Evolution of Quaternary groundwater system in North China Plain

The Quaternary groundwater system in the North China Plain is formed mainly through the terrestrial water flow action on the united geological and tectonic backgrounds. The analysis of groundwater dynamic field, simulation of groundwater geochemistry, and the¹⁴C dating and extraction of isotope information have provided more evidence for recognizing and assessing the evolution of groundwater circulation system and studying the past global changes. The exploitation and utilization of groundwater on a large scale and overexploitation have given rise to the decline of regional groundwater level, change of flow field, decrease of water resources and downward movement of saline water body. The water environment has entered a new evolution stage in which it is intensely disturbed by the mankind’s activities. Project supported by the National Natural Science Foundation of China.     

Factors contributing to nitrate contamination in a groundwater recharge area of the North China Plain

Nitrate contamination is a common problem in groundwater of the North China Plain (NCP) owing to overuse of fertilizers and discharge of wastewater. Accordingly, it is important to investigate nitrate contamination in recharge areas to understand the fate of nitrate in the plains area. In this study, the spatial and temporal distribution characteristics of nitrate and factors contributing to its sources and transformation in shallow groundwater of the Beiyishui River watershed, NCP, were analysed by a combination of multiple regression and multi‐tracer methods. The nitrate concentration of 79% of the samples exceeded the natural environmental standard of 13.3 mg l^?1, while that of 23% of the samples exceeded the World Health Organization (WHO) drinking water standard of 50 mg l^?1. Groundwater age estimation of the hill regions based on chlorofluorocarbons (CFCs) revealed a mix of young water from 1982 to 1990 and old, low CFC water. The analysis based on the variations in land use in past years revealed that part of the grassland was converted into woodland between 1980 and 1995; therefore, the land use at the recharge time was used to determine which surface conditions influence groundwater nitrate concentrations. Multiple regression analysis showed that point source pollution contributed to the high concentration of nitrate in the hill region. Fertilizer application associated with land use change from grassland to woodland was also related to the present nitrate concentration. In the plains area, the contribution of fresh water from fault fractures and denitrification led to 31 to 72% and 6 to 51% reductions in nitrate concentrations, respectively. Our results suggested that controlling point source contamination and fertilizer input to hilly regions of the study will prevent groundwater of the plains area from deterioration in future years by mixing fresh water into the aquifers and decreasing denitrification, and therefore nitrate concentrations. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluating actual evapotranspiration and impacts of groundwater storage change in the North China Plain

As a critical water discharge term in basin‐scale water balance, accurate estimation of evapotranspiration (ET) is therefore important for sustainable water resources management. The understanding of the relationship between ET and groundwater storage change can improve our knowledge on the hydrological cycle in such regions with intensive agricultural land usage. Since the 1960s, the North China Plain (NCP) has experienced groundwater depletion because of overexploitation of groundwater for agriculture and urban development. Using meteorological data from 23 stations, the complementary relationship areal evapotranspiration model is evaluated against estimates of ET derived from regional water balance in the NCP during the period 1993–2008. The discrepancies between calculated ET and that derived by basin water balance indicate seasonal and interannual variations in model parameters. The monthly actual ET variations during the period from 1960 to 2008 are investigated by the calibrated model and then are used to derive groundwater storage change. The estimated actual ET is positively correlated with precipitation, and the general higher ET than precipitation indicates the contributions of groundwater irrigation to the total water supply. The long term decreasing trend in the actual ET can be explained by declining in precipitation, sunshine duration and wind speed. Over the past ~50 years, the calculated average annual water storage change, represented by the difference between actual ET and precipitation, was approximately 36 mm, or 4.8 km³; and the cumulative groundwater storage depletion was approximately 1700 mm, or 220 km³ in the NCP. The significantly groundwater storage depletion conversely affects the seasonal and interannual variations of ET. Irrigation especially during spring cause a marked increase in seasonal ET, whereas the rapid increasing of agricultural coverage over the NCP reduces the annual ET and is the primary control factor of the strong linear relationship between actual and potential ET. Copyright © 2013 John Wiley & Sons, Ltd.     

