安徽庐枞地区正长岩类稳定同位素研究   总被引：1，自引：1，他引：1  

孙冶东  刘孝善 《岩石学报》1991,7(3):95-97

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SEARCH FOR CORRELATIVITY OF LIGHTNING(STROKE)WITH ATMOSPHERIC STRATIFICATION FACTORS          下载免费PDF全文

Zhang Xixuan  Zhang Cuihua 《Acta Meteorologica Sinica》1991,5(2):252-252

In this paper the statistical analysis is carried out on the correlation between lightning strokes andatmospheric stratification factors.It is shown that the total number of strokes in lightning process is mainlydecided by environmental temperature at altitude with the residual instability of 5℃(T_r).The instabilityshould also affect the total number of strokc in lightning process.A forecasting equation of stroke in light-ning process has been deduced and two interesting preliminary conclusions have been obtained.  相似文献   

同位素指示的巴丹吉林沙漠南缘地下水补给来源   总被引：14，自引：0，他引：14  

马金珠  黄天明  丁贞玉  W. M. Edmunds 《地球科学进展》2007,22(9):922-930

通过恢复巴丹吉林沙漠及其周边地区大气降水氚值，并结合区域稳定同位素组合特征，揭示了区域地下水氚年龄的多解性与地下水稳定同位素的温度效应。恢复的1963年核试验期氚高峰值达到2 100 TU，进入90年代平均为60 TU。1960年以来降水补给的地下水氚值都应大于15 TU，而1963年的高峰氚衰变至今应在200 TU左右。地下水实测氚值较低，表明由现代少量降水补给的地下水与大量的古水进行了混合。影响降水中δ18O和δ2H分布的主要影响因子是月平均空气温度，对δ18O与δ2H的影响权重分别占到59.9%和57.0%。巴丹吉林沙漠及其周边地区地下水较低的稳定同位素组成表明，其补给主要是晚更新世较冷环境下形成的，来源于东南部的雅布赖山区，部分浅层地下水接受现代降水与河流的补给。   相似文献   

Tracing infiltration and recharge using stable isotope in Taihang Mt., North China   总被引：3，自引：0，他引：3  

Fadong Li  Xianfang Song  Changyuan Tang  Changming Liu  Jingjie Yu  Wanjun Zhang 《Environmental Geology》2007,53(3):687-696

The groundwater in headwater region is an important recharge source for the adjacent mountain-front plain. In order to reveal the relationship among precipitation, soil water and groundwater, from June to September in 2004, stable isotopes (deuterium and oxygen-18) in precipitation and soil waters at the depths of 10, 20, 30, 50, 70, 90, and 110 cm were analyzed at two sites covered by black locust (Robinia Pseudoacia L.) (Site A) and grass predominated by Themeda triandra (T. japonica (Willd.) Tanaka) and Bothriochloa ischaemum (B. ischaemum (L.) Keng) (Site B) in an experimental catchment at Taihang Mt., North China, respectively. The δ¹⁸O of precipitation in daily rain events shows large variations (−13.3 to −4.3‰) with a mean of 8.1‰. The δ¹⁸O and δ D of soil waters along profiles in two sites suggest that the influence of canopy cover was just up to 10 cm in top soil water. The soil water moved over the zero flux plane at 70 cm in-depth is expected to escape the evaporative effect at the end of September in both sites. The results show that the stable isotope, instead of tritium as tradition, can be used to trace the soil water behaviors based on the movement of isotopic peak along the vertical profiles in this semi-arid and semi-humid mountainous region. The infiltration depths of soil water in Taihang Mt. are 12 and 10 mm/day from June to September in 2004 in Site A and Site B, respectively. Tracing by stable isotope, recharge fluxes of soil water to local groundwater are of 3.8 and 3.2 mm/day in Site A and Site B, respectively. The results provide desirable information for assessment of local groundwater resources. An erratum to this article can be found at  相似文献   

Hydrogeology of the Winnipeg Formation in Manitoba, Canada     

Grant A. G. Ferguson  Robert N. Betcher  Stephen E. Grasby 《Hydrogeology Journal》2007,15(3):573-587

The Winnipeg Formation is the basal sedimentary unit throughout much of southern and central Manitoba, Canada, where it forms a regional aquifer over most of its extent. This aquifer is an important source of water in southeastern Manitoba and in Manitoba’s Interlake area, but in most other areas, groundwater within the aquifer is saline. Chemical and isotopic evidence indicate the presence of groundwaters of three different origins: (1) basin brines; (2) modern meteoric recharge; and (3) subglacial recharge that occurred during the late Pleistocene. Hydraulic head and sedimentary facies distributions indicate that the flow system in parts of the area is not in a state of equilibrium and saline waters will encroach on areas currently occupied by freshwater in some areas, while in other areas, freshwater will replace saline water. These features must be considered in groundwater resource management, as groundwater withdrawals will likely hasten these processes.

