Geochronology, Geochemistry, Fluid Inclusion and C, O Isotope Compositions of Calcite Veins in the Paleogene of the Jiangling Basin, South China: Implications for Fluid Evolution and Brine Potash Mineralization          下载免费PDF全文

YU Xiaocan  WANG Chunlian  LIU Chenglin  WANG Jiuyi  SHEN Lijian 《《地质学报》英文版》2023,97(2):513-525

Deep-seated potassium-rich brines were identified in the Jiangling Basin, South China. Although magmatic-hydrothermal sources have been proposed, the relationship between brine-type potash mineralization and volcanism remains unclear. In this study, U-Pb geochronology, geochemistry, fluid inclusion and C-O isotopic compositions of hydrothermal vein minerals in the Jiangling Basin are examined. Laser ablation U-Pb dating of calcite veins indicates that the ages are slightly younger than the formation age of the Balingshan basalt. Fluid inclusions in hydrothermal minerals show medium–low homogenization temperatures (160–220°C) and low salinities (0.14 to 4.9 wt% NaCl eqv.) and densities (0.882–0.944 g/cm3). The liquid compositions of fluid inclusions in calcite veins from sedimentary strata have higher contents of potassium, compared with those from basalt. The coupled negative δ13CPDB (?10.3‰ to ?8.0‰) and positive δ18OSMOW (17.4‰ to 20.7‰) values imply that calcite precipitation resulted from CO2 degassing of the basaltic magmatic fluids, as indicated by the gas composition of these inclusions in hydrothermal minerals. Rare earth element patterns indicate that water-rock interaction between hydrothermal fluids and sedimentary wall rocks contributed to the calcite precipitation in sedimentary strata. It is proposed that high-temperature water-rock interaction between magmatic fluids and sedimentary strata resulted in the potassium enrichment in fluids, interpreted as one of the sources of potassium-rich brines in the Jiangling Basin.  相似文献   

Uncertainty analysis of soil-pile interactions of monopile offshore wind turbine support structures     

《Applied Ocean Research》2019

The objective of this work is to study the uncertainties involved in the modelling of the soil-pile interaction concerning their influence on the prediction of the dynamic structural response of monopile offshore wind turbine support structures. Two main issues are identified and addressed: the adequacy of the method used to deal with the soil-pile interactions and the adequacy of the soil properties reflecting the behaviour of the soil. The present study develops an approach that defines the penetrated pile length depending on the soil profile. Also, a parameter is defined to avoid the excessive usage of steel for the penetrated pile structure. The uncertainties are included in the probabilistic free vibration analysis and the contribution of each random variable to the scatter of the response is estimated by performing a sensitivity analysis. The results indicate that the uncertainty involved in the modelling of the soil profile has a significant effect on the coefficient of variance of the natural frequency, which is a serious issue to be considered in the fatigue life assessment of offshore wind turbine support structures.  相似文献   

A geomorphology‐based integrated stream–aquifer interaction model for semi‐gauged catchments     

Soumyaranjan Sahoo  Bhabagrahi Sahoo 《水文研究》2019,33(9):1362-1377

Many of the existing stream–aquifer interaction models available in the literature are very complex with limited applicability in semi‐gauged and ungauged catchments. In this study, to estimate the influent and effluent subsurface water fluxes under limited geo‐hydrometeorological data availability conditions, a simple stream–aquifer interaction model, namely, the variable parameter McCarthy–Muskingum (VPMM) hillslope‐storage Boussinesq (hsB) model, has been developed. This novel model couples the VPMM streamflow transport with the hsB groundwater flow transport modules in online mode. In this integrated model, the surface water–groundwater flux exchange process is modelled by the Darcian approach with the variable hydraulic heads between the river stage and groundwater table accounting for the rainfall forcing. Considering the exchange fluxes in the hyporheic zone and lateral overland flow contribution, this approach is field tested in a typical 48‐km stretch of the Brahmani River in eastern India to simulate the streamflow and its depth with the minimum Nash–Sutcliffe efficiency of 94% and 88%; the maximum root mean square error of 134 m³/s and 0.35 m; and the minimum index of agreement of 98% and 97%, respectively. This modelling approach could be very well utilized in data‐scarce world‐river basins to estimate the stream–aquifer exchange flux due to rainfall forcings.  相似文献   

A Raman investigation on the boron form occurring in salt lake brine during evaporation          下载免费PDF全文