Signals of short‐term climatic periodicities detected in the groundwater of North China Plain

Growing demand on groundwater resources and the semi‐arid climate in the North China Plain (NCP) highlight the need for improved understanding of connections between regional climate change and groundwater recharge. Hydrologic time series of precipitation and groundwater levels were analyzed in three representative geographical zones throughout the NCP for the period of 1960–2008 using trend analysis and spectral analysis methods. A significant change point around 1975 is followed by a long‐term decline trend in precipitation time series, which coincides with the Pacific Decadal Oscillation positive phase. However, the magnitudes of groundwater level variability due to heavy pumping overwhelm the low‐frequency signal of groundwater levels. Nonlinear trends that related to long‐term climatic variability and anthropogenic activities are removed by using the Singular Spectrum Analysis method. Spectral analyses of the detrended residuals demonstrate significant short‐term oscillations at the frequencies of 2–7 years, which have strong correlations with the El Niño–Southern Oscillation modes. This study contributes to improved understanding of dynamic relationship between groundwater and climate variability modes in the NCP and demonstrates the importance of reliable detrending methods for groundwater levels that are affected greatly by pumping. Copyright © 2015 John Wiley & Sons, Ltd.     

Characteristics of chemistry and stable isotopes in groundwater of Chaobai and Yongding River basin,North China Plain

To identify the groundwater flow system in the North China Plain, the chemical and stable isotopes of the groundwater and surface water were analysed along the Chaobai River and Yongding River basin. According to the field survey, the study area in the North China Plain was classified hydrogeologically into three parts: mountain, piedmont alluvial fan and lowland areas. The change of electrical conductance and pH values coincided with groundwater flow from mountain to lowland areas. The following groundwater types are recognized: Ca? HCO₃ and Ca? Mg? HCO₃ in mountain areas, Ca? Mg? HCO₃ and Na? K? HCO₃ in piedmont alluvial fan areas, and HCO₃? Na in lowland areas. The stable isotope distribution of groundwater in the study area also has a good corresponding relation with other chemical characteristics. Stable isotope signatures reveal a major recharge from precipitation and surface water in the mountain areas. Chemical and stable isotope analysis data suggest that mountain and piedmont alluvial fan areas were the major recharge zones and the lowland areas belong to the main discharge zone. Precipitation and surface water were the major sources for groundwater in the North China Plain. Stable isotopic enrichment of groundwater near the dam area in front of the piedmont alluvial fan areas shows that the dam water infiltrated to the ground after evaporation. As a result, from the stable isotope analysis, isotope value of groundwater tends to deplete from sea level (horizontal ground surface) to both top of the mountain and the bottom of the lowland areas in symmetrically. This suggests that groundwater in the study area is controlled by the altitude effect. Shallow groundwater in the study area belongs to the local flow system and deep groundwater part of the regional flow system. Copyright © 2007 John Wiley & Sons, Ltd.     

Impact of water transfer on interaction between surface water and groundwater in the lowland area of North China Plain

