Taiyuan Basin Research Articles

Regional stress field around the Taigu fault zone in Shanxi Province, China

A comprehensive study on regional stress field around the Taigu fault zone in Shanxi Province, China, was performed in this study. To get a better understanding of the present-day stress status in this area, 31 focal mechanisms of M L ≥3 earthquakes since 1965 were compiled, and the best stress tensor was then inverted based on the database. Additionally, magnetic fabrics along the Taigu fault zone were investigated to get an indication of the regional stress field in the past. Our results show that the present-day stress field around the Taigu fault zone is characterized by astable NW-SE extension with a strike-slip component, consistent with the geological surveys and recent GPS data. Results from magnetic fabrics indicate that the orientations of principal stress axes from magnetic fabrics of sedimentary rocks in Neogene coincide to the orientations of principal stress axes from focal mechanisms. The south segment of the Taigu fault displays more complicated magnetic fabrics and more activity of moderate earthquakes. It is connected with the Mianshan west fault and intersects with NW-SE striking Fenyang fault and the north fault of the Lingshi uplift at the south edge of Taiyuan basin. This may be the area needing more attention in terms of seismic risk along the Taigu fault.

A study on expansions of extensive land use in rural area of China based on the analysis of winter wheat cropping acreage change in Taiyuan Basin

A study on expansions of extensive land use in rural area of China based on the analysis of winter wheat cropping acreage change in Taiyuan Basin

Recent ground deformation of Taiyuan basin (China) investigated with C-, L-, and X-bands SAR images

C-, L- and X-bands Synthetic Aperture Radar (SAR) images acquired from November 2006 to June 2011 were processed with Small BAseline Subset DInSAR (SBAS-DInSAR) technique to investigate spatial and temporal variations in deformation over Taiyuan basin, China. The annual deformation rate, created by integrating C-, L- and X-bands interferograms, revealed severe subsidence regions in the basin, where the average subsidence exceeded 10cm/y and the maximum subsidence reached to 24cm/y. Meanwhile, it was found that shapes of these subsidence areas were characterized as either subsiding bowls or elongated subsiding belts, implying an intimate connection among groundwater exploration, ground subsidence and faults. Additionally, significant differences in displacement were identified near the faults. This phenomenon could be explained that faults acted as barriers to groundwater flow, impeding the horizontal propagation of fluid-pressure changes and therefore creating groundwater level difference across them. Furthermore, the time series of deformation maps presented inconspicuous nonlinear periodic variations, which might be caused by the seasonal groundwater level fluctuations. In view of the poor water resource and presented features of subsidence over the study area, we deduced that excessive pumping of groundwater was the dominant process driving land subsidence. Our results could provide scientific evidence on a sound management of ground water pumping to mitigate potential damages on infrastructures and environments.

Geochemistry of iodine-rich groundwater in the Taiyuan Basin of central Shanxi Province, North China

This paper presents the results of studies on the geochemistry of iodine-rich groundwater in the southwest of the Taiyuan Basin, Shanxi Province, North China. A total of 950 water samples were collected from shallow (≤50m), medium-depth (50–200m) and deep (≥200m) wells in the southwestern Taiyuan Basin. Total and inorganic iodine concentrations, including species of iodide and iodate, were determined using inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography- ICP-MS (HPLC-ICP-MS). The results indicate that there are 76.8%, 70.3% and 85.2% of groundwater samples from the above-mentioned three levels, respectively, that exceed the national drinking water standard for iodine (150μg/L), with the highest iodine concentration of up to 4117μg/L, 27 times higher than the standard, tested in shallow groundwater. The main species of iodine in the groundwater is iodide ion with a small proportion of iodate. Organic iodine was detected in about 60% of the water samples with relatively low content. The main factors causing the high iodine concentrations in groundwater include the unique topography, geomorphologic features and aquifer structures in the study area, resulting in hindered movement of groundwater. Furthermore, salinization of surface soil in the low-lying lands intensifies the elevation of iodine concentrations in shallow groundwater. The enrichment of iodine in groundwater is inextricably linked to the geological environment of marine, lacustrine and fluvial sedimentations. The results of this research could provide scientific bases for optimization of water supply scheme in China's iodine excess areas.