彭姣玉  陈婧  王兴鹏  董亚萍  李武 《盐湖研究》2019,27(1)

Boron resources are abundant in Da Qaidam salt lake of Qaidamu Basin. It has been given great attention for the polyborate species present in brine. In this study, the Raman spectroscopy was applied to investigate the existing-form of boron in brine during evaporation. The prepared solutions of MgO·2B2O3-H2O, MgO·2B2O3-MgCl2 -H2O, and MgO·2B2O3-MgSO4-H2O was also evaporated and recorded to study the influence of boron concentration, pH, and electrolytes on the borate speciation in brine. The mononborates of B(OH)3 and B(OH)4- were found to be the only forms present in the original salt lake brine. Brine evaporation promotes the formation of polyborate anions B3O3(OH)4-, B5O6(OH)4-, and B6O7(OH)62- and also disappearance of the B(OH)4- ion in brine with boron concentration of more than 11 g/L in B2O3. The pentaborate ion of B5O6(OH)4- was sensitive to the solution pH and found to be appeared under the pH value of 8.0. While the hexaborate ion of B6O7(OH)62- was observed more dependent on the electrolyte of magnesium chloride due to its special properties, such as promoting boron accumulation, lowering solution pH, and also the strong af?nity for water molecules, which is beneficial to the polymerization of borate ions in brine. The interaction mechanisms among polyborate anions during evaporation had also been proposed.  相似文献   

Water level observations from unmanned aerial vehicles for improving estimates of surface water–groundwater interaction          下载免费PDF全文

Filippo Bandini  Michael Butts  Torsten Vammen Jacobsen  Peter Bauer‐Gottwein 《水文研究》2017,31(24):4371-4383

Integrated hydrological models are usually calibrated against observations of river discharge and piezometric head in groundwater aquifers. Calibration of such models against spatially distributed observations of river water level can potentially improve their reliability and predictive skill. However, traditional river gauging stations are normally spaced too far apart to capture spatial patterns in the water surface, whereas spaceborne observations have limited spatial and temporal resolution. Unmanned aerial vehicles can retrieve river water level measurements, providing (a) high spatial resolution; (b) spatially continuous profiles along or across the water body, and (c) flexible timing of sampling. A semisynthetic study was conducted to analyse the value of the new unmanned aerial vehicle‐borne datatype for improving hydrological models, in particular estimates of groundwater–surface water (GW–SW) interaction. Mølleåen River (Denmark) and its catchment were simulated using an integrated hydrological model (MIKE 11–MIKE SHE). Calibration against distributed surface water levels using the Differential Evolution Adaptive Metropolis algorithm demonstrated a significant improvement in estimating spatial patterns and time series of GW–SW interaction. After water level calibration, the sharpness of the estimates of GW–SW time series improves by ~50% and root mean square error decreases by ~75% compared with those of a model calibrated against discharge only.  相似文献   

Performance of seismically loaded shearwalls on nonlinear shallow foundations     

Prishati Raychowdhury  Tara C. Hutchinson 《国际地质力学数值与分析法杂志》2011,35(7):846-858

If utilized, the energy dissipative capability of seismically loaded shallow foundations due to inelastic behavior can result in more economic design, provided the consequences, such as excessive deformations are accounted for. In this article, a Beam‐on‐Nonlinear‐Winkler‐Foundation (BNWF) model is used to assess the performance of shearwall‐foundation systems with different attributes, when subjected to ground motions of varied hazard levels. The numerical study indicates that the force and drift demands to the shearwall reduce significantly, when nonlinear foundation behavior is realized, while permanent settlement is well below the permissible limit. These results support the concept of shallow foundation capacity mobilization in future design. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

浅析动画效果地图的公开表示     

周昕薇  狄琳  白敬辉  刘杰  刘晓辉 《测绘通报》2020,(2):118-120

公开地图的表示关乎国家安全、领土完整、民族尊严，具有严肃的政治性、严密的科学性和严格的法定性。动画效果地图是大众喜闻乐见而又十分有效的信息传播载体。但在公开表示方面存在盲区，是"问题地图"的高发区，可能造成严重的不良影响。本文总结了动画效果地图的常见类型、高发问题及成因，提出了动画效果地图表示方法建议，明确了地图底图和动画效果都要符合公开地图表示有关要求，对动画效果地图的制作和公开使用具有一定的指导性和启发性。  相似文献   