The contradiction between the freshwater shortage and the large demand of freshwater by irrigation was the key point in cultivated lowland area of North China Plain. Water transfer project brings fresh water from water resource‐rich area to water shortage area, which can in turn change the hydrological cycle in this region. Major ions and stable isotopes were used to study the temporal variations of interaction between surface water and groundwater in a hydrological year after a water transfer event in November 2014. Irrigation canal received transferred Yellow River, with 2.9% loss by evaporation during water transfer process. The effect of transferred water on shallow groundwater decreased with increasing distance from the irrigation canal. Pit pond without water transfer receives groundwater discharge. During dry season after water transfer event, shallow groundwater near the irrigation canal was recharged by lateral seepage and deep percolation of irrigation, whereas shallow groundwater far from irrigation canal was recharged by deep percolation of deep groundwater irrigation. Canal water lost by evaporation was 2.7–17.4%. Influence of water transfer gradually disappeared until March as the water usage of agricultural irrigation increased. In the dry season, groundwater discharged to irrigation canal and pond; 2.2–31.6% canal water and 11.3–20.0% pond water were lost by evaporation. In the rainy season (June to September), surface water was fed mainly by precipitation and surface run‐off, whereas groundwater was recharged by infiltration of precipitation. The two‐end member mix model showed that the mixing ratio of precipitation in pond and irrigation canal were 73–83.4% (except one pond with 28.1%) and 77.3–99.9%, respectively. Transferred water and precipitation were the important recharge sources for shallow groundwater, which decreased groundwater salinity in cultivated lowland area of North China Plain. With the temporary and spatial limitation of water transfer effects, increased water transfer amounts and frequency may be an effective way of mitigating regional water shortage. In addition, reducing the evaporation of surface water is also an important way to increase the utilization of transfer water.     

华北地区地下水开采对地壳应力的影响

近50年来华北地区遭受持续大面积过量开采地下水,已形成区域地下水漏斗、地面沉降、地陷地裂等地质灾害.然而,地下水的抽取减小了地壳的载荷,造成地壳应力场变化,这一点至今尚未被充分认识.为探索华北地区地下水超采对地壳应力场的影响,本文建立了二维有限元模型,定量计算地下水超采引起地壳变形和应力场变化.结果表明:华北地区地下水开采会引起地表抬升达+12.4 cm;漏斗区上、中地壳的水平拉应力增量分别达到70 kPa和35 kPa;而在地下水开采区外围,水平压应力增量达20 kPa;而华北地区构造主压应力积累速率约为0.5 kPa·a-1.通过对比华北地区1980年前后5级以上地震的分布状况,本文认为地下水开采对区域构造应力场的扰动不可忽略, 其卸载过程可能对华北地区大地震孕震过程存在减缓作用.     

华北平原地下水开采对区域地震活动性的影响

华北作为中国大陆强震区,同时也是我国人口最多的平原,20世纪60年代以来经历了大规模的地下水开采.本文基于华北平原1959—2016年地下水水位变化,结合区域地质背景建立了有限元孔隙弹性模型,定量分析地下水开采对区域地震活动性的影响.结果显示,地下水开采引起的卸载作用导致区域地壳隆升,最大约35 mm,同时在垂直方向上产生拉伸,地下10 km深度处拉应力最大达92 kPa.根据华北地区历史地震震源参数计算库仑应力变化,结果表明地下水弹性卸载增大了断层面上的正应力,但开采引起的孔隙压力减小使开采区内库仑应力变化为负,而开采区外结果为正.通过分析认为库仑应力变化结果受断层产状、位置等的影响,华北平原地下水开采减小了该地区强震发生的可能性,但随着开采速率放缓及未来可能的水位抬升,会对区域地震活动性产生进一步影响.

     

A study of soil water movement combining soil water potential with stable isotopes at two sites of shallow groundwater areas in the North China Plain

In the shallow groundwater areas of the North China Plain (NCP), precipitation infiltration and evapotranspiration in the vertical direction are the main processes of the water cycle, in which the unsaturated zone plays an important role in the transformation process between precipitation and groundwater. In this paper, two typical sites in Cangzhou (CZ) and Hengshui (HS) of Hebei province with shallow water tables were selected to analyse the relationship among precipitation, soil water and groundwater. At each site, precipitation, soil water at depths 10, 20, 30, 50, 70, 100, 150, 200, 300 cm, and groundwater were sampled to analyse the stable isotope compositions of hydrogen and oxygen. The soil water potentials at the corresponding depths were observed. Although the climates at the two sites are similar, there are some differences in the infiltration process, soil water movement and groundwater recharge sources. Evaporation occurred at the upper depths, which led to the decrease of soil potential and the enrichment of heavy isotopes. At the CZ site, precipitation infiltrated with piston mode, and an obvious mixture effect existed during the infiltration process. Preferential flow may exist in the soil above 100 cm depth. However, at the HS site soil water moved in piston mode, and groundwater was mainly recharged by precipitation. When precipitation recharged the groundwater it experienced a strong evaporation effect. The results of the soil water movement mechanism provides the transformation relationship among precipitation, soil water and groundwater in the middle and eastern NCP. Copyright © 2009 John Wiley & Sons, Ltd.     

