准噶尔大型坳陷湖盆坡折带的类型和分布特征   总被引：64，自引：3，他引：64  

王英民  刘豪等 《地球科学》2002,27(6):683-688

在海相盆地和断陷湖盆中都发育坡折带，并对层序和沉积起重要控制作用，这一观点已得到广泛关注并被普遍接受。对准噶尔盆地侏罗系的研究表明，在大型坳陷湖盆中也发育坡折带，其成因带型丰富，可划分为构造坡折、沉积坡折和侵蚀坡折。并且分布广泛，表现为多级坡折的特点，在剖面上具有正向阶梯状组合、逆向阶梯状组合、沟谷组合、山梁组合和沟梁组合等组合样式；在平面上具有梳状组合、帚状组合、斜交组合、喇叭状组合和平行组合等组合样式。于一定构造背景下发育的一组有成因联系并具类似组合样式特征的坡折带可构成一个构造坡折域。在准噶尔盆地侏罗纪湖盆中共划分出6个构造坡折域。坡折带对层序、沉积和非构造圈闭的发育具有十分重要的控制作用，在不同构造坡折域形成不同的水系和沉积体系特征。  相似文献   

Palaeoseismicity studies on end-Pleistocene and Holocene lake deposits around Basle, Switzerland   总被引：3，自引：0，他引：3  

Arnfried Becker  Colin A. Davenport  Domenico Giardini 《Geophysical Journal International》2002,149(3):659-678

  相似文献   

滇池现代沉积物中磷的地球化学及其对环境影响   总被引：47，自引：2，他引：47  

夏学惠  东野脉兴  周建民  田升平  张灼  彭彦华 《沉积学报》2002,20(3):416-420

湖泊沉积物中,磷是产生富营养化的重要元素.湖泊中磷元素含量、地球化学行为以及它的复杂矿物学特征,使人们对磷的研究极为重视.滇池湖中总磷超标10.3倍,底泥沉积物中P2O5平均含量0.52%,最高可达1.92%.滇池地处磷矿区,是磷质来源最丰富的湖泊,统计表明,磷含量每年在不断增长.滇池沉积物中磷主要以吸附态、有机态、铁结合态、钙结合态、铝结合态等几种形式存在.这些形态磷在底泥中是不稳定的,它们在环境改变条件下,又将磷释放到水体中.微生物在磷的循环过程中起了重要作用,乳酸菌对不溶性磷酸盐的分解,使湖泊中可溶磷含量增高.聚磷菌对磷元素的富集以及聚磷菌死亡后发生有机磷的矿化作用,是湖泊中水合磷酸盐矿物沉积的重要途径.当湖泊中这种不稳定的水合磷酸盐矿物在条件具备的情况下,经沉积物覆盖成岩作用后,最终形成磷灰石。  相似文献   

潜江盐湖盆地盐间沉积的石油地质特征   总被引：15，自引：0，他引：15  

方志雄 《沉积学报》2002,20(4):608-613

盐间沉积是潜江凹陷中的一种特殊盐湖盆地沉积物,它并非某种单一的岩性,而是随发育地区的不同而变化的特殊混合岩石。根据其岩石学特征难以命名。本文讨论了这种盐间沉积的岩石组分、沉积特征和油气地质意义。这类盐间沉积在化学成分和碎屑组成方面的韵律性变化具有明显的湖面升降变化含义,因而可将其韵律特性与层序地层单元进行对比分析。更重要的是,这类盐间沉积还是一种独特的集生油岩和储集岩于一体的含油气岩层,各种次生孔隙的发育使它成为一种潜在的有利储集层,近期的油气勘探已在其中获高产油气流。  相似文献   