Investigation of inner-basin variation: Impact of large reservoirs on water regimes of downstream water bodies     

Xue Dai  Zhongbo Yu  Guishan Yang  Chong-Yu Xu  Rongrong Wan 《水文研究》2021,35(5):e14241

Large dams and reservoirs alter not only the natural flow regimes of streams and rivers but also their flooding cycles and flood magnitudes. Although the effect of dams and reservoirs has been reported for some vulnerable locations, the understanding of the inner-basin variation with respect to the effects remains limited. In this study, we analyse the Three Gorges Dam (TGD) built on the Changjiang mainstream (Yangtze River) to investigate the dam effect variations in the system of interconnected water bodies located downstream. We investigated the effect of flow alterations along the downstream river network using discharge time series at different gauging stations. The river–lake interactions (referring to the interactions between the Changjiang mainstream and its tributary lakes i.e. the Dongting and Poyang lakes) and their roles in modifying the TGD effect intensity were also investigated in the large-scale river–lake system. The results show that the water storage of the tributary lakes decreased after the activation of the TGD. Severe droughts occurred in the lakes, weakening their ability to recharge the Changjiang mainstream. As a consequence, the effect of the TGD on the Changjiang flow increase during the dry season diminished quickly downstream of the dam, whereas its impact on the flow decrease during the wet season gradually exacerbated along the mainstream, especially at sites located downstream of the lake outlets. Therefore, when assessing dam-induced hydrological changes, special attention should be paid to the changes in the storage of tributary lakes and the associated effects in the mainstream. This is of high importance for managing the water resource trade-offs between different water bodies in dam-affected riverine systems.  相似文献   

Improved spatial delineation of streambed properties and water fluxes using distributed temperature sensing          下载免费PDF全文

Landon J. S. Halloran  Hamid Roshan  Gabriel C. Rau  Martin S. Andersen  R. Ian Acworth 《水文研究》2016,30(15):2686-2702

A new method was developed for analysing and delineating streambed water fluxes, flow conditions and hydraulic properties using coiled fibre‐optic distributed temperature sensing or closely spaced discrete temperature sensors. This method allows for a thorough treatment of the spatial information embedded in temperature data by creating a matrix visualization of all possible sensor pairs. Application of the method to a 5‐day field dataset reveals the complexity of shallow streambed thermal regimes. To understand how velocity estimates are affected by violations of assumptions of one‐dimensional, saturated, homogeneous flow and to aid in the interpretation of field observations, the method was also applied to temperature data generated by numerical models of common field conditions: horizontal layering, presence of lateral flow and variable streambed saturation. The results show that each condition creates a distinct signature visible in the triangular matrices. The matrices are used to perform a comparison of the behaviour of one‐dimensional analytical heat‐tracing models. The results show that the amplitude ratio‐based method of velocity calculation leads to the most reliable estimates. The minimum sensor spacing required to obtain reliable velocity estimates with discrete sensors is also investigated using field data. The developed method will aid future heat‐tracing studies by providing a technique for visualizing and comparing results from fibre‐optic distributed temperature sensing installations and testing the robustness of analytical heat‐tracing models. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

An analytical solution for deforming twin‐parallel tunnels in an elastic half plane          下载免费PDF全文

Jinyang Fu  Junsheng Yang  Li Yan  Syed Muntazir Abbas 《国际地质力学数值与分析法杂志》2015,39(5):524-538

The interaction between twin‐parallel tunnels affects the tunnelling‐induced ground deformation, which may endanger the nearby structures. In this paper, an analytical solution is presented for problems in determining displacements and stresses around deforming twin‐parallel tunnels in an elastic half plane, on the basis of complex variable theory. As an example, a uniform radial displacement was assumed as the boundary condition for each of the two tunnels. Special attention was paid to the effects of tunnel depth and spacing between the two tunnels on the surface movement to gain deep insight into the effect of the interaction between twin‐parallel tunnels using the proposed analytical approach. It is revealed that the influence of twin tunnel interaction on surface movements diminishes with both the increase of the tunnel depth and the spacing between the two tunnels. The presented analytical solution manifests that, similar to most of the existing numerical results, the principle of superposition can be applied to determine ground deformation of twin‐parallel tunnels with a certain large depth and spacing; otherwise, the interaction effect between the two tunnels should be taken into account for predicting reliable ground movement. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献