Estimation of groundwater use by crop production simulated by DSSAT‐wheat and DSSAT‐maize models in the piedmont region of the North China Plain

Sustainable water use is in serious crisis in the piedmont region of the Taihang Mountains in the North China Plain, owing to rapid groundwater drawdown. Estimating the water requirement for agriculture, the biggest user of groundwater, will be helpful in understanding groundwater decline. Through the use of DSSAT‐3·5 wheat and maize models, we assessed water use in winter wheat and maize, two staple crops in the region, in 1987–2001. Trends between groundwater change and simulated agricultural water use were compared. The results showed that groundwater decline was sensitive to simulated crop water requirement and irrigation requirement. According to regression analysis, 100 mm of water requirement by cultivated land (mainly wheat and maize) resulted in about 0·64 m of groundwater decline. This relationship might be useful in understanding the regional water balance and to help decision‐makers control groundwater decline through controlling crop water use or through long‐distance water transfer. The study demonstrated the usefulness of using the DSSAT model for estimating crop water use and the effectiveness of clarifying the reason for groundwater decline using the simulation results of water use. Copyright © 2006 John Wiley & Sons, Ltd.     

Water, heat fluxes and water use efficiency measurement and modeling above a farmland in the North China Plain

Net radiation (Rn), water vapor flux (LE), sensible heat flux (Hs) and soil heat flux (G)were measured above a summer maize field with the eddy-covariance technique, simulation and analysis of water, heat fluxes and crop water use efficiency were made with the RZ-SHAW model at the same time in this study. The results revealed significant diurnal and seasonal variability of water vapor flux for summer maize. Most part of Rn was consumed by the evapotranspiration of the summer maize. The proportion of water vapor flux to net radiation ((LE/Rn) increased with the crop development and peaked around milk-filling stage with a value of 60%, a slightly lower than that obtained by the RZ-SHAW model. Daily evapotranspiration estimated by the model agreed with the results measured with the eddy-covariance technique, indices of agreement (IA) for hourly water vapor fluxes simulated and measured were above 0.75, root mean square errors (RMSE) were no more than 1.0. Diurnal patterns of Hs showed the shape of inverted "U" shifted to the forenoon with a maximum value around 11:30 (Beijing time), while LE exhibited an inverted "V" with a maximum value at around 13:00, about an hour later than Hs. Diurnal change of CO2showed an asymmetrical "V" curve and its maximal rates occurred at about 11:30. Variations of water use efficiency during the phonological stages of the summer maize showed a rapid increase with the photosynthetic photon flux density (PPFD) after sunrise, a state of equilibrium around 10:00 followed a decrease. Maximum values of water use efficiency were 24.3, and its average value ranged from 7.6 to 10.3 g kg-1.     