罗布泊第四纪卤水钾矿储层孔隙成因与储集机制研究   总被引：16，自引：1，他引：16  

刘成林  焦鹏程等 《地质论评》2002,48(4):437-443

罗布泊第四纪盐层中储集丰富的卤水钾盐资源，储集层主要为钙芒硝岩。研究表明，其储卤孔隙可划分为：原生晶间孔隙、准原生晶间孔隙、次生孔隙；次生孔隙又分为溶蚀孔隙、交代孔隙和晶洞孔隙。本文主要通过类比分析，确定钙芒硝岩在浅埋藏期间，在其原生沉积孔隙基础上，发育准原生晶闸孔隙，即蜂窝状孔隙，并在其中储集了大量富钾卤水。研究揭示出钙芒硝岩孔隙的发育的与矿物的菱片－菱板状结构、点－面式接触的“杂乱分布”密切相关。由于钙芒硝岩具有相对较的在硬度，其中大多数孔隙在埋藏过程中得以保存，同时，钙芒硝岩在承压环境中受溶蚀作用还可产生晶沿孔隙，这两种孔隙均储集了大量的卤水钾资源。  相似文献   

青藏高原腹地湖泊沉积纪录的“仙女木期”古气候颤动事件   总被引：7，自引：0，他引：7       下载免费PDF全文

胡东生  张华京  李炳元  温景春 《地质学报》2002,76(2):272-278

通过对青藏高原腹地钻孔岩心剖面的最新研究,用层序地层学与年代地层学和气候地层学相结合的方法,分辨出可可西里地区苟弄措湖泊沉积记录(孔深7.25 m)约30 ka BP以来的古气候变化,并在孔深3.32～1.98 m处识别出“仙女本期”的3个气候颤动事件,即:①老仙女术事件(孔深3.32～2.62 m);②中仙女本事件(孔深2.62～2.43 m);③新仙女本事件(孔深2.43～1.98 m)。这3个气候颤动事件都是以冷干时段开始、以冷湿时段结束的,并有越向后期其冷干的时段越长的变化趋势,而其后的冷湿时段却具有等时的变化趋势。岩心沉积物的有机碳、有机氮和磁化率以及化学元素含量的变化,都与仙女本期气候变化具有十分吻合的变化态势。仙女术期气候在湖泊沉积物中的响应,在青藏高原环境演化中还是首次发现,为研究第四纪末次冰期冰消期以来的气候变化提供了新的信息。  相似文献   

Trapping of aeolian sediments and build‐up of the ice cover of a dry‐based Antarctic lake     

S. Sleewaegen  R. Lorrain  Z. Offer  E. Azmon  S. Fitzsimons  R. Souchez 《地球表面变化过程与地形》2002,27(3):307-315

Among the perennially frozen lakes of the Dry Valleys of South Victoria Land (Antarctica), some are dry‐based, i.e. frozen to the bottom. One of these is studied here by a multiparametric investigation (isotopic composition in δD and δ¹⁸O, ions, gas and ice texture analyses). A sediment layer about 10 cm thick appearing at a depth of 3·5 m is also studied by grain size, X‐ray diffraction and scanning electron microscope analyses. The information retrieved indicates that this ice‐block lake results from a build‐up in two steps and explains how aeolian sediments were included as a layer into the ice. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

滇池湖泊磷负荷及其对水环境的影响   总被引：19，自引：1，他引：19  

田升平  东野脉兴  周建民  夏学惠  张灼 《化工矿产地质》2002,24(1):11-16

磷是滇池湖泊富营养化的限制性营养元素。滇池湖泊磷负荷来源一般可分为外环境发生源输入的磷负荷和内环境发生源输出的磷负荷两大类。累积在滇池湖泊内的磷,主要分布在水体与底部沉积物中,滇池湖泊水体中总磷浓度由北向南含量降低,底部沉积物中P2O5含量分布由北向南呈递增趋势。底部0-3m的沉积物P2O5含量由上至下呈明显递减趋势,表明滇池湖泊磷负荷逐年加重。近几年资料显示滇池湖泊单位面积磷负荷达1.52g/m2·a,超过总磷公认允许负荷量中危险值的11.7倍,滇池已成为富营养型湖泊。控制滇池富营养化,在解决入湖磷外负荷的同时,对湖泊底部沉积物中磷内负荷也应予以高度重视。  相似文献   