Haze particles over a coal‐burning region in the China Loess Plateau in winter: Three flight missions in December 2010

Heavy haze frequently occurs in winter over a coal‐burning region, the Taiyuan Basin, in the eastern China Loess Plateau, which is the upstream area of the North China Plain. We participated in three research flights to collect aerosol particles and to monitor SO2concentration in hazes from the ground (780 m asl) up to ∼4000 m during 17–18 December, 2010. Meteorological records reveal that the whole haze column (ground to 4000 m) was stable and could be further divided into three sub‐layers depending on the sampling altitude, which are characterized by two shifts of the lapse rate of virtual potential temperature and water vapor mixing ratio: Layer‐1, surface to 1500 m; Layer‐2, 1500 ∼ 3000 m on 17 December, and 1500 ∼ 2500 m on 18 December; Layer‐3, above 3000 m on 17 December and above 2500 m on 18 December. SO2concentration was 16–116 ppb with an average of 58 ppb in the Layer‐1, 2–45 ppb with an average of 10 ppb in the Layer‐2, and 1–10 ppb with an average of 4 ppb in the Layer‐3. The accumulation of SO2in the Layer‐1 was due to the stable meteorological conditions and the strong anthropogenic emissions in addition to the possible valley topography. Analyses of the collected particles using a transmission electron microscope revealed the dominance of organic particles and fly ash in the Layer‐1 and Layer‐2 and sulfate particles in the Layer‐3. The organic aerosols frequently contained certain amounts of Si and Cl. Fly ash particles consisted of O and Si with minor Fe, Mn, Zn, Ti, Pb, As, Co, and Cr. These two types of aerosol particles are typically emitted from coal burning. These results indicate that the haze particles were characterized in principle by aerosols from primary emissions of coal burning, which are different from those over the North China Plain where secondary sulfate particles are the dominant component.

Mechanism Analysis of Tectonic-Type Ground Fissures in Shanxi down-Faulted Basin

Shanxi downed-faulted basin mainly consists of Datong basin, Taiyuan basin, Linfen basin and Yuncheng basin, having thick quaternary stratum. Affected by geological structure, topography, stratum conditions and other factors, ground fissure disasters are well developed. Using the development and evolution of tectonic-type ground fissures in the faulted basin as research objects, from the two aspects of horst-graben structure and basal activity of fault belt, this study explored the causes of quaternary ground fissures in Shanxi down-faulted basin. Studying the distribution characteristics, formation mechanism and the disaster-causing effects has the theoretical significance of a better summary and understanding on ground fissures and other geological disasters, as well as providing theoretical basis for prediction and prevention means of the disasters.

Geochemical provenance and spatial distribution of fluoride in groundwater of Taiyuan basin, China

Hydrogeochemistry data were utilized to understand origin, distribution, and geochemical evolution of the high-fluoride groundwater in Taiyuan basin, China. In the study area, the spatial distribution of the high-fluoride groundwater are strictly controlled by the host rock and geomorphic conditions. Three types of groundwater with the F− concentration of 2 mg/L are located in the areas bordering the limestone zones, in the areas bordering the sandstone of Permian and Carboniferous, and in the depressions of the central parts of the basin, respectively. The high-fluoride groundwater mostly have the high values of TDS, and its values of pH range from 7.2 to 8.8. The most common water types of the high-fluoride groundwater are Na·Ca–HCO3 and Na·Mg–HCO3. The geochemical mode reveals that the dissolution of the fluorine-containing minerals and the evaporation effect of the shallow groundwater control the evolution of high F− concentration in Taiyuan basin.