Characterising deep vadose zone water movement and solute transport under typical irrigated cropland in the North China Plain

Understanding the dynamics and mechanisms of soil water movement and solute transport is essential for accurately estimating recharge rates and evaluating the impacts of agricultural activities on groundwater resources. In a thick vadose zone (0–15 m) under irrigated cropland in the piedmont region of the North China Plain, soil water content, matric potential, and solute concentrations were measured. Based on these data, the dynamics of soil water and solutes were analysed to investigate the mechanisms of soil water and solute transport. The study showed that the 0–15‐m vadose zone can be divided into three layers: an infiltration and evaporation layer (0–2 m), an unsteady infiltration layer (2–6 m), and a quasi‐steady infiltration layer (6–15 m). The chloride, nitrate, and sulphate concentrations all showed greater variations in the upper soil layer (0–1 m) compared to values in the deep vadose zone (below 2 m). The average concentrations of these three anions in the deep vadose zone varied insignificantly with depth and approached values of 125, 242, and 116 mg/L. The accumulated chloride, sulphate, and nitrate were 2,179 ± 113, 1,760 ± 383, and 4,074 ± 421 kg/ha, respectively. The soil water potential and solute concentrations indicated that uniform flow and preferential flow both occurred in the deep vadose zone, and uniform flow was the dominant mechanism of soil water movement in this study. The piston‐like flow velocity of solute transport was 1.14 m per year, and the average value of calculated leached nitrate nitrogen was 107 kg/ha?year below the root zone. The results can be used to better understand recharge processes and improve groundwater resources management.     

Using multivariate statistical techniques and geochemical modelling to identify factors controlling the evolution of groundwater chemistry in a typical transitional area between Taihang Mountains and North China Plain

Identifying the key factors controlling groundwater chemical evolution in mountain-plain transitional areas is crucial for the security of groundwater resources in both headwater basins and downstream plains. In this study, multivariate statistical techniques and geochemical modelling were used to analyse the groundwater chemical data from a typical headwater basin of the North China Plain. Groundwater samples were divided into three groups, which evolved from Group A with low mineralized Ca-HCO₃ water, through Group B with moderate mineralized Ca-SO₄-HCO₃ water, to Group C with highly saline Ca-SO₄ and Ca-Cl water. Water-rock interaction and nitrate contamination were mainly responsible for the variation in groundwater chemistry. Groundwater chemical compositions in Group A were mainly influenced by dissolution of carbonates and cation exchange, and suffered less nitrate contamination, closely relating to their locations in woodland and grassland with less pronounced human interference. Chemical evolution of groundwater in Groups B and C was gradually predominated by the dissolution of evaporites, reverse ion exchange, and anthropogenic factors. Additionally, the results of the inverse geochemical model showed that dedolomitization caused by gypsum dissolution, played a key role in the geochemical evolution from Group A to Group B. Heavy nitrate enrichment in most groundwater samples of Groups B and C was closely associated with the land-use patterns of farmland and residential areas. Apart from the high loads of chemical fertilizers in irrigation return flow as the main source for nitrate contamination, the stagnant zones, flood irrigation pattern, mine drainage, and groundwater-exploitation reduction program were also important contributors for such high mineralization and heavy NO₃⁻ contents in Group C. The important findings of this work not only provide the conceptual framework for the headwater basin but also have important implications for sustainable management of groundwater resources in other headwater basins of the North China Plain.     

Combination of CFCs and stable isotopes to characterize the mechanism of groundwater–surface water interactions in a headwater basin of the North China Plain

Mountainous areas are characterized by steep slopes and rocky landforms, with hydrological conditions varying rapidly from upstream to downstream, creating variable interactions between groundwater and surface water. In this study, mechanisms of groundwater–surface water interactions within a headwater catchment of the North China Plain were assessed along the stream length and during different seasons, using hydrochemical and stable isotope data, and groundwater residence times estimated using chlorofluorocarbons. These tracers indicate that the river is gaining, due to groundwater discharge in the headwater catchment both in the dry and rainy seasons. Residence time estimation of groundwater using chlorofluorocarbons data reveals that groundwater flow in the shallow sedimentary aquifer is dominated by the binary mixing of water approximating a piston flow model along 2 flow paths: old water, carried by a regional flow system along the direction of river flow, along with young water, which enters the river through local flow systems from hilly areas adjacent to the river valley (particularly during the rainy season). The larger mixing ratio of young water from lateral groundwater recharge and return flow of irrigation during the rainy season result in higher ion concentrations in groundwater than in the dry season. The binary mixing model showed that the ratio of young water versus total groundwater ranged from 0.88 to 0.22 and 1.0 to 0.74 in the upper and lower reaches, respectively. In the middle reach, meandering stream morphology allows some loss of river water back into the aquifer, leading to increasing estimates of the ratio of young water (from 0.22 to 1). This is also explained by declining groundwater levels near the river, due to groundwater extraction for agricultural irrigation. The switch from a greater predominance of regional flow in the dry season, to more localized groundwater flow paths in the wet season is an important groundwater–surface water interactions mechanism, with important catchment management implications.     

