest areas in China were analyzed by X-ray powder diffractometry after mineral separation and enrichment. The density gradient separation method with sequential extraction by acetone-methylene iodide mixtures was applied for the separation of fine sand fraction of soil samples. The clay fraction (< 2μm) was separated from silt fraction of soil samples prior to examination. Mineral components in some fine sand and clay samples were compared, and their weathering potentiality and buffering capacity against acidic precipitation were discussed.     

孤岛馆陶组注水开发储层性质动态变化特征研究

综合利用取心资料、实验室分析化验数据和矿场动态测井资料，研究了孤岛油田低含水期、中高含水期、特高含水期馆陶组砂岩油层岩性、物性、含油性和电性的变化特征。经过长期的注水开发，造成油层泥质含量、碳酸盐含量、含油饱和度和束缚水饱和度降低，平均孔隙直径增大，岩石粒度中值提高，导致渗透率、孔隙度增大。在物性总体增大的同时，孔渗参数的分异度增加；同时，也会由于水敏和速敏的影响使物性变差。声波时差和自然电位、感应电阻率都发生了明显变化，不同岩性的储层参数变化程度有差异，粉砂岩的变化程度小于细砂岩。     

鲁西南平原区第四纪全新世地层划分

鲁西南平原区第四纪全新世地层自下而上划分为5个组：下部为黑土湖组,中部为同期异相的巨野组、单县组、鱼台组,上部为黄河组。熏土湖组为全新世早-中期湖沼相沉积的灰-灰黑色粘土类粉砂质粘土,含大量淡水螺蚌介壳;巨野组为全新世黄河早期沉积,由褐黄色粉砂夹棕红色粘土组成;单县组为黄河古决口扇、古河道沉积,岩性主要为细砂、粉砂;鱼台组为黄河古决口扇前缘洼地沉积,岩性为-套棕红色粘土,局部夹粉砂土。黄河组为黄河现代河床及河漫滩沉积,由灰黄色粉砂土、粘质砂土夹粘土层及砂土组成。     

Distributions of surface sediments surrounding the Antarctic Peninsula and its environmental significance

We analyzed grain size composition to provide information on the types and distributions as well as depositional varieties of marine surface sediments from the area surrounding the Antarctic Peninsula. The samples retrieved from the study area contain gravel, sand, silt and clay. As suggested by bathymetry and morphology, the study area is characterized by neritic, hemipelagic and pelagic deposits. The glacial-marine sediments can be divided into two types, residual paratill and compound paratill, which are primarily transported by glaciers and as ice-rafted debris. Ocean current effects on deposition are more obvious, and the deposit types are distributed consistently with terrain variations.