History, organization and contents of the Yellow River basin groundwater project

The Yellow River is the second largest river of China, and the river basin is the birthplace of Chinese civilization. In the basin, the Hehuang Valley, Yinchuan Plain, Hubao Plain, Ordos Basin, Guanzhong Basin, Taiyuan Basin, etc. are important grain-producing areas as well as energy and chemical industrial bases, showing great potential for economic development. However, the Yellow River basin is situated in arid and semiarid regions of China, where water resources are not sufficient, economic environment is fragile, and droughts and fl oods occur frequently, all of which greatly constrain the sustainable development of social economy of the basin. From 1970s to the end of 1990s, drying up of the Yellow River occurred almost every year. The discharge of many tributaries decreased continuously. Groundwater was over-extracted in many cities. The areas where lowering of groundwater level occurs have expanded year after year, and quality of surface and groundwater has deteriorated. All these have seriously constrained the sustainable development of social economy of the basin area. In accordance wi th the Memorandum of Understanding between China Geological Survey (CGS) and National Institute of Advanced Industrial Science and Technology (AIST), Japan, the two institutions signed an agreement to jointly work on the project of “Collaboration on Modeling and Future Prediction of Balance, Circulation and Utilization of Groundwater” in March 2003. Through research on the balance, circulation and utilization of groundwater in the Yellow River basin, the project aimed to set up a numerical model of groundwater in the basin, to predict the trend of groundwater changes in the coming 10 to 20 years, so as to provide scientific support for the rational development and utilization of groundwater in the basin. During the development of the project in China, concern and support were shown by Ms. Shou Jiahua, former Vice Minister of Land and Resources and Mr. Wang Min, Vice Minister of Land and Resources and Director General of China Geological Survey, Mr. Yin Yueping, Director of the Department of Hydrogeology and Environmental Geology, China Geological Survey, Mr. Wu Xuanmin, Deputy Director of the same department, Mr. Shi Jiansheng, Director of the Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences. Other experts concerned have offered guidance to the framework of the project often, thereby providing important guarantee for the smooth implementation of the project. The target of the project was to carry out in-depth research on the changes of frozen soil in the source area of the Yellow River based on a systematic collection of relevant data, and on the groundwater dynamic features, isotope characteristics, and the circulation and balance of groundwater in the Yellow River basin to establish numerical model of groundwater in the basin, and to make prediction of future groundwater changes in the basin.

A new model (DRARCH) for assessing groundwater vulnerability to arsenic contamination at basin scale: a case study in Taiyuan basin, northern China

A modified DRASTIC model for groundwater vulnerability assessment (abbreviated as DRARCH model by combining the first letters of its six assessment indices) was proposed. It is essentially the specific application of DRASTIC model rather than a new model. Both natural hydrogeological conditions that prevent groundwater from contamination and important intrinsic hydrogeochemical properties of sediments in vadose zone that are related to the retardation of contaminants were considered as vulnerability indices. The DRARCH model consists of six indices: (1) Depth to the water table, (2) net Recharge, (3) Aquifer thickness, (4) Ratio of cumulative thickness of clay layers to total thickness of vadose zone, (5) Contaminant adsorption coefficient of sediment in vadose zone, and (6) Hydraulic conductivity of aquifer. The rating values and the weights of these vulnerability indices were obtained by contaminant transport simulation and factor analysis method respectively. Furthermore, the DRARCH model was applied to evaluate the groundwater vulnerability to arsenic contamination in Taiyuan basin, northern China, where groundwaters with high arsenic concentration occur in some localities. GIS-based mapping of groundwater vulnerability using this model indicates that the distribution of very high and high-vulnerability areas corresponds well to that of high-arsenic groundwaters. The DRARCH model is therefore reliable and useful for guiding groundwater environment management.

Geochemical processes controlling the elevated fluoride concentrations in groundwaters of the Taiyuan Basin, Northern China