A soil‐water‐balance approach to quantify groundwater recharge from irrigated cropland in the North China Plain

Rapidly depleting unconfined aquifers are the primary source of water for irrigation on the North China Plain. Yet, despite its critical importance, groundwater recharge to the Plain remains an enigma. We introduce a one‐dimensional soil‐water‐balance model to estimate precipitation‐ and irrigation‐generated areal recharge from commonly available crop and soil characteristics and climate data. To limit input data needs and to simplify calculations, the model assumes that water flows vertically downward under a unit gradient; infiltration and evapotranspiration are separate, sequential processes; evapotranspiration is allocated to evaporation and transpiration as a function of leaf‐area index and is limited by soil‐moisture content; and evaporation and transpiration are distributed through the soil profile as exponential functions of soil and root depth, respectively. For calibration, model‐calculated water contents of 11 soil‐depth intervals from 0 to 200 cm were compared with measured water contents of loam soil at four sites in Luancheng County, Hebei Province, over 3 years (1998–2001). Each 50‐m² site was identically cropped with winter wheat and summer maize, but received a different irrigation treatment. Average root mean‐squared error between measured and model‐calculated water content of the top 180 cm was 4·2 cm, or 9·3% of average total water content. In addition, model‐calculated evapotranspiration compared well with that measured by a large‐scale lysimeter. To test the model, 12 additional sites were simulated successfully. Model results demonstrate that drainage from the soil profile is not a constant fraction of precipitation and irrigation inputs, but rather the fraction increases as the inputs increase. Because this drainage recharges the underlying aquifer, improving irrigation efficiency by reducing seepage will not reverse water‐table declines. Copyright © 2003 John Wiley & Sons, Ltd.     

基于GRACE的空间约束方法监测华北平原地下水储量变化

华北平原作为我国重要的工农业基地和政治经济中心,面临着严重的水资源危机.因此,开展对华北平原地下水储量变化的监测工作具有重要现实意义与科学价值.本文基于GRACE重力卫星的空间约束方法,研究了华北平原地下水储量变化的时空分布规律,并与地面水井实测与地下水模型结果进行了综合比较和分析.结果表明：2002—2014年,华北平原地下水存在明显的长期亏损,GRACE估计的亏损速率为-7.4±0.9 km³·a^-1,而地面水井资料估计的浅层地下水亏损速率为-1.2 km³·a^-1.对比两者之间的差异可以发现,华北平原的地下水亏损以深层地下水为主.2002—2008年,GRACE估计的华北平原地下水亏损速率为-5.3±2.2 km³·a^-1,这与华北平原两个地下水模型得到的平均亏损速率-5.4 km³·a^-1十分吻合.通过华北平原区域地下水模型的独立验证,说明GRACE可以有效评估华北平原的地下水储量变化趋势.除了长期亏损的趋势项之外,华北平原地下水还存在明显的年际变化特征,并与该地区年降雨量变化特征一致.在降雨偏少的2002年、2005—2009年和2014年,华北平原地下水储量显著减少.在空间分布上,GRACE结果表明,华北平原的地下水储量减少主要发生在山前平原和中部平原区,这也与水井实测资料和区域地下水模型结果较为吻合.与GRACE和区域地下水模型相比,目前的全球水文模型仍无法准确估计华北平原地下水变化的空间分布和亏损速率.上述研究表明,GRACE提供了评估华北平原地下水储量变化的重要监测手段.

