黄骅裂谷盆地第三系水循环和渗流场形成演化的重溯

在简述盆地地质环境和含水系统、水文地质期与水压系统类型定位的基础上，通过建立数学模型，采用反演、比拟和地静压力等方法，模拟计算了各研究层在各研究时期泥岩压出水水头值（m),Es^2层的依次为2－28，2－26，2－6，2－16，0．5－3．5；Es^1层的依次为2－42，2－26，2－6，10－54，1－14；Ed层的依次为2－22，2－54，2－12；Ng层的依次为10－24，1－5；Nm层的为12－24。各研究层在各研究时期的压挤式水交替强度均小于1，累加值Es^2,Es^1,Ed层的均大于1，Ng，Nm层的小于1；Ed层渗入水交替强度为0.44。各研究层在各研究时期渗流场的高水压带位置和流动态具有相似性，并均以离心型流动型为主要特征。     

Denudation and cooling of the Lake Teletskoye Region in the Altai Mountains (South Siberia) as revealed by apatite fission-track thermochronology

Lake Teletskoye occupies a narrow graben located in the northwestern sector of the Altai fold belt in South Siberia. The lake basin is thought to have formed during the Pleistocene as a distant result of the Cenozoic collision of India and Eurasia that caused a tectonic reactivation of the Palaeozoic Gorny–Altai (GA) and West Sayan (WS) blocks.The present work reports of a pilot fission-track study performed on 13 apatite separates collected from rocks that were sampled along two profiles in close proximity of the lake. The age–length data and AFT thermochronological modelling reveal two important phases of cooling in the Altai Mountains, a first one during the Late Jurassic–Early Cretaceous and a second one that started in the Miocene–Pliocene and that persists until today. The first event is interpreted to result from uplift-induced denudation probably related to the closure of the Mongol–Okhotsk Ocean; the second event can be linked to the young Cenozoic movements that lie at the origin of the formation of the Lake Teletskoye basin.     

Evidence for compressionally induced high subsidence rates in the Kurile Basin (Okhotsk Sea)

A combined volcanological, geochemical, paleo-oceanological, geochronological and geophysical study was undertaken on the Kurile Basin, in order to constrain the origin and evolution of this basin. Very high rates of subsidence were determined for the northeastern floor and margin of the Kurile Basin. Dredged volcanic samples from the Geophysicist Seamount, which were formed under subaerial or shallow water conditions but are presently located at depths in excess of 2300 m, were dated at 0.84±0.06 and 1.07±0.04 Ma with the laser ⁴⁰Ar/³⁹Ar single crystal method, yielding a minimum average subsidence rate of 1.6 mm/year for the northeast basin floor in the Quaternary. Trace element and Sr–Nd–Pb isotope data from the volcanic rocks show evidence for contamination within lower continental crust and/or the subcontinental lithospheric mantle, indicating that the basement presently at 6-km depth is likely to represent thinned continental crust. Average subsidence rates of 0.5–2.0 mm/year were estimated for the northeastern slope of the Kurile Basin during the Pliocene and Quaternary through the determination of the age and paleo-environment (depth) of formation of sediments from a canyon wall. Taken together, the data from the northeastern part of the Kurile Basin indicate that subsidence began in or prior to the Early Pliocene and that subsidence rates have increased in the Quaternary. Similar rates of subsidence have been obtained from published studies on the Sakhalin Shelf and Slope and from volcanoes in the rear of the Kurile Arc. The recent stress field of the Kurile Basin is inferred from the analysis of seismic activity, focal mechanism solutions and from the structure of the sedimentary cover and of the Alaid back-arc volcano. Integration of these results suggests that compression is responsible for the rapid subsidence of the Kurile Basin and that subsidence may be an important step in the transition from basin formation to its destruction. The compression of the Kurile Basin results from squeezing of the Okhotsk Plate between four major plates: the Pacific, North American, Eurasian and Amur. We predict that continued compression could lead to subduction of the Kurile Basin floor beneath Hokkaido and the Kurile Arc in the future and thus to basin closure.     

Dissolved silica budget in the North basin of Lake Lugano

We studied the dissolved silica cycle in the water column of the North basin of Lake Lugano, Switzerland/Italy. Lake Lugano is a meromictic, eutrophic lake, permanently stratified below 100-m depth. A one-box model was used to calculate a silica mass-balance over 1993, based on various lake measurements, such as sediment traps, sediment cores, water analysis and biota countings. We found that the North basin of Lake Lugano is at steady state as far as dissolved silica is concerned. The primary source of dissolved silica in the lake is river input (about 80%), with diffusion from bottom sediments and groundwater input also playing a role. Atmospheric input is negligible. The main export of dissolved silica occurs via biogenic uptake by diatoms and final burial of their frustules in the bottom sediment. Loss of dissolved silica through the lake outflow only represents 15% of the total output. Of the total amount of Si exported to the lake bottom through diatom sinking, less than 20% is re-supplied to the surface water by diffusion. Thus, the lake acts as an important permanent sink for silica. The long residence time of dissolved silica in the lake (7 years) is related to the strong physical stratification of the lake. Only about 10% of the standing stock are available to phytoplankton uptake.     