High fluoride groundwater with F − concentration up to 6.20 mg/L occurs in Taiyuan basin, northern China. The high fluoride groundwater zones are mainly located in the discharge areas, especially in places where shallow groundwater occurs (the groundwater depth is less than 4 m). Regional hydrogeochemical investigation indicates that processes including hydrolysis of silicate minerals, cation exchange, and evaporation should be responsible for the increase in average contents of major ions in groundwater from the recharge areas to the discharge areas. The concentration of F − in groundwater is positively correlated with that of HCO 3 − and Na +, indicating that groundwater with high HCO 3 − and Na + contents help dissolve some fluoride-rich minerals. The water samples with high F − concentration generally have relatively higher pH value, implying that alkaline environment favors the replacement of exchangeable F − in fluoride-rich minerals by OH − in groundwater. In addition, the mixing of karst water along the western mountain front and the evaporation may also be important factors for the occurrence of high fluoride groundwater. The inverse geochemical modeling using PHREEQC supports the results of hydrogeochemical analyses. The modeling results show that in the recharge and flow-through area of the northern Taiyuan basin, interactions between groundwater and fluoride-rich minerals are the major factor for the increase of F − concentration, whereas in the discharge area of the northern basin, the evaporation as well as the mixing of karst water has greater contribution to the fluoride enrichment in groundwater.

GIS-based regionalization of a karst water system in Xishan Mountain area of Taiyuan Basin, north China

A clear description of the structural features and path of groundwater flow for a karst water system is a basis for establishing a hydrogeologic conceptual model in a basin. In a case study of the karst system of Xishan Mountain of Taiyuan Basin, typical of hydrogeologic systems in north China and elsewhere in the world, we extracted quantitative information of hydrogeologic structure and regionalized the interior structure of the karst water system using a geographic information system (GIS) technique. The information, extracted from lithofacies paleogeography, geology, tectonics and hydrogeology, includes the isolines of the top of the regional aquiclude, the projected section of both planes of a fault, and plotting the regional saturated zone, the passage zone, and the local saturated zone in the karst water system. We analyzed the distribution range of karst water aquifers of Xishan Mountain, the permeability of the stratum, the boundary characteristics and the relationship between the interior and exterior system. It was essential to clarify the interactions among the karst water systems of the mountain area, surface water, pore water in the Caenozoic unconsolidated materials and the deep karst water under the basin. This research shows that the study area can be divided into two subsystems: (1) Lancun spring and Jinci spring, and (2) Xiye spring. Subsystem (1) includes the regional saturated zone, the passage zone and the local saturated zone. We demonstrated that Lancun spring and Jinci spring belong to the same regional karst water system. Subsystem (2) results from the perched groundwater formed by a local impermeable bed. The results show that this type of integrated analysis is a useful method to extract hydrogeologic information and can be applied to a mountain area without much investigated data, in particular where carbonate formations or layered permeable rock are the most important aquifers.

Coseismic versus interseismic ground deformations, fault rupture inversion and segmentation revealed by 2003 Mw 6.8 Chengkung earthquake in eastern Taiwan

The 2003 Chengkung earthquake (Mw 6.8) provided diagnostic evidence for a source model showing the deformation process of the seismogenic Chihshang fault in eastern Taiwan. The aftershocks show a fault‐bend at a depth of 18 km. Coseismic ground displacements recorded by strong‐motion records allow us to deduce instant rupturing of this event. Our resulting model shows a fault length of ∼33 km and dip‐slip dominant rupture on fault‐plane deeper than 18 km. Estimated coseismic displacements constrain two fault planes: one at 5–18 km depth dipping 60°E and 18–36 km depth dipping 45°E. The uppermost fault‐plane of the Chihshang Fault (0–5 km) did not break immediately after the main shock; however, it may have a major role in after‐slip and even interseismic ground deformation. The Taiyuan basin developed in the hanging wall is a geomorphic feature consistent with and adequately explained by coseismic ground displacements.

Structural evolution from Paleogene extension to Latest Miocene-Recent arc-continent collision offshore Taiwan: comparison with on land geology