     

Numerical studies on the influences of the South‐to‐North Water Transfer Project on groundwater level changes in the Beijing Plain,China

Groundwater is an important component of the water supply, and overexploitation has triggered many problems in the Beijing Plain. The South‐to‐North Water Transfer Project has been proposed as a promising solution to alleviate these problems. Evaluation of different scenarios of groundwater management after the implementation of the South‐to‐North Water Transfer Project is necessarily required. In this study, a numerical model of groundwater flow was established using FEFLOW software and was well calibrated by parameter optimization and groundwater withdrawal inversion in the Beijing Plain. Sixteen scenarios that considered groundwater exploitation, artificial recharge, and precipitation were designed to simulate the groundwater dynamics after 11 years of the project. The results showed that the groundwater level in the study area would recover to various degrees due to the reductions of groundwater withdrawal and the increments of infiltration; additionally, it was concluded that groundwater was significantly affected by precipitation. Generally, in the designed scenarios, the groundwater‐level increment in the upper streams of the model area was higher than that in the lower streams. The groundwater level would obviously increase from artificial recharge in the immediate and adjacent areas. In addition, modes of reducing exploitation had no significant influence on the change in groundwater level during the 11‐year study period. The developed model offers a reliable and effective way to improve groundwater management.     

Discussion of Some Problems in the Research into the Seismotectonics of Strong Earthquakes on the North China Plain

The tectonic characteristics and research problems of five earthquakes with M≥7.0 on the North China Plain over the last 300 years are addressed in the paper, including the cognition that there were no ground fractures in the 1966 Xingtai earthquake, the question caused by the thrust activity of the seismic fault of the Tangshan Earthquake and the discussion of the seismotectonic environment of the 1830 Cixian earthquake and the 1937 Heze earthquake. The author thinks that the main reason for the problems in research of strong earthquake tectonics in the region is that the status of activity of the main tectonics during the Late Quaternary are unknown. This affects the founding of discrimination criteria for seismotectonics of strong earthquakes on the North China Plain. Discriminating the Holocene active faults from the large number of faults is the most effective method for seismic hazard assessment in the area in future.     

The abnormal mantle and deep tectonic process in the southern region of North China Plain

ＴｈｅａｂｎｏｒｍａｌｍａｎｔｌｅａｎｄｄｅｅｐｔｅｃｔｏｎｉｃｐｒｏｃｅｓｓｉｎｔｈｅｓｏｕｔｈｅｒｎｒｅｇｉｏｎｏｆＮｏｒｔｈＣｈｉｎａＰｌａｉｎＳｈｉ－ＹｕＧＡＯ（高世玉），Ｈｏｎｇ－ＸｉａｎｇＨＵ（胡鸿翔）ａｎｄＳｈａｎＤＩＮＧ（丁山）（Ｉｎ...     

华北地区现今地壳运动动力学初步研究

本文基于GPS、断层形变等观测资料,实现华北地区构造运动有限元数值模拟,研究其现今地壳运动及形变动力学机理.结果表明,鄂尔多斯地块、华南地块、东北亚地块等周边构造块体的相对运动基本决定了华北地区现今表面运动及应力场格局.而另一方面,当考虑区域下部岩石层较快速的“拖动”作用时,表面速度场可以得到更好模拟,并同时形成共轭分布的剪应力梯度带.可见太平洋板块的俯冲作用、印-欧板块的碰撞挤压作用等可能造成岩石层深部、浅部运动差异,从而对研究区现今地壳运动产生深刻影响.此外,地形重力作用、断层分布及区域流变结构非均匀性也对现今地壳运动具有一定影响作用,但处于次要地位.