湖北牛山湖高体鳑鮍的年龄、生长与繁殖

图 3　卵粒大小的频数分布 (ａ)具成熟卵细胞 (ｂ)无成熟卵细胞Ｆｉｇ 3ＦｒｅｑｕｅｎｃｙｄｉｓｔｒｉｂｕｔｉｏｎｏｆｅｇｇｓｉｚｅｏｆＲｈｏｄｅｕｓｏｃｅｌｌａｔｕｓ(ａ)ｗｉｔｈｓｏｍｅｍａｔｕｒｅｅｇｇｓ ,(ｂ)ｗｉｔｈｏｕｔｍａｔｕｒｅｄｅｇｇｓ图 4繁殖力 (Ｆ ,ｅｇｇｓ)与体重 (Ｗ ,ｇ)及全长 (ＴＬ ,ｍｍ )的关系Ｆｉｇ 4Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｆｅｃｕｎｄｉｔｙ (Ｆ ,ｅｇｇｓ)ａｎｄｂｏｄｙｗｅｉｇｈｔ (Ｗ ,ｇ)ｏｒｔｏｔａｌｌｅｎｇｔｈ (ＴＬ ,ｍｍ)湖北牛山湖高体鳑鮍的年龄、生长与繁殖@…     

坝上高原安固里淖粒度年纹层与环境变化

在安固里淖湖心区获取一未扰动沉积物样柱，分析发现了由冬季风搬运物与湖心沉积共同形成的粒度年纹层，建立了纹层年表，恢复了安固里淖湖区8507aB.P，以来的环境变化过程。8507-5429aB.P。冬季风活动较弱，后期的所波动；5429-3244aB.P.冬季风活动较强，3244-2494aB.P。冬季风活动减弱；2494-1165aB.P。冬季风活动略有增强；1165aB.P以来，冬季风活动减弱。安固里小淖粒度年纹层反映的冬季风变化情况与我国北方地区同期的环境变化和海平面变化有很好的对应关系。     

GIS支持下青海湖地区草地蝗虫发生的地形分析

草地蝗虫发生的地形分析是建立草地蝗虫发生预报模型的基础，以青海湖地区为实验区，在Arc/Info和ArcView地理信息系统的支持下，进行草地蝗虫发生与各地形变量（包括海拔高度、坡度与坡向）的叠置分析，提取草地蝗虫发生的地形信息数据库，然后，分别采用T－检验（对连续变量－海拔高度和坡度）和卡方（Chisquare)检验（对类变量－坡向类型）进行各地形变量对草地蝗虫发生的差异显著性检验，结果表明，海拔高度和坡度对草地蝗虫发生的影响极为显著（显著性水平p=0.000)，而坡向地草地蝗虫发生的影响不是特别明显（显著性水平p=0.039)。     

疏勒河流域昌马灌区泉水量预测分析

疏勒河流域农业灌溉主要采用地表水灌溉 ,泉水为该区农业灌溉的主要水源之一 ,该文利用 2 0世纪 90年代的测流资料 ,采用有限差分方法对疏勒河中游泉水量的变化趋势进行预测分析 ,结果显示 ,随着时间的延长 ,泉流量呈逐渐减小的趋势 ,但下降梯度逐渐变小 ,最终趋于稳定     

A 1500-year record of climatic and environmental change in ElkLake, Minnesota I: Varve thickness and gray-scale density

The deepest part (29.5 m) of Elk Lake, ClearwaterCounty, northwestern Minnesota, contains a complete Holocene section that iscontinuously varved. The varve components are predominantly autochthonous(CaCO₃, organic matter, biogenic silica, and several iron andmanganese minerals), but the varves do contain a minor detrital-clastic(aluminosilicate) component that is predominantly wind-borne (eolian) andprovides an important record of atmospheric conditions. Singular spectrumanalysis (SSA) and wavelet analysis of varve thickness recognized significantperiodicities in the multicentennial and multidecadal bands that varied inpower (i.e., variable significance) and position (i.e., variable period) withinthe periodic bands. Persistent periodicities of about 10, 22, 40, and 90 years,and, in particular, multicentennial periodicities in varve thickness and otherproxy variables are similar to those in spectra of radiocarbon production, aproxy for past solar activity. This suggests that there may be a solar control,perhaps through geomagnetic effects on atmospheric circulation. Multicentennialand multidecadal periodicities also occur in wavelet spectra of relativegray-scale density. However, gray-scale density does not appear to correlatewith any of the measured proxy variables, and at this point we do not know whatcontrolled gray scale.     

Wetland vegetation biomass estimation and mapping from Landsat ETM data:a case study of Poyang Lake

Poyang Lake is the largest freshwater lake in China. This paper conducted a digital and rapid investigation of the lake’s wetland vegetation biomass using Landsat ETM data acquired on April 16, 2000. First, utilizing the false color composite derived from the ETM data as one of the main references, the authors designed a reasonable sampling route for field measurement of the biomass, and carried it out on April 18-28, 2000. Then after both the sampling data and the ETM data were geometrically corrected to an equal-area projection of Albers, linear relationships among the sampling data and some transformed data derived from the ETM data and the ETM 4 were calculated. The results show that the sampling data is best relative to the band 4 data with a high correlation coefficient of 0.86, followed by the DVI and NDVI data with 0.83 and 0.80 respectively. Therefore, a linear regression model, which was based on the field data and band 4 data, was used to estimate the total biomass of entire Poyang Lake, and then the map of the biomass distribution was compiled.