Paleolimnological evidence for increased landslide activity due to forest clearing and land-use since 3600 cal BP in the western Swiss Alps     

Florence Dapples  André F. Lotter  Jacqueline F.N. van Leeuwen  Willem O. van der Knaap  Sophia Dimitriadis  Daniel Oswald 《Journal of Paleolimnology》2002,27(2):239-248

Schwarzsee is located in the western Swiss Alps, in a region that has been affected by numerous landslides during the Holocene, as evidenced by geological surveys. Lacustrine sediments were cored to a depth of 13 m. The vegetation history of the lake's catchment was reconstructed and investigated to identify possible impacts on slope stability. The pollen analyses record development of forest cover during the middle and late Holocene, and provide strong evidence for regional anthropogenic influence such as forest clearing and agricultural activity. Vegetation change is characterized by continuous landscape denudation that begins at ca. 4300 cal. yrs BP, with five distinct pulses of increased deforestation, at 3650, 2700, 1500, 900, and 450 cal. yrs BP. Each pulse can be attributed to increased human impact, recorded by the appearance or increase of specific anthropogenic indicator plant taxa. These periods of intensified deforestation also appear to be correlated with increased landslide activity in the lake's catchment and increased turbidite frequency in the sediment record. Therefore, this study gives new evidence for a strong influence of vegetation changes on slope stability during the middle and late Holocene in the western Swiss Alps, and may be used as a case study for anthropogenically induced landslide activity.  相似文献   

Diatoms as indicators of climatic and limnological change in Swedish Lapland: a 100-lake calibration set and its validation for paleoecological reconstructions   总被引：2，自引：0，他引：2  

Christian Bigler  Roland I. Hall 《Journal of Paleolimnology》2002,27(1):97-115

This study investigated the distribution of subfossil diatom assemblages in surficial sediments of 100 lakes along steep ecological and climatic gradients in northernmost Sweden (Abisko region, 67.07° N to 68.48° N latitude, 17.67° E to 23.52° E longitude) to develop and cross-validate transfer functions for paleoenvironmental reconstruction. Of 19 environmental variables determined for each site, 15 were included in the statistical analysis. Lake-water pH (8.0%), sedimentary loss-on-ignition (LOI, 5.9% and estimated mean July air temperature (July T, 4.8%) explained the greatest amounts of variation in the distribution of diatom taxa among the 100 lakes. Temperature and pH optima and tolerances were calculated for abundant taxa. Transfer functions, based on WA-PLS (weighted averaging partial least squares), were developed for pH (r² = 0.77, root-mean-square-error of prediction (RMSEP) = 0.19 pH units, maximum bias = 0.31, as assessed by leave-one-out cross-validation) based on 99 lakes and for July T (r² = 0.75, RMSEP = 0.96 °C, max. bias = 1.37 °C) based on the full 100 lake set. We subsequently assessed the ability of the diatom transfer functions to estimate lake-water pH and July T using a form of independent cross-validation. To do this, the 100-lake set was divided in two subsets. An 85-lake training-set (based on single limnological measurements) was used to develop transfer functions with similar performance as those based on the full 100 lakes, and a 15-lake test-set (with 2 years of monthly limnological measurements throughout the ice-free seasons) was used to test the transfer functions developed from the 85-lake training-set. Results from the intra-set cross-validation exercise demonstrated that lake-specific prediction errors (RMSEP) for the 15-lake test-set corresponded closely with the median measured values (pH) and the estimations based on spatial interpolations of data from weather stations (July T). The prediction errors associated with diatom inferences were usually within the range of seasonal and interannual variability. Overall, our results confirm that diatoms can provide reliable and robust estimates of lake-water pH and July T, that WA-PLS is a robust calibration method and that long-term environmental data are needed for further improvement of paleolimnological transfer functions.  相似文献