Marine structures observed in seismic profiles across the NE South China Sea–Taiwan Strait–Luzon Arc region show that they are comparable to those observed onshore Taiwan. The Hanjiang Depression and Dongsha Uplift off the SE China coast extend to the Penghu Basin and Penghu Platform, respectively, in the Taiwan Strait, while the Tainan Basin in the south of Penghu Platform is connected to the Chaoshan Depression south of the Dongsha Uplift. The Hanjiang Depression and the Penghu Basin are composed of Paleogene syn-rift sequences on the Mesozoic basement and are unconformably overlain by Neogene post-rift strata. Similar successions are found underneath the coastal plain or have been thrust up as a fold-and-thrust belt bordering the Peikang Basement High onshore central Taiwan.East of the Manila Trench, off southwestern Taiwan, parts of the Tainan Basin are thrust into the submarine syn-collision accretionary wedge (the fold-and-thrust Kaoping Slope) in the initial arc-continent collision zone. They have also been exposed in the fold-and-thrust Western Foothills south of the Peikang Basement High in southern Taiwan during an advanced stage of arc-continent collision since the Late Pliocene. Further east, the pre-collision accretionary wedge (the Hengchun Ridge) shoals northward to the Hengchun Peninsula, with Late Miocene turbidites unconformably overlain by Plio–Pleistocene shallow-marine slope basin sequences. In the arc domain, east of the arc-prism boundary fault, the western forearc sequences in the North Luzon Trough are deformed. Two normal-faulted intra-arc basins occur on the eastern part of the Lanhsu Island in the Luzon Arc. The scenario of the deformed forearc sequences and the development of the two intra-arc basins in the initial arc-continent collision zone are analogous to the Lichi Mélange–Taiyuan Basin and the intra-arc basins in the southern Coastal Range, eastern Taiwan.Additionally, the lateral change in the marine structure from the passive Asian continental margin to the Manila subduction system is comparable to the temporal evolution from Paleogene normal faulting, through Neogene subduction, to Latest Miocene-Recent arc-continent collision observed onshore Taiwan.

Infiltration into Freezing and Thawing Soils under Differing Field Treatments

Infiltration characteristics of seasonally frozen soil influence agricultural management and hydrology in many areas. In northern and northwestern China, winter and spring irrigation is conducted during periods with frozen soil when water is available. The shortage of water resources is one of the major factors restricting the further development of cropland and pasture land in this region. Therefore, heightening irrigation efficiency and determining irrigation paramaters has become a high priority for agricultural management. A series of field experiments was conducted from November through March in the middle of Taiyuan Basin, Shanxi Province, China, to develop predictive equations of frozen soil infiltration for differing field treatments and varying water contents. Infiltration measurements were made on three field treatments: green bean standing stubble, winter wheat, and deep ploughing. Cumulative infiltration was greatest on the deep ploughing treatment, which had the lowest soil bulk density as compared with other treatments. A strong inverse power function (R² > 0.90) was demonstrated between water infiltration and water content during the freezing period, and the coefficients for this power function were related to frost depth. The resulting estimates of cumulative infiltration resulted in a coefficient of determination of 0.905. Double frozen layers due to surface diurnal freeze/thaw cycles during soil thawing provided an impediment to infiltration. This study provides a practical basis for determining infiltration parameters for irrigation and water resource management.

Detection of early pregnancy factor-like activity in human amniotic fluid

The Taiyuan basin is in the Shanxi rift system of China. Results of tectonic studies indicate that the Moho is uplifted by 2–3 km under the Taiyuan basin. However, there is no quantitative evidence showing whether the rift is still in the status of mantle upwelling. Herein, we estimated mantle upwelling rate of Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data in this paper. In order to utilize the absolute gravity measurements in terms of tectonic study it is necessary to reduce all disturbing environmental effects. Many of those can be modeled, such as tide, polar motion, ocean tidal loading and atmospheric mass components. The Taiyuan station located in the Taiyuan basin, and absolute gravity measurements with a FG5 instrument were performed from 2009 to 2014, a secular trend was obtained. In-situ GPS data was used to estimate the vertical motion rate since 2011, and the result indicated a land subsidence. In-situ groundwater level was collected with daily surveys from 2009 to 2015, and local hydrology impact on effect was made. The global terrestrial water storage loading effect on gravity at Taiyuan station was computed by using GLDAS global hydrology model. Furthermore there is a good agreement between GRACE results and GLDAS hydrological model results. Subtracting the gravity change rate attributable to the land subsidence, groundwater level and global hydrology from the absolute gravity change rate, the residual gravity change rate was obtained. It reflects mantle upwelling about 2.1 ± 2.6 cm/yr beneath Taiyuan basin.