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Resumen La Formación Winnipeg es la unidad sedimentaria basal en la mayor parte de Manitoba central, Canadá, donde forma un acuífero regional en la mayor parte de su extensión. Este acuífero es una fuente importante de agua en el Sureste de Manitoba y el área de entrelagos de Manitoba, pero en la mayoría de las otras zonas del acuífero, el agua es salina. Las evidencias químicas e isotópicas indican que existen aguas subterráneas de tres orígenes diferentes: (1) salmueras de cuenca; (2) recarga meteórica actual; y (3) recarga subglacial ocurrida durante el Pleistoceno Superior. Los niveles piezométricos y la distribución de las facies sedimentarias indican que el sistema de flujo no se encuentra en estado de equilibrio en parte del área y las aguas salinas irán invadiendo áreas actualmente ocupadas con aguas dulces, mientras que en otras zonas el agua dulce está reemplazando al agua salina. Estos hechos deben ser considerados en la gestión de las aguas subterráneas como recurso, ya que las extracciones de agua acelerarán probablemente estos procesos.

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Résumé La Formation de Winnipeg est l’unité sédimentaire de base sur la plus grande partie du Sud et du centre du Manitoba au Canada, où elle forme un aquifère régional sur pratiquement toute son extension. Cet aquifère représente une ressource en eau importante dans le Sud-Est du Manitoba et dans les zones d’entre les lacs, mais salée dans la plus part des autres zones. Les indications isotopiques et chimiques permettent de distinguer trois différentes origines des eaux souterraines: (1) les saumures de bassin; (2) la recharge météoritique moderne; (3) la recharge sub-glaciaire qui est apparue durant le Pléistocène récent. Les charges hydrauliques et la distribution des faciès sédimentaires indiquent que le système d’écoulement dans certaines zones n’est pas dans un état d’équilibre et que les eaux salées empièteront sur des zones d’eau douce, tandis que dans d’autres zones l’eau douce remplacera les eaux salées. Ces aspects doivent être considérés dans la gestion des ressources en eau souterraine, car le prélèvement des eaux souterraines pourrait accentuer ces processus.

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Evaluation of ostracod-based palaeoenvironmental reconstruction with instrumental data from the arid Faiyum Depression,Egypt     

K. W. Keatings  I. Hawkes  J. A. Holmes  R. J. Flower  M. J. Leng  R. H. Abu-Zied  A. R. Lord 《Journal of Paleolimnology》2007,38(2):261-283

The utility of ostracod-based palaeoenvironmental reconstruction was evaluated using instrumental data for Lake Qarun, Egypt. The euryhaline ostracod Cyprideis torosa was the only species found in the lake’s recent sediment record. This species is known to tolerate salinity levels and water solute compositions that may prevent colonisation by other species. Oxygen and carbon isotope ratios of ostracod carbonate from lake sediments covary with changes in instrumental values for lake level and salinity for the period 1890–1974. δ¹³C-values correlate negatively with lake water salinity (r ² = 0.87) and δ¹⁸O-values correlate negatively with measured lake level changes (r ² = 0.41). Other ostracod proxy data provide qualitative information on lake level trends. Fossil assemblage data (juvenile/adult and valve/carapace ratios and valve preservation) provide information on wave energy. Ecophenotypic variation of C. torosa valves provided some useful palaeolimnological information. Sr/Ca and Mg/Ca ratios in ostracods were not found to reflect water composition, due to the uncoupling of these ratios with salinity in Lake Qarun. Overall, our results highlight the need to calibrate ostracod proxy data in modern systems prior to their use for palaeoenvironmental reconstruction.  相似文献   

Parameterisation of the vertical transport in a small thermally stratified lake     

Christoph von Rohden  Karl Wunderle  Johann Ilmberger 《Aquatic Sciences - Research Across Boundaries》2007,69(1):129-137

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华北地块东段和龙超镁铁质科马提岩的发现及特征          下载免费PDF全文

刘劲鸿 《地质论评》2001,47(4):420-424

和龙岩体赋存于新太古代夹皮沟—金城洞花岗绿岩带中,与围岩发生同变形变质。岩体具有典型的科马提岩冷凝结构分层和鬣刺结构、冷凝多面体节理。上述特征是作者1990年发现确认的。该科马提岩的矿物学特征:玻璃质脱玻形成铁皂石等矿物;斜方辉石和橄榄石鬣刺呈中空骸晶状,大部被滑石、铁白云石、绿泥石、磁铁矿等取代,但仍保留完好的长柱状假像;堆积带中橄榄石呈微细粒、新鲜,仅发生网状蛇纹石化。岩石化学特征富MgO,CaO/Al_2O_3=1.04,用科马提岩分类图判别为超镁铁质科马提岩。  相似文献   

高温高压下蒙脱石显微变形与力学性质的研究          下载免费PDF全文

冯锦江  李建国 《地震地质》1992,14(4):376-380

通过研究高温高压条件下蒙脱石的变形特征和机制,着重阐述了蒙脱石的显微变形特征与温度压力之间的关系,以及对应力-应变的影响。研究表明,在围压为200M Pa条件下,温度升高将导致蒙脱石的变形增大。对相同应变量所需的差异应力则随温度上升而下降。但是,当温度>500℃时,相同应变量所需差异应力较300℃时显著增大,其屈服强度和变形模量在T≥500℃,σ≥300MPa时均因脱水明显增大。蒙脱石在高温高压下均为渐进失稳  相似文献   

大陆岩石圈流变学研究   总被引：2，自引：1，他引：2  

索书田 《地质科技情报》1992,11(2):6-10

简单介绍了流变学的概念和两种基本研究方法,基于大陆岩石圈较大洋岩石圈有更为复杂的流变特征客观事实,指出研究大陆岩石圈流变学的重要性,并提出几个主要的研究方向和领域